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Flowmaps distortion

Started by Enjoy Dec 13, 2012 at 8:45 AM 3 replies 2.2k views

Original Post

Dec 13, 2012 at 8:45 AM

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:

spek

Dec 13, 2012 at 10:08 AM

Not sure, but in the lower picture it seems as if you can see "tiles", where a tile is probably mapped on a single pixel of the flowmap. Using a larger resolution flowmap and having linear-filtering on that texture enabled helps? What doe you see if you directly draw the flowmap itself on the waterplane, instead of the water?

Postie

Dec 13, 2012 at 12:40 PM

My guess is that setting the offset back to 0 when it exceeds the cycle length is the culprit. At faster flow rates the offset will overshoot by more than with a slower rate, so there will be a more obvious discontinuity. Try subtracting cycle from the offset instead of setting it to 0.

Enjoy

Dec 13, 2012 at 4:53 PM

My guess is that setting the offset back to 0 when it exceeds the cycle length is the culprit. At faster flow rates the offset will overshoot by more than with a slower rate, so there will be a more obvious discontinuity. Try subtracting cycle from the offset instead of setting it to 0.

No luck so far... Any other ideas? Using higher resolution flowmap didn't solve the problem.

Enjoy

Dec 14, 2012 at 12:06 PM

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;

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