Glitches on Mobile

[miketucker]

When running on an ES 2.0 mobile device there are visual artifacts that are not present on the desktop version. I thought this could be a precision problem, but changing to 'highp' didn't seem to work. Could this be the actual math operations on the GPUs? Or the compiler maybe? Completely stumped.

[fluffyfreak]

Woah, this runs on mobile?!?

Firstly I'm amazed and curious what you're running it on and how you got it on there? I wrote this for desktop and developed it on Windows 7/8.1 with Visual Studio so not really surprised it's not running.

Are you using the master branch as a base? It needs texture lookup in the vertex shader to do the displacement. According a post on StackOverflow that might be a problem as your hardware may not have it implemented.

Let me know, maybe we can work around it.

[miketucker]

haha, it's ES2.0 compatible, right? WebGL and mobile ES2.0 are usually pretty similar (with the exception of bugs like this)

Here's how I'm implementing below. Just grabbing the position from the vertex, and doing a color of the billow function. Leaning towards it being a precision problem, but defining all vec3s and floats as 'highp' didn't seem to help.

It's running as a GLSL shader in Unity, and the previous screen is from an iPad.

Looks fine on the desktop editor, see image:

varyin vec3 pos;

#ifdef VERTEX


void main()
{
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
    pos = vec3(gl_Position.x,gl_Position.y,gl_Position.z);
}

#endif


#ifdef FRAGMENT


uniform float _Lacunarity;
uniform float _Roughness;
uniform float _Frequency;
uniform float _TimeOffset;
uniform int _Octaves;


void main()
{
    gl_FragColor = vec4(1) * billow_octavenoise(_Octaves, _Roughness, _Lacunarity, pos, _Frequency, _TimeOffset);
}

#endif
ENDGLSL

[fluffyfreak]

Hmm, that does look like a precision problem.
You're just using the noise part then none of the rest of the code?
Perhaps you can try a more densely tessellated cube?

The noise library I use is, with only a few additions or changes, just the one from Ashima so you might have better luck there or by asking on StackOverflow if that's the only part you're using.