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Fixed crash due to me incorrectly deciding that the max number of quads which could share a vertex was four. I believe the correct value should actually be six.

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David Williams 2012-01-07 11:46:25 +00:00
parent c0eed7f7d3
commit a1ac90c711
2 changed files with 16 additions and 11 deletions
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7
library/PolyVoxCore/include/PolyVoxCore/CubicSurfaceExtractor.h
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@ -87,10 +87,9 @@ namespace PolyVox
//is the user needs per-vertex attributes, or to perform per vertex lighting. //is the user needs per-vertex attributes, or to perform per vertex lighting.
bool m_bMergeQuads; bool m_bMergeQuads;
//Although we try to avoid creating multiple vertices at the same location, sometimes this is unavoidable //This constant defines the maximum number of quads which can share a
//if they have different materials. For example, four different materials next to each other would mean //vertex in a cubic style mesh. See the initialisation for more details.
//four quads (though more triangles) sharing the vertex. As far as I can tell, four is the worst case scenario. static const uint32_t MaxVerticesPerPosition;
static const uint32_t MaxQuadsSharingVertex;
}; };
} }

20
library/PolyVoxCore/include/PolyVoxCore/CubicSurfaceExtractor.inl
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@ -23,8 +23,14 @@ freely, subject to the following restrictions:
namespace PolyVox namespace PolyVox
{ {
// We try to avoid duplicate vertices by checking whether a vertex has already been added at a given position.
// However, it is possible that vertices have the same position but differnt materials. In this case, the
// vertices are not true duplicates and both must be added to the mesh. As far as I can tell, it is possible to have
// at most six vertices with the same position but different materials. This worst-case scenario happens when we
// have a 2x2x2 group of voxels (all with different materials) and then we delete two voxels from opposing corners.
// The vertex position at the center of this group is then going to be used by six quads all with different materials.
template< template<typename> class VolumeType, typename VoxelType> template< template<typename> class VolumeType, typename VoxelType>
const uint32_t CubicSurfaceExtractor<VolumeType, VoxelType>::MaxQuadsSharingVertex = 4; const uint32_t CubicSurfaceExtractor<VolumeType, VoxelType>::MaxVerticesPerPosition = 6;
template< template<typename> class VolumeType, typename VoxelType> template< template<typename> class VolumeType, typename VoxelType>
CubicSurfaceExtractor<VolumeType, VoxelType>::CubicSurfaceExtractor(VolumeType<VoxelType>* volData, Region region, SurfaceMesh<PositionMaterial>* result, bool bMergeQuads) CubicSurfaceExtractor<VolumeType, VoxelType>::CubicSurfaceExtractor(VolumeType<VoxelType>* volData, Region region, SurfaceMesh<PositionMaterial>* result, bool bMergeQuads)
@ -43,7 +49,7 @@ namespace PolyVox
uint32_t uArrayWidth = m_regSizeInVoxels.getUpperCorner().getX() - m_regSizeInVoxels.getLowerCorner().getX() + 2; uint32_t uArrayWidth = m_regSizeInVoxels.getUpperCorner().getX() - m_regSizeInVoxels.getLowerCorner().getX() + 2;
uint32_t uArrayHeight = m_regSizeInVoxels.getUpperCorner().getY() - m_regSizeInVoxels.getLowerCorner().getY() + 2; uint32_t uArrayHeight = m_regSizeInVoxels.getUpperCorner().getY() - m_regSizeInVoxels.getLowerCorner().getY() + 2;
uint32_t arraySize[3]= {uArrayWidth, uArrayHeight, MaxQuadsSharingVertex}; uint32_t arraySize[3]= {uArrayWidth, uArrayHeight, MaxVerticesPerPosition};
m_previousSliceVertices.resize(arraySize); m_previousSliceVertices.resize(arraySize);
m_currentSliceVertices.resize(arraySize); m_currentSliceVertices.resize(arraySize);
memset(m_previousSliceVertices.getRawData(), 0xff, m_previousSliceVertices.getNoOfElements() * sizeof(IndexAndMaterial)); memset(m_previousSliceVertices.getRawData(), 0xff, m_previousSliceVertices.getNoOfElements() * sizeof(IndexAndMaterial));
@ -241,7 +247,7 @@ namespace PolyVox
uint32_t uX = static_cast<uint32_t>(fX + 0.75f); uint32_t uX = static_cast<uint32_t>(fX + 0.75f);
uint32_t uY = static_cast<uint32_t>(fY + 0.75f); uint32_t uY = static_cast<uint32_t>(fY + 0.75f);
for(uint32_t ct = 0; ct < MaxQuadsSharingVertex; ct++) for(uint32_t ct = 0; ct < MaxVerticesPerPosition; ct++)
{ {
IndexAndMaterial& rEntry = existingVertices[uX][uY][ct]; IndexAndMaterial& rEntry = existingVertices[uX][uY][ct];
@ -261,10 +267,10 @@ namespace PolyVox
} }
} }
//If we exit the loop here then apparently all the slots were full but none of // If we exit the loop here then apparently all the slots were full but none of them matched. I don't think
//them matched. I don't think this can happen so let's put an assert to make sure. // this can happen so let's put an assert to make sure. If you hit this assert then please report it to us!
assert(false); assert(false);
return 0; return -1; //Should never happen.
} }
template< template<typename> class VolumeType, typename VoxelType> template< template<typename> class VolumeType, typename VoxelType>
@ -301,7 +307,7 @@ namespace PolyVox
bool CubicSurfaceExtractor<VolumeType, VoxelType>::mergeQuads(Quad& q1, Quad& q2) bool CubicSurfaceExtractor<VolumeType, VoxelType>::mergeQuads(Quad& q1, Quad& q2)
{ {
//All four vertices of a given quad have the same material, //All four vertices of a given quad have the same material,
//so just check that the first pair or vertices match. //so just check that the first pair of vertices match.
if(std::abs(m_meshCurrent->getVertices()[q1.vertices[0]].getMaterial() - m_meshCurrent->getVertices()[q2.vertices[0]].getMaterial()) < 0.001) if(std::abs(m_meshCurrent->getVertices()[q1.vertices[0]].getMaterial() - m_meshCurrent->getVertices()[q2.vertices[0]].getMaterial()) < 0.001)
{ {
//Now check whether quad 2 is adjacent to quad one by comparing vertices. //Now check whether quad 2 is adjacent to quad one by comparing vertices.