maths.Pow turned out to be seriously terrible

1 files changed, 6 insertions, 3 deletions

diff --git a/material.go b/material.go
index 62a0467..6b3a528 100644
--- a/material.go
+++ b/material.go
@@ -65,7 +65,7 @@ func (d Dielectric) Scatter(r Ray, hit HitRecord) Ray {
 
   unit_dir := r.Direction.Unit();
   cos_theta := maths.Min(unit_dir.Neg().Dot(hit.N), 1.0);
-  sin_theta := maths.Sqrt(1.0 - maths.Pow(cos_theta, 2));
+  sin_theta := maths.Sqrt(1.0 - cos_theta * cos_theta);
 
   cannot_refract := ri * sin_theta > 1.0;
 
@@ -80,7 +80,10 @@ func (d Dielectric) Scatter(r Ray, hit HitRecord) Ray {
 }
 
 func schlick_reflect(cos_theta float64, ri float64) bool {
-  r0 := maths.Pow((1 - ri) / (1 + ri), 2);
-  approx := r0 + (1 - r0) * maths.Pow(1 - cos_theta, 5);
+  r0 := (1 - ri) / (1 + ri);
+  r0 = r0 * r0;
+  ct5 := 1 - cos_theta;
+  ct5 = ct5 * ct5 * ct5 * ct5 * ct5;
+  approx := r0 + (1 - r0) * ct5;
   return approx > Interval{0, 1}.Sample();
 }