Ocean 4: foam, fine ripples and haze

Three more touches turn a nice sea into a convincing one.

1. Fine ripples. Two more waves with very small amplitude but high frequency add the little ripples that catch the light. (They are invisible as a shape, but huge for the normals.)

2. Foam. Whitecaps form on the tops of waves. Foam where the height is large, but not as a clean blob: add a noise value to the height before the threshold so the edge becomes lacy: smoothstep(0.15, 0.25, h + (lace - 0.5) * 0.22). The noise scrolls a little with time so the foam seems to drift.

3. Haze. Distant water loses contrast in the air: blend towards the horizon color with distance, 1.0 - exp(-t * 0.012). This one line is what makes the picture feel big. (The same trick, called fog, works in every 3D scene.)

float lace = fbm2(pos.xz * 3.5 + float2(time * 0.3, 0.0));
float foam = smoothstep(0.15, 0.25, h + (lace - 0.5) * 0.22);
col = lerp(col, float3(0.95, 0.97, 1.0), foam * 0.85);
col = lerp(col, float3(0.75, 0.82, 0.9), 1.0 - exp(-t * 0.012));