vec3 eye_pos = (inverse(eye_world_matrix)*vec4(0.0, 0.0, 0.0, 1.0)).xyz;
out vec3 world_look_dir = normalize(world_vertex.xyz-eye_pos);
vec3 eye_pos = (inverse(eye_world_matrix)*vec4(0.0, 0.0, 0.0, 1.0)).xyz;
out vec3 world_look_dir = normalize(world_vertex.xyz-eye_pos);