Progress on pbrt parser

ray-tracing-core/src/affine_transform.rs

@@ -77,6 +77,27 @@ impl AffineTransform {
         }
     }
 
+    pub fn look_at(pos: Pos3, look: Pos3, up: Dir3) -> Self {
+        let dir = (look - pos).normalize();
+        let right = Dir3::cross(up.normalize(), dir).normalize();
+        let new_up = Dir3::cross(dir, right);
+
+        let mat = [
+            [right.x(), new_up.x(), dir.x(), pos.x()],
+            [right.y(), new_up.y(), dir.y(), pos.y()],
+            [right.z(), new_up.z(), dir.z(), pos.z()],
+        ];
+
+        let inv = Self::invert(mat);
+
+        Self { mat, inv }
+    }
+
+    fn invert(mat: [[Float; 4]; 3]) -> [[Float; 3]; 3] {
+        eprintln!("Matrix inversion not implemented");
+        [[0.0; 3]; 3]
+    }
+
     pub fn transform_pos(&self, pos: Pos3) -> Pos3 {
         Pos3::new(
             self.mat[0][0] * pos.x()
@@ -93,6 +114,13 @@ impl AffineTransform {
                 + self.mat[2][3],
         )
     }
+    pub fn transform_dir(&self, dir: Dir3) -> Dir3 {
+        Dir3::new(
+            self.mat[0][0] * dir.x() + self.mat[0][1] * dir.y() + self.mat[0][2] * dir.z(),
+            self.mat[1][0] * dir.x() + self.mat[1][1] * dir.y() + self.mat[1][2] * dir.z(),
+            self.mat[2][0] * dir.x() + self.mat[2][1] * dir.y() + self.mat[2][2] * dir.z(),
+        )
+    }
     pub fn transform_normal(&self, pos: Pos3) -> Pos3 {
         Pos3::new(
             self.inv[0][0] * pos.x() + self.inv[0][1] * pos.y() + self.inv[0][2] * pos.z(),