-vec3 phong_one_light(vec3 light, vec3 normal, vec3 look, vec3 light_color, vec3 surface_diffuse, vec3 surface_specular, float shininess)
+vec3 phong_one_light(vec3 light, vec3 normal, vec3 look, vec3 surface_diffuse, vec3 surface_specular, float shininess)