In Program 16.4, shadows can be very easily disabled by commenting out one particular line of code. Identify that line of code.

Program 16.4

Compute Shader vec3 ads_phong_lighting (Ray r, Collision c) { // Compute the ambient contribution from the ambient and positional lights vec4 ambient = worldAmb_ambient + pointLight_ambient * objMat_ambient; // initialize diffuse and specular contributions vec4 diffuse = vec4(0.0); vec4 specular = vec4(0.0); // Check to see if any object is casting a shadow on this surface Ray light_ray; light_ray.start = c.p + c.n * 0.01; light_ray.dir = normalize(pointLight_position - c.p); bool in shadow = false; // Cast the ray against the scene Collision c_shadow = get_closest_collision(light_ray);