// Title: Marx
// Author Leo Coogan - 2025 - existential.beauty
// Based on: https://thebookofshaders.com/edit.php#11/simplex-grid.frag
// Author @patriciogv - 2015 - patriciogonzalezvivo.com

#ifdef GL_ES
precision mediump float;
#endif

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



vec2 skew (vec2 st) {
    vec2 r = vec2(0.0);
    r.x = 1.1547*st.x;
    r.y = r.x+0.5*st.x;
    return r;
}

vec3 simplexGrid (vec2 st) {
    vec3 xyz = vec3(0.0);

    vec2 p = fract(skew(st));
    if (p.x > p.y) {
        xyz.xy = 1.0-vec2(p.x,p.y-p.x);
        xyz.z = p.y;
    } else {
        xyz.yz = 1.0-vec2(p.x-p.y,p.y);
        xyz.x = p.x;
    }

    return fract(xyz);
}

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

    // Scale the space to see the grid
    st *= 30. + u_mouse * sin(0.0001 + u_time );

    // Show the 2D grid
    color.rb = abs(st * sin(st.y));
  color.rg = fract(st * sin(st.x * 0.1));
  
  

    // Skew the 2D grid
     //color.rg = fract(skew(st));

    // Subdivide the grid into to equilateral triangles
    //color = simplexGrid(st);
  
    // vec3 pos = vec3(st*5.0,u_time*0.5);

    // color = vec3(cnoise(pos));
      // vec4 ixy = permute(permute(ix) + iy);



    gl_FragColor = vec4(color,1.0);
}