Flowmaps distortion

Unity Engine
1

I’ve implemented flowmaps based on the following article: http://graphicsrunner.blogspot.ru/2010/08/water-using-flow-maps.html

For smaller values of flowSpeed everything is fine, but for larger values the water surface is getting extremely distorted. Is there any solution to this problem?

Here’s how do the FlowMapOffset calculation:

flowMapOffset0 += flowSpeed * Time.deltaTime;
flowMapOffset1 += flowSpeed * Time.deltaTime;
if ( flowMapOffset0 >= cycle )
     flowMapOffset0 = .0f;

Small flowSpeed:

Large flowSpeed:

Thanks!

2

To answer your question: Yes.

To be slightly more helpful:
Make sure you switch between the two sampled values based on the offset, not time.

It looks like the article you read was based on some presentations that might also help you solve your problem.
Water Flow in Portal 2
Making and Using Non-Standard Textures: Manipulating UVs through Color Data in Portal 2
You could also take a look for the publication UCRL JC-120638 “Flow visualization using moving textures.”

3

I’m switching between the two sampled values based on offset, as in the original article.
For some reason the UVs get stretched at large speeds. Any ideas?

4

I was able to solve the issue. In case somebody else encounters the problem, you just have to set the cycle to a much lower value. The optimal value for cycle is somewhere around: cycle = 15.0f;