public class InclineSimulatorXY {

    // Mass and angle.
    public double mass = 1;
    public double angle = 30;

    // Separate acceleration, velocity and distance for x and y shadows.
    double ax = 0, ay = 0;
    double vx = 0, vy = 0;
    double x = 0, y = 0;

    // Time and time-step.
    double t = 0;
    double delT = 0.001; 

    // Vertical acceleration.
    double g = 9.8;
    

    public double run (double stopTime)
    {
        // Acceleration along incline: g*sin(alpha).
        double angleRadians = 2*Math.PI*angle / 360.0;
        double a = g * Math.sin(angleRadians);

	// Initialize variables.
        vx = 0;  vy = 0;
        x = 0;  y = 0;
        t = 0;

        // We'll track total distance traveled along incline.
        double d = 0;

	while (true) {
	    // Update time.
	    t += delT;

            // Acceleration along x and y.
            ax = a * Math.cos (angleRadians);
            ay = a * Math.sin (angleRadians);

            // Increase velocity according to appropriate acceleration.
            vx = vx + delT * ax;
            vy = vy - delT * ay;

            // Increase distance in each direction according to appropriate velocity.
            double nextX = x + delT * vx;
            double nextY = y + delT * vy;

            // Update total distance traveled.
            d = d + Math.sqrt ((nextX-x)*(nextX-x) + (nextY-y)*(nextY-y));

            x = nextX;
            y = nextY;

	    if (t >= stopTime) {
                break;
	    }
	}

        return d;
    }

}