def generate_ray(self, sample): """Generate a Ray from the camera.""" # Generate raster and camera samples p_ras = Point(sample.image_x, sample.image_y, 0) p_camera = self.raster_to_camera(p_ras) ray = Ray(Point(0, 0, 0), normalize(Vector.from_point(p_camera)), 0.0, float('inf')) # Modify ray for depth of field if self.lens_radius > 0.0: # Sample point on lens lens_u, lens_v = concentric_sample_disk(sample.lens_u, sample.lens_v) lens_u *= self.lens_radius lens_v *= self.lens_radius # Compute point on plane of focus ft = self.focal_distance / ray.d.z p_focus = ray(ft) # Update ray for effect of lens ray.o = Point(lens_u, lens_v, 0.0) ray.d = normalize(p_focus - ray.o) ray.time = sample.time ray = self.camera_to_world(ray) return 1.0, ray