michael/pathfinder
michael
/
pathfinder
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Optimize `y_extrema()` with some SIMD

This commit is contained in:
Patrick Walton 2019-01-10 15:11:41 -08:00
parent 0da1ee7cd3
commit 289938b03b
1 changed files with 19 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
utils/tile-svg/src/main.rs
View File

@ -857,20 +857,27 @@ impl<'s> CubicSegment<'s> {
self.split(t).1
}
// TODO(pcwalton): Optimize with SIMD.
fn y_extrema(self) -> (Option<f32>, Option<f32>) {
let (from, to) = (self.0.baseline.from_y(), self.0.baseline.to_y());
let (ctrl0, ctrl1) = (self.0.ctrl.from_y(), self.0.ctrl.to_y());
let discrim = -from * ctrl1 + from * to + ctrl0 * ctrl0 - ctrl0 * ctrl1 - ctrl0 * to +
ctrl1 * ctrl1;
if discrim < 0.0 {
return (None, None)
let (t0, t1);
unsafe {
let mut p0p1p2p3 = Sse41::setzero_ps();
p0p1p2p3[0] = self.0.baseline.from_y();
p0p1p2p3[1] = self.0.ctrl.from_y();
p0p1p2p3[2] = self.0.ctrl.to_y();
p0p1p2p3[3] = self.0.baseline.to_y();
let pxp0p1p2 = Sse41::shuffle_ps(p0p1p2p3, p0p1p2p3, 0b1001_0000);
let pxv0v1v2 = Sse41::sub_ps(p0p1p2p3, pxp0p1p2);
let (v0, v1, v2) = (pxv0v1v2[1], pxv0v1v2[2], pxv0v1v2[3]);
let (v0_to_v1, v2_to_v1) = (v0 - v1, v2 - v1);
let discrim = f32::sqrt(v1 * v1 - v0 * v2);
let denom = 1.0 / (v0_to_v1 + v2_to_v1);
t0 = (v0_to_v1 + discrim) * denom;
t1 = (v0_to_v1 - discrim) * denom;
}
let discrim_sqrt = discrim.sqrt();
let b = from - 2.0 * ctrl0 + ctrl1;
let denom = from - 3.0 * ctrl0 + 3.0 * ctrl1 - to;
let (t0, t1) = ((b + discrim_sqrt) / denom, (b - discrim_sqrt) / denom);
//println!("t0={} t1={}", t0, t1);
return match (t0 > EPSILON && t0 < 1.0 - EPSILON, t1 > EPSILON && t1 < 1.0 - EPSILON) {
(false, false) => (None, None),
(true, false) => (Some(t0), None),