// GridAccel Method Definitions
GridAccel::GridAccel(const vector<Reference<Primitive> > &p,
bool forRefined, bool refineImmediately)
: gridForRefined(forRefined) {
// Initialize _prims_ with primitives for grid
vector<Reference<Primitive> > prims;
if (refineImmediately)
for (u_int i = 0; i < p.size(); ++i)
p[i]->FullyRefine(prims);
else
prims = p;
// Initialize mailboxes for grid
nMailboxes = prims.size();
mailboxes = (MailboxPrim *)AllocAligned(nMailboxes *
sizeof(MailboxPrim));
for (u_int i = 0; i < nMailboxes; ++i)
new (&mailboxes[i]) MailboxPrim(prims[i]);
// Compute bounds and choose grid resolution
for (u_int i = 0; i < prims.size(); ++i)
bounds = Union(bounds, prims[i]->WorldBound());
Vector delta = bounds.pMax - bounds.pMin;
// Find _voxelsPerUnitDist_ for grid
int maxAxis = bounds.MaximumExtent();
float invMaxWidth = 1.f / delta[maxAxis];
Assert(invMaxWidth > 0.f); // NOBOOK
float cubeRoot = 3.f * powf(float(prims.size()), 1.f/3.f);
float voxelsPerUnitDist = cubeRoot * invMaxWidth;
for (int axis = 0; axis < 3; ++axis) {
NVoxels[axis] =
Round2Int(delta[axis] * voxelsPerUnitDist);
NVoxels[axis] = Clamp(NVoxels[axis], 1, 64);
}
// Compute voxel widths and allocate voxels
for (int axis = 0; axis < 3; ++axis) {
Width[axis] = delta[axis] / NVoxels[axis];
InvWidth[axis] =
(Width[axis] == 0.f) ? 0.f : 1.f / Width[axis];
}
int nVoxels = NVoxels[0] * NVoxels[1] * NVoxels[2];
voxels = (Voxel **)AllocAligned(nVoxels * sizeof(Voxel *));
memset(voxels, 0, nVoxels * sizeof(Voxel *));
// Add primitives to grid voxels
for (u_int i = 0; i < prims.size(); ++i) {
// Find voxel extent of primitive
BBox pb = prims[i]->WorldBound();
int vmin[3], vmax[3];
for (int axis = 0; axis < 3; ++axis) {
vmin[axis] = PosToVoxel(pb.pMin, axis);
vmax[axis] = PosToVoxel(pb.pMax, axis);
}
// Add primitive to overlapping voxels
for (int z = vmin[2]; z <= vmax[2]; ++z)
for (int y = vmin[1]; y <= vmax[1]; ++y)
for (int x = vmin[0]; x <= vmax[0]; ++x) {
int offset = Offset(x, y, z);
if (!voxels[offset]) {
// Allocate new voxel and store primitive in it
voxels[offset] = new (voxelArena) Voxel(&mailboxes[i]);
}
else {
// Add primitive to already-allocated voxel
voxels[offset]->AddPrimitive(&mailboxes[i]);
}
}
static StatsRatio nPrimitiveVoxels("Grid Accelerator", // NOBOOK
"Voxels covered vs # / primitives"); // NOBOOK
nPrimitiveVoxels.Add((1 + vmax[0]-vmin[0]) * (1 + vmax[1]-vmin[1]) * // NOBOOK
(1 + vmax[2]-vmin[2]), 1); // NOBOOK
}
// Update grid statistics
static StatsPercentage nEmptyVoxels("Grid Accelerator",
"Empty voxels");
static StatsRatio avgPrimsInVoxel("Grid Accelerator",
"Average # of primitives in voxel");
static StatsCounter maxPrimsInVoxel("Grid Accelerator",
"Max # of primitives in a grid voxel");
nEmptyVoxels.Add(0, NVoxels[0] * NVoxels[1] * NVoxels[2]);
avgPrimsInVoxel.Add(0,NVoxels[0] * NVoxels[1] * NVoxels[2]);
for (int z = 0; z < NVoxels[2]; ++z)
for (int y = 0; y < NVoxels[1]; ++y)
for (int x = 0; x < NVoxels[0]; ++x) {
int offset = Offset(x, y, z);
if (!voxels[offset]) nEmptyVoxels.Add(1, 0);
else {
int nPrims = voxels[offset]->nPrimitives;
maxPrimsInVoxel.Max(nPrims);
avgPrimsInVoxel.Add(nPrims, 0);
}
}
}
void PBRT_KDTREE_CREATED_LEAF(int nprims, int depth) {
++kdTreeLeafNodes;
kdTreeMaxPrims.Max(nprims);
kdTreeMaxDepth.Max(depth);
}