// Determines which triangles of the surface are facing towards the light origin.
// The facing array should be allocated with one extra index than the number of surface triangles, which will be used to handle dangling edge silhouettes.
static void R_CalcInteractionFacing(IRenderEntity ent, SrfTriangles tri, IRenderLight light, ref SrfCullInfo cullInfo)
{
if (cullInfo.facing != null)
{
return;
}
Vector3 localLightOrigin;
R_GlobalPointToLocal(ent.modelMatrix, light.globalLightOrigin, out localLightOrigin);
var numFaces = tri.numIndexes / 3;
if (tri.facePlanes == null || !tri.facePlanesCalculated)
{
R_DeriveFacePlanes(tri);
}
cullInfo.facing = (byte *)R_StaticAlloc((numFaces + 1) * sizeof(byte));
// calculate back face culling
var planeSide = stackalloc float[numFaces + floatX.ALLOC16]; planeSide = (float *)_alloca16(planeSide);
// exact geometric cull against face
fixed(Plane *facePlanesP = tri.facePlanes) Simd.Dotcp(planeSide, localLightOrigin, facePlanesP, numFaces);
Simd.CmpGE(cullInfo.facing, planeSide, 0f, numFaces);
cullInfo.facing[numFaces] = 1; // for dangling edges to reference
}
// We want to cull a little on the sloppy side, because the pre-clipping of geometry to the lights in dmap will give many cases that are right
// at the border we throw things out on the border, because if any one vertex is clearly inside, the entire triangle will be accepted.
static void R_CalcInteractionCullBits(IRenderEntity ent, SrfTriangles tri, IRenderLight light, ref SrfCullInfo cullInfo)
{
int i, frontBits;
if (cullInfo.cullBits != null)
{
return;
}
frontBits = 0;
// cull the triangle surface bounding box
for (i = 0; i < 6; i++)
{
R_GlobalPlaneToLocal(ent.modelMatrix, -light.frustum[i], out cullInfo.localClipPlanes[i]);
// get front bits for the whole surface
if (tri.bounds.PlaneDistance(cullInfo.localClipPlanes[i]) >= IInteraction.LIGHT_CLIP_EPSILON)
{
frontBits |= 1 << i;
}
}
// if the surface is completely inside the light frustum
if (frontBits == ((1 << 6) - 1))
{
cullInfo.cullBits = IInteraction.LIGHT_CULL_ALL_FRONT; return;
}
cullInfo.cullBits = (byte *)R_StaticAlloc(tri.numVerts * sizeof(byte));
Simd.Memset(cullInfo.cullBits, 0, tri.numVerts * sizeof(byte));
var planeSide = stackalloc float[tri.numVerts + floatX.ALLOC16]; planeSide = (float *)_alloca16(planeSide);
for (i = 0; i < 6; i++)
{
// if completely infront of this clipping plane
if ((frontBits & (1 << i)) != 0)
{
continue;
fixed(DrawVert *vertsD = tri.verts) Simd.Dotpd(planeSide, cullInfo.localClipPlanes[i], vertsD, tri.numVerts);
Simd.CmpLTb(cullInfo.cullBits, (byte)i, planeSide, IInteraction.LIGHT_CLIP_EPSILON, tri.numVerts);
}
}