void init_active_pixels(const BufferView<Ray> &rays,
BufferView<int> &active_pixels,
bool use_gpu,
ThrustCachedAllocator &thrust_alloc) {
assert(rays.size() == active_pixels.size());
DISPATCH(use_gpu, thrust::sequence, active_pixels.begin(), active_pixels.end());
auto op = is_invalid_ray{rays.begin()};
auto new_end = DISPATCH_CACHED(use_gpu, thrust_alloc, thrust::remove_if,
active_pixels.begin(), active_pixels.end(),
active_pixels.begin(), op);
active_pixels.count = new_end - active_pixels.begin();
}
void update_active_pixels(const BufferView<int> &active_pixels,
const BufferView<Intersection> &isects,
BufferView<int> &new_active_pixels,
bool use_gpu) {
auto op = is_valid_intersection{isects.begin()};
auto new_end = DISPATCH(use_gpu, thrust::copy_if,
active_pixels.begin(), active_pixels.end(),
new_active_pixels.begin(), op);
new_active_pixels.count = new_end - new_active_pixels.begin();
}
