   return normal * sqrt(1.0 - r) + dir * sqrt(r);
 }
 
+// tracer parameters
+#define N_BOUNCES 4
+#define IMAGE_BRIGHTNESS 1.0
+
 #if 1
 float weight1(float p1, float p2) {
     //return 0.5;

#define light_2_pos vec3(0.0, ROOM_W*0.5, ROOM_H)

// materials
#define light_1_emission vec3(0.8, 0.8, 1.0)*200.0;
#define light_2_emission vec3(1.0, 0.8, 0.6)*200.0;

#define sphere_1_diffuse vec3(.5, .8, .9)
#define box_diffuse vec3(1., 1., 1.)*.7

// helpers
#define UNIT_SPHERE_AREA (4.0*M_PI)

                    probThis = 1.0;
                }

                cur_color += ray_color * emission * weight1(probThis, probOther);
            }

            // visibility test
