// Bubble sort, because the arrays are small and NativeArray doesn't have a sort method
void NativeArraySort(NativeArray <float4> a, int start, int length, TrianglePointComparer comparer)
{
int upperBound = start + length;
float4 t = 0f;
for (int p = start; p <= upperBound - 2; p++)
{
for (int i = start; i <= upperBound - 2; i++)
{
if (comparer.Compare(a[i], a[i + 1]) > 0)
{
t = a[i + 1];
a[i + 1] = a[i];
a[i] = t;
}
}
}
}
public void Execute()
{
int generatedTriangleCount = 0;
int scratchPointsCount;
Triangle sourceTriangle = Triangle.zero;
// Comparer for sorting new points around a normal
TrianglePointComparer comparer = TrianglePointComparer.zero;
// For each source triangle, find a new set of points against the unit cube
for (int tIndex = 0; tIndex < NumSourceTriangles; tIndex++)
{
if (generatedTriangleCount >= DecalProjector.MaxDecalTriangles)
{
break;
}
// We need to build our own version of T, otherwise burst complains
sourceTriangle.CopyFrom(SourceTriangles[tIndex]);
// Start over from the beginning of the reused array
scratchPointsCount = 0;
// Some verts may actually be directly inside the projector
if (UnitCubeContains(sourceTriangle.Vertex0))
{
ScratchPoints[scratchPointsCount++] = sourceTriangle.Vertex0;
}
if (UnitCubeContains(sourceTriangle.Vertex1))
{
ScratchPoints[scratchPointsCount++] = sourceTriangle.Vertex1;
}
if (UnitCubeContains(sourceTriangle.Vertex2))
{
ScratchPoints[scratchPointsCount++] = sourceTriangle.Vertex2;
}
// Early out
// If all three points of the triangle were in the projector, we don't need to do anything.
if (scratchPointsCount == 3)
{
GeneratedTriangles[generatedTriangleCount++] = sourceTriangle;
continue;
}
// Test each triangle edge against the projector planes
ScratchTriangleEdges[0] = sourceTriangle.Edge0;
ScratchTriangleEdges[1] = sourceTriangle.Edge1;
ScratchTriangleEdges[2] = sourceTriangle.Edge2;
ClipToPlanes(sourceTriangle, ScratchTriangleEdges, UnitCubePlanes, ScratchPoints, TestPointMode.UnitCube, scratchPointsCount, out scratchPointsCount);
// Test each projector edge against the triangle plane
ScratchTrianglePlanes[0] = sourceTriangle.Plane;
ClipToPlanes(sourceTriangle, UnitCubeEdges, ScratchTrianglePlanes, ScratchPoints, TestPointMode.Triangle, scratchPointsCount, out scratchPointsCount);
// No points
if (scratchPointsCount == 0)
{
continue;
}
// Sort the points by dot product around the median.
float4 middle = MiddlePoint(ScratchPoints, scratchPointsCount);
float4 orientation = middle - ScratchPoints[0];
// Provide the comparer with some state, and sort the array
comparer.Update(orientation, middle, sourceTriangle.Normal);
NativeArraySort(ScratchPoints, 0, scratchPointsCount, comparer);
Triangle newTriangle = Triangle.zero;
// Create triangles from the points
for (int p = 0; p < scratchPointsCount; p++)
{
newTriangle.SetFrom(
middle, ScratchPoints[p], ScratchPoints[(p + 1) % scratchPointsCount]
);
GeneratedTriangles[generatedTriangleCount++] = newTriangle;
if (generatedTriangleCount >= DecalProjector.MaxDecalTriangles)
{
break;
}
}
}
NumGeneratedTriangles[0] = generatedTriangleCount;
}