+ return normalize(world_normal);
+}
+
+virtual IncomingLight get_incoming_light(int index, vec3 world_pos)
+{
+ vec4 light_pos = light_sources[index].position;
+ vec3 rel_pos = light_pos.xyz-world_pos*light_pos.w;
+ float d = length(rel_pos);
+ float attenuation = 1.0/dot(vec3(1.0, d, d*d), light_sources[index].attenuation);
+ return IncomingLight(rel_pos/d, light_sources[index].color*attenuation);