Chapter 10

1 files changed, 44 insertions, 0 deletions

diff --git a/material.go b/material.go
new file mode 100644
index 0000000..66ea256
--- /dev/null
+++ b/material.go
@@ -0,0 +1,44 @@
+package main
+
+//Material
+
+type Material interface {
+  Attenuation() Vec3
+  Scatter(r Ray, hit HitRecord) Ray
+}
+
+//Lambertian
+
+type Lambertian struct {
+  Albedo Vec3
+}
+
+func (l Lambertian) Attenuation() Vec3 {
+  return l.Albedo;
+}
+
+func (l Lambertian) Scatter(r Ray, hit HitRecord) Ray {
+  scat_dir := hit.N.Add(RandomVec3OnUnitSphere());
+  if scat_dir.NearZero() {
+    scat_dir = hit.N;
+  }
+  return Ray{hit.P, scat_dir, true};
+}
+
+//Metal
+
+type Metal struct {
+  Albedo Vec3
+  Fuzz float64
+}
+
+func (m Metal) Attenuation() Vec3 {
+  return m.Albedo;
+}
+
+func (m Metal) Scatter(r Ray, hit HitRecord) Ray {
+  refl := r.Direction.Reflect(hit.N).Unit().
+          Add(SplatVec3(m.Fuzz).Mul(RandomVec3OnUnitSphere()));
+  valid := refl.Dot(hit.N) > 0;
+  return Ray{hit.P, refl, valid};
+}