55 lines
1.3 KiB
HLSL
55 lines
1.3 KiB
HLSL
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#ifndef VERTEX_CUBE_SLICING
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# define VERTEX_CUBE_SLICING
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// Box - plane slicing from 'A Vertex Program for Efficient Box-Plane Intersection'
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// Optimized with 'A COMPARISON OF GPU BOX-PLANE INTERSECTION ALGORITHMS FOR DIRECT VOLUME RENDERING'
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static const int sequence[16] = {
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0, 1, 2, 3, 4, 5, 6, 7,
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1, 2, 3, 0, 7, 4, 5, 6,
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};
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static const int v1[24] = {
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0, 1, 4, -1,
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1, 0, 1, 4,
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0, 2, 5, -1,
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2, 0, 2, 5,
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0, 3, 6, -1,
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3, 0, 3, 6
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};
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static const int v2[24] = {
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1, 4, 7, -1,
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5, 1, 4, 7,
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2, 5, 7, -1,
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6, 2, 5, 7,
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3, 6, 7, -1,
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4, 3, 6, 7
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};
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#ifdef GET_CUBE_VERTEX_POSITION
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float3 ComputeCubeSliceVertexPositionRWS(float3 cameraViewDirection, float planeDistance, int vertexId)
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{
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float3 position = 0;
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for (int i = 0; i < 4; ++i)
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{
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int vidx1 = sequence[int(v1[vertexId * 4 + i])];
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int vidx2 = sequence[int(v2[vertexId * 4 + i])];
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float3 vecV1 = GET_CUBE_VERTEX_POSITION(vidx1);
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float3 vecV2 = GET_CUBE_VERTEX_POSITION(vidx2);
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float3 intersection = 0;
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if (RayPlaneSegmentIntersect(vecV1, vecV2 - vecV1, cameraViewDirection, planeDistance, intersection))
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{
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position = intersection;
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break;
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}
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}
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return position;
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}
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#endif // GET_CUBE_VERTEX_POSITION
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#endif // VERTEX_CUBE_SLICING
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