maaaath :33

raytracer/src/ray.rs

@@ -0,0 +1,58 @@
+use alloc::vec::Vec;
+use cgmath::{Matrix4, Vector3, Vector4, num_traits::Num};
+
+pub struct Ray<T> {
+    pub(crate) origin: Vector3<T>,
+    pub(crate) direction: Vector3<T>,
+}
+
+pub fn construct_primary_rays(
+    (width, height): (usize, usize),
+    (pixel_x_coord, pixel_y_coord): (usize, usize),
+    cam_to_world_matrix: &Matrix4<f32>,
+    focal_length: f32,
+    rays_per_pixel: usize,
+) -> Vec<Ray> {
+    let mut rays: Vec<Ray> = Vec::with_capacity(rays_per_pixel);
+
+    //generate all rays for this pixel and add them to the rays vector
+    for _ in 0..rays_per_pixel {
+        rays.push(generate_single_primary_ray(
+            (width, height),
+            cam_to_world_matrix,
+            focal_length,
+            pixel_x_coord,
+            pixel_y_coord,
+            //no noise
+            0.0f,
+            0.0f,
+        ));
+    }
+
+    rays
+}
+
+fn generate_single_primary_ray(
+    (buffer_width, buffer_height): (usize, usize),
+    cam_to_world_transform: &Matrix4<f32>,
+    focal_length: f32,
+    u: usize,
+    v: usize,
+    u_offset: f32,
+    v_offset: f32,
+) -> Ray {
+    //calculate the ray direction and translate it to world space
+    let direction_camera_space: Vector4<f32> = Vector4::new(
+        u as f32 - (buffer_width as f32 / 2.0) + u_offset,
+        v as f32 - (buffer_height as f32 / 2.0) + v_offset,
+        focal_length,
+        0.0,
+    );
+
+    let direction_world_space = cam_to_world_transform * direction_camera_space.normalize();
+
+    Ray {
+        origin: cam_to_world_transform.w.truncate(),
+        direction: direction_world_space.truncate().normalize(),
+    }
+}