From bd3bbdd239fd91056442384bfe3a86b2b8c0e68e Mon Sep 17 00:00:00 2001
From: Nat Lasseter <user@4574.co.uk>
Date: Mon, 24 Jun 2024 17:26:09 +0100
Subject: chapter 9

---
 vec3.go | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

(limited to 'vec3.go')

diff --git a/vec3.go b/vec3.go
index 4212b46..bc16a07 100644
--- a/vec3.go
+++ b/vec3.go
@@ -52,16 +52,37 @@ func (v Vec3) Cross(w Vec3) Vec3 {
               v.X * w.Y - v.Y * w.X};
 }
 
+func linear_to_gamma(comp float64) float64 {
+  if comp > 0 {
+    return maths.Sqrt(comp);
+  }
+  return 0;
+}
+
 func (v Vec3) ToPPM() string {
   i := Interval{0, 0.999};
 
-  r := uint8(256 * i.Clamp(v.X));
-  g := uint8(256 * i.Clamp(v.Y));
-  b := uint8(256 * i.Clamp(v.Z));
+  r := uint8(256 * i.Clamp(linear_to_gamma(v.X)));
+  g := uint8(256 * i.Clamp(linear_to_gamma(v.Y)));
+  b := uint8(256 * i.Clamp(linear_to_gamma(v.Z)));
 
   return fmt.Sprintf("%3d %3d %3d", r, g, b);
 }
 
-func Splat(f float64) Vec3 {
+func SplatVec3(f float64) Vec3 {
   return Vec3{f, f, f};
 }
+
+func RandomVec3OnUnitSphere() (v Vec3) {
+  i := Interval{-1, 1}
+
+  for true {
+    v = i.RandomVec3()
+    if v.MagSqr() < 1 {
+      v = v.Unit();
+      return;
+    }
+  }
+
+  return;
+}
-- 
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