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Correct tangent generation #1

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Correct tangent generation #1

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7389128
See line 612 in mikktspace.c
watlok Dec 21, 2025
df71cce
Correct bitangent generation. See line 986 in mikktspace.c
watlok Dec 21, 2025
e975a31
Could generate incorrect tangents and caused sign flip on final tange…
watlok Dec 21, 2025
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6 changes: 3 additions & 3 deletions mikktspace.odin
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Original file line number Diff line number Diff line change
Expand Up @@ -525,7 +525,7 @@ merge_verts_fast :: proc(piTriList_in_and_out: []int, pTmpVert: []Tmp_Vert, pCon
// is no longer strictly between fMin and fMax values.
if fSep >= fvMax[channel] || fSep <= fvMin[channel] {
// complete the weld
for l in 0 ..= iR_in {
for l in iL_in ..= iR_in {
i := pTmpVert[l].index
index := piTriList_in_and_out[i]
vP := get_position(pContext, index)
Expand Down Expand Up @@ -898,7 +898,7 @@ init_tri_info :: proc(pTriInfos: []Tri_Info, piTriListIn: []int, pContext: ^Cont
fSignedAreaSTx2 := t21x * t31y - t21y * t31x

vOs := (t31y * d1) - (t21y * d2)
vOt := (-t31x * d1) - (t21x * d2)
vOt := (-t31x * d1) + (t21x * d2)

if fSignedAreaSTx2 > 0.0 {
pTriInfos[f].iFlag |= {.OrientPreserving}
Expand All @@ -908,7 +908,7 @@ init_tri_info :: proc(pTriInfos: []Tri_Info, piTriListIn: []int, pContext: ^Cont
fAbsArea := math.abs(fSignedAreaSTx2)
fLenOs := linalg.length(vOs)
fLenOt := linalg.length(vOt)
fS: f32 = .OrientPreserving in pTriInfos[f].iFlag ? (-1.0) : 1.0
fS: f32 = .OrientPreserving in pTriInfos[f].iFlag ? 1.0 : (-1.0)
if fLenOs != 0.0 do pTriInfos[f].vOs = (fS / fLenOs) * vOs
if fLenOt != 0.0 do pTriInfos[f].vOt = (fS / fLenOt) * vOt

Expand Down