Pixel-Composer/shaders/sh_grid/sh_grid.fsh

//
// Simple passthrough fragment shader
//
varying vec2 v_vTexcoord;
varying vec4 v_vColour;

uniform vec2  position;
uniform vec2  scale;
uniform float angle;
uniform float width;

void main() {
	vec2 pos = v_vTexcoord - position, _pos;
	_pos.x = pos.x * cos(angle) - pos.y * sin(angle);
	_pos.y = pos.x * sin(angle) + pos.y * cos(angle);
	
	vec2 dist = _pos - floor(_pos * scale) / scale;
	float ww = width / 2.;
	
	if(dist == clamp(dist, vec2(ww), vec2(1. / scale - ww)))
		gl_FragColor = vec4(1.);
	else
		gl_FragColor = vec4(vec3(0.), 1.);
}