         float percent= diff/size;
         color = (nightblue_color + (sunset_color - nightblue_color) * percent);
         color = mix(color, nightblue_color, phi_diff);
-        // color = vec3(phi_diff, 0,0 );
-
     // sunrise to high_noon OR high_noon to sunset
     } else if (sun_z > sun_start && sun_z < high_noon_start) {
         float size = high_noon_start - sun_start;

    // night
    if (sun_z < nighttime) {
        color = nightblue_color;
        // color = vec3(phi_diff, 0,0 );

    // night to sunrise OR sunset to night
    } else if (sun_z > nighttime && sun_z < sun_start) {
        float size = sun_start - nighttime;

    if (phi_diff > 0.5) {
        phi_diff = 1.0 - phi_diff;
    }
    phi_diff *= 2.0;

    float sun_start;
    if (sun_x > 0) {
        sun_start = sunrise_start;
    } else {
