screen to ray to world orthographic projection

projection.rs

/// Convert the cursor's screen position to a camera ray for orthographic projection.
pub fn cursor_to_world_orthographic(
    camera_world: &Transform,
    camera_projection: &OrthographicProjection,
    window: &Window,
) -> Option<Ray> {
    // Get our cursor's position or return None if no cursor exists.
    let cursor = cursor_normalised(window, &camera_projection.window_origin);
    if cursor.is_none() {
        return None;
    }
    let cursor_pos = cursor.unwrap();

    let mut position = camera_world.right() * cursor_pos.x * camera_projection.scale;
    position += camera_world.up() * cursor_pos.y * camera_projection.scale;

    Some(Ray {
        origin: camera_world.translation + position,
        direction: camera_world.forward(),
    })
}

/// The ray 
pub struct Ray {
    pub origin: Vec3,
    pub direction: Vec3,
}

/// Find the intersection point of this ray and an infinite plane.
impl Ray {
    pub fn intersect_plane(&self, normal: Vec3, origin: Vec3) -> Vec3 {
        let origin = origin - self.origin;
        let distance = origin.dot(normal) / self.direction.dot(normal);
        self.origin + self.direction * distance
    }
}