Android Question Ripple Effect using Libgdx + Shaders

MarcTG said:

Hello

I'd like to use a ripple effect on touch and I read that this could be done with shaders. I found vertex and fragment code for ripple effects but I am not sure how to use them... The attached file contains the B4a code + the shader program.

Please help

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Informatix said:

I'm a real beginner with shaders. It's a good opportunity to improve my skills. I plan to include a few shader demos in the new version of libGDX (should be released this week).

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MarcTG said:

Hello

I'd like to use a ripple effect on touch and I read that this could be done with shaders. I found vertex and fragment code for ripple effects but I am not sure how to use them... The attached file contains the B4a code + the shader program.

Please help

Click to expand...

Informatix said:

The fragment shader in your archive is unusable without knowing what parameters are expected (e.g. the code uses two textures; without details on these textures, I cannot do anything).
I tried to find another ripple shader but the only one that I found is not very convincing.

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MarcTG said:

Hey Fred, thanks for trying

I probably have to look for other shaders once I understand what I should be looking for... If I may ask, can you share an example where a sprite is being used with a shader touch event... Even though you found a ripple effect that is not convincing, can you please share a working example of that?

At this point I am more interested in learning how it works (additional comments in the code are always much appreciated ).

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Informatix said:

You cannot pass a sprite to your shader. Shaders are written in GLSL, and so use only OpenGL objects. You have to know the basics of OpenGL to start using shaders. If you don't know what are vertices and texture unit, you will be in trouble and won't do anything. You have to understand also the basics of this new language. The language is not very complicated but the terminology is unusual (the variables passed from the vertex shader to the fragment are declared with "varying", the variables exchanged with the application are "uniforms", etc.).
By playing with shaders, I saw that all shaders written for WebGL, which can be found on popular sites like ShaderToy, can be reused in your LibGDX app with almost no change. I created an example (easily) with these two shaders:
https://www.shadertoy.com/view/lsfGzr
https://www.shadertoy.com/view/Mdf3zr

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MarcTG said:

here's an example of a ripple effect for libgdx:
https://github.com/libgdx/libgdx/bl.../src/com/badlogic/gdx/tests/WaterRipples.java

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