attribute vec2 position;
        varying vec2 vPosition;
        void main(void) {
            vPosition = position;
            gl_Position = vec4(position, 0.0, 1.0);
        }
    

        precision lowp float;

        varying vec2 vPosition;
        uniform float time;
        uniform float width;
        uniform float height;
        uniform float slider_a;
        uniform float slider_b;
        uniform float slider_c;

        void main() {
            float pi = 3.14159;
            float x = (vPosition.x / height) * 36.2;
            float y = (vPosition.y / width)  * 36.2;
            float n = 762.5 * slider_b * sin(time*0.0075);
            float m = 420.7 * slider_c * cos(time*0.07);
            float a = cos(n * pi * x) * cos(m * pi * y) - cos(m * pi * x) * cos(n * pi * y);
            vec3 c = mix(
                vec3(0.9,0.9,0.9),
                vec3(0.1,0.1,0.1),
                floor(a + slider_a));
            gl_FragColor = vec4(c, 1);
        }