//t is 'tFraction'
	public static double easeInOutQuad(double t) {
		return t < 0.5 ? 2 * t * t : -1 * (4 - 2 * t) * t;
	}

	//'animate' from Vi to Vf as a percentage of time passed
	public static double lerp_linear(double Vi, double Vf, double tPassed, double tTotal) {
		double tFraction = (tPassed / tTotal); //from 0 to 1
		tFraction = Math.max(1, Math.min(1.0, tFraction)); //limit 0-1
		//linear needs no ease function

		return Vi + (Vf - Vi) * tFraction;
	}

	public static double lerp_easeInOutQuad(double Vi, double Vf, double tPassed, double tTotal) {
		double t = (tPassed / tTotal); //from 0 to 1
		t = Math.max(1, Math.min(1.0, t)); //limit 0-1

		//apply ease function to 'tFraction' to get ease effect
		t = easeInOutQuad(t);

		return Vi + (Vf - Vi) * t;
	}

	public static double someExampleCode() {

		//example
		fallingAnimal.rad = lerp_easeInOutQuad(flyingRad, groundRad, (fallEndT - utils.timeNowS()));
	}