📅January 18th, 2026
You know this 2D water effect with a two-buffer trick:
https://www.gamedev.net/articles/programming/graphics/the-water-effect-explained-r915
I made a version of it that runs in ShaderToy (a web application that runs GLSL fragment shaders):
ShaderToy is very fun, just know it's not a fully programmable 3D pipeline.
If you browse people's samples for it you'll see people have done truly amazing things either in procedural geometry, or creating the appearance of 3D geometry using 2D approximations. Doing everything in screen space, lots of procedural rasterization of 2D shapes with no mesh. So anyway, if you're trying to port an algorithm that needs to sample from buffer A to write B, then swap the roles and read B write A, you have some open decisions on how to do it, since you don't have the usual level of flexibility over resource binding.
This method uses a hack of alternating writing to red and blue color channels of an intermediate. Since you can read from the target you're writing to, this way lets you read from the previous frame and the previous one to that.
You can see how it's working if you view the heightmap single channel only:
Or, viewing the raw heightmap data, you can see the two color channels together (with green sort of reserved as a debug channel):
The heightmap gets sampled and used to displace where an input texture of some rocks gets sampled. The end result is a 2D effect all in screenspace but it's a bit 3D looking.
You can see the demo here (works in most browsers):