#pragma once

// noises "usually" start in the range -1..1
entityclass(Noise);
classfield(Noise).float noise_baccum;
classfield(Noise).float noise_paccum;
classfield(Noise).float noise_paccum2;
classfield(Noise).float noise_paccum3;
classfield(Noise).float noise_bstate;

ERASEABLE
float Noise_Brown(entity e, float dt)
{
	e.noise_baccum += random() * sqrt(dt);  // same stddev for all dt
	return e.noise_baccum;
}
ERASEABLE
float Noise_Pink(entity e, float dt)
{
	float f;
	f = dt * 60;
	// http://home.earthlink.net/~ltrammell/tech/pinkalg.htm
	if (random() > (0.3190 ** f)) e.noise_paccum = 0.34848 * (2 * random() - 1);
	if (random() > (0.7756 ** f)) e.noise_paccum2 = 0.28768 * (2 * random() - 1);
	if (random() > (0.9613 ** f)) e.noise_paccum3 = 0.43488 * (2 * random() - 1);
	return e.noise_paccum + e.noise_paccum2 + e.noise_paccum3;
}
ERASEABLE
float Noise_White(entity e, float dt)
{
	return random() * 2 - 1;
}
/** +1 or -1 */
ERASEABLE
float Noise_Burst(entity e, float dt, float p)
{
	if (random() > (p ** dt)) e.noise_bstate = !e.noise_bstate;
	return 2 * e.noise_bstate - 1;
}