MovingCells3.frag

#ifdef GL_ES
precision mediump float;
#endif

#define PI 3.14159265358979323846

uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;

//---------------------------------------------------------------------

float random (in vec2 _st) {
    return fract(sin(dot(_st.xy,vec2(12.9898,78.233)))*43758.5453123);
}

float box(vec2 _st, vec2 _size){
    _size = vec2(0.5)-_size*0.5;
    vec2 uv = smoothstep(_size,_size+vec2(1e-4),_st);
    uv *= smoothstep(_size,_size+vec2(1e-4),vec2(1.0)-_st);
    return uv.x*uv.y;
}

vec2 brickTile(vec2 _st, float _zoom){
    _st *= _zoom;

    // Here is where the offset is happening
    _st.x += step(1., mod(_st.y,2.0)) * 0.5;
    _st.x -= u_time;

    return fract(_st);
}

//---------------------------------------------------------------------

void main() {
    vec2 st = gl_FragCoord.xy/u_resolution.xy;
    vec3 color = vec3(0.0);

    // Divide the space in 4
    st = brickTile(st, 10000.);
    // Draw a square
    float b = box(vec2(random(st), random(st)), vec2(.95));
    color = vec3(fract(b * random(vec2(u_time))), fract(b * random(vec2(u_time))), fract(b * random(vec2(u_time))));

    gl_FragColor = vec4(color,1.0);
}