GLSL for simple water surface effects

Question

I'm looking for some pointers on how to implement simple water surface effects in OpenGL ES 2.0. Nothing fancy like reflection or refraction, just a basic ripple/wave effect that modulates over time. Performance is critical. I'm assuming this will be best done in a shader.

Any pointers on how to best handle this?

Answer 1

There is an old trick to simulate water waves & ripples using minimum effort in terms of equations. It's used in many places, and I can't find the original, but you can grab it, for example, from here.

You'll need 2 textures, each containing just height. Simulation is done by ping-ponging between them (using one as a source and second as destination each time).

When rendering, you might need to derive surface normal from the neighbour heights.

Answer 2

Adrian Boeing's blog has example GL code, accompanied by clear explanations, for a number of effects including ripple.