Add another test case for smooth rendering

assignment-1c/examples/smooth.txt

@@ -0,0 +1,27 @@
+eye 0 0 4
+viewdir 0 0 -1
+updir 0 1 0
+hfov 60
+imsize 640 480
+
+bkgcolor 0.1 0.1 0.1
+light -2 1 0 1 1 1 1
+mtlcolor 1 0.6 1 1 1 1 0.1 0.4 0.4 20
+
+
+v 0 0 0
+v 1 0 -1
+v 0 1 -1
+v -1 0 -1
+v 0 -1 -1
+
+vn 0 0 1
+vn 1 0 1
+vn 0 1 1
+vn -1 0 1
+vn 0 -1 1
+
+f 1//1 2//2 3//3
+f 1//1 3//3 4//4
+f 1//1 4//4 5//5
+f 1//1 5//5 2//2

assignment-1c/src/scene/triangle.rs

@@ -11,6 +11,7 @@ use super::Scene;
 
 #[derive(Debug)]
 pub struct Triangle {
+  /// Indexes into the scene's vertex list
   pub vertices: Vector3<usize>,
 
   /// Indexes into the scene's normal coordinates list
@@ -48,11 +49,13 @@ impl Triangle {
           ([x0, y0, z0], [xd, yd, zd]) => (x0, y0, z0, xd, yd, zd),
           _ => unreachable!("lol rip no tuple interface"),
         };
+
       let denom = a * xd + b * yd + c * zd;
       if denom == 0.0 {
         // The ray is parallel to the plane, so there is no intersection point.
         return Ok(None);
       };
+
       -(a * x0 + b * y0 + c * z0 + d) / denom
     };
 
@@ -74,13 +77,13 @@ impl Triangle {
       return Ok(None);
     }
 
-    // If surface normals are provided, then interpolate the normals to do
-    // smooth shading
     let normal = match self.normals {
+      // If surface normals are provided, then interpolate the normals to do
+      // smooth shading
       Some(normals) => {
-        let n0 = scene.vertex_normals[normals[self.vertices.x]];
+        let n0 = scene.vertex_normals[normals.x];
-        let n1 = scene.vertex_normals[normals[self.vertices.y]];
+        let n1 = scene.vertex_normals[normals.y];
-        let n2 = scene.vertex_normals[normals[self.vertices.z]];
+        let n2 = scene.vertex_normals[normals.z];
 
         (alpha * n0 + beta * n1 + gamma * n2).normalize()
       }
@@ -94,6 +97,8 @@ impl Triangle {
     }))
   }
 
+  /// Get the (u, v) texture coordinates corresponding to the point provided in
+  /// the intersection context
   pub fn get_texture_coord(
     &self,
     scene: &Scene,
@@ -146,6 +151,7 @@ impl Triangle {
     (p0, e1, e2)
   }
 
+  /// Compute barycentric coordinates
   fn compute_barycentric_coordinates(
     &self,
     scene: &Scene,