bool intersect_shadow(BVHAccelerator* bvh, int nodeid, const ray3f& ray,
const intersect_func& intersect_elem_shadow) {
// grab node
auto& node = bvh->nodes[nodeid];
// intersect bbox
if(not intersect_bbox(ray, node.bbox)) return false;
// recursively intersect nodes
if(node.leaf) {
// for(auto idx : range(node.start,node.end)) {
for(int idx = node.start; idx < node.end; idx++) {
auto i = bvh->prims[idx];
if(intersect_elem_shadow(i,ray)) return true;
}
} else {
if(intersect_shadow(bvh,node.n0,ray,intersect_elem_shadow)) return true;
if(intersect_shadow(bvh,node.n1,ray,intersect_elem_shadow)) return true;
}
return false;
}
// intersects the scene and return for any intersection
bool intersect_shadow(Scene* scene, ray3f ray) {
// foreach surface
for(auto surface : scene->surfaces) {
// if it is a quad
if(surface->isquad) {
// compute ray intersection (and ray parameter), continue if not hit
auto tray = transform_ray_inverse(surface->frame,ray);
// intersect quad
if(intersect_quad(tray, surface->radius)) return true;
} else {
// compute ray intersection (and ray parameter), continue if not hit
auto tray = transform_ray_inverse(surface->frame,ray);
// intersect sphere
if(intersect_sphere(tray, surface->radius)) return true;
}
}
// foreach mesh
for(auto mesh : scene->meshes) {
// quads are not supported: check for error
error_if_not(mesh->quad.empty(), "quad intersection is not supported");
// tranform the ray
auto tray = transform_ray_inverse(mesh->frame, ray);
// if it is accelerated
if(mesh->bvh) {
if(intersect_shadow(mesh->bvh, 0, tray,
[mesh](int tid, ray3f tray){
// grab triangle
auto triangle = mesh->triangle[tid];
// grab vertices
auto v0 = mesh->pos[triangle.x];
auto v1 = mesh->pos[triangle.y];
auto v2 = mesh->pos[triangle.z];
// return if intersected
return intersect_triangle(tray, v0, v1, v2);})) return true;
} else {
// foreach triangle
for(auto triangle : mesh->triangle) {
// grab vertices
auto v0 = mesh->pos[triangle.x];
auto v1 = mesh->pos[triangle.y];
auto v2 = mesh->pos[triangle.z];
// intersect triangle
if(intersect_triangle(tray, v0, v1, v2)) return true;
}
}
}
// no intersection found
return false;
}
bool geometry::intersect(nex::ray* ray) const
{
nex::ray object_ray(ray->origin * world_inverse, ray->direction * world_inverse, ray->max, ray->depth);
float t;
if (intersect_shadow(object_ray, &t) && (t > nex::EPSILON) && (t <= ray->max)) {
ray->max = t;
return true;
}
return false;
}
