gzdoom/wadsrc/static/shaders/glsl/func_warp2.fp

uniform float timer;

vec4 ProcessTexel()
{
	vec2 texCoord = vTexCoord.st;

	const float pi = 3.14159265358979323846;
	vec2 offset = vec2(0.0,0.0);

	offset.y = 0.5 + sin(pi * 2.0 * (texCoord.y + timer * 0.61 + 900.0/8192.0)) + sin(pi * 2.0 * (texCoord.x * 2.0 + timer * 0.36 + 300.0/8192.0));
	offset.x = 0.5 + sin(pi * 2.0 * (texCoord.y + timer * 0.49 + 700.0/8192.0)) + sin(pi * 2.0 * (texCoord.x * 2.0 + timer * 0.49 + 1200.0/8192.0));

	texCoord += offset * 0.025;

	return getTexel(texCoord);
}