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Work on MeshDecimator.

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This commit is contained in:
David Williams
2011-01-03 21:46:40 +00:00
parent 996dfac39c
commit 773cfc4887
7 changed files with 223 additions and 335 deletions
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370
library/PolyVoxCore/include/MeshDecimator.inl
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@ -34,11 +34,7 @@ namespace PolyVox
template <typename VertexType>
void MeshDecimator<VertexType>::execute()
{
// We will need the information from this function to
// determine when material boundary edges can collapse.
countNoOfNeighboursUsingMaterial();
buildTriangles();
buildConnectivityData();
fillInitialVertexMetadata(m_vecInitialVertexMetadata);
uint32_t noOfEdgesCollapsed;
@ -46,6 +42,12 @@ namespace PolyVox
{
noOfEdgesCollapsed = performDecimationPass(fMinDotProductForCollapse);
m_pInputMesh->removeDegenerateTris();
if(noOfEdgesCollapsed > 0)
{
//Build the connectivity data for the next pass. If this is slow, then look
//at adjusting it (based on vertex mapper?) rather than bulding from scratch.
buildConnectivityData();
}
//m_pInputMesh->removeUnusedVertices();
}while(noOfEdgesCollapsed > 0);
@ -58,36 +60,8 @@ namespace PolyVox
}
template <typename VertexType>
void MeshDecimator<VertexType>::buildTriangles(void)
void MeshDecimator<VertexType>::buildConnectivityData(void)
{
// Each triangle exists in this vector once.
vecOfTriCts.clear();
vecOfTriCts.resize(m_pInputMesh->m_vecTriangleIndices.size() / 3);
for(int triCt = 0; triCt < vecOfTriCts.size(); triCt++)
{
vecOfTriCts[triCt] = triCt;
}
vecOfTriNormals.clear();
vecOfTriNormals.resize(vecOfTriCts.size());
for(int ct = 0; ct < vecOfTriCts.size(); ct++)
{
int triCt = vecOfTriCts[ct];
int v0 = m_pInputMesh->m_vecTriangleIndices[triCt * 3 + 0];
int v1 = m_pInputMesh->m_vecTriangleIndices[triCt * 3 + 1];
int v2 = m_pInputMesh->m_vecTriangleIndices[triCt * 3 + 2];
//Handle degenerates?
Vector3DFloat v0v1 = m_pInputMesh->m_vecVertices[v1].position - m_pInputMesh->m_vecVertices[v0].position;
Vector3DFloat v0v2 = m_pInputMesh->m_vecVertices[v2].position - m_pInputMesh->m_vecVertices[v0].position;
Vector3DFloat normal = v0v1.cross(v0v2);
normal.normalise();
vecOfTriNormals[ct] = normal;
}
m_vecTriangles.clear();
m_vecTriangles.resize(m_pInputMesh->m_vecTriangleIndices.size() / 3);
for(int triCt = 0; triCt < m_vecTriangles.size(); triCt++)
@ -107,25 +81,27 @@ namespace PolyVox
m_vecTriangles[triCt].normal = normal;
}
trianglesUsingVertex.clear();
trianglesUsingVertex.resize(m_pInputMesh->m_vecVertices.size());
for(int ct = 0; ct < m_vecTriangles.size(); ct++)
{
trianglesUsingVertex[m_vecTriangles[ct].v0].push_back(ct);
trianglesUsingVertex[m_vecTriangles[ct].v1].push_back(ct);
trianglesUsingVertex[m_vecTriangles[ct].v2].push_back(ct);
}
}
template <typename VertexType>
void MeshDecimator<VertexType>::fillInitialVertexMetadata(std::vector<InitialVertexMetadata>& vecVertexMetadata)
void MeshDecimator<PositionMaterial>::fillInitialVertexMetadata(std::vector<InitialVertexMetadata>& vecVertexMetadata)
{
vecVertexMetadata.clear();
vecVertexMetadata.resize(m_pInputMesh->m_vecVertices.size());
//Initialise the metadata
for(int ct = 0; ct < vecVertexMetadata.size(); ct++)
{
vecVertexMetadata[ct].trianglesUsingVertex.clear();
vecVertexMetadata[ct].normal.setElements(0,0,0);
vecVertexMetadata[ct].isOnRegionEdge = false;
vecVertexMetadata[ct].isOnMaterialEdge = false;
}
for(int ct = 0; ct < m_vecTriangles.size(); ct++)
{
vecVertexMetadata[m_vecTriangles[ct].v0].trianglesUsingVertex.push_back(ct);
vecVertexMetadata[ct].vertexFlags.reset();
}
for(int outerCt = 0; outerCt < m_pInputMesh->m_vecVertices.size()-1; outerCt++)
@ -140,13 +116,10 @@ namespace PolyVox
}
}
//noOfDifferentNormals.clear();
//noOfDifferentNormals.resize(m_pInputMesh->m_vecVertices.size());
//std::fill(vecVertexMetadata.noOfDifferentNormals.begin(), vecVertexMetadata.noOfDifferentNormals.end(), 0);
for(int ct = 0; ct < m_pInputMesh->m_vecVertices.size(); ct++)
{
Vector3DFloat sumOfNormals(0.0f,0.0f,0.0f);
for(list<uint32_t>::const_iterator iter = vecVertexMetadata[ct].trianglesUsingVertex.cbegin(); iter != vecVertexMetadata[ct].trianglesUsingVertex.cend(); iter++)
for(list<uint32_t>::const_iterator iter = trianglesUsingVertex[ct].cbegin(); iter != trianglesUsingVertex[ct].cend(); iter++)
{
sumOfNormals += m_vecTriangles[*iter].normal;
}
@ -155,51 +128,77 @@ namespace PolyVox
vecVertexMetadata[ct].normal.normalise();
}
Vector3DFloat offset = static_cast<Vector3DFloat>(m_pInputMesh->m_Region.getLowerCorner());
for(int ct = 0; ct < m_pInputMesh->m_vecVertices.size(); ct++)
for(int ct = 0; ct < vecVertexMetadata.size(); ct++)
{
bool bInside = m_pInputMesh->m_Region.containsPoint(m_pInputMesh->m_vecVertices[ct].getPosition() + offset);
vecVertexMetadata[ct].isOnRegionEdge = !bInside;
Region regTransformed = m_pInputMesh->m_Region;
regTransformed.shift(regTransformed.getLowerCorner() * static_cast<int16_t>(-1));
//Plus and minus X
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_NEG_X, m_pInputMesh->m_vecVertices[ct].getPosition().getX() < regTransformed.getLowerCorner().getX() + 0.001f);
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_POS_X, m_pInputMesh->m_vecVertices[ct].getPosition().getX() > regTransformed.getUpperCorner().getX() - 0.001f);
//Plus and minus Y
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_NEG_Y, m_pInputMesh->m_vecVertices[ct].getPosition().getY() < regTransformed.getLowerCorner().getY() + 0.001f);
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_POS_Y, m_pInputMesh->m_vecVertices[ct].getPosition().getY() > regTransformed.getUpperCorner().getY() - 0.001f);
//Plus and minus Z
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_NEG_Z, m_pInputMesh->m_vecVertices[ct].getPosition().getZ() < regTransformed.getLowerCorner().getZ() + 0.001f);
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_POS_Z, m_pInputMesh->m_vecVertices[ct].getPosition().getZ() > regTransformed.getUpperCorner().getZ() - 0.001f);
}
}
template <typename VertexType>
void MeshDecimator<VertexType>::fillCurrentVertexMetadata(std::vector<CurrentVertexMetadata>& vecVertexMetadata)
void MeshDecimator<PositionMaterialNormal>::fillInitialVertexMetadata(std::vector<InitialVertexMetadata>& vecVertexMetadata)
{
vecVertexMetadata.clear();
vecVertexMetadata.resize(m_pInputMesh->m_vecVertices.size());
//Initialise the metadata
for(int ct = 0; ct < vecVertexMetadata.size(); ct++)
{
vecVertexMetadata[ct].trianglesUsingVertex.clear();
{
vecVertexMetadata[ct].vertexFlags.reset();
vecVertexMetadata[ct].isOnMaterialEdge = false;
vecVertexMetadata[ct].normal = m_pInputMesh->m_vecVertices[ct].normal;
}
//Determine triangles using each vertex
/*trianglesUsingVertex.clear();
trianglesUsingVertex.resize(m_pInputMesh->m_vecVertices.size());*/
for(int ct = 0; ct < m_pInputMesh->m_vecTriangleIndices.size(); ct++)
for(int ct = 0; ct < vecVertexMetadata.size(); ct++)
{
int triangle = ct / 3;
Region regTransformed = m_pInputMesh->m_Region;
regTransformed.shift(regTransformed.getLowerCorner() * static_cast<int16_t>(-1));
vecVertexMetadata[m_pInputMesh->m_vecTriangleIndices[ct]].trianglesUsingVertex.push_back(triangle);
//Plus and minus X
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_NEG_X, m_pInputMesh->m_vecVertices[ct].getPosition().getX() < regTransformed.getLowerCorner().getX() + 0.001f);
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_POS_X, m_pInputMesh->m_vecVertices[ct].getPosition().getX() > regTransformed.getUpperCorner().getX() - 0.001f);
//Plus and minus Y
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_NEG_Y, m_pInputMesh->m_vecVertices[ct].getPosition().getY() < regTransformed.getLowerCorner().getY() + 0.001f);
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_POS_Y, m_pInputMesh->m_vecVertices[ct].getPosition().getY() > regTransformed.getUpperCorner().getY() - 0.001f);
//Plus and minus Z
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_NEG_Z, m_pInputMesh->m_vecVertices[ct].getPosition().getZ() < regTransformed.getLowerCorner().getZ() + 0.001f);
vecVertexMetadata[ct].vertexFlags.set(VF_ON_GEOMETRY_EDGE_POS_Z, m_pInputMesh->m_vecVertices[ct].getPosition().getZ() > regTransformed.getUpperCorner().getZ() - 0.001f);
}
//If all three vertices have the same material then we are not on a material edge. If any vertex has a different
//material then all three vertices are on a material edge. E.g. If one vertex has material 'a' and the other two
//have material 'b', then the two 'b's are still on an edge (with 'a') even though they are the same as eachother.
for(int ct = 0; ct < m_vecTriangles.size(); ct++)
{
uint32_t v0 = m_vecTriangles[ct].v0;
uint32_t v1 = m_vecTriangles[ct].v1;
uint32_t v2 = m_vecTriangles[ct].v2;
bool allMatch =
(m_pInputMesh->m_vecVertices[v0].material == m_pInputMesh->m_vecVertices[v1].material) &&
(m_pInputMesh->m_vecVertices[v1].material == m_pInputMesh->m_vecVertices[v2].material);
if(!allMatch)
{
vecVertexMetadata[v0].isOnMaterialEdge = true;
vecVertexMetadata[v1].isOnMaterialEdge = true;
vecVertexMetadata[v2].isOnMaterialEdge = true;
}
}
}
template <typename VertexType>
uint32_t MeshDecimator<VertexType>::performDecimationPass(float fMinDotProductForCollapse)
{
// I'm using a vector of lists here, rather than a vector of sets,
// because I don't believe that duplicates should occur. But this
// might be worth checking if we have problems in the future.
/*trianglesUsingVertexCurrently.clear();
trianglesUsingVertexCurrently.resize(m_pInputMesh->m_vecVertices.size());
for(int ct = 0; ct < m_pInputMesh->m_vecTriangleIndices.size(); ct++)
{
int triangle = ct / 3;
trianglesUsingVertexCurrently[m_pInputMesh->m_vecTriangleIndices[ct]].push_back(triangle);
}*/
// Count how many edges we have collapsed
uint32_t noOfEdgesCollapsed = 0;
@ -223,13 +222,9 @@ namespace PolyVox
vertexLocked[ct] = false;
}
buildTriangles();
fillCurrentVertexMetadata(m_vecCurrentVertexMetadata);
//For each triange...
//For each triangle...
for(int ctIter = 0; ctIter < m_vecTriangles.size(); ctIter++)
{
if(attemptEdgeCollapse(m_vecTriangles[ctIter].v0, m_vecTriangles[ctIter].v1))
{
++noOfEdgesCollapsed;
@ -266,6 +261,12 @@ namespace PolyVox
template <typename VertexType>
bool MeshDecimator<VertexType>::attemptEdgeCollapse(uint32_t uSrc, uint32_t uDst)
{
//A vertex will be locked if it has already been involved in a collapse this pass.
if(vertexLocked[uSrc] || vertexLocked[uDst])
{
return false;
}
if(canCollapseEdge(uSrc, uDst))
{
//Move v0 onto v1
@ -280,51 +281,13 @@ namespace PolyVox
return false;
}
//This function looks at every vertex in the mesh and determines
//how many of it's neighbours have the same material.
template <typename VertexType>
void MeshDecimator<VertexType>::countNoOfNeighboursUsingMaterial(void)
{
//Find all the neighbouring vertices for each vertex
std::vector< std::set<int> > neighbouringVertices(m_pInputMesh->m_vecVertices.size());
for(int triCt = 0; triCt < m_pInputMesh->m_vecTriangleIndices.size() / 3; triCt++)
{
int v0 = m_pInputMesh->m_vecTriangleIndices[(triCt * 3 + 0)];
int v1 = m_pInputMesh->m_vecTriangleIndices[(triCt * 3 + 1)];
int v2 = m_pInputMesh->m_vecTriangleIndices[(triCt * 3 + 2)];
neighbouringVertices[v0].insert(v1);
neighbouringVertices[v0].insert(v2);
neighbouringVertices[v1].insert(v0);
neighbouringVertices[v1].insert(v2);
neighbouringVertices[v2].insert(v0);
neighbouringVertices[v2].insert(v1);
}
//For each vertex, check how many neighbours have the same material
m_vecNoOfNeighboursUsingMaterial.resize(m_pInputMesh->m_vecVertices.size());
for(int vertCt = 0; vertCt < m_pInputMesh->m_vecVertices.size(); vertCt++)
{
m_vecNoOfNeighboursUsingMaterial[vertCt] = 0;
for(std::set<int>::iterator iter = neighbouringVertices[vertCt].begin(); iter != neighbouringVertices[vertCt].end(); iter++)
{
if(m_pInputMesh->m_vecVertices[vertCt].getMaterial() == m_pInputMesh->m_vecVertices[*iter].getMaterial())
{
m_vecNoOfNeighboursUsingMaterial[vertCt]++;
}
}
}
}
// Returns true if every bit which is set in 'a' is also set in 'b'. The reverse does not need to be true.
template <typename VertexType>
bool MeshDecimator<VertexType>::isSubset(std::bitset<VF_NO_OF_FLAGS> a, std::bitset<VF_NO_OF_FLAGS> b)
{
bool result = true;
for(int ct = 1; ct < 7; ct++) //Start at '1' to skip material flag
for(int ct = 0; ct < VF_NO_OF_FLAGS; ct++)
{
if(a.test(ct))
{
@ -342,90 +305,15 @@ namespace PolyVox
//template <typename VertexType>
bool MeshDecimator<PositionMaterialNormal>::canCollapseEdge(uint32_t uSrc, uint32_t uDst)
{
//A vertex will be locked if it has already been involved in a collapse this pass.
if(vertexLocked[uSrc] || vertexLocked[uDst])
{
return false;
}
if(m_pInputMesh->m_vecVertices[uSrc].getMaterial() != m_pInputMesh->m_vecVertices[uDst].getMaterial())
{
return false;
}
//For now, don't collapse vertices on material edges...
if(m_pInputMesh->m_vecVertices[uSrc].isOnMaterialEdge() || m_pInputMesh->m_vecVertices[uDst].isOnMaterialEdge())
{
if(true)
{
bool pass = false;
bool allMatch = false;
// On the original undecimated mesh a material boundary vertex on a straight edge will
// have four neighbours with the same material. If it's on a corner it will have a
// different number. We only collapse straight edges to avoid changingthe shape of the
// material boundary.
if(m_vecNoOfNeighboursUsingMaterial[uSrc] == m_vecNoOfNeighboursUsingMaterial[uDst])
{
if(m_vecNoOfNeighboursUsingMaterial[uSrc] == 4)
{
allMatch = true;
}
}
bool movementValid = false;
Vector3DFloat movement = m_pInputMesh->m_vecVertices[uDst].getPosition() - m_pInputMesh->m_vecVertices[uSrc].getPosition();
movement.normalise();
if(movement.dot(Vector3DFloat(0,0,1)) > 0.999)
{
movementValid = true;
}
if(movement.dot(Vector3DFloat(0,1,0)) > 0.999)
{
movementValid = true;
}
if(movement.dot(Vector3DFloat(1,0,0)) > 0.999)
{
movementValid = true;
}
if(movement.dot(Vector3DFloat(0,0,-1)) > 0.999)
{
movementValid = true;
}
if(movement.dot(Vector3DFloat(0,-1,0)) > 0.999)
{
movementValid = true;
}
if(movement.dot(Vector3DFloat(-1,0,0)) > 0.999)
{
movementValid = true;
}
if(movementValid && allMatch)
{
pass = true;
}
if(!pass)
{
return false;
}
}
else //Material collapses not allowed
{
return false;
}
if(m_vecInitialVertexMetadata[uSrc].isOnMaterialEdge || m_vecInitialVertexMetadata[uDst].isOnMaterialEdge)
{
return false;
}
// Vertices on the geometrical edge of surface meshes need special handling.
// We check for this by whether any of the edge flags are set.
if(m_pInputMesh->m_vecVertices[uSrc].m_bFlags.any() || m_pInputMesh->m_vecVertices[uDst].m_bFlags.any())
if(m_vecInitialVertexMetadata[uSrc].vertexFlags.any() || m_vecInitialVertexMetadata[uDst].vertexFlags.any())
{
// Assume we can't collapse until we prove otherwise...
bool bCollapseGeometryEdgePair = false;
@ -433,7 +321,7 @@ namespace PolyVox
// We can collapse normal vertices onto edge vertices, and edge vertices
// onto corner vertices, but not vice-versa. Hence we check whether all
// the edge flags in the source vertex are also set in the destination vertex.
if(isSubset(m_pInputMesh->m_vecVertices[uSrc].m_bFlags, m_pInputMesh->m_vecVertices[uDst].m_bFlags))
if(isSubset(m_vecInitialVertexMetadata[uSrc].vertexFlags, m_vecInitialVertexMetadata[uDst].vertexFlags))
{
// In general adjacent regions surface meshes may collapse differently
// and this can cause cracks. We solve this by only allowing the collapse
@ -468,38 +356,26 @@ namespace PolyVox
return true;
}
//template <typename VertexType>
bool MeshDecimator<PositionMaterial>::canCollapseEdge(uint32_t uSrc, uint32_t uDst)
{
//A vertex will be locked if it has already been involved in a collapse this pass.
if(vertexLocked[uSrc] || vertexLocked[uDst])
{
return false;
}
bool bCanCollapse = true;
if(m_vecInitialVertexMetadata[uSrc].isOnMaterialEdge)
{
if(m_vecInitialVertexMetadata[uSrc].isOnRegionEdge)
{
assert(false); //Shouldn't be on both edge types.
return false;
}
else
{
return canCollapseMaterialEdge(uSrc, uDst);
}
bCanCollapse &= canCollapseMaterialEdge(uSrc, uDst);
}
else
if(m_vecInitialVertexMetadata[uSrc].vertexFlags.any())
{
if(m_vecInitialVertexMetadata[uSrc].isOnRegionEdge)
{
return canCollapseRegionEdge(uSrc, uDst);
}
else
{
return canCollapseNormalEdge(uSrc, uDst);
}
bCanCollapse &= canCollapseRegionEdge(uSrc, uDst);
}
if(bCanCollapse) //Only bother with this is the earlier tests passed.
{
bCanCollapse &= canCollapseNormalEdge(uSrc, uDst);
}
return bCanCollapse;
}
template <typename VertexType>
@ -510,43 +386,18 @@ namespace PolyVox
template <typename VertexType>
bool MeshDecimator<VertexType>::canCollapseRegionEdge(uint32_t uSrc, uint32_t uDst)
{
return false;
if(m_vecInitialVertexMetadata[uDst].isOnRegionEdge)
{
if(isSubset(m_vecInitialVertexMetadata[uSrc].vertexFlags, m_vecInitialVertexMetadata[uDst].vertexFlags) == false)
{
int matchingCoordinates = 0;
if(abs(m_pInputMesh->m_vecVertices[uSrc].getPosition().getX() - m_pInputMesh->m_vecVertices[uDst].getPosition().getX()) < 0.001)
{
matchingCoordinates++;
}
if(abs(m_pInputMesh->m_vecVertices[uSrc].getPosition().getY() - m_pInputMesh->m_vecVertices[uDst].getPosition().getY()) < 0.001)
{
matchingCoordinates++;
}
if(abs(m_pInputMesh->m_vecVertices[uSrc].getPosition().getZ() - m_pInputMesh->m_vecVertices[uDst].getPosition().getZ()) < 0.001)
{
matchingCoordinates++;
}
if(matchingCoordinates != 2)
{
return false;
}
if(m_vecInitialVertexMetadata[uSrc].trianglesUsingVertex.size() != m_vecInitialVertexMetadata[uDst].trianglesUsingVertex.size()) //Corner
{
return false;
}
if(m_vecInitialVertexMetadata[uSrc].normal.dot(m_vecInitialVertexMetadata[uDst].normal) < 0.999f)
{
return false;
}
return !collapseChangesFaceNormals(uSrc, uDst, 0.999f);
return false;
}
return false;
if(m_vecInitialVertexMetadata[uSrc].normal.dot(m_vecInitialVertexMetadata[uDst].normal) < 0.999f)
{
return false;
}
return true;
}
template <typename VertexType>
@ -559,12 +410,7 @@ namespace PolyVox
bool MeshDecimator<VertexType>::collapseChangesFaceNormals(uint32_t uSrc, uint32_t uDst, float fThreshold)
{
bool faceFlipped = false;
//list<uint32_t> triangles = trianglesUsingVertexCurrently[v0];
list<uint32_t> triangles = m_vecCurrentVertexMetadata[uSrc].trianglesUsingVertex;
/*set<uint32_t> triangles;
std::set_union(trianglesUsingVertex[v0].begin(), trianglesUsingVertex[v0].end(),
trianglesUsingVertex[v1].begin(), trianglesUsingVertex[v1].end(),
std::inserter(triangles, triangles.begin()));*/
list<uint32_t> triangles = trianglesUsingVertex[uSrc];
for(list<uint32_t>::iterator triIter = triangles.begin(); triIter != triangles.end(); triIter++)
{