/* Pixel unit conversion function */
vec2 pos(in float x, in float y) { return st + vec2(x * rx, y * rx); }
vec2 pos(in float x) { return pos(x, x); }
vec2 pos(in vec2 p) { return pos(p.x, p.y); }
float size(in float x) { return x * rx; }
vec2 size(in float x, in float y) { return vec2(x * rx, y * rx); }

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));

    // Output to screen
    fragColor = vec4(col,1.0);
}