Utility function for the tessellation of the [0, 1] plane.
npm install glsl-tiling
#pragma glslify: tiling = require(glsl-tiling);
void main() {
vec2 p = gl_FragCoord.xy / resolution.xy;
// t.xy is a vec2 with the new coordinates.
// t.zw is a vec2 with the tiles i, j indexes, from 0 to the number of columns(rows) - 1.
vec4 t = tiling(p, vec2(3., 2.)); // 3 columns and 2 rows
gl_FragColor = vec4(t.xy, vec2(1.0));
}