Difficulty curve generation

Difficulty curve

inline function shape(input:Float, drive:Float):Float{
	var k:Float = 2.0 * drive / (1.0 - drive);
	return (1.0 + k) * input / (1.0 + k * Math.abs(input));
}

inline function tri(a:Float, x:Float):Float {
	x = x / (2.0*Math.PI);
	x = x % 1.0;
	if( x<0.0 ) x = 1.0+x;
	if(x<a) x=x/a; else x=1.0-(x-a)/(1.0-a);
	return -1.0+2.0*x;
}

public function genDifficultyCurve(t:Float, diff:Float) {
	var v = tri(0.7+diff*0.1, t * 6.28) * 0.5 + 0.5;
	v = shape(v, 0.4);
	v = shape(v, -0.9+diff*1);
	v = 1 - v;
	return v;
}