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Factored some calculations into the outer loop of BVH4 traversal.

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Provides a small but noticable speed boost.
This commit is contained in:
Nathan Vegdahl 2017-04-16 00:51:13 -07:00
parent 7d5bda2a3b
commit 2c4f103db5
1 changed files with 19 additions and 10 deletions
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29
src/accel/bvh4.rs
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@ -103,6 +103,10 @@ impl<'a> BVH4<'a> {
let node_order_code = {
TRAVERSAL_TABLE[ray_code as usize][traversal_code as usize]
};
let noc1 = node_order_code & 3;
let noc2 = (node_order_code >> 2) & 3;
let noc3 = (node_order_code >> 4) & 3;
let noc4 = (node_order_code >> 6) & 3;
// Ray testing
let part = partition(&mut rays[..ray_i_stack[stack_ptr]], |r| {
@ -113,20 +117,25 @@ impl<'a> BVH4<'a> {
if hits != 0 {
// Push hit bits onto ray's traversal stack
let mut shuffled_hits = 0;
for i in 0..children.len() {
let ii = (node_order_code >> (i * 2)) & 3;
shuffled_hits |= ((hits >> ii) & 1) << i;
}
let shuffled_hits = match children.len() {
4 => {
((hits >> noc1) & 1) | (((hits >> noc2) & 1) << 1) |
(((hits >> noc3) & 1) << 2) |
(((hits >> noc4) & 1) << 3)
}
3 => {
((hits >> noc1) & 1) | (((hits >> noc2) & 1) << 1) |
(((hits >> noc3) & 1) << 2)
}
2 => ((hits >> noc1) & 1) | (((hits >> noc2) & 1) << 1),
_ => unreachable!(),
};
r.trav_stack.push_n(shuffled_hits, children.len() as u8);
true
} else {
false
return true;
}
} else {
false
}
return false;
});
// Update stack based on ray testing results