#glsl cave

gistfile1.as

#ifdef GL_ES
precision highp float;
#endif

uniform vec2 resolution;
uniform float time;
uniform sampler2D tex0;
uniform sampler2D tex1;
uniform sampler2D tex2;
uniform sampler2D tex3;

void main(void)
{
    vec2 p = -1.0 + 2.0 * gl_FragCoord.xy / resolution.xy;
    vec2 uv;

    float r = pow( pow(p.x*p.x,16.0) + pow(p.y*p.y,16.0), 1.0/32.0 );
    uv.x = .5*time + 0.5/r;
    uv.y = 2.0*atan(p.y,p.x)/3.1416+2.5;    
    vec3 col0 = texture2D(tex0,uv).xyz;
    vec3 col1 = texture2D(tex1,uv).xyz;
    vec3 col2 = texture2D(tex2,uv).xyz;
    vec3 col3 = texture2D(tex3,uv).xyz;
    vec3 col  = vec3(0);
    col += (step (4.0,uv.y) + step(uv.y,1.0)) * col0; 
    col += step (1.0,uv.y) * step(uv.y,2.0) * col1;
    col += step (2.0,uv.y) * step(uv.y,3.0) * col2;
    col += step (3.0,uv.y) * step(uv.y,4.0) * col3;
    gl_FragColor = vec4(col*r*r*r,1.0);
}