From 0d5e6bd9363d5ed5c4f28174819fc0f5fd9aa586 Mon Sep 17 00:00:00 2001
From: Julian T <julian@jtle.dk>
Date: Sat, 6 Feb 2021 17:27:42 +0100
Subject: Reorganized scene module, and fixed bug in sphere intersect

---
 src/scene/shapes/sphere.rs | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

(limited to 'src/scene/shapes/sphere.rs')

diff --git a/src/scene/shapes/sphere.rs b/src/scene/shapes/sphere.rs
index da7f321..acca2b7 100644
--- a/src/scene/shapes/sphere.rs
+++ b/src/scene/shapes/sphere.rs
@@ -3,7 +3,7 @@
 //! Spheres are relatively easy to calculate intersections between
 use crate::Float;
 use crate::core::{Ray, Vector3f};
-use super::Shape;
+use crate::scene::{Hittable, Intersection};
 
 pub struct Sphere {
     radius: Float,
@@ -17,11 +17,17 @@ impl Sphere {
             center,
         }
     }
+
+    fn norm_at(&self, point: &Vector3f) -> Vector3f {
+        let mut v = *point - self.center;
+        v /= self.radius;
+        v
+    }
 }
 
-impl Shape for Sphere {
+impl Hittable for Sphere {
     // Implementation from ray tracing in a weekend
-    fn intersect(&self, ray: &Ray) -> Option<Float> {
+    fn intersect(&self, ray: &Ray) -> Option<Intersection> {
         let oc = ray.origin - self.center;
         let a = ray.direction.len_squared();
         let half_b = oc.dot(&ray.direction);
@@ -29,18 +35,20 @@ impl Shape for Sphere {
         let disc = half_b*half_b - a*c;
 
         if disc < 0.0 {
-            None
+            return None
         } else {
-            Some( (-half_b - disc.sqrt()) / a)
+            let distance = (-half_b - disc.sqrt()) / a;
+            if distance < 0.0 {
+                return None
+            }
+            let w = ray.at(distance);
+            Some(Intersection {
+                n: self.norm_at(&w),
+                p: w,
+            })
         }
 
     }
-
-    fn norm_at(&self, point: &Vector3f) -> Vector3f {
-        let mut v = *point - self.center;
-        v /= self.radius;
-        v
-    }
 }
 
 #[cfg(test)]
-- 
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