(ray: &Ray, scene: &Scene, bvh: &Bvh)
| 881 | } |
| 882 | |
| 883 | fn intersect_bvh(ray: &Ray, scene: &Scene, bvh: &Bvh) -> Option<Hit> { |
| 884 | let mut closest: Option<Hit> = None; |
| 885 | let mut max_t = f32::INFINITY; |
| 886 | |
| 887 | // Fixed-size stack of node indices to visit. Depth 64 supports |
| 888 | // BVHs up to 2^64 triangles — way past any scene we'll see. Using |
| 889 | // a stack rather than recursion both avoids the call overhead and |
| 890 | // makes the traversal order (near-child-first) explicit. |
| 891 | let mut stack = [0u32; 64]; |
| 892 | let mut sp: usize = 1; |
| 893 | stack[0] = 0; |
| 894 | |
| 895 | while sp > 0 { |
| 896 | sp -= 1; |
| 897 | let node = &bvh.nodes[stack[sp] as usize]; |
| 898 | if intersect_aabb(ray, node.bounds_min, node.bounds_max, max_t).is_none() { |
| 899 | continue; |
| 900 | } |
| 901 | if node.tri_count > 0 { |
| 902 | // Leaf: test each triangle. |
| 903 | for i in 0..node.tri_count as usize { |
| 904 | let tri_idx = bvh.triangle_indices[node.first_triangle as usize + i] as usize; |
| 905 | let tri = &scene.triangles[tri_idx]; |
| 906 | if let Some((t, bary)) = intersect_triangle(ray, tri, max_t) { |
| 907 | max_t = t; |
| 908 | closest = Some(Hit { |
| 909 | t, |
| 910 | barycentric: bary, |
| 911 | triangle_index: tri_idx as u32, |
| 912 | }); |
| 913 | } |
| 914 | } |
| 915 | } else { |
| 916 | // Internal: visit both children, near first. Pushing the |
| 917 | // far child first means the near is popped first. |
| 918 | let left = node.first_triangle; |
| 919 | let right = left + 1; |
| 920 | let ln = &bvh.nodes[left as usize]; |
| 921 | let rn = &bvh.nodes[right as usize]; |
| 922 | let lt = intersect_aabb(ray, ln.bounds_min, ln.bounds_max, max_t); |
| 923 | let rt = intersect_aabb(ray, rn.bounds_min, rn.bounds_max, max_t); |
| 924 | match (lt, rt) { |
| 925 | (Some(ld), Some(rd)) => { |
| 926 | if ld < rd { |
| 927 | if sp < 63 { |
| 928 | stack[sp] = right; |
| 929 | sp += 1; |
| 930 | } |
| 931 | if sp < 63 { |
| 932 | stack[sp] = left; |
| 933 | sp += 1; |
| 934 | } |
| 935 | } else { |
| 936 | if sp < 63 { |
| 937 | stack[sp] = left; |
| 938 | sp += 1; |
| 939 | } |
| 940 | if sp < 63 { |
no test coverage detected