-const Material mtl_sph = Material(vec3(1.0, 1.0, 1.0) * 0.1, vec3(1.0, 1.0, 1.0), 80.0, 0.8, 0.0, 1.0);
-const Material mtl_glass = Material(vec3(1.0, 1.0, 1.0) * 0.01, vec3(1.0, 1.0, 1.0), 80.0, 0.0, 0.99, 1.52);
-const Material mtl_air = Material(vec3(1.0, 1.0, 1.0) * 0.01, vec3(1.0, 1.0, 1.0), 80.0, 0.0, 0.99, 1.0);
-const Material mtl_floor = Material(vec3(0.5, 0.5, 0.5), vec3(0.0, 0.0, 0.0), 1.0, 0.0, 0.0, 1.0);
+#define GREY(x) vec3(x, x, x)
+
+const Material mtl_sph = Material(GREY(0.1), GREY(1.0), 80.0, 0.8, 0.0, 0.0);
+const Material mtl_glass = Material(GREY(0.0), GREY(0.99), 80.0, 0.99, 0.99, 1.52);
+const Material mtl_air = Material(GREY(0.0), GREY(0.99), 80.0, 0.99, 0.99, 1.0);
+const Material mtl_floor = Material(GREY(0.5), GREY(0.0), 1.0, 0.0, 0.0, 0.0);