diff --git a/demo/main.js b/demo/main.js
index 5812615..f9096fe 100644
--- a/demo/main.js
+++ b/demo/main.js
@@ -49,7 +49,7 @@ class DemoApp {
             const [px, py] = this.prevPos;
             const [x, y] = [e.offsetX, e.offsetY];
             this.prevPos = [x, y];
-            
+
             let [yaw, pitch, dist] = this.viewParams.cameraYPD;
             yaw -= (x-px)*0.01;
             pitch -= (y-py)*0.01;
@@ -57,6 +57,13 @@ class DemoApp {
             this.viewParams.cameraYPD.set([yaw, pitch, dist]);
         });
 
+        this.canvas.addEventListener('wheel', e=>{
+            let [yaw, pitch, dist] = this.viewParams.cameraYPD;
+            dist -= e.deltaY*0.001;
+            dist = Math.min(Math.max(dist, 0.01), 20);
+            this.viewParams.cameraYPD.set([yaw, pitch, dist]);
+        });
+
         let name = location.hash.slice(1);
         if (!(name in this.demos)) {
             name = 'NeuralCA';
@@ -164,4 +171,4 @@ class DemoApp {
         if (f) f.apply(canvas);
     }
 
-}
\ No newline at end of file
+}