TraversalState BVH::Traverse(TraversalState state, const SlimRay& ray, HitRecord* nearest,
function<bool (uint32_t index, const SlimRay& ray, HitRecord* hit, bool* request_suspend)> intersector,
bool resume) {
// Precompute the inverse direction of the ray.
vec3 inv_dir(1.0f / ray.direction.x,
1.0f / ray.direction.y,
1.0f / ray.direction.z);
// Initialize traversal based on passed state.
TraversalState traversal = state;
bool request_suspend = false;
if (resume) {
if (traversal.state == TraversalState::State::FROM_PARENT) {
goto resume_parent;
} else if (traversal.state == TraversalState::State::FROM_SIBLING) {
goto resume_sibling;
} else {
TERRLN("Must be in FROM_PARENT or FROM_SIBLING state to resume traversal!");
}
}
while (true) {
switch (traversal.state) {
case TraversalState::State::FROM_PARENT:
if (!BoundingHit(_nodes[traversal.current].bounds, ray, inv_dir, nearest->t)) {
// Ray missed the near child, try the far child.
traversal.current = Sibling(traversal.current);
traversal.state = TraversalState::State::FROM_SIBLING;
} else if (_nodes[traversal.current].leaf) {
// Ray hit the near child and it's a leaf node.
request_suspend = false;
traversal.hit = intersector(_nodes[traversal.current].index, ray, nearest, &request_suspend) || traversal.hit;
if (request_suspend) goto suspend_traversal;
resume_parent: traversal.current = Sibling(traversal.current);
traversal.state = TraversalState::State::FROM_SIBLING;
} else {
// Ray hit the near child and it's an interior node.
traversal.current = NearChild(traversal.current, ray.direction);
traversal.state = TraversalState::State::FROM_PARENT;
}
break;
case TraversalState::State::FROM_SIBLING:
if (!BoundingHit(_nodes[traversal.current].bounds, ray, inv_dir, nearest->t)) {
// Ray missed the far child, backtrack to the parent.
traversal.current = _nodes[traversal.current].parent;
traversal.state = TraversalState::State::FROM_CHILD;
} else if (_nodes[traversal.current].leaf) {
// Ray hit the far child and it's a leaf node.
request_suspend = false;
traversal.hit = intersector(_nodes[traversal.current].index, ray, nearest, &request_suspend) || traversal.hit;
if (request_suspend) goto suspend_traversal;
resume_sibling: traversal.current = _nodes[traversal.current].parent;
traversal.state = TraversalState::State::FROM_CHILD;
} else {
// Ray hit the far child and it's an interior node.
traversal.current = NearChild(traversal.current, ray.direction);
traversal.state = TraversalState::State::FROM_PARENT;
}
break;
case TraversalState::State::FROM_CHILD:
if (traversal.current == 0) {
// Traversal has finished.
return traversal;
}
if (traversal.current == NearChild(_nodes[traversal.current].parent, ray.direction)) {
// Coming back up through the near child, so traverse
// to the far child.
traversal.current = Sibling(traversal.current);
traversal.state = TraversalState::State::FROM_SIBLING;
} else {
// Coming back up through the far child, so continue
// backtracking through the parent.
traversal.current = _nodes[traversal.current].parent;
traversal.state = TraversalState::State::FROM_CHILD;
}
break;
default:
TERRLN("BVH traversal in unknown state!");
exit(EXIT_FAILURE);
break;
}
}
/// Shouldn't ever get here...
TERRLN("Unexpected exit path in BVH traversal.");
return TraversalState();
suspend_traversal:
return traversal;
}
bool BoundingBox::IntersectP(const Ray & ray)
{
//shadow ray and reflected ray returns false mistakenly
//probably because they are in the box
Vector3f pos(ray.getStartPosition());
Vector3f inv_dir(ray.getInvDirection());
float tx1 = (min_pos.x() - pos.x())*inv_dir.x();
float tx2 = (max_pos.x() - pos.x())*inv_dir.x();
float tmin = min(tx1, tx2);
float tmax = max(tx1, tx2);
float ty1 = (min_pos.y() - pos.y())*inv_dir.y();
float ty2 = (max_pos.y() - pos.y())*inv_dir.y();
tmin = max(tmin, min(ty1, ty2));
tmax = min(tmax, max(ty1, ty2));
//TODO, t should >0
if (tmax >= tmin)
{
float tz1 = (min_pos.z() - pos.z())*inv_dir.z();
float tz2 = (max_pos.z() - pos.z())*inv_dir.z();
tmin = max(tmin, min(tz1, tz2));
tmax = min(tmax, max(tz1, tz2));
//To confirm?? tmax>0
if(tmax >= tmin && tmax > 0)
{
//the line of ray will intersect
//but maybe the t < 0
return true;
}
}
return false;
//Vector3f dir(ray.getDirection());
//Vector3f inv_dir(ray.getInvDirection());
//float tx1 = (min_pos.x() - dir.x())*inv_dir.x();
//float tx2 = (max_pos.x() - dir.x())*inv_dir.x();
//float tmin = min(tx1, tx2);
//float tmax = max(tx1, tx2);
//float ty1 = (min_pos.y() - dir.y())*inv_dir.y();
//float ty2 = (max_pos.y() - dir.y())*inv_dir.y();
//tmin = max(tmin, min(ty1, ty2));
//tmax = min(tmax, max(ty1, ty2));
////TODO, t should >0
//if (tmax >= tmin)
//{
// float tz1 = (min_pos.z() - dir.z())*inv_dir.z();
// float tz2 = (max_pos.z() - dir.z())*inv_dir.z();
// tmin = max(tmin, min(tz1, tz2));
// tmax = min(tmax, max(tz1, tz2));
// if(tmax >= tmin)
// {
// //the line of ray will intersect
// //but maybe the t < 0
// //TODO
// return true;
// }
//}
//return false;
}
