void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    // Normalized pixel coordinates (from 0 to 1)
    vec2 uv = fragCoord/iResolution.xy;

    // Time varying pixel color
    vec3 col = 0.5 + 0.5*cos(iTime+uv.xyx+vec3(0,2,4));
    float cdw = iResolution.x/20.0;
    float cdh = iResolution.y/20.0;
    float lw = 600.0;
    float a = sin(iTime/20.0)*0.5;
    float r = ceil(uv.x*cdw)+ceil(uv.y*cdh);
    vec3 col2 = vec3( sin( ((uv.x*lw*sin(r*a))+(uv.y*lw*cos(r*a)))) );
    // Output to screen
    fragColor = vec4(ceil((0.3-col.rrr-col2)),1.0);
}