Use camera settings from pbrt file

ray-tracing-core/src/affine_transform.rs

@@ -40,6 +40,10 @@ impl AffineTransform {
         Some(Self { mat, inv })
     }
 
+    pub fn get(&self, i: usize, j: usize) -> Float {
+        self.mat[j][i]
+    }
+
     pub fn identity() -> Self {
         Self {
             mat: [
@@ -127,7 +131,7 @@ impl AffineTransform {
     pub fn look_at(pos: Pos3, look: Pos3, up: Dir3) -> Option<Self> {
         let dir = (look - pos).normalize();
         let right = Dir3::cross(up.normalize(), dir).normalize();
-        let new_up = Dir3::cross(dir, right);
+        let new_up = Dir3::cross(right, dir);
 
         let mat = [
             [right.x(), new_up.x(), dir.x(), pos.x()],

ray-tracing-core/src/camera.rs

@@ -1,4 +1,4 @@
-use crate::prelude::*;
+use crate::{affine_transform::AffineTransform, prelude::*};
 
 pub trait Camera<R: Rng> {
     fn forward(&self, x: u32, y: u32, rng: &mut R) -> Ray;
@@ -41,6 +41,25 @@ impl BasicCamera {
         }
     }
 
+    pub fn from_affine_transform(
+        width: u32,
+        height: u32,
+        tm: AffineTransform,
+        horizontal_fov: Float,
+    ) -> Self {
+        assert!(horizontal_fov < FloatConsts::PI);
+
+        let l = Float::sin(0.5 * horizontal_fov);
+
+        Self {
+            width,
+            height,
+            pos: Pos3::new(tm.get(3, 0), tm.get(3, 1), tm.get(3, 2)),
+            dir: Dir3::new(tm.get(2, 0), tm.get(2, 1), tm.get(2, 2)),
+            h: l * Dir3::new(tm.get(0, 0), tm.get(0, 1), tm.get(0, 2)),
+            v: l * Dir3::new(tm.get(1, 0), tm.get(1, 1), tm.get(1, 2)),
+        }
+    }
     pub fn from_look_at(
         width: u32,
         height: u32,