Fixing encoding when lines and points are encountered
Clement Jacob
parent
fc0cf2ea8d
commit
fc2c12ad6a
|
|
@ -82,8 +82,7 @@ namespace {
|
|||
* @brief Helper struct used to simplify NGON encoding functions.
|
||||
*/
|
||||
struct NGONEncoder {
|
||||
NGONEncoder(const aiFace * outTriArray, size_t outTriArraySize)
|
||||
: mOutTriArrayBeg(outTriArray), mOutTriArrayEnd(outTriArray + outTriArraySize) {}
|
||||
NGONEncoder() : mLastNGONFirstIndex((unsigned int)-1) {}
|
||||
|
||||
/**
|
||||
* @brief Encode the current triangle, and make sure it is recognized as a triangle.
|
||||
|
|
@ -92,10 +91,9 @@ namespace {
|
|||
* part of the previous ngon. This method is to be used whenever you want to emit a real triangle,
|
||||
* and make sure it is seen as a triangle.
|
||||
*
|
||||
* @param tri Current triangle, must be in bounds of the outTriArray (= be a cell within the array).
|
||||
* @param tri Triangle to encode.
|
||||
*/
|
||||
void ngonEncodeTriangle(aiFace * tri) const {
|
||||
ai_assert(tri >= mOutTriArrayBeg && tri < mOutTriArrayEnd);
|
||||
void ngonEncodeTriangle(aiFace * tri) {
|
||||
ai_assert(tri->mNumIndices == 3);
|
||||
|
||||
// Rotate indices in new triangle to avoid ngon encoding false ngons
|
||||
|
|
@ -104,6 +102,40 @@ namespace {
|
|||
std::swap(tri->mIndices[0], tri->mIndices[2]);
|
||||
std::swap(tri->mIndices[1], tri->mIndices[2]);
|
||||
}
|
||||
|
||||
mLastNGONFirstIndex = tri->mIndices[0];
|
||||
}
|
||||
|
||||
/**
|
||||
* @brief Encode a quad (2 triangles) in ngon encoding, and make sure they are seen as a single ngon.
|
||||
*
|
||||
* @param tri1 First quad triangle
|
||||
* @param tri2 Second quad triangle
|
||||
*
|
||||
* @pre Triangles must be properly fanned from the most appropriate vertex.
|
||||
*/
|
||||
void ngonEncodeQuad(aiFace *tri1, aiFace *tri2) {
|
||||
ai_assert(tri1->mNumIndices == 3);
|
||||
ai_assert(tri2->mNumIndices == 3);
|
||||
ai_assert(tri1->mIndices[0] == tri2->mIndices[0]);
|
||||
|
||||
// If the selected fanning vertex is the same as the previously
|
||||
// emitted ngon, 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
|
||||
if (isConsideredSameAsLastNgon(tri1)) {
|
||||
// Right-rotate indices for tri1 (index 2 becomes the new fanning vertex)
|
||||
std::swap(tri1->mIndices[0], tri1->mIndices[2]);
|
||||
std::swap(tri1->mIndices[1], tri1->mIndices[2]);
|
||||
|
||||
// Left-rotate indices for tri2 (index 2 becomes the new fanning vertex)
|
||||
std::swap(tri2->mIndices[1], tri2->mIndices[2]);
|
||||
std::swap(tri2->mIndices[0], tri2->mIndices[2]);
|
||||
|
||||
ai_assert(tri1->mIndices[0] == tri2->mIndices[0]);
|
||||
}
|
||||
|
||||
mLastNGONFirstIndex = tri1->mIndices[0];
|
||||
}
|
||||
|
||||
/**
|
||||
|
|
@ -114,26 +146,12 @@ namespace {
|
|||
* @return false If used as is, this triangle is not considered part of the last ngon.
|
||||
*/
|
||||
bool isConsideredSameAsLastNgon(const aiFace * tri) const {
|
||||
ai_assert(tri >= mOutTriArrayBeg && tri < mOutTriArrayEnd);
|
||||
ai_assert(tri->mNumIndices == 3);
|
||||
|
||||
// First triangle to be emitted, so no problem here
|
||||
if (tri == mOutTriArrayBeg) return false;
|
||||
|
||||
const aiFace * prevTri = tri - 1;
|
||||
return tri->mIndices[0] == prevTri->mIndices[0];
|
||||
return tri->mIndices[0] == mLastNGONFirstIndex;
|
||||
}
|
||||
|
||||
private:
|
||||
/**
|
||||
* @brief Begining of triangulation process out triangles array
|
||||
*/
|
||||
const aiFace * mOutTriArrayBeg;
|
||||
|
||||
/**
|
||||
* @brief End of triangulation process out triangles array (out of bounds, a la C++ iterators).
|
||||
*/
|
||||
const aiFace * mOutTriArrayEnd;
|
||||
unsigned int mLastNGONFirstIndex;
|
||||
};
|
||||
|
||||
}
|
||||
|
|
@ -245,7 +263,7 @@ bool TriangulateProcess::TriangulateMesh( aiMesh* pMesh)
|
|||
std::vector<aiVector3D> temp_verts3d(max_out+2); /* temporary storage for vertices */
|
||||
std::vector<aiVector2D> temp_verts(max_out+2);
|
||||
|
||||
const NGONEncoder ngonEncoder(out, numOut);
|
||||
NGONEncoder ngonEncoder;
|
||||
|
||||
// Apply vertex colors to represent the face winding?
|
||||
#ifdef AI_BUILD_TRIANGULATE_COLOR_FACE_WINDING
|
||||
|
|
@ -290,7 +308,9 @@ bool TriangulateProcess::TriangulateMesh( aiMesh* pMesh)
|
|||
nface.mIndices = face.mIndices;
|
||||
face.mIndices = nullptr;
|
||||
|
||||
// points and lines don't require ngon encoding (and are not supported either!)
|
||||
if (nface.mNumIndices == 3) ngonEncoder.ngonEncodeTriangle(&nface);
|
||||
|
||||
continue;
|
||||
}
|
||||
// optimized code for quadrilaterals
|
||||
|
|
@ -333,20 +353,6 @@ bool TriangulateProcess::TriangulateMesh( aiMesh* pMesh)
|
|||
nface.mIndices[1] = temp[(start_vertex + 1) % 4];
|
||||
nface.mIndices[2] = temp[(start_vertex + 2) % 4];
|
||||
|
||||
// Due to NGON encoding, if the selected fanning vertex is the same as the previously
|
||||
// emitted ngon, 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
|
||||
//
|
||||
// @warning No need to call ngonEncoder.ngonEncodeTriangle() here. We want these 2 faces to be seen as
|
||||
// a single quad, not 2 separate triangles. This is the whole purpose!
|
||||
if (ngonEncoder.isConsideredSameAsLastNgon(&nface)) {
|
||||
start_vertex = (start_vertex+2) % 4;
|
||||
nface.mIndices[0] = temp[start_vertex];
|
||||
nface.mIndices[1] = temp[(start_vertex + 1) % 4];
|
||||
nface.mIndices[2] = temp[(start_vertex + 2) % 4];
|
||||
}
|
||||
|
||||
aiFace& sface = *curOut++;
|
||||
sface.mNumIndices = 3;
|
||||
sface.mIndices = new unsigned int[3];
|
||||
|
|
@ -357,6 +363,9 @@ bool TriangulateProcess::TriangulateMesh( aiMesh* pMesh)
|
|||
|
||||
// prevent double deletion of the indices field
|
||||
face.mIndices = nullptr;
|
||||
|
||||
ngonEncoder.ngonEncodeQuad(&nface, &sface);
|
||||
|
||||
continue;
|
||||
}
|
||||
else
|
||||
|
|
|
|||
Loading…
Reference in New Issue