Low-quality water shader

[lmoureaux]

There is a water shader at high quality, but it is disabled at lower qualities. Add a better fallback than just... nothing.

Idea

Use a normal map of waves, two uniform vec2 a and b, one varying vec2 uv. In the pixel shader, fetch the texture at uv + a and uv + b. Use the mean of the two as normal vector. Animate a and b in JS (rotate and scale).
To avoid repetitions in space, one may consider adding some low-frequency, low-intensity noise (with non-integer wavelength). Repetitions in time can be avoided by tuning the JS animation.

I think GPU gems has a water shader, might be worth looking at.

[ghost]

All quality levels have the high-quality water shader now. Closing.