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varying lowp vec4 VertexColor;
#ifdef GL_ES
precision mediump float;
#endif
uniform vec2 u_resolution;
vec2 skew (vec2 st) {
vec2 r = vec2(0.0);
r.x = 1.1547*st.x;
r.y = st.y+0.5*r.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 = VertexColor.xyz
// Scale the space to see the grid
st *= 10.;
// Show the 2D grid
color.rg = fract(st);
// Skew the 2D grid
// color.rg = fract(skew(st));
// Subdivide the grid into to equilateral triangles
// color = simplexGrid(st);
gl_FragColor = vec4(color,1.0);
}
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