void BVHSpatialSplit::split_curve_reference(const BVHReference& ref,
const Mesh *mesh,
int dim,
float pos,
BoundBox& left_bounds,
BoundBox& right_bounds)
{
split_curve_primitive(mesh,
NULL,
ref.prim_index(),
PRIMITIVE_UNPACK_SEGMENT(ref.prim_type()),
dim,
pos,
left_bounds,
right_bounds);
}
bool operator()(const BVHReference& ra, const BVHReference& rb)
{
NO_EXTENDED_PRECISION float ca = ra.bounds().min[dim] + ra.bounds().max[dim];
NO_EXTENDED_PRECISION float cb = rb.bounds().min[dim] + rb.bounds().max[dim];
if(ca < cb) return true;
else if(ca > cb) return false;
else if(ra.prim_object() < rb.prim_object()) return true;
else if(ra.prim_object() > rb.prim_object()) return false;
else if(ra.prim_index() < rb.prim_index()) return true;
else if(ra.prim_index() > rb.prim_index()) return false;
else if(ra.prim_segment() < rb.prim_segment()) return true;
else if(ra.prim_segment() > rb.prim_segment()) return false;
return false;
}
void BVHSpatialSplit::split_triangle_reference(const BVHReference& ref,
const Mesh *mesh,
int dim,
float pos,
BoundBox& left_bounds,
BoundBox& right_bounds)
{
split_triangle_primitive(mesh,
NULL,
ref.prim_index(),
dim,
pos,
left_bounds,
right_bounds);
}
void BVHSpatialSplit::split_reference(const BVHBuild& builder,
BVHReference& left,
BVHReference& right,
const BVHReference& ref,
int dim,
float pos)
{
/* initialize boundboxes */
BoundBox left_bounds = BoundBox::empty;
BoundBox right_bounds = BoundBox::empty;
/* loop over vertices/edges. */
const Object *ob = builder.objects[ref.prim_object()];
const Mesh *mesh = ob->mesh;
if(ref.prim_type() & PRIMITIVE_ALL_TRIANGLE) {
split_triangle_reference(ref,
mesh,
dim,
pos,
left_bounds,
right_bounds);
}
else if(ref.prim_type() & PRIMITIVE_ALL_CURVE) {
split_curve_reference(ref,
mesh,
dim,
pos,
left_bounds,
right_bounds);
}
else {
split_object_reference(ob,
dim,
pos,
left_bounds,
right_bounds);
}
/* intersect with original bounds. */
left_bounds.max[dim] = pos;
right_bounds.min[dim] = pos;
left_bounds.intersect(ref.bounds());
right_bounds.intersect(ref.bounds());
/* set references */
left = BVHReference(left_bounds, ref.prim_index(), ref.prim_object(), ref.prim_type());
right = BVHReference(right_bounds, ref.prim_index(), ref.prim_object(), ref.prim_type());
}
BVHSpatialSplit::BVHSpatialSplit(const BVHBuild& builder,
BVHSpatialStorage *storage,
const BVHRange& range,
vector<BVHReference> *references,
float nodeSAH)
: sah(FLT_MAX),
dim(0),
pos(0.0f),
storage_(storage),
references_(references)
{
/* initialize bins. */
float3 origin = range.bounds().min;
float3 binSize = (range.bounds().max - origin) * (1.0f / (float)BVHParams::NUM_SPATIAL_BINS);
float3 invBinSize = 1.0f / binSize;
for(int dim = 0; dim < 3; dim++) {
for(int i = 0; i < BVHParams::NUM_SPATIAL_BINS; i++) {
BVHSpatialBin& bin = storage_->bins[dim][i];
bin.bounds = BoundBox::empty;
bin.enter = 0;
bin.exit = 0;
}
}
/* chop references into bins. */
for(unsigned int refIdx = range.start(); refIdx < range.end(); refIdx++) {
const BVHReference& ref = references_->at(refIdx);
float3 firstBinf = (ref.bounds().min - origin) * invBinSize;
float3 lastBinf = (ref.bounds().max - origin) * invBinSize;
int3 firstBin = make_int3((int)firstBinf.x, (int)firstBinf.y, (int)firstBinf.z);
int3 lastBin = make_int3((int)lastBinf.x, (int)lastBinf.y, (int)lastBinf.z);
firstBin = clamp(firstBin, 0, BVHParams::NUM_SPATIAL_BINS - 1);
lastBin = clamp(lastBin, firstBin, BVHParams::NUM_SPATIAL_BINS - 1);
for(int dim = 0; dim < 3; dim++) {
BVHReference currRef = ref;
for(int i = firstBin[dim]; i < lastBin[dim]; i++) {
BVHReference leftRef, rightRef;
split_reference(builder, leftRef, rightRef, currRef, dim, origin[dim] + binSize[dim] * (float)(i + 1));
storage_->bins[dim][i].bounds.grow(leftRef.bounds());
currRef = rightRef;
}
storage_->bins[dim][lastBin[dim]].bounds.grow(currRef.bounds());
storage_->bins[dim][firstBin[dim]].enter++;
storage_->bins[dim][lastBin[dim]].exit++;
}
}
/* select best split plane. */
for(int dim = 0; dim < 3; dim++) {
/* sweep right to left and determine bounds. */
BoundBox right_bounds = BoundBox::empty;
storage_->right_bounds.resize(BVHParams::NUM_SPATIAL_BINS);
for(int i = BVHParams::NUM_SPATIAL_BINS - 1; i > 0; i--) {
right_bounds.grow(storage_->bins[dim][i].bounds);
storage_->right_bounds[i - 1] = right_bounds;
}
/* sweep left to right and select lowest SAH. */
BoundBox left_bounds = BoundBox::empty;
int leftNum = 0;
int rightNum = range.size();
for(int i = 1; i < BVHParams::NUM_SPATIAL_BINS; i++) {
left_bounds.grow(storage_->bins[dim][i - 1].bounds);
leftNum += storage_->bins[dim][i - 1].enter;
rightNum -= storage_->bins[dim][i - 1].exit;
float sah = nodeSAH +
left_bounds.safe_area() * builder.params.primitive_cost(leftNum) +
storage_->right_bounds[i - 1].safe_area() * builder.params.primitive_cost(rightNum);
if(sah < this->sah) {
this->sah = sah;
this->dim = dim;
this->pos = origin[dim] + binSize[dim] * (float)i;
}
}
}
}
