void kdtree::draw(scene& scene, ray& ray, hit& hit)
{
float tentry, texit;
if (!_boundingBox.intersect(ray, tentry, texit))
return;
ray.tfar = texit;
if (tentry < 0.f) tentry = 0.f;
stackitem stack[MAX_STACK_SIZE];
//push dummy element
stack[0].node = 0;
stack[0].texit = BPRAY_INF;
uint32_t stackptr = 1;
kdnode* currNode = _nodes + 1;
static uint64_t rayid = 0;
++rayid;
while (true) {
if (!currNode->isLeaf()) {
int axis = currNode->getAxis();
float dist = currNode->getSplit() - ray.O()[axis];
int left = currNode->getLeft();
if (dist <= tentry * ray.D()[axis]) { // right node traversed first
if (dist >= texit * ray.D()[axis]) {
stack[stackptr].node = left;
stack[stackptr].texit = texit;
++stackptr;
texit = dist * ray.rcpD()[axis];
}
currNode = _nodes + left + 1;
}
else { //left node traversed first
if (dist <= texit * ray.D()[axis]) { // exit in right
stack[stackptr].node = left + 1;
stack[stackptr].texit = texit;
++stackptr;
texit = dist * ray.rcpD()[axis];
}
currNode = _nodes + left;
}
}
else {
int primidx = currNode->getPrimitiveOffset();
int primcount = currNode->getNumPrims();
for (int i = 0; i != primcount; ++i) {
int t = _prims[primidx + i];
//prefetch
int t2 = _prims[primidx + i + 1];
_mm_prefetch((char*)&scene._accels[t2], _MM_HINT_T0);
//mailboxing
if (mbox.find(scene, rayid, t)) continue;
scene.intersect(t, ray, hit);
mbox.add(scene, rayid, t);
}
if (ray.tfar < texit) return;
--stackptr;
tentry = texit;
currNode = stack[stackptr].node + _nodes;
texit = stack[stackptr].texit;
}
}
}
