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Merge pull request #4892 from lsnoel/fixLHNormals 

Correctly consider aiProcess_FlipWindingOrder and aiProcess_MakeLeftHanded when generating normals
pull/4904/head
Kim Kulling 2023-01-24 00:16:21 +01:00 committed by GitHub
parent 8463242449 57054415cf
commit 3e7121e1cc
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 12 additions and 4 deletions
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7
code/PostProcessing/GenFaceNormalsProcess.cpp
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@ -67,6 +67,7 @@ GenFaceNormalsProcess::~GenFaceNormalsProcess() = default;
bool GenFaceNormalsProcess::IsActive(unsigned int pFlags) const {
force_ = (pFlags & aiProcess_ForceGenNormals) != 0;
flippedWindingOrder_ = (pFlags & aiProcess_FlipWindingOrder) != 0;
leftHanded_ = (pFlags & aiProcess_MakeLeftHanded) != 0;
return (pFlags & aiProcess_GenNormals) != 0;
}
@ -131,8 +132,10 @@ bool GenFaceNormalsProcess::GenMeshFaceNormals(aiMesh *pMesh) {
const aiVector3D *pV1 = &pMesh->mVertices[face.mIndices[0]];
const aiVector3D *pV2 = &pMesh->mVertices[face.mIndices[1]];
const aiVector3D *pV3 = &pMesh->mVertices[face.mIndices[face.mNumIndices - 1]];
if (flippedWindingOrder_)
std::swap( pV2, pV3 );
// Boolean XOR - if either but not both of these flags is set, then the winding order has
// changed and the cross product to calculate the normal needs to be reversed
if (flippedWindingOrder_ != leftHanded_)
std::swap(pV2, pV3);
const aiVector3D vNor = ((*pV2 - *pV1) ^ (*pV3 - *pV1)).NormalizeSafe();
for (unsigned int i = 0; i < face.mNumIndices; ++i) {

1
code/PostProcessing/GenFaceNormalsProcess.h
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@ -81,6 +81,7 @@ private:
bool GenMeshFaceNormals(aiMesh* pcMesh);
mutable bool force_ = false;
mutable bool flippedWindingOrder_ = false;
mutable bool leftHanded_ = false;
};
} // end of namespace Assimp

7
code/PostProcessing/GenVertexNormalsProcess.cpp
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@ -69,6 +69,7 @@ GenVertexNormalsProcess::~GenVertexNormalsProcess() = default;
bool GenVertexNormalsProcess::IsActive(unsigned int pFlags) const {
force_ = (pFlags & aiProcess_ForceGenNormals) != 0;
flippedWindingOrder_ = (pFlags & aiProcess_FlipWindingOrder) != 0;
leftHanded_ = (pFlags & aiProcess_MakeLeftHanded) != 0;
return (pFlags & aiProcess_GenSmoothNormals) != 0;
}
@ -141,8 +142,10 @@ bool GenVertexNormalsProcess::GenMeshVertexNormals(aiMesh *pMesh, unsigned int m
const aiVector3D *pV1 = &pMesh->mVertices[face.mIndices[0]];
const aiVector3D *pV2 = &pMesh->mVertices[face.mIndices[1]];
const aiVector3D *pV3 = &pMesh->mVertices[face.mIndices[face.mNumIndices - 1]];
if (flippedWindingOrder_)
std::swap( pV2, pV3 );
// Boolean XOR - if either but not both of these flags is set, then the winding order has
// changed and the cross product to calculate the normal needs to be reversed
if (flippedWindingOrder_ != leftHanded_)
std::swap(pV2, pV3);
const aiVector3D vNor = ((*pV2 - *pV1) ^ (*pV3 - *pV1)).NormalizeSafe();
for (unsigned int i = 0; i < face.mNumIndices; ++i) {

1
code/PostProcessing/GenVertexNormalsProcess.h
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@ -105,6 +105,7 @@ private:
ai_real configMaxAngle;
mutable bool force_ = false;
mutable bool flippedWindingOrder_ = false;
mutable bool leftHanded_ = false;
};
} // end of namespace Assimp