private static unsafe void CollectAllVerticesFromSubTree(BoundingVolumeHierarchy.Node *nodes, int subTreeNodeIndex,
NativeList <MeshConnectivityBuilder.Primitive> primitives, NativeList <float3> vertices)
{
int *nodesIndexStack = stackalloc int[BoundingVolumeHierarchy.Constants.UnaryStackSize];
int stackSize = 1;
nodesIndexStack[0] = subTreeNodeIndex;
do
{
BoundingVolumeHierarchy.Node node = nodes[nodesIndexStack[--stackSize]];
if (node.IsLeaf)
{
for (int i = 0; i < 4; i++)
{
if (node.IsChildValid(i))
{
MeshConnectivityBuilder.Primitive p = primitives[node.Data[i]];
vertices.Add(p.Vertices[0]);
vertices.Add(p.Vertices[1]);
vertices.Add(p.Vertices[2]);
if ((p.Flags & MeshConnectivityBuilder.PrimitiveFlags.DefaultTrianglePairFlags) != 0)
{
vertices.Add(p.Vertices[3]);
}
}
}
}
else
{
for (int i = 0; i < 4; i++)
{
if (node.IsChildValid(i))
{
nodesIndexStack[stackSize++] = node.Data[i];
}
}
}
} while (stackSize > 0);
}
private static unsafe NativeArray <int> ProducedPrimitivesCountPerSubTree(BoundingVolumeHierarchy.Node *nodes, int nodeCount)
{
var primitivesPerNode = new NativeArray <int>(nodeCount, Allocator.Temp);
for (int nodeIndex = nodeCount - 1; nodeIndex >= 0; nodeIndex--)
{
BoundingVolumeHierarchy.Node node = nodes[nodeIndex];
if (node.IsLeaf)
{
primitivesPerNode[nodeIndex] = node.NumValidChildren();
}
else
{
primitivesPerNode[nodeIndex] =
primitivesPerNode[node.Data[0]] + primitivesPerNode[node.Data[1]] +
primitivesPerNode[node.Data[2]] + primitivesPerNode[node.Data[3]];
}
}
return(primitivesPerNode);
}
internal static unsafe TempSection BuildSections(BoundingVolumeHierarchy.Node *nodes, int nodeCount, NativeList <MeshConnectivityBuilder.Primitive> primitives)
{
var tempSections = new TempSection()
{
PrimitivesFlags = new NativeList <Mesh.PrimitiveFlags>(Allocator.Temp),
Primitives = new NativeList <Mesh.PrimitiveVertexIndices>(Allocator.Temp),
Vertices = new NativeList <float3>(Allocator.Temp),
Ranges = new NativeList <TempSectionRanges>(Allocator.Temp)
};
if (primitives.Length == 0)
{
// Early-out in the case of no input primitives
return(tempSections);
}
// Traverse the tree and break out geometry into sections
int *nodesIndexStack = stackalloc int[BoundingVolumeHierarchy.Constants.UnaryStackSize];
int stackSize = 1;
nodesIndexStack[0] = 1;
const float uniqueVerticesPerPrimitiveFactor = 1.5f;
var primitivesCountInSubTree = ProducedPrimitivesCountPerSubTree(nodes, nodeCount);
var subTreeIndices = new NativeList <int>(Allocator.Temp);
var nodeIndices = new NativeList <int>(Allocator.Temp);
var tmpVertices = new NativeList <float3>(Allocator.Temp);
do
{
int nodeIndex = nodesIndexStack[--stackSize];
int subTreeVertexCountEstimate = (int)(uniqueVerticesPerPrimitiveFactor * primitivesCountInSubTree[nodeIndex]);
subTreeIndices.Clear();
if (subTreeVertexCountEstimate < Mesh.Section.MaxNumVertices)
{
subTreeIndices.Add(nodeIndex);
}
else
{
// Sub tree is too big, break it up.
BoundingVolumeHierarchy.Node node = nodes[nodeIndex];
for (int i = 0; i < 4; i++)
{
if (node.IsChildValid(i))
{
int childNodeIndex = node.Data[i];
int nodeSubTreeVertexCount = (int)(uniqueVerticesPerPrimitiveFactor * primitivesCountInSubTree[childNodeIndex]);
if (nodeSubTreeVertexCount < Mesh.Section.MaxNumVertices)
{
subTreeIndices.Add(childNodeIndex);
}
else
{
nodesIndexStack[stackSize++] = childNodeIndex;
}
}
}
}
float tempUniqueVertexPrimitiveFactor = 1.0f;
const float factorStepIncrement = 0.25f;
while (subTreeIndices.Length > 0)
{
// Try to combine sub trees if multiple sub trees can fit into one section.
nodeIndices.Clear();
int vertexCountEstimate = 0;
for (var i = 0; i < subTreeIndices.Length; ++i)
{
var subTreeNodeIndex = subTreeIndices[i];
int nodeIndexCount = (int)(tempUniqueVertexPrimitiveFactor * primitivesCountInSubTree[subTreeNodeIndex]);
if (vertexCountEstimate + nodeIndexCount < Mesh.Section.MaxNumVertices)
{
vertexCountEstimate += nodeIndexCount;
nodeIndices.Add(subTreeNodeIndex);
}
}
if (nodeIndices.Length == 0)
{
// We failed to fit any sub tree into sections.
// Split up nodes and push them to stack.
for (var index = 0; index < subTreeIndices.Length; ++index)
{
var subTreeNodeIndex = subTreeIndices[index];
BoundingVolumeHierarchy.Node nodeToSplit = nodes[subTreeNodeIndex];
for (int i = 0; i < 4; i++)
{
if (nodeToSplit.IsChildValid(i))
{
nodesIndexStack[stackSize++] = nodeToSplit.Data[i];
}
}
}
subTreeIndices.Clear();
continue;
}
// Collect vertices from all sub trees.
tmpVertices.Clear();
for (var i = 0; i < nodeIndices.Length; ++i)
{
var subTreeNodeIndex = nodeIndices[i];
CollectAllVerticesFromSubTree(nodes, subTreeNodeIndex, primitives, tmpVertices);
}
var vertexIndices = new NativeArray <int>(tmpVertices.Length, Allocator.Temp);
for (int i = 0; i < vertexIndices.Length; i++)
{
vertexIndices[i] = i;
}
NativeList <float3> uniqueVertices = MeshConnectivityBuilder.WeldVertices(vertexIndices, new NativeArray <float3>(tmpVertices, Allocator.Temp));
if (uniqueVertices.Length < Mesh.Section.MaxNumVertices)
{
BuildSectionGeometry(tempSections, primitives, nodeIndices, nodes, new NativeArray <float3>(uniqueVertices, Allocator.Temp));
// Remove used indices
for (var i = 0; i < nodeIndices.Length; ++i)
{
var nodeTreeIndex = nodeIndices[i];
subTreeIndices.RemoveAtSwapBack(subTreeIndices.IndexOf(nodeTreeIndex));
}
}
else
{
// Estimate of num vertices per primitives was wrong.
// Increase the tempUniqueVertexPrimitiveFactor.
tempUniqueVertexPrimitiveFactor += factorStepIncrement;
}
}
}while (stackSize > 0);
return(tempSections);
}
private static unsafe void BuildSectionGeometry(TempSection sections, NativeList <MeshConnectivityBuilder.Primitive> primitives, NativeList <int> subTreeNodeIndices, BoundingVolumeHierarchy.Node *nodes, NativeArray <float3> vertices)
{
var sectionIndex = sections.Ranges.Length;
var newSectionRange = new TempSectionRanges
{
VerticesMin = sections.Vertices.Length,
PrimitivesFlagsMin = sections.PrimitivesFlags.Length,
PrimitivesMin = sections.Primitives.Length
};
sections.Vertices.AddRange(vertices);
int *nodesIndexStack = stackalloc int[BoundingVolumeHierarchy.Constants.UnaryStackSize];
for (var rootIndex = 0; rootIndex < subTreeNodeIndices.Length; ++rootIndex)
{
var root = subTreeNodeIndices[rootIndex];
int stackSize = 1;
nodesIndexStack[0] = root;
do
{
int nodeIndex = nodesIndexStack[--stackSize];
ref BoundingVolumeHierarchy.Node node = ref nodes[nodeIndex];
if (node.IsLeaf)
{
for (int i = 0; i < 4; i++)
{
if (node.IsChildValid(i))
{
MeshConnectivityBuilder.Primitive p = primitives[node.Data[i]];
sections.PrimitivesFlags.Add(ConvertPrimitiveFlags(p.Flags));
int vertexCount = (p.Flags & MeshConnectivityBuilder.PrimitiveFlags.IsTrianglePair) != 0 ? 4 : 3;
Mesh.PrimitiveVertexIndices sectionPrimitive = new Mesh.PrimitiveVertexIndices();
byte *vertexIndices = §ionPrimitive.A;
for (int v = 0; v < vertexCount; v++)
{
vertexIndices[v] = (byte)vertices.IndexOf(p.Vertices[v]);
}
if (vertexCount == 3)
{
sectionPrimitive.D = sectionPrimitive.C;
}
sections.Primitives.Add(sectionPrimitive);
int primitiveSectionIndex = sections.Primitives.Length - newSectionRange.PrimitivesMin - 1;
// Update primitive index in the BVH.
node.Data[i] = (sectionIndex << 8) | primitiveSectionIndex;
}
}
}
else
{
for (int i = 0; i < 4; i++)
{
if (node.IsChildValid(i))
{
nodesIndexStack[stackSize++] = node.Data[i];
}
}
}
} while (stackSize > 0);
}
