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Adding quad proper handling

pull/3695/head
Clement Jacob 2021-03-29 15:20:40 +02:00
parent 8e589221d7
commit 6d1a0c6054
1 changed files with 14 additions and 7 deletions
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21
code/PostProcessing/TriangulateProcess.cpp
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@ -214,14 +214,14 @@ bool TriangulateProcess::TriangulateMesh( aiMesh* pMesh)
aiFace* const last_face = curOut;
// ngon encoding: making sure that triangles are not recognized as false ngons.
// To do so, we make sure the first indice is not the same as previous triangle emitted.
unsigned int prev_first_indice = (unsigned int)-1;
if (curOut != out) prev_first_indice = (curOut - 1)->mIndices[0];
// if it's a simple point,line or triangle: just copy it
if( face.mNumIndices <= 3)
{
// ngon encoding: making sure that triangles are not recognized as false ngons.
// To do so, we make sure the first indice is not the same as previous triangle emitted.
unsigned int prev_first_indice = (unsigned int)-1;
if (curOut != out) prev_first_indice = (curOut - 1)->mIndices[0];
aiFace& nface = *curOut++;
nface.mNumIndices = face.mNumIndices;
nface.mIndices = face.mIndices;
@ -241,6 +241,11 @@ bool TriangulateProcess::TriangulateMesh( aiMesh* pMesh)
// quads can have at maximum one concave vertex. Determine
// this vertex (if it exists) and start tri-fanning from
// it.
//
// Due to ngon encoding, if this concave vertex is the same as the previously
// emitted triangle, we use the opposite vertex which also happens to work
// for tri-fanning a concave quad.
// ref: https://github.com/assimp/assimp/pull/3695#issuecomment-805999760
unsigned int start_vertex = 0;
for (unsigned int i = 0; i < 4; ++i) {
const aiVector3D& v0 = verts[face.mIndices[(i+3) % 4]];
@ -259,8 +264,10 @@ bool TriangulateProcess::TriangulateMesh( aiMesh* pMesh)
const float angle = std::acos(left*diag) + std::acos(right*diag);
if (angle > AI_MATH_PI_F) {
// this is the concave point
start_vertex = i;
// i is the concave point
// ngon encoding: if the concave vertex is same as last triangle first index,
// then we chose the opposite vertex.
start_vertex = (face.mIndices[i] != prev_first_indice) ? i : ((i+2) % 4);
break;
}
}