void onSphereRandom(float *x,float *y,float *z){

	// 0 <= theta <= 2PI
	float theta = floatRand() * (2*PI);

	// -1 <= u <= 1
	float u = (floatRand() * 2) -1.0;

	*x = cos(theta) * sqrt(1.0-(u*u));
	*y = sin(theta) * sqrt(1.0-(u*u));
	*z = u;
}