// turns out that nightRatio falls off much faster than
// actual brightness of artificial light in relation to natual light.
// Power ratio was measured on torches in MTG (brightness = 14).
- float adjusted_night_ratio = pow(nightRatio, 0.6);
+ float adjusted_night_ratio = pow(max(0.0, nightRatio), 0.6);
// cosine of the normal-to-light angle when
// we start to apply self-shadowing