From 1e77295876e20702d5ccb477b2f01df980723f04 Mon Sep 17 00:00:00 2001
From: Martin Lehoux <martin@lehoux.net>
Date: Sat, 4 Apr 2020 16:46:06 -0700
Subject: feat - sphere colors

---
 color.go   | 5 +++--
 hitable.go | 6 +++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/color.go b/color.go
index dbcb47a..1ac8141 100644
--- a/color.go
+++ b/color.go
@@ -18,8 +18,9 @@ func LinearBlend(color1 Color, color2 Color, param float64) Color {
 
 func RayColor(ray Ray, hitable Hitable) Color {
 	hit := hitable.Hit(ray)
-	if hit.time > 0 {
-		return Color{1.0, 0.0, 0.0}
+	if hit.time > 0.0 {
+		vec := AddVec3D(hit.normal, Vec3D{1.0, 1.0, 1.0})
+		return LinearBlend(Color{vec.x, vec.y, vec.z}, Color{0.0, 0.0, 0.0}, 0.5)
 	}
 	param := 0.5 * (ray.direction.Unit().y + 1)
 	return LinearBlend(Color{0.5, 0.7, 1.0}, Color{1.0, 1.0, 1.0}, param)
diff --git a/hitable.go b/hitable.go
index 1443110..ed18a5d 100644
--- a/hitable.go
+++ b/hitable.go
@@ -19,7 +19,7 @@ type Sphere struct {
 }
 
 func (sphere Sphere) Normal(point Vec3D) Vec3D {
-	return (SubVec3D(point, sphere.center)).Unit()
+	return SubVec3D(point, sphere.center).Unit()
 }
 
 func (sphere Sphere) Hit(ray Ray) HitRecord {
@@ -31,7 +31,7 @@ func (sphere Sphere) Hit(ray Ray) HitRecord {
 	if discriminant < 0 {
 		return HitRecord{}
 	}
-	time := (-b - math.Sqrt(discriminant)) / 2.0 / a
+	time := (-b - math.Sqrt(discriminant)) / (2.0 * a)
 	point := ray.PointAt(time)
-	return HitRecord{time, point, SubVec3D(point, sphere.Normal(point))}
+	return HitRecord{time, point, sphere.Normal(point)}
 }
-- 
cgit v1.3