AlainBarrios

vec2 rotate(vec2 v, float a) {
	float s = sin(a);
	float c = cos(a);
	mat2 m = mat2(c, -s, s, c);
	return m * v;
}

AlainBarrios

  float shape(vec2 p, int N, float size){
    p = p * 2. - 1.;
    
    float a = atan(p.x, p.y) + PI;
    float r = TWO_PI / float(N); 
    float l = length(p);
    
    float d = cos(floor(.5 + a / r) * r - a) * l;
    
    return step(size, d);