Fixed bug in ray intersection code.

The max_t was getting overwritten during transforms.

src/ray.rs

@@ -34,4 +34,14 @@ impl Ray {
         self.dir = self.dir * *mat;
         self.dir_inv = Vector { co: Float4::new(1.0, 1.0, 1.0, 1.0) / self.dir.co };
     }
+
+    pub fn update_from_world_ray(&mut self, wr: &Ray) {
+        self.orig = wr.orig;
+        self.dir = wr.dir;
+    }
+
+    pub fn update_from_xformed_world_ray(&mut self, wr: &Ray, mat: &Matrix4x4) {
+        self.update_from_world_ray(wr);
+        self.transform(mat);
+    }
 }

src/tracer.rs

@@ -68,8 +68,7 @@ impl<'a> Tracer<'a> {
                 for ray in &mut rs[..] {
                     let id = ray.id;
                     let t = ray.time;
-                    *ray = wrays[id as usize];
-                    ray.transform(&lerp_slice(xforms, t));
+                    ray.update_from_xformed_world_ray(&wrays[id as usize], &lerp_slice(xforms, t));
                 }
             }
 
@@ -95,14 +94,13 @@ impl<'a> Tracer<'a> {
                     for ray in &mut rs[..] {
                         let id = ray.id;
                         let t = ray.time;
-                        *ray = wrays[id as usize];
-                        ray.transform(&lerp_slice(xforms, t));
+                        ray.update_from_xformed_world_ray(&wrays[id as usize],
+                                                          &lerp_slice(xforms, t));
                     }
                 } else {
                     for ray in &mut rs[..] {
                         let id = ray.id;
-                        let t = ray.time;
-                        *ray = wrays[id as usize];
+                        ray.update_from_world_ray(&wrays[id as usize]);
                     }
                 }
             }

todo.txt

@@ -1,2 +1,2 @@
-- Basic scene parsing with triangle meshes.
+//- Basic scene parsing with triangle meshes.
 - Unit tests for scene parsing.