From 4dc7a814a6e75ace4e3d0fb7485d8cbd4a963094 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Sat, 23 Nov 2024 23:54:32 -0800
Subject: [PATCH 01/34] use extensions to fetch platform devices for EGL

---
 include/polyscope/options.h         |  5 ++
 src/options.cpp                     |  2 +
 src/render/opengl/gl_engine_egl.cpp | 75 +++++++++++++++++++++++++----
 3 files changed, 73 insertions(+), 9 deletions(-)

diff --git a/include/polyscope/options.h b/include/polyscope/options.h
index a439ddda..6ffcae0f 100644
--- a/include/polyscope/options.h
+++ b/include/polyscope/options.h
@@ -119,6 +119,11 @@ extern std::function<void()> configureImGuiStyleCallback;
 // assign your own function to create custom styles. If this callback is null, default fonts will be used.
 extern std::function<std::tuple<ImFontAtlas*, ImFont*, ImFont*>()> prepareImGuiFontsCallback;
 
+// === Backend and low-level options
+
+// When using the EGL backend, which device to try to initialize with
+// (default is -1 which means try all of them)
+extern int eglDeviceIndex;
 
 // === Debug options
 
diff --git a/src/options.cpp b/src/options.cpp
index 5bcaca32..703ff5da 100644
--- a/src/options.cpp
+++ b/src/options.cpp
@@ -55,6 +55,8 @@ bool openImGuiWindowForUserCallback = true;
 std::function<void()> configureImGuiStyleCallback = configureImGuiStyle;
 std::function<std::tuple<ImFontAtlas*, ImFont*, ImFont*>()> prepareImGuiFontsCallback = prepareImGuiFonts;
 
+// Backend and low-level options
+int eglDeviceIndex = -1; // means "try all of them"
 
 // enabled by default in debug mode
 #ifndef NDEBUG
diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 81a0c3cf..280c7590 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -14,12 +14,25 @@
 #include <algorithm>
 #include <set>
 
+#include <EGL/egl.h>
+#include <EGL/eglext.h>
+
 namespace polyscope {
 namespace render {
 namespace backend_openGL3 {
 
 namespace { // anonymous helpers
 
+// Helper function to get an EGL (extension?) function and error-check that
+// we got it successfully
+void* getEGLProcAddressAndCheck(std::string name) {
+  void* procAddr = (void*)(eglGetProcAddress(name.c_str()));
+  if (!procAddr) {
+    error("EGL failed to get function pointer for " + name);
+  }
+  return procAddr;
+}
+
 void checkEGLError(bool fatal = true) {
 
   if (!options::enableRenderErrorChecks) {
@@ -129,22 +142,66 @@ void GLEngineEGL::initialize() {
 
   // === Initialize EGL
 
-  // Get the default display
-  eglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
-  if (eglDisplay == EGL_NO_DISPLAY) {
-    exception("ERROR: Failed to initialize EGL, could not get default display");
+  // Pre-load required extension functions
+  PFNEGLQUERYDEVICESEXTPROC eglQueryDevicesEXT =
+      (PFNEGLQUERYDEVICESEXTPROC)getEGLProcAddressAndCheck("eglQueryDevicesEXT");
+
+  // Query the available EGL devices
+  const int N_MAX_DEVICE = 256;
+  EGLDeviceEXT devices[N_MAX_DEVICE];
+  EGLint nDevices;
+  if (!eglQueryDevicesEXT(N_MAX_DEVICE, devices, &nDevices)) {
+    error("EGL: failed to query devices.");
+  }
+  if (nDevices == 0) {
+    error("EGL: no devices found.");
+  }
+  info("EGL: Found " + std::to_string(nDevices) + " EGL devices.");
+
+  if (options::eglDeviceIndex == -1) {
+    info("EGL: no device index specified, attempting to intialize with each device sequentially until success.")
+  } else {
+    info("EGL: device index " + std::to_string(options::eglDeviceIndex) + " manually selected, using that device.");
+
+    if (options::eglDeviceIndex >= nDevices) {
+      error("EGL: device index " + std::to_string(options::eglDeviceIndex) + " manually selected, but only " +
+            std::to_string(nDevices) + " devices available.");
+    }
   }
 
-  // Configure
+  bool successfulInit = false;
   EGLint majorVer, minorVer;
-  bool success = eglInitialize(eglDisplay, &majorVer, &minorVer);
-  if (!success) {
-    checkEGLError(false);
+  for (int32_t iDevice = 0; iDevice < nDevices; iDevice++) {
+
+    if (options::eglDeviceIndex != -1 && iDevice != options::eglDeviceIndex) {
+      // implement manualy selection by skipping the others
+      continue;
+    }
+
+    info("EGL: attempting initialization with device " + std::to_string(iDevice));
+
+    // Select the first device (custom logic can go here to pick a specific one)
+    EGLDeviceEXT device = devices[iDevice];
+
+    // Get an EGLDisplay for the device
+    // (use the -platform / EXT version because it is the only one that seems to work in headless environments)
+    eglDisplay = eglGetPlatformDisplay(EGL_PLATFORM_DEVICE_EXT, device, NULL);
+    if (eglDisplay == EGL_NO_DISPLAY) {
+      continue;
+    }
+
+    // Configure
+    successfulInit = eglInitialize(eglDisplay, &majorVer, &minorVer);
+    if (successfulInit) {
+      break;
+    }
+  }
+
+  if (!successfulInit) {
     exception("ERROR: Failed to initialize EGL");
   }
   checkEGLError();
 
-
   // this has something to do with the EGL configuration, I don't understand exactly what
   // clang-format off
   const EGLint configAttribs[] = {

From 05881c57b7fab6505c4162df42f1f5ae353d774e Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Sun, 24 Nov 2024 00:00:36 -0800
Subject: [PATCH 02/34] fix typo

---
 src/render/opengl/gl_engine_egl.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 280c7590..5a35529c 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -159,7 +159,7 @@ void GLEngineEGL::initialize() {
   info("EGL: Found " + std::to_string(nDevices) + " EGL devices.");
 
   if (options::eglDeviceIndex == -1) {
-    info("EGL: no device index specified, attempting to intialize with each device sequentially until success.")
+    info("EGL: no device index specified, attempting to intialize with each device sequentially until success.");
   } else {
     info("EGL: device index " + std::to_string(options::eglDeviceIndex) + " manually selected, using that device.");
 

From 94f8c6b781b016ba1cc1c9cd9853f1f2150f43d1 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Thu, 28 Nov 2024 21:50:02 -0800
Subject: [PATCH 03/34] small fixes, formatter

---
 src/render/opengl/gl_engine_egl.cpp | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 5a35529c..ce79d1d9 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -151,20 +151,20 @@ void GLEngineEGL::initialize() {
   EGLDeviceEXT devices[N_MAX_DEVICE];
   EGLint nDevices;
   if (!eglQueryDevicesEXT(N_MAX_DEVICE, devices, &nDevices)) {
-    error("EGL: failed to query devices.");
+    error("EGL: Failed to query devices.");
   }
   if (nDevices == 0) {
-    error("EGL: no devices found.");
+    error("EGL: No devices found.");
   }
   info("EGL: Found " + std::to_string(nDevices) + " EGL devices.");
 
   if (options::eglDeviceIndex == -1) {
-    info("EGL: no device index specified, attempting to intialize with each device sequentially until success.");
+    info("EGL: No device index specified, attempting to intialize with each device sequentially until success.");
   } else {
-    info("EGL: device index " + std::to_string(options::eglDeviceIndex) + " manually selected, using that device.");
+    info("EGL: Device index " + std::to_string(options::eglDeviceIndex) + " manually selected, using that device.");
 
     if (options::eglDeviceIndex >= nDevices) {
-      error("EGL: device index " + std::to_string(options::eglDeviceIndex) + " manually selected, but only " +
+      error("EGL: Device index " + std::to_string(options::eglDeviceIndex) + " manually selected, but only " +
             std::to_string(nDevices) + " devices available.");
     }
   }
@@ -178,11 +178,11 @@ void GLEngineEGL::initialize() {
       continue;
     }
 
-    info("EGL: attempting initialization with device " + std::to_string(iDevice));
-
-    // Select the first device (custom logic can go here to pick a specific one)
+    info("EGL: Attempting initialization with device " + std::to_string(iDevice));
     EGLDeviceEXT device = devices[iDevice];
 
+    // TODO use eglQueryDeviceStringEXT to prefer hardware-accelerated devices
+
     // Get an EGLDisplay for the device
     // (use the -platform / EXT version because it is the only one that seems to work in headless environments)
     eglDisplay = eglGetPlatformDisplay(EGL_PLATFORM_DEVICE_EXT, device, NULL);
@@ -201,6 +201,7 @@ void GLEngineEGL::initialize() {
     exception("ERROR: Failed to initialize EGL");
   }
   checkEGLError();
+  info("EGL: Initialization successful");
 
   // this has something to do with the EGL configuration, I don't understand exactly what
   // clang-format off

From 30c8ce35e7d867e47d61c829263767f0f071edc6 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Thu, 28 Nov 2024 23:17:15 -0800
Subject: [PATCH 04/34] device preference sorting

---
 .../polyscope/render/opengl/gl_engine_egl.h   |  3 +
 src/render/opengl/gl_engine_egl.cpp           | 62 ++++++++++++++++---
 2 files changed, 57 insertions(+), 8 deletions(-)

diff --git a/include/polyscope/render/opengl/gl_engine_egl.h b/include/polyscope/render/opengl/gl_engine_egl.h
index a57f8863..1f996ef7 100644
--- a/include/polyscope/render/opengl/gl_engine_egl.h
+++ b/include/polyscope/render/opengl/gl_engine_egl.h
@@ -74,6 +74,9 @@ class GLEngineEGL : public GLEngine {
   // Internal windowing and engine details
   EGLDisplay eglDisplay;
   EGLContext eglContext;
+
+  // helpers
+  void sortAvailableDevicesByPreference(std::vector<int32_t>& devices);
 };
 
 } // namespace backend_openGL3
diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index ce79d1d9..db124afa 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -158,8 +158,15 @@ void GLEngineEGL::initialize() {
   }
   info("EGL: Found " + std::to_string(nDevices) + " EGL devices.");
 
+  // Build an ordered list of which devices to try initializing with
+  std::vector<int32_t> devicesToTry;
   if (options::eglDeviceIndex == -1) {
     info("EGL: No device index specified, attempting to intialize with each device sequentially until success.");
+
+    devicesToTry.resize(nDevices);
+    std::iota(devicesToTry.begin(), devicesToTry.end(), 0);
+    sortDevicesByPreference(devicesToTry);
+
   } else {
     info("EGL: Device index " + std::to_string(options::eglDeviceIndex) + " manually selected, using that device.");
 
@@ -167,22 +174,17 @@ void GLEngineEGL::initialize() {
       error("EGL: Device index " + std::to_string(options::eglDeviceIndex) + " manually selected, but only " +
             std::to_string(nDevices) + " devices available.");
     }
+
+    devicesToTry.push_back(options::eglDeviceIndex);
   }
 
   bool successfulInit = false;
   EGLint majorVer, minorVer;
-  for (int32_t iDevice = 0; iDevice < nDevices; iDevice++) {
-
-    if (options::eglDeviceIndex != -1 && iDevice != options::eglDeviceIndex) {
-      // implement manualy selection by skipping the others
-      continue;
-    }
+  for (int32_t iDevice : eglDeviceIndex) {
 
     info("EGL: Attempting initialization with device " + std::to_string(iDevice));
     EGLDeviceEXT device = devices[iDevice];
 
-    // TODO use eglQueryDeviceStringEXT to prefer hardware-accelerated devices
-
     // Get an EGLDisplay for the device
     // (use the -platform / EXT version because it is the only one that seems to work in headless environments)
     eglDisplay = eglGetPlatformDisplay(EGL_PLATFORM_DEVICE_EXT, device, NULL);
@@ -280,6 +282,50 @@ void GLEngineEGL::initialize() {
   checkError();
 }
 
+void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& devices) {
+
+  // Pre-load required extension functions
+  PFNEGLQUERYDEVICESTRINGEXTPROC eglQueryDeviceStringEXT =
+      (PFNEGLQUERYDEVICESTRINGEXTPROC)getEGLProcAddressAndCheck("eglQueryDeviceStringEXT");
+
+  // Build a list of devices and assign a score to each
+  std::vector<std::tuple<int32_t, int32_t>> scoreDevices;
+  for (int32_t iDevice : devices) {
+    int score = 0;
+
+    std::string vendorStr = eglQueryDeviceStringEXT(devices[i], EGL_VENDOR);
+
+    // lower-case it for the steps below
+    std::transform(vendorStr.begin(), vendorStr.end(), vendorStr.begin(), std::tolower);
+
+    // Problem: we want to detect and prefer discrete graphics cars over integrated GPUs and
+    // software / VM renderers. However, I can't figure out how to get an "is integrated"
+    // property from the query device strings above. Even worse, 'AMD" and "Intel" are both
+    // ambiguous and could refer to the integrated GPU or a discrete GPU.
+    //
+    // As a workaround, we assign scores based on the vendor: nvidia is always discrete, amd could be either, intel is
+    // usually integrated, but still preferred over software renderers
+    //
+    // ONEDAY: figure out a better policy to detect discrete devices....
+
+    // assign scores based on vendors to prefer discrete gpus
+    if (vendorStr.find("intel") != std::string::npos) score += 1;
+    if (vendorStr.find("amd") != std::string::npos) score += 2;
+    if (vendorStr.find("nvidia") != std::string::npos) score += 3;
+
+    scoreDevices.emplace_back(score, iDevice);
+  }
+
+  // sort them by highest score
+  std::sort(scoreDevices.begin(), scoreDevices.end());
+  std::reverse(scoreDevices.begin(), scoreDevices.end());
+
+  // store them back in the given array
+  for (size_t i = 0; i < devices.size(); i++) {
+    devices[i] = std::get<1>(scoreDevices[i]);
+  }
+}
+
 
 void GLEngineEGL::initializeImGui() {
 

From d016854cfa74103b76a8f30f189f00a7d20d727e Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Thu, 28 Nov 2024 23:39:20 -0800
Subject: [PATCH 05/34] few more fixes

---
 src/render/opengl/gl_engine_egl.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index db124afa..b2488fe3 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -12,7 +12,9 @@
 #include "stb_image.h"
 
 #include <algorithm>
+#include <cctype>
 #include <set>
+#include <string>
 
 #include <EGL/egl.h>
 #include <EGL/eglext.h>
@@ -165,7 +167,7 @@ void GLEngineEGL::initialize() {
 
     devicesToTry.resize(nDevices);
     std::iota(devicesToTry.begin(), devicesToTry.end(), 0);
-    sortDevicesByPreference(devicesToTry);
+    sortAvailableDevicesByPreference(devicesToTry);
 
   } else {
     info("EGL: Device index " + std::to_string(options::eglDeviceIndex) + " manually selected, using that device.");
@@ -180,7 +182,7 @@ void GLEngineEGL::initialize() {
 
   bool successfulInit = false;
   EGLint majorVer, minorVer;
-  for (int32_t iDevice : eglDeviceIndex) {
+  for (int32_t iDevice : devicesToTry) {
 
     info("EGL: Attempting initialization with device " + std::to_string(iDevice));
     EGLDeviceEXT device = devices[iDevice];
@@ -293,7 +295,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& devices
   for (int32_t iDevice : devices) {
     int score = 0;
 
-    std::string vendorStr = eglQueryDeviceStringEXT(devices[i], EGL_VENDOR);
+    std::string vendorStr = eglQueryDeviceStringEXT(devices[iDevice], EGL_VENDOR);
 
     // lower-case it for the steps below
     std::transform(vendorStr.begin(), vendorStr.end(), vendorStr.begin(), std::tolower);

From 8ba375ef0c51d77a0c557990991747e5b67cb542 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Thu, 28 Nov 2024 23:44:42 -0800
Subject: [PATCH 06/34] use vector of device

---
 include/polyscope/render/opengl/gl_engine_egl.h |  2 +-
 src/render/opengl/gl_engine_egl.cpp             | 15 ++++++++-------
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/include/polyscope/render/opengl/gl_engine_egl.h b/include/polyscope/render/opengl/gl_engine_egl.h
index 1f996ef7..70e8bfe4 100644
--- a/include/polyscope/render/opengl/gl_engine_egl.h
+++ b/include/polyscope/render/opengl/gl_engine_egl.h
@@ -76,7 +76,7 @@ class GLEngineEGL : public GLEngine {
   EGLContext eglContext;
 
   // helpers
-  void sortAvailableDevicesByPreference(std::vector<int32_t>& devices);
+  void sortAvailableDevicesByPreference(std::vector<EGLDevice>& devices);
 };
 
 } // namespace backend_openGL3
diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index b2488fe3..60e1077d 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -284,21 +284,22 @@ void GLEngineEGL::initialize() {
   checkError();
 }
 
-void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& devices) {
+void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<EGLDevice>& devices) {
 
   // Pre-load required extension functions
   PFNEGLQUERYDEVICESTRINGEXTPROC eglQueryDeviceStringEXT =
       (PFNEGLQUERYDEVICESTRINGEXTPROC)getEGLProcAddressAndCheck("eglQueryDeviceStringEXT");
 
   // Build a list of devices and assign a score to each
-  std::vector<std::tuple<int32_t, int32_t>> scoreDevices;
-  for (int32_t iDevice : devices) {
+  std::vector<std::tuple<int32_t, EGLDevice>> scoreDevices;
+  for (EGLDevice device : devices) {
     int score = 0;
 
-    std::string vendorStr = eglQueryDeviceStringEXT(devices[iDevice], EGL_VENDOR);
+    std::string vendorStr = eglQueryDeviceStringEXT(device, EGL_VENDOR);
 
-    // lower-case it for the steps below
-    std::transform(vendorStr.begin(), vendorStr.end(), vendorStr.begin(), std::tolower);
+    // lower-case it for the checks below
+    std::transform(vendorStr.begin(), vendorStr.end(), vendorStr.begin(),
+                   [](unsigned char c) { return std::tolower(c); });
 
     // Problem: we want to detect and prefer discrete graphics cars over integrated GPUs and
     // software / VM renderers. However, I can't figure out how to get an "is integrated"
@@ -315,7 +316,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& devices
     if (vendorStr.find("amd") != std::string::npos) score += 2;
     if (vendorStr.find("nvidia") != std::string::npos) score += 3;
 
-    scoreDevices.emplace_back(score, iDevice);
+    scoreDevices.emplace_back(score, device);
   }
 
   // sort them by highest score

From c2b08abe0e44cf084156119fbb0883b1a826d707 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Thu, 28 Nov 2024 23:46:36 -0800
Subject: [PATCH 07/34] use EGLDeviceEXT

---
 include/polyscope/render/opengl/gl_engine_egl.h | 3 ++-
 src/render/opengl/gl_engine_egl.cpp             | 6 +++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/polyscope/render/opengl/gl_engine_egl.h b/include/polyscope/render/opengl/gl_engine_egl.h
index 70e8bfe4..aa8999c4 100644
--- a/include/polyscope/render/opengl/gl_engine_egl.h
+++ b/include/polyscope/render/opengl/gl_engine_egl.h
@@ -12,6 +12,7 @@
 #include "glad/glad.h"
 // glad must come first
 #include <EGL/egl.h>
+#include <EGL/eglext.h>
 #endif
 
 
@@ -76,7 +77,7 @@ class GLEngineEGL : public GLEngine {
   EGLContext eglContext;
 
   // helpers
-  void sortAvailableDevicesByPreference(std::vector<EGLDevice>& devices);
+  void sortAvailableDevicesByPreference(std::vector<EGLDeviceEXT>& devices);
 };
 
 } // namespace backend_openGL3
diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 60e1077d..1f4f94d8 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -284,15 +284,15 @@ void GLEngineEGL::initialize() {
   checkError();
 }
 
-void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<EGLDevice>& devices) {
+void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<EGLDeviceEXT>& devices) {
 
   // Pre-load required extension functions
   PFNEGLQUERYDEVICESTRINGEXTPROC eglQueryDeviceStringEXT =
       (PFNEGLQUERYDEVICESTRINGEXTPROC)getEGLProcAddressAndCheck("eglQueryDeviceStringEXT");
 
   // Build a list of devices and assign a score to each
-  std::vector<std::tuple<int32_t, EGLDevice>> scoreDevices;
-  for (EGLDevice device : devices) {
+  std::vector<std::tuple<int32_t, EGLDeviceEXT>> scoreDevices;
+  for (EGLDeviceEXT device : devices) {
     int score = 0;
 
     std::string vendorStr = eglQueryDeviceStringEXT(device, EGL_VENDOR);

From b6c23a217b62f8fe58b320945e335c201fc4940f Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Thu, 28 Nov 2024 23:52:17 -0800
Subject: [PATCH 08/34] use list of ints

---
 .../polyscope/render/opengl/gl_engine_egl.h   |  2 +-
 src/render/opengl/gl_engine_egl.cpp           | 29 ++++++++++---------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/include/polyscope/render/opengl/gl_engine_egl.h b/include/polyscope/render/opengl/gl_engine_egl.h
index aa8999c4..31d23ce1 100644
--- a/include/polyscope/render/opengl/gl_engine_egl.h
+++ b/include/polyscope/render/opengl/gl_engine_egl.h
@@ -77,7 +77,7 @@ class GLEngineEGL : public GLEngine {
   EGLContext eglContext;
 
   // helpers
-  void sortAvailableDevicesByPreference(std::vector<EGLDeviceEXT>& devices);
+  void sortAvailableDevicesByPreference(std::vector<int32_t>& deviceInds, EGLDeviceEXT rawDevices[]);
 };
 
 } // namespace backend_openGL3
diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 1f4f94d8..5912d985 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -150,9 +150,9 @@ void GLEngineEGL::initialize() {
 
   // Query the available EGL devices
   const int N_MAX_DEVICE = 256;
-  EGLDeviceEXT devices[N_MAX_DEVICE];
+  EGLDeviceEXT rawDevices[N_MAX_DEVICE];
   EGLint nDevices;
-  if (!eglQueryDevicesEXT(N_MAX_DEVICE, devices, &nDevices)) {
+  if (!eglQueryDevicesEXT(N_MAX_DEVICE, rawDevices, &nDevices)) {
     error("EGL: Failed to query devices.");
   }
   if (nDevices == 0) {
@@ -161,13 +161,13 @@ void GLEngineEGL::initialize() {
   info("EGL: Found " + std::to_string(nDevices) + " EGL devices.");
 
   // Build an ordered list of which devices to try initializing with
-  std::vector<int32_t> devicesToTry;
+  std::vector<int32_t> deviceIndsToTry;
   if (options::eglDeviceIndex == -1) {
     info("EGL: No device index specified, attempting to intialize with each device sequentially until success.");
 
-    devicesToTry.resize(nDevices);
-    std::iota(devicesToTry.begin(), devicesToTry.end(), 0);
-    sortAvailableDevicesByPreference(devicesToTry);
+    deviceIndsToTry.resize(nDevices);
+    std::iota(deviceIndsToTry.begin(), deviceIndsToTry.end(), 0);
+    sortAvailableDevicesByPreference(deviceIndsToTry);
 
   } else {
     info("EGL: Device index " + std::to_string(options::eglDeviceIndex) + " manually selected, using that device.");
@@ -177,15 +177,15 @@ void GLEngineEGL::initialize() {
             std::to_string(nDevices) + " devices available.");
     }
 
-    devicesToTry.push_back(options::eglDeviceIndex);
+    deviceIndsToTry.push_back(options::eglDeviceIndex);
   }
 
   bool successfulInit = false;
   EGLint majorVer, minorVer;
-  for (int32_t iDevice : devicesToTry) {
+  for (int32_t iDevice : deviceIndsToTry) {
 
     info("EGL: Attempting initialization with device " + std::to_string(iDevice));
-    EGLDeviceEXT device = devices[iDevice];
+    EGLDeviceEXT device = rawDevices[iDevice];
 
     // Get an EGLDisplay for the device
     // (use the -platform / EXT version because it is the only one that seems to work in headless environments)
@@ -284,15 +284,16 @@ void GLEngineEGL::initialize() {
   checkError();
 }
 
-void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<EGLDeviceEXT>& devices) {
+void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceInds, EGLDeviceEXT rawDevices[]) {
 
   // Pre-load required extension functions
   PFNEGLQUERYDEVICESTRINGEXTPROC eglQueryDeviceStringEXT =
       (PFNEGLQUERYDEVICESTRINGEXTPROC)getEGLProcAddressAndCheck("eglQueryDeviceStringEXT");
 
   // Build a list of devices and assign a score to each
-  std::vector<std::tuple<int32_t, EGLDeviceEXT>> scoreDevices;
-  for (EGLDeviceEXT device : devices) {
+  std::vector<std::tuple<int32_t, int32_t>> scoreDevices;
+  for (int32_t iDevice : deviceInds) {
+    EGLDeviceEXT device = rawDevices[iDevice];
     int score = 0;
 
     std::string vendorStr = eglQueryDeviceStringEXT(device, EGL_VENDOR);
@@ -316,7 +317,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<EGLDeviceEXT>& de
     if (vendorStr.find("amd") != std::string::npos) score += 2;
     if (vendorStr.find("nvidia") != std::string::npos) score += 3;
 
-    scoreDevices.emplace_back(score, device);
+    scoreDevices.emplace_back(score, iDevice);
   }
 
   // sort them by highest score
@@ -325,7 +326,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<EGLDeviceEXT>& de
 
   // store them back in the given array
   for (size_t i = 0; i < devices.size(); i++) {
-    devices[i] = std::get<1>(scoreDevices[i]);
+    deviceInds[i] = std::get<1>(scoreDevices[i]);
   }
 }
 

From 7f2294f949ad91980d6c960e4b9c9fabe747e17d Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Thu, 28 Nov 2024 23:53:01 -0800
Subject: [PATCH 09/34] two more small fixes

---
 src/render/opengl/gl_engine_egl.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 5912d985..c3b4b118 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -167,7 +167,7 @@ void GLEngineEGL::initialize() {
 
     deviceIndsToTry.resize(nDevices);
     std::iota(deviceIndsToTry.begin(), deviceIndsToTry.end(), 0);
-    sortAvailableDevicesByPreference(deviceIndsToTry);
+    sortAvailableDevicesByPreference(deviceIndsToTry, rawDevices);
 
   } else {
     info("EGL: Device index " + std::to_string(options::eglDeviceIndex) + " manually selected, using that device.");
@@ -325,7 +325,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
   std::reverse(scoreDevices.begin(), scoreDevices.end());
 
   // store them back in the given array
-  for (size_t i = 0; i < devices.size(); i++) {
+  for (size_t i = 0; i < deviceInds.size(); i++) {
     deviceInds[i] = std::get<1>(scoreDevices[i]);
   }
 }

From 058a4743b8be34ea38fd4279c8a79ecb88b8010d Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Thu, 28 Nov 2024 23:58:57 -0800
Subject: [PATCH 10/34] string safety and logging

---
 src/render/opengl/gl_engine_egl.cpp | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index c3b4b118..49c38722 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -296,7 +296,18 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
     EGLDeviceEXT device = rawDevices[iDevice];
     int score = 0;
 
-    std::string vendorStr = eglQueryDeviceStringEXT(device, EGL_VENDOR);
+    const char* vendorStrRaw = eglQueryDeviceStringEXT(device, EGL_VENDOR);
+
+    if (vendorStrRaw == nullptr) {
+      if (polyscope::options::verbosity > 5) {
+        std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << "NULL"
+                  << "  priority score: " << score << std::endl;
+      }
+      scoreDevices.emplace_back(score, iDevice);
+      continue;
+    }
+
+    std::string vendorStr = vendorStrRaw;
 
     // lower-case it for the checks below
     std::transform(vendorStr.begin(), vendorStr.end(), vendorStr.begin(),
@@ -324,6 +335,12 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
   std::sort(scoreDevices.begin(), scoreDevices.end());
   std::reverse(scoreDevices.begin(), scoreDevices.end());
 
+  // at high verbosity levels, log the priority
+  if (polyscope::options::verbosity > 5) {
+    std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << vendorStr
+              << "  priority score: " << score << std::endl;
+  }
+
   // store them back in the given array
   for (size_t i = 0; i < deviceInds.size(); i++) {
     deviceInds[i] = std::get<1>(scoreDevices[i]);

From ed0af02ebc29474abddd63f4cccc15f5d52fa775 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 00:00:31 -0800
Subject: [PATCH 11/34] nest logging correctly

---
 src/render/opengl/gl_engine_egl.cpp | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 49c38722..608e4ce1 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -328,6 +328,12 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
     if (vendorStr.find("amd") != std::string::npos) score += 2;
     if (vendorStr.find("nvidia") != std::string::npos) score += 3;
 
+    // at high verbosity levels, log the priority
+    if (polyscope::options::verbosity > 5) {
+      std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << vendorStr
+                << "  priority score: " << score << std::endl;
+    }
+
     scoreDevices.emplace_back(score, iDevice);
   }
 
@@ -335,11 +341,6 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
   std::sort(scoreDevices.begin(), scoreDevices.end());
   std::reverse(scoreDevices.begin(), scoreDevices.end());
 
-  // at high verbosity levels, log the priority
-  if (polyscope::options::verbosity > 5) {
-    std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << vendorStr
-              << "  priority score: " << score << std::endl;
-  }
 
   // store them back in the given array
   for (size_t i = 0; i < deviceInds.size(); i++) {

From eddea5e7d9101ca19e90d1049bfc778beb596e2b Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 00:04:55 -0800
Subject: [PATCH 12/34] check for extension

---
 src/render/opengl/gl_engine_egl.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 608e4ce1..c56d4a07 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -286,6 +286,15 @@ void GLEngineEGL::initialize() {
 
 void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceInds, EGLDeviceEXT rawDevices[]) {
 
+  // check that we actually have the query extension
+  const char* extensions = eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS);
+  if (extensions && std::string(extensions).find("EGL_EXT_device_query") != std::string::npos) {
+      // good case, supported
+  } else {
+      info("EGL: cannot sort devices by preference, EGL_EXT_device_query is not supported")
+      return;
+  }
+
   // Pre-load required extension functions
   PFNEGLQUERYDEVICESTRINGEXTPROC eglQueryDeviceStringEXT =
       (PFNEGLQUERYDEVICESTRINGEXTPROC)getEGLProcAddressAndCheck("eglQueryDeviceStringEXT");

From e4f8d4352ee079aa307b2577405c923a8266eece Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 00:05:24 -0800
Subject: [PATCH 13/34] missing semicolon

---
 src/render/opengl/gl_engine_egl.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index c56d4a07..1887c40e 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -291,7 +291,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
   if (extensions && std::string(extensions).find("EGL_EXT_device_query") != std::string::npos) {
       // good case, supported
   } else {
-      info("EGL: cannot sort devices by preference, EGL_EXT_device_query is not supported")
+      info("EGL: cannot sort devices by preference, EGL_EXT_device_query is not supported");
       return;
   }
 

From 50954fdb43983f023cb7c95e0ee9357b56e34e6b Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 00:10:38 -0800
Subject: [PATCH 14/34] more logging

---
 src/render/opengl/gl_engine_egl.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 1887c40e..c5305008 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -184,8 +184,8 @@ void GLEngineEGL::initialize() {
   EGLint majorVer, minorVer;
   for (int32_t iDevice : deviceIndsToTry) {
 
-    info("EGL: Attempting initialization with device " + std::to_string(iDevice));
     EGLDeviceEXT device = rawDevices[iDevice];
+    info("EGL: Attempting initialization with device ind: " + std::to_string(iDevice) + " handle: " + std::to_string(device));
 
     // Get an EGLDisplay for the device
     // (use the -platform / EXT version because it is the only one that seems to work in headless environments)
@@ -295,7 +295,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
       return;
   }
 
-  // Pre-load required extension functions
+  // Pre-load query extension functions
   PFNEGLQUERYDEVICESTRINGEXTPROC eglQueryDeviceStringEXT =
       (PFNEGLQUERYDEVICESTRINGEXTPROC)getEGLProcAddressAndCheck("eglQueryDeviceStringEXT");
 
@@ -309,7 +309,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
 
     if (vendorStrRaw == nullptr) {
       if (polyscope::options::verbosity > 5) {
-        std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << "NULL"
+        std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << " . device: " << device << "  vendor: " << "NULL"
                   << "  priority score: " << score << std::endl;
       }
       scoreDevices.emplace_back(score, iDevice);

From 044999ef26b186c1b3d48facc931eccd649a4920 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 00:12:49 -0800
Subject: [PATCH 15/34] cast

---
 src/render/opengl/gl_engine_egl.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index c5305008..05d6712c 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -185,7 +185,7 @@ void GLEngineEGL::initialize() {
   for (int32_t iDevice : deviceIndsToTry) {
 
     EGLDeviceEXT device = rawDevices[iDevice];
-    info("EGL: Attempting initialization with device ind: " + std::to_string(iDevice) + " handle: " + std::to_string(device));
+    info("EGL: Attempting initialization with device ind: " + std::to_string(iDevice) + " handle: " + std::to_string((size_t)device));
 
     // Get an EGLDisplay for the device
     // (use the -platform / EXT version because it is the only one that seems to work in headless environments)
@@ -309,7 +309,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
 
     if (vendorStrRaw == nullptr) {
       if (polyscope::options::verbosity > 5) {
-        std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << " . device: " << device << "  vendor: " << "NULL"
+        std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << " . device: " << (size_t)device << "  vendor: " << "NULL"
                   << "  priority score: " << score << std::endl;
       }
       scoreDevices.emplace_back(score, iDevice);

From 09854e4cdf7254bf44f82cf2f539413e6ab1bc3e Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 00:15:33 -0800
Subject: [PATCH 16/34] test

---
 src/render/opengl/gl_engine_egl.cpp | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 05d6712c..0cd904db 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -160,6 +160,30 @@ void GLEngineEGL::initialize() {
   }
   info("EGL: Found " + std::to_string(nDevices) + " EGL devices.");
 
+{
+  PFNEGLQUERYDEVICESEXTPROC eglQueryDevicesEXT = (PFNEGLQUERYDEVICESEXTPROC)eglGetProcAddress("eglQueryDevicesEXT");
+PFNEGLQUERYDEVICESTRINGEXTPROC eglQueryDeviceStringEXT = (PFNEGLQUERYDEVICESTRINGEXTPROC)eglGetProcAddress("eglQueryDeviceStringEXT");
+
+if (!eglQueryDevicesEXT || !eglQueryDeviceStringEXT) {
+    fprintf(stderr, "Required extension functions not available.\n");
+    return EXIT_FAILURE;
+}
+
+EGLDeviceEXT devices[10];
+EGLint num_devices;
+if (eglQueryDevicesEXT(10, devices, &num_devices)) {
+    for (int i = 0; i < num_devices; i++) {
+        const char* vendor = eglQueryDeviceStringEXT(devices[i], EGL_VENDOR);
+        printf("Device %d: Vendor: %s\n", i, vendor ? vendor : "Unknown");
+    }
+} else {
+    fprintf(stderr, "eglQueryDevicesEXT failed.\n");
+}
+
+}
+
+
+
   // Build an ordered list of which devices to try initializing with
   std::vector<int32_t> deviceIndsToTry;
   if (options::eglDeviceIndex == -1) {

From 348d4f6e1c29dcc13d524d9e9fc1653768b54c7e Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 00:15:50 -0800
Subject: [PATCH 17/34] test

---
 src/render/opengl/gl_engine_egl.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 0cd904db..3a01b041 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -166,7 +166,7 @@ PFNEGLQUERYDEVICESTRINGEXTPROC eglQueryDeviceStringEXT = (PFNEGLQUERYDEVICESTRIN
 
 if (!eglQueryDevicesEXT || !eglQueryDeviceStringEXT) {
     fprintf(stderr, "Required extension functions not available.\n");
-    return EXIT_FAILURE;
+    // return EXIT_FAILURE;
 }
 
 EGLDeviceEXT devices[10];

From cb04777b05859fdceba8cf5f8009b058a9c6e731 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 00:35:41 -0800
Subject: [PATCH 18/34] try fake initialize

---
 src/render/opengl/gl_engine_egl.cpp | 48 ++++++++++++-----------------
 1 file changed, 19 insertions(+), 29 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 3a01b041..1b70454d 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -160,30 +160,6 @@ void GLEngineEGL::initialize() {
   }
   info("EGL: Found " + std::to_string(nDevices) + " EGL devices.");
 
-{
-  PFNEGLQUERYDEVICESEXTPROC eglQueryDevicesEXT = (PFNEGLQUERYDEVICESEXTPROC)eglGetProcAddress("eglQueryDevicesEXT");
-PFNEGLQUERYDEVICESTRINGEXTPROC eglQueryDeviceStringEXT = (PFNEGLQUERYDEVICESTRINGEXTPROC)eglGetProcAddress("eglQueryDeviceStringEXT");
-
-if (!eglQueryDevicesEXT || !eglQueryDeviceStringEXT) {
-    fprintf(stderr, "Required extension functions not available.\n");
-    // return EXIT_FAILURE;
-}
-
-EGLDeviceEXT devices[10];
-EGLint num_devices;
-if (eglQueryDevicesEXT(10, devices, &num_devices)) {
-    for (int i = 0; i < num_devices; i++) {
-        const char* vendor = eglQueryDeviceStringEXT(devices[i], EGL_VENDOR);
-        printf("Device %d: Vendor: %s\n", i, vendor ? vendor : "Unknown");
-    }
-} else {
-    fprintf(stderr, "eglQueryDevicesEXT failed.\n");
-}
-
-}
-
-
-
   // Build an ordered list of which devices to try initializing with
   std::vector<int32_t> deviceIndsToTry;
   if (options::eglDeviceIndex == -1) {
@@ -327,16 +303,32 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
   std::vector<std::tuple<int32_t, int32_t>> scoreDevices;
   for (int32_t iDevice : deviceInds) {
     EGLDeviceEXT device = rawDevices[iDevice];
-    int score = 0;
+    scoreDevices.emplace_back(0, iDevice);
+    int& score = std::get<0>(scoreDevices.back());
+
+    {
+      EGLDisplay display = eglGetPlatformDisplayEXT(EGL_PLATFORM_DEVICE_EXT, device, NULL);
+      if (display == EGL_NO_DISPLAY) {
+          fprintf(stderr, "Failed to get EGLDisplay for device %d.\n", i);
+          continue;
+      }
 
-    const char* vendorStrRaw = eglQueryDeviceStringEXT(device, EGL_VENDOR);
+      if (!eglInitialize(display, NULL, NULL)) {
+          fprintf(stderr, "Failed to initialize EGLDisplay for device %d.\n", i);
+          continue;
+      }
 
+      const char* vendor = eglQueryString(display, EGL_VENDOR);
+      printf("Device %d Vendor from Display: %s\n", i, vendor ? vendor : "Unknown");
+      eglTerminate(display);
+    }
+
+    const char* vendorStrRaw = eglQueryDeviceStringEXT(device, EGL_VENDOR);
     if (vendorStrRaw == nullptr) {
       if (polyscope::options::verbosity > 5) {
         std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << " . device: " << (size_t)device << "  vendor: " << "NULL"
                   << "  priority score: " << score << std::endl;
       }
-      scoreDevices.emplace_back(score, iDevice);
       continue;
     }
 
@@ -366,8 +358,6 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
       std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << vendorStr
                 << "  priority score: " << score << std::endl;
     }
-
-    scoreDevices.emplace_back(score, iDevice);
   }
 
   // sort them by highest score

From 119e4bcb0802469ac82e13c36fbc7332f9b7adc3 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 00:36:52 -0800
Subject: [PATCH 19/34] compile fixes

---
 src/render/opengl/gl_engine_egl.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 1b70454d..9fcbc1d8 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -307,19 +307,19 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
     int& score = std::get<0>(scoreDevices.back());
 
     {
-      EGLDisplay display = eglGetPlatformDisplayEXT(EGL_PLATFORM_DEVICE_EXT, device, NULL);
+      EGLDisplay display = eglGetPlatformDisplay(EGL_PLATFORM_DEVICE_EXT, device, NULL);
       if (display == EGL_NO_DISPLAY) {
-          fprintf(stderr, "Failed to get EGLDisplay for device %d.\n", i);
+          fprintf(stderr, "Failed to get EGLDisplay for device %d.\n", iDevice);
           continue;
       }
 
       if (!eglInitialize(display, NULL, NULL)) {
-          fprintf(stderr, "Failed to initialize EGLDisplay for device %d.\n", i);
+          fprintf(stderr, "Failed to initialize EGLDisplay for device %d.\n", iDevice);
           continue;
       }
 
       const char* vendor = eglQueryString(display, EGL_VENDOR);
-      printf("Device %d Vendor from Display: %s\n", i, vendor ? vendor : "Unknown");
+      printf("Device %d Vendor from Display: %s\n", iDevice, vendor ? vendor : "Unknown");
       eglTerminate(display);
     }
 

From 9eb6d7ceba9bb22120e7e506b12afb3a41bfb7c9 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 01:12:05 -0800
Subject: [PATCH 20/34] revert debugging

---
 src/render/opengl/gl_engine_egl.cpp | 30 ++++++++---------------------
 1 file changed, 8 insertions(+), 22 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 9fcbc1d8..1887c40e 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -184,8 +184,8 @@ void GLEngineEGL::initialize() {
   EGLint majorVer, minorVer;
   for (int32_t iDevice : deviceIndsToTry) {
 
+    info("EGL: Attempting initialization with device " + std::to_string(iDevice));
     EGLDeviceEXT device = rawDevices[iDevice];
-    info("EGL: Attempting initialization with device ind: " + std::to_string(iDevice) + " handle: " + std::to_string((size_t)device));
 
     // Get an EGLDisplay for the device
     // (use the -platform / EXT version because it is the only one that seems to work in headless environments)
@@ -295,7 +295,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
       return;
   }
 
-  // Pre-load query extension functions
+  // Pre-load required extension functions
   PFNEGLQUERYDEVICESTRINGEXTPROC eglQueryDeviceStringEXT =
       (PFNEGLQUERYDEVICESTRINGEXTPROC)getEGLProcAddressAndCheck("eglQueryDeviceStringEXT");
 
@@ -303,32 +303,16 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
   std::vector<std::tuple<int32_t, int32_t>> scoreDevices;
   for (int32_t iDevice : deviceInds) {
     EGLDeviceEXT device = rawDevices[iDevice];
-    scoreDevices.emplace_back(0, iDevice);
-    int& score = std::get<0>(scoreDevices.back());
-
-    {
-      EGLDisplay display = eglGetPlatformDisplay(EGL_PLATFORM_DEVICE_EXT, device, NULL);
-      if (display == EGL_NO_DISPLAY) {
-          fprintf(stderr, "Failed to get EGLDisplay for device %d.\n", iDevice);
-          continue;
-      }
-
-      if (!eglInitialize(display, NULL, NULL)) {
-          fprintf(stderr, "Failed to initialize EGLDisplay for device %d.\n", iDevice);
-          continue;
-      }
-
-      const char* vendor = eglQueryString(display, EGL_VENDOR);
-      printf("Device %d Vendor from Display: %s\n", iDevice, vendor ? vendor : "Unknown");
-      eglTerminate(display);
-    }
+    int score = 0;
 
     const char* vendorStrRaw = eglQueryDeviceStringEXT(device, EGL_VENDOR);
+
     if (vendorStrRaw == nullptr) {
       if (polyscope::options::verbosity > 5) {
-        std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << " . device: " << (size_t)device << "  vendor: " << "NULL"
+        std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << "NULL"
                   << "  priority score: " << score << std::endl;
       }
+      scoreDevices.emplace_back(score, iDevice);
       continue;
     }
 
@@ -358,6 +342,8 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
       std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << vendorStr
                 << "  priority score: " << score << std::endl;
     }
+
+    scoreDevices.emplace_back(score, iDevice);
   }
 
   // sort them by highest score

From e10b602b289a90b69de1d9dae1c966ea8f6c953b Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 01:17:03 -0800
Subject: [PATCH 21/34] clean up logging

---
 src/render/initialize_backend.cpp | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/src/render/initialize_backend.cpp b/src/render/initialize_backend.cpp
index 95e20772..30591a60 100644
--- a/src/render/initialize_backend.cpp
+++ b/src/render/initialize_backend.cpp
@@ -55,8 +55,7 @@ void initializeRenderEngine(std::string backend) {
       initSucces = true;
     } catch (const std::exception& e) {
       if (options::verbosity > 0) {
-        info("Attempting automatic initialization. Could not initialize backend [openGL3_glfw]. Message: " +
-             std::string(e.what()));
+        info("Attempting automatic initialization. Could not initialize backend [openGL3_glfw].");
       }
     }
     if (initSucces) return;
@@ -70,16 +69,15 @@ void initializeRenderEngine(std::string backend) {
       initSucces = true;
     } catch (const std::exception& e) {
       if (options::verbosity > 0) {
-        info("Attempting automatic initialization. Could not initialize backend [openGL3_egl]. Message: " +
-             std::string(e.what()));
+        info("Attempting automatic initialization. Could not initialize backend [openGL3_egl].");
       }
     }
     if (initSucces) {
       if (options::verbosity > 0) {
         info("Automatic initialization could not create an interactive backend, and created a headless backend "
              "instead. This likely means no displays are available. With the headless backend, you can still run "
-             "Polyscope and even render, for instance to record screenshots. However no interactive windows can be "
-             "created.");
+             "Polyscope and even render, for instance to save images of visualizations. However no interactive "
+             "windows can be created.");
       }
       return;
     }

From a60e2c56a90fa4bff9925821fd33820077c87f55 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 01:21:09 -0800
Subject: [PATCH 22/34] cleanup

---
 src/render/opengl/gl_engine_egl.cpp | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 1887c40e..fe04f5c8 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -289,10 +289,10 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
   // check that we actually have the query extension
   const char* extensions = eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS);
   if (extensions && std::string(extensions).find("EGL_EXT_device_query") != std::string::npos) {
-      // good case, supported
+    // good case, supported
   } else {
-      info("EGL: cannot sort devices by preference, EGL_EXT_device_query is not supported");
-      return;
+    info("EGL: cannot sort devices by preference, EGL_EXT_device_query is not supported");
+    return;
   }
 
   // Pre-load required extension functions
@@ -305,8 +305,14 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
     EGLDeviceEXT device = rawDevices[iDevice];
     int score = 0;
 
+    // Add the device index as a weak term, so we prefer the original order
+    score += (deviceInds.size() - iDevice - 1);
+
+
     const char* vendorStrRaw = eglQueryDeviceStringEXT(device, EGL_VENDOR);
 
+    // NOTE: on many machines (cloud VMs?) the query string above is nullptr, and this whole function does nothing
+    // useful
     if (vendorStrRaw == nullptr) {
       if (polyscope::options::verbosity > 5) {
         std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << "NULL"
@@ -333,9 +339,10 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
     // ONEDAY: figure out a better policy to detect discrete devices....
 
     // assign scores based on vendors to prefer discrete gpus
-    if (vendorStr.find("intel") != std::string::npos) score += 1;
-    if (vendorStr.find("amd") != std::string::npos) score += 2;
-    if (vendorStr.find("nvidia") != std::string::npos) score += 3;
+    const int32_t VENDOR_MULT = 100; // give this score entry a very high preference
+    if (vendorStr.find("intel") != std::string::npos) score += 1 * VENDOR_MULT;
+    if (vendorStr.find("amd") != std::string::npos) score += 2 * VENDOR_MULT;
+    if (vendorStr.find("nvidia") != std::string::npos) score += 3 * VENDOR_MULT;
 
     // at high verbosity levels, log the priority
     if (polyscope::options::verbosity > 5) {

From d47099cd56ed10ac9e8ae0834d0f70c514ceada0 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 01:37:27 -0800
Subject: [PATCH 23/34] back to front

---
 src/render/opengl/gl_engine_egl.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index fe04f5c8..a45be795 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -305,9 +305,9 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
     EGLDeviceEXT device = rawDevices[iDevice];
     int score = 0;
 
-    // Add the device index as a weak term, so we prefer the original order
-    score += (deviceInds.size() - iDevice - 1);
-
+    // Heuristic, non-software renderers seem to come last, so add a term to the score that prefers later-listed entries
+    // TODO find a way to test for software rsterization for real
+    score += iDevice;
 
     const char* vendorStrRaw = eglQueryDeviceStringEXT(device, EGL_VENDOR);
 

From 0fb4b2708935027c522ed71438a4a04afb35cbba Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 29 Nov 2024 01:39:32 -0800
Subject: [PATCH 24/34] cleanup

---
 src/render/opengl/gl_engine_egl.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index a45be795..6c327ef2 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -163,7 +163,8 @@ void GLEngineEGL::initialize() {
   // Build an ordered list of which devices to try initializing with
   std::vector<int32_t> deviceIndsToTry;
   if (options::eglDeviceIndex == -1) {
-    info("EGL: No device index specified, attempting to intialize with each device sequentially until success.");
+    info("EGL: No device index specified, attempting to intialize with each device in heuristic-guess order until "
+         "success.");
 
     deviceIndsToTry.resize(nDevices);
     std::iota(deviceIndsToTry.begin(), deviceIndsToTry.end(), 0);

From a5b4e999b124794e4c08f0eda5c5852f36b658f3 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 27 Dec 2024 12:12:57 -0500
Subject: [PATCH 25/34] add user-facing options for headless setup

---
 examples/demo-app/demo_app.cpp                | 12 +++--
 include/polyscope/options.h                   |  7 ++-
 include/polyscope/polyscope.h                 |  6 +++
 include/polyscope/render/engine.h             |  3 ++
 .../polyscope/render/opengl/gl_engine_egl.h   |  3 ++
 src/options.cpp                               |  1 +
 src/polyscope.cpp                             | 18 ++++++++
 src/render/initialize_backend.cpp             | 46 +++++++++++--------
 8 files changed, 74 insertions(+), 22 deletions(-)

diff --git a/examples/demo-app/demo_app.cpp b/examples/demo-app/demo_app.cpp
index f7a0d6cb..27b826a2 100644
--- a/examples/demo-app/demo_app.cpp
+++ b/examples/demo-app/demo_app.cpp
@@ -846,6 +846,7 @@ int main(int argc, char** argv) {
   // polyscope::options::maxFPS = -1;
   polyscope::options::verbosity = 100;
   polyscope::options::enableRenderErrorChecks = true;
+  polyscope::options::allowHeadlessBackends = true;
 
   // Initialize polyscope
   polyscope::init();
@@ -871,9 +872,14 @@ int main(int argc, char** argv) {
   // Add a few gui elements
   polyscope::state::userCallback = callback;
 
-  // Show the gui
-  polyscope::show();
-
+  if (polyscope::isHeadless()) {
+    // save a screenshot to prove we initialized
+    std::cout << "Headless mode detected, saving screenshot" << std::endl;
+    polyscope::screenshot("headless_screenshot.png");
+  } else {
+    // Show the gui
+    polyscope::show();
+  }
   // main loop using manual frameTick() instead
   // while (true) {
   //   polyscope::frameTick();
diff --git a/include/polyscope/options.h b/include/polyscope/options.h
index 6ffcae0f..9a92f381 100644
--- a/include/polyscope/options.h
+++ b/include/polyscope/options.h
@@ -13,7 +13,9 @@
 
 
 namespace polyscope {
-namespace options { // A general name to use when referring to the program in window headings.
+namespace options {
+
+// A general name to use when referring to the program in window headings.
 extern std::string programName;
 
 // How much should polyscope print to std::out?
@@ -28,6 +30,9 @@ extern std::string printPrefix;
 // Should errors throw exceptions, or just display? (default false)
 extern bool errorsThrowExceptions;
 
+// Allow initialization to create headless backends (default: false)
+extern bool allowHeadlessBackends; 
+
 // Don't let the main loop run at more than this speed. (-1 disables) (default: 60)
 extern int maxFPS;
 
diff --git a/include/polyscope/polyscope.h b/include/polyscope/polyscope.h
index c7205399..25f1f29d 100644
--- a/include/polyscope/polyscope.h
+++ b/include/polyscope/polyscope.h
@@ -66,6 +66,12 @@ void shutdown(bool allowMidFrameShutdown=false);
 // deciding when to exit your control loop when using frameTick()
 bool windowRequestsClose();
 
+// Is Polyscope running in 'headless' mode? Headless means there is no physical display to open windows on,
+// e.g. when running on a remote server. It is still possible to run Polyscope in such settings with a supported
+// backend (currently, the EGL backend only), and render to save screenshots or for other purposes.
+// Can only be called after initialization.
+bool isHeadless();
+
 // === Global variables ===
 namespace state {
 
diff --git a/include/polyscope/render/engine.h b/include/polyscope/render/engine.h
index 3d71e8c0..7a89a93b 100644
--- a/include/polyscope/render/engine.h
+++ b/include/polyscope/render/engine.h
@@ -445,6 +445,9 @@ class Engine {
   virtual void shutdown() {};
   virtual void checkError(bool fatal = false) = 0;
   void buildEngineGui();
+  
+  // 'headless' means there is no physical display to actually render to, e.g. when running on a remote server
+  virtual bool isHeadless() { return false; } 
 
   virtual void clearDisplay();
   virtual void bindDisplay();
diff --git a/include/polyscope/render/opengl/gl_engine_egl.h b/include/polyscope/render/opengl/gl_engine_egl.h
index 31d23ce1..45f50d41 100644
--- a/include/polyscope/render/opengl/gl_engine_egl.h
+++ b/include/polyscope/render/opengl/gl_engine_egl.h
@@ -42,6 +42,9 @@ class GLEngineEGL : public GLEngine {
   virtual void shutdown() override;
   void swapDisplayBuffers() override;
   void checkError(bool fatal = false) override;
+  
+  // EGL backend is always headless
+  virtual bool isHeadless() override { return true; } 
 
   // === Windowing and framework things
 
diff --git a/src/options.cpp b/src/options.cpp
index 703ff5da..3b87de4d 100644
--- a/src/options.cpp
+++ b/src/options.cpp
@@ -9,6 +9,7 @@ namespace options {
 std::string programName = "Polyscope";
 int verbosity = 2;
 std::string printPrefix = "[polyscope] ";
+bool allowHeadlessBackends = false; 
 bool errorsThrowExceptions = false;
 bool debugDrawPickBuffer = false;
 int maxFPS = 60;
diff --git a/src/polyscope.cpp b/src/polyscope.cpp
index 575f8e2b..40f7a28e 100644
--- a/src/polyscope.cpp
+++ b/src/polyscope.cpp
@@ -893,6 +893,14 @@ void show(size_t forFrames) {
   if (!state::initialized) {
     exception("must initialize Polyscope with polyscope::init() before calling polyscope::show().");
   }
+
+  if (isHeadless() && forFrames == 0) {
+    info("You called show() while in headless mode. In headless mode there is no display to create windows on. By "
+         "default, the show() call will block indefinitely. If you did not mean to run in headless mode, check the "
+         "initialization settings. Otherwise, be sure to set a callback to make something happen while polyscope is "
+         "showing the UI, or use functions like screenshot() to render directly without calling show().");
+  }
+
   unshowRequested = false;
 
   // the popContext() doesn't quit until _after_ the last frame, so we need to decrement by 1 to get the count right
@@ -934,6 +942,16 @@ bool windowRequestsClose() {
   return false;
 }
 
+bool isHeadless() {
+  if (!isInitialized()) {
+    exception("must initialize Polyscope with init() before calling isHeadless().");
+  }
+  if (render::engine) {
+    return render::engine->isHeadless();
+  }
+  return false;
+}
+
 void shutdown(bool allowMidFrameShutdown) {
 
   if (!allowMidFrameShutdown && contextStack.size() > 1) {
diff --git a/src/render/initialize_backend.cpp b/src/render/initialize_backend.cpp
index 30591a60..7c19283d 100644
--- a/src/render/initialize_backend.cpp
+++ b/src/render/initialize_backend.cpp
@@ -46,6 +46,7 @@ void initializeRenderEngine(std::string backend) {
     // Attempt to automatically initialize by trynig
 
     bool initSucces = false;
+    std::string extraMessage = "";
 
 #ifdef POLYSCOPE_BACKEND_OPENGL3_GLFW_ENABLED
     // First try GLFW, if available
@@ -55,38 +56,47 @@ void initializeRenderEngine(std::string backend) {
       initSucces = true;
     } catch (const std::exception& e) {
       if (options::verbosity > 0) {
-        info("Attempting automatic initialization. Could not initialize backend [openGL3_glfw].");
+        info("Automatic initialization status: could not initialize backend [openGL3_glfw].");
       }
     }
     if (initSucces) return;
 #endif
 
 #ifdef POLYSCOPE_BACKEND_OPENGL3_EGL_ENABLED
-    // Then, try EGL if available
-    engineBackendName = "openGL3_egl";
-    try {
-      backend_openGL3::initializeRenderEngine_egl();
-      initSucces = true;
-    } catch (const std::exception& e) {
-      if (options::verbosity > 0) {
-        info("Attempting automatic initialization. Could not initialize backend [openGL3_egl].");
+
+    if (options::allowHeadlessBackends) {
+
+      // Then, try EGL if available
+      engineBackendName = "openGL3_egl";
+      try {
+        backend_openGL3::initializeRenderEngine_egl();
+        initSucces = true;
+      } catch (const std::exception& e) {
+        if (options::verbosity > 0) {
+          info("Automatic initialization status: could not initialize backend [openGL3_egl].");
+        }
       }
-    }
-    if (initSucces) {
-      if (options::verbosity > 0) {
-        info("Automatic initialization could not create an interactive backend, and created a headless backend "
-             "instead. This likely means no displays are available. With the headless backend, you can still run "
-             "Polyscope and even render, for instance to save images of visualizations. However no interactive "
-             "windows can be created.");
+      if (initSucces) {
+        if (options::verbosity > 0) {
+          info("Automatic initialization could not create an interactive backend, and created a headless backend "
+               "instead. This likely means no displays are available. With the headless backend, you can still run "
+               "Polyscope and even render, for instance to save images of visualizations. However no interactive "
+               "windows can be created.");
+        }
+        return;
       }
-      return;
+
+    } else {
+      extraMessage = " The headless EGL backend was available, but allowHeadlessBackends=false. Set it to true for "
+                     "headless initialization.";
     }
+
 #endif
 
     // Don't bother trying the 'mock' backend, it is unlikely to be what the user wants from the 'auto' option
 
     // Failure
-    exception("Automatic initialization: no Polyscope backends could be initialized successfully.");
+    exception("Automatic initialization: no Polyscope backends could be initialized successfully." + extraMessage);
 
   } else {
     exception("unrecognized Polyscope backend " + backend);

From 2ffb0fef014c67ef443c8bad87ccef5e65df5e06 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 27 Dec 2024 12:30:24 -0500
Subject: [PATCH 26/34] fix framecount check

---
 src/polyscope.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/polyscope.cpp b/src/polyscope.cpp
index 40f7a28e..a4f176fd 100644
--- a/src/polyscope.cpp
+++ b/src/polyscope.cpp
@@ -894,7 +894,7 @@ void show(size_t forFrames) {
     exception("must initialize Polyscope with polyscope::init() before calling polyscope::show().");
   }
 
-  if (isHeadless() && forFrames == 0) {
+  if (isHeadless() && forFrames == std::numeric_limits<size_t>::max()) {
     info("You called show() while in headless mode. In headless mode there is no display to create windows on. By "
          "default, the show() call will block indefinitely. If you did not mean to run in headless mode, check the "
          "initialization settings. Otherwise, be sure to set a callback to make something happen while polyscope is "

From 3ce6a6e945490dd938b19891b993fd9555cf0939 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 27 Dec 2024 19:10:54 -0500
Subject: [PATCH 27/34] try testing EGL on ci

---
 .github/workflows/linux.yml | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 8f7b2b00..2b0a5d00 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -45,10 +45,13 @@ jobs:
       run: sudo apt-get update && sudo apt-get install -y xorg-dev libglu1-mesa-dev xpra xserver-xorg-video-dummy freeglut3-dev
 
     - name: configure
-      run: cd test && mkdir build && cd build && cmake -DBUILD_SHARED_LIBS=TRUE -DCMAKE_BUILD_TYPE=Debug -DPOLYSCOPE_BACKEND_OPENGL3_GLFW=ON -DPOLYSCOPE_BACKEND_OPENGL_MOCK=ON ..
+      run: cd test && mkdir build && cd build && cmake -DBUILD_SHARED_LIBS=TRUE -DCMAKE_BUILD_TYPE=Debug -DPOLYSCOPE_BACKEND_OPENGL3_GLFW=ON -DPOLYSCOPE_BACKEND_OPENGL_MOCK=ON -DPOLYSCOPE_BACKEND_OPENGL3_EGL=ON ..
 
     - name: build
       run: cd test/build && make
 
-    - name: run test
+    - name: run test mock backend
       run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_mock
+    
+    - name: run test egl backend
+      run: ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_egl

From e3752af97be935bf3899d933c56c85b69e4002a9 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 27 Dec 2024 19:17:24 -0500
Subject: [PATCH 28/34] fix ci script

---
 .github/workflows/linux.yml | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 2b0a5d00..d89e65c5 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -27,8 +27,11 @@ jobs:
     - name: build
       run: cd test/build && make
 
-    - name: run test
+    - name: run test mock backend
       run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_mock
+    
+    - name: run test egl backend
+      run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_egl
   
   build_shared:
     strategy:
@@ -54,4 +57,4 @@ jobs:
       run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_mock
     
     - name: run test egl backend
-      run: ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_egl
+      run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_egl

From 95982411208b88565fff7b10dbd0938316069086 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Fri, 27 Dec 2024 19:29:09 -0500
Subject: [PATCH 29/34] fix backend string

---
 .github/workflows/linux.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index d89e65c5..1bd35f07 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -31,7 +31,7 @@ jobs:
       run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_mock
     
     - name: run test egl backend
-      run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_egl
+      run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL3_egl
   
   build_shared:
     strategy:
@@ -57,4 +57,4 @@ jobs:
       run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_mock
     
     - name: run test egl backend
-      run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_egl
+      run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL3_egl

From 612c367c0428644c833709c86a440f8c7d89a9ff Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Sat, 28 Dec 2024 00:34:17 -0500
Subject: [PATCH 30/34] improve logging string formatting

---
 src/render/opengl/gl_engine_egl.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
index 6c327ef2..c6c0c01d 100644
--- a/src/render/opengl/gl_engine_egl.cpp
+++ b/src/render/opengl/gl_engine_egl.cpp
@@ -316,7 +316,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
     // useful
     if (vendorStrRaw == nullptr) {
       if (polyscope::options::verbosity > 5) {
-        std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << "NULL"
+        std::cout << polyscope::options::printPrefix << "  EGLDevice " << iDevice << " -- vendor: " << "NULL"
                   << "  priority score: " << score << std::endl;
       }
       scoreDevices.emplace_back(score, iDevice);
@@ -347,7 +347,7 @@ void GLEngineEGL::sortAvailableDevicesByPreference(std::vector<int32_t>& deviceI
 
     // at high verbosity levels, log the priority
     if (polyscope::options::verbosity > 5) {
-      std::cout << polyscope::options::printPrefix << "  EGLDevice ind" << iDevice << "  vendor: " << vendorStr
+      std::cout << polyscope::options::printPrefix << "  EGLDevice " << iDevice << " -- vendor: " << vendorStr
                 << "  priority score: " << score << std::endl;
     }
 

From 736eacb0b87bec6a15cbc7287340b11d0661e92f Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Sat, 28 Dec 2024 15:06:07 -0500
Subject: [PATCH 31/34] clean up context stack on shutdown

---
 src/polyscope.cpp             | 3 ++-
 test/include/polyscope_test.h | 7 +------
 test/src/basics_test.cpp      | 5 +++++
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/polyscope.cpp b/src/polyscope.cpp
index a4f176fd..a21fd16f 100644
--- a/src/polyscope.cpp
+++ b/src/polyscope.cpp
@@ -894,7 +894,7 @@ void show(size_t forFrames) {
     exception("must initialize Polyscope with polyscope::init() before calling polyscope::show().");
   }
 
-  if (isHeadless() && forFrames == std::numeric_limits<size_t>::max()) {
+  if (isHeadless() && forFrames == 0) {
     info("You called show() while in headless mode. In headless mode there is no display to create windows on. By "
          "default, the show() call will block indefinitely. If you did not mean to run in headless mode, check the "
          "initialization settings. Otherwise, be sure to set a callback to make something happen while polyscope is "
@@ -973,6 +973,7 @@ void shutdown(bool allowMidFrameShutdown) {
   // Shut down the render engine
   render::engine->shutdown();
   delete render::engine;
+  contextStack.clear();
   render::engine = nullptr;
   state::backend = "";
   state::initialized = false;
diff --git a/test/include/polyscope_test.h b/test/include/polyscope_test.h
index c5b4a6e9..c3d8a572 100644
--- a/test/include/polyscope_test.h
+++ b/test/include/polyscope_test.h
@@ -38,12 +38,7 @@ class PolyscopeTest : public ::testing::Test {
   // Per-test-suite tear-down.
   // Called after the last test in this test suite.
   // Can be omitted if not needed.
-  /*
-  static void TearDownTestSuite() {
-    delete shared_resource_;
-    shared_resource_ = NULL;
-  }
-  */
+  static void TearDownTestSuite() { polyscope::shutdown(); }
 
   // You can define per-test set-up logic as usual.
   // virtual void SetUp() { ... }
diff --git a/test/src/basics_test.cpp b/test/src/basics_test.cpp
index afb2aafc..7f2cdc9d 100644
--- a/test/src/basics_test.cpp
+++ b/test/src/basics_test.cpp
@@ -88,6 +88,11 @@ TEST_F(PolyscopeTest, ShutdownAndReinitialize) {
   polyscope::shutdown();
   SetUpTestSuite();
   polyscope::show(3);
+
+  // do it twice -- we've had some bugs where the first shutdown doesn't clean up properly 
+  polyscope::shutdown();
+  SetUpTestSuite();
+  polyscope::show(3);
 }
 
 // Make sure that creating an empty buffer does not throw errors

From 21438934aab59205353949938246d0ad36adb1a4 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Sat, 28 Dec 2024 15:24:05 -0500
Subject: [PATCH 32/34] don't check asan leaks in egl test

---
 .github/workflows/linux.yml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 1bd35f07..0771284f 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -57,4 +57,7 @@ jobs:
       run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_mock
     
     - name: run test egl backend
-      run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL3_egl
+      # We get memory leaks inside of EGL that I can't track down. With ASAN, this means the exit code is always nonzero,
+      # which is indistinguishable from tests failing. The ASAN_OPTIONS=detect_leaks=0 skips checking leaks for this test 
+      # as a workaround.
+      run: cd test/build && ASAN_OPTIONS=detect_leaks=0 ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL3_egl

From c5eafee44d68474778194fd6ca0f779e24a27df4 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Sat, 28 Dec 2024 15:43:15 -0500
Subject: [PATCH 33/34] use asan settings for both configurations

---
 .github/workflows/linux.yml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 0771284f..656953a0 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -31,7 +31,10 @@ jobs:
       run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL_mock
     
     - name: run test egl backend
-      run: cd test/build && ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL3_egl
+      # We get memory leaks inside of EGL that I can't track down. With ASAN, this means the exit code is always nonzero,
+      # which is indistinguishable from tests failing. The ASAN_OPTIONS=detect_leaks=0 skips checking leaks for this test 
+      # as a workaround.
+      run: cd test/build && ASAN_OPTIONS=detect_leaks=0 ./bin/polyscope-test --gtest_catch_exceptions=0 backend=openGL3_egl
   
   build_shared:
     strategy:

From 59b7119c213f13e469dd5e1a8d4352883e064519 Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Sun, 29 Dec 2024 20:07:37 -0500
Subject: [PATCH 34/34] comment clarity

---
 include/polyscope/options.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/polyscope/options.h b/include/polyscope/options.h
index 9a92f381..356412ea 100644
--- a/include/polyscope/options.h
+++ b/include/polyscope/options.h
@@ -30,8 +30,9 @@ extern std::string printPrefix;
 // Should errors throw exceptions, or just display? (default false)
 extern bool errorsThrowExceptions;
 
-// Allow initialization to create headless backends (default: false)
-extern bool allowHeadlessBackends; 
+// Allow initialization to create headless backends when selecting a backend automatically
+// (they can still created explicitly by name) (default: false)
+extern bool allowHeadlessBackends;
 
 // Don't let the main loop run at more than this speed. (-1 disables) (default: 60)
 extern int maxFPS;