public static unsafe int[] GenerateIndexBufferAEN(IndexBufferBinding indexBuffer, VertexBufferBinding vertexBuffer, CommandList commandList = null)
{
// More info at http://developer.download.nvidia.com/whitepapers/2010/PN-AEN-Triangles-Whitepaper.pdf
// This implementation might need some performance improvements
var triangleCount = indexBuffer.Count / 3;
var newIndices = new int[triangleCount * 12];
var positionMapping = GenerateIndexMapping(vertexBuffer, commandList, "POSITION");
var dominantEdges = new Dictionary <EdgeKeyAEN, EdgeAEN>();
var dominantVertices = new Dictionary <int, int>();
var indexSize = indexBuffer.Is32Bit? 4: 2;
fixed(byte *indexBufferStart = &indexBuffer.Buffer.GetDataSafe(commandList)[indexBuffer.Offset])
{
var triangleIndices = stackalloc int[3];
var positionIndices = stackalloc int[3];
// Step 2: prepare initial data
for (int i = 0; i < triangleCount; ++i)
{
var oldIndices = indexBufferStart + i * 3 * indexSize;
if (indexSize == 2)
{
var oldIndicesShort = (short *)oldIndices;
triangleIndices[0] = oldIndicesShort[0];
triangleIndices[1] = oldIndicesShort[1];
triangleIndices[2] = oldIndicesShort[2];
}
else
{
var oldIndicesShort = (int *)oldIndices;
triangleIndices[0] = oldIndicesShort[0];
triangleIndices[1] = oldIndicesShort[1];
triangleIndices[2] = oldIndicesShort[2];
}
positionIndices[0] = positionMapping.Indices[triangleIndices[0]];
positionIndices[1] = positionMapping.Indices[triangleIndices[1]];
positionIndices[2] = positionMapping.Indices[triangleIndices[2]];
newIndices[i * 12 + 0] = triangleIndices[0];
newIndices[i * 12 + 1] = triangleIndices[1];
newIndices[i * 12 + 2] = triangleIndices[2];
newIndices[i * 12 + 3] = triangleIndices[0];
newIndices[i * 12 + 4] = triangleIndices[1];
newIndices[i * 12 + 5] = triangleIndices[1];
newIndices[i * 12 + 6] = triangleIndices[2];
newIndices[i * 12 + 7] = triangleIndices[2];
newIndices[i * 12 + 8] = triangleIndices[0];
newIndices[i * 12 + 9] = triangleIndices[0];
newIndices[i * 12 + 10] = triangleIndices[1];
newIndices[i * 12 + 11] = triangleIndices[2];
// Step 2b/2c: Build dominant vertex/edge list
for (int j = 0; j < 3; ++j)
{
dominantVertices[positionIndices[j]] = triangleIndices[j];
var edge = new EdgeAEN(
triangleIndices[((j + 0) % 3)],
triangleIndices[((j + 1) % 3)],
positionIndices[((j + 0) % 3)],
positionIndices[((j + 1) % 3)]);
dominantEdges[new EdgeKeyAEN(edge)] = edge;
edge = edge.Reverse();
dominantEdges[new EdgeKeyAEN(edge)] = edge;
}
}
// Step3: Find dominant vertex/edge
for (int i = 0; i < triangleCount; ++i)
{
var oldIndices = indexBufferStart + i * 3 * indexSize;
if (indexSize == 2)
{
var oldIndicesShort = (short *)oldIndices;
triangleIndices[0] = oldIndicesShort[0];
triangleIndices[1] = oldIndicesShort[1];
triangleIndices[2] = oldIndicesShort[2];
}
else
{
var oldIndicesShort = (int *)oldIndices;
triangleIndices[0] = oldIndicesShort[0];
triangleIndices[1] = oldIndicesShort[1];
triangleIndices[2] = oldIndicesShort[2];
}
positionIndices[0] = positionMapping.Indices[triangleIndices[0]];
positionIndices[1] = positionMapping.Indices[triangleIndices[1]];
positionIndices[2] = positionMapping.Indices[triangleIndices[2]];
for (int j = 0; j < 3; ++j)
{
// Dominant edge
int vertexKey;
if (dominantVertices.TryGetValue(positionIndices[j], out vertexKey))
{
newIndices[i * 12 + 9 + j] = vertexKey;
}
// Dominant vertex
EdgeAEN edge;
var edgeKey = new EdgeKeyAEN(positionIndices[((j + 0) % 3)], positionIndices[((j + 1) % 3)]);
if (dominantEdges.TryGetValue(edgeKey, out edge))
{
newIndices[i * 12 + 3 + j * 2 + 0] = edge.Index0;
newIndices[i * 12 + 3 + j * 2 + 1] = edge.Index1;
}
}
}
}
return(newIndices);
}
/// <summary>
/// Generates the index buffer with dominant edge and vertex informations.
/// Each triangle gets its indices expanded to 12 control points, with 0 to 2 being original triangle,
/// 3 to 8 being dominant edges and 9 to 11 being dominant vertices.
/// </summary>
/// <param name="meshData">The mesh data.</param>
public static unsafe void GenerateIndexBufferAEN(this MeshDrawData meshData)
{
// For now, require a MeshData with only one vertex buffer and one index buffer
if (meshData.VertexBuffers.Length != 1 || meshData.IndexBuffer == null)
{
throw new NotImplementedException();
}
// More info at http://developer.download.nvidia.com/whitepapers/2010/PN-AEN-Triangles-Whitepaper.pdf
// This implementation might need some performance improvements
var indexBuffer = meshData.IndexBuffer;
var triangleCount = indexBuffer.Count / 3;
var newIndices = new int[triangleCount * 12];
var positionMapping = GenerateIndexMapping(meshData.VertexBuffers[0], "POSITION");
var dominantEdges = new Dictionary <EdgeKeyAEN, EdgeAEN>();
var dominantVertices = new Dictionary <int, int>();
fixed(byte *indexBufferStart = &indexBuffer.Buffer.Value.Content[indexBuffer.Offset])
{
var oldIndices = (int *)indexBufferStart;
var triangleIndices = stackalloc int[3];
var positionIndices = stackalloc int[3];
// Step 2: prepare initial data
for (int i = 0; i < triangleCount; ++i)
{
triangleIndices[0] = oldIndices[i * 3 + 0];
triangleIndices[1] = oldIndices[i * 3 + 1];
triangleIndices[2] = oldIndices[i * 3 + 2];
positionIndices[0] = positionMapping.Indices[triangleIndices[0]];
positionIndices[1] = positionMapping.Indices[triangleIndices[1]];
positionIndices[2] = positionMapping.Indices[triangleIndices[2]];
newIndices[i * 12 + 0] = triangleIndices[0];
newIndices[i * 12 + 1] = triangleIndices[1];
newIndices[i * 12 + 2] = triangleIndices[2];
newIndices[i * 12 + 3] = triangleIndices[0];
newIndices[i * 12 + 4] = triangleIndices[1];
newIndices[i * 12 + 5] = triangleIndices[1];
newIndices[i * 12 + 6] = triangleIndices[2];
newIndices[i * 12 + 7] = triangleIndices[2];
newIndices[i * 12 + 8] = triangleIndices[0];
newIndices[i * 12 + 9] = triangleIndices[0];
newIndices[i * 12 + 10] = triangleIndices[1];
newIndices[i * 12 + 11] = triangleIndices[2];
// Step 2b/2c: Build dominant vertex/edge list
for (int j = 0; j < 3; ++j)
{
dominantVertices[positionIndices[j]] = triangleIndices[j];
var edge = new EdgeAEN(
triangleIndices[((j + 0) % 3)],
triangleIndices[((j + 1) % 3)],
positionIndices[((j + 0) % 3)],
positionIndices[((j + 1) % 3)]);
dominantEdges[new EdgeKeyAEN(edge)] = edge;
edge = edge.Reverse();
dominantEdges[new EdgeKeyAEN(edge)] = edge;
}
}
// Step3: Find dominant vertex/edge
for (int i = 0; i < triangleCount; ++i)
{
triangleIndices[0] = oldIndices[i * 3 + 0];
triangleIndices[1] = oldIndices[i * 3 + 1];
triangleIndices[2] = oldIndices[i * 3 + 2];
positionIndices[0] = positionMapping.Indices[triangleIndices[0]];
positionIndices[1] = positionMapping.Indices[triangleIndices[1]];
positionIndices[2] = positionMapping.Indices[triangleIndices[2]];
for (int j = 0; j < 3; ++j)
{
// Dominant edge
int vertexKey;
if (dominantVertices.TryGetValue(positionIndices[j], out vertexKey))
{
newIndices[i * 12 + 9 + j] = vertexKey;
}
// Dominant vertex
EdgeAEN edge;
var edgeKey = new EdgeKeyAEN(positionIndices[((j + 0) % 3)], positionIndices[((j + 1) % 3)]);
if (dominantEdges.TryGetValue(edgeKey, out edge))
{
newIndices[i * 12 + 3 + j * 2 + 0] = edge.Index0;
newIndices[i * 12 + 3 + j * 2 + 1] = edge.Index1;
}
}
}
}
// Generate index buffer
var indexBufferData = new byte[triangleCount * 12 * Utilities.SizeOf <int>()];
fixed(int *indexDataStart = &newIndices[0])
fixed(byte *indexBufferDataStart = &indexBufferData[0])
{
Utilities.CopyMemory((IntPtr)indexBufferDataStart, (IntPtr)indexDataStart, indexBufferData.Length);
meshData.IndexBuffer = new IndexBufferBindingData(new BufferData(BufferFlags.IndexBuffer, indexBufferData), true, triangleCount * 12);
}
meshData.DrawCount = triangleCount * 12;
meshData.PrimitiveType = PrimitiveType.PatchList.ControlPointCount(12);
}