WiiLab Example Code - BouncingBall: lift

Note: MATLAB R2007a or greater is required for this code to run correctly.

Annotations

While the user is keeping the Wiimote's 'B' button pressed, the ball can be moved vertically as the Wiimote is tilted up or down, making use of the Wiimote's y-accelerometer. This code also ensures that the ball cannot be moved any higher or lower than the confines of the window it's in.

Raw Source Code

The source code is also available as a .m file download at the bottom of the page.

function lift(ball)
%  usage:    lift(ball)
%  purpose:  allows the user to move the ball vertically to the position
%            from which they want to throw it

% while the user is holding down the B trigger
    while (isButtonPressed('B'))
        % get the Wiimote's current acceleration
        [xVel yVel] = getWiimoteAccel();
        % get the ball's current position
        [x, y] = getCenter(ball);
        
        % if the default motion will put the ball off the bottom of the
        % window, adjust it so that it'll stop at the bottom of the window
        if ((y - 0.4*yVel) < 10)
            yVel = 10 - y;
            yMove(ball, yVel);
        % if the default motion will put the ball off the top of the
        % window, adjust it so that it'll stop at the top of the window
        elseif ((y - 0.4*yVel) > 290)
            yVel = 290 - y;
            yMove(ball, yVel);
        % default motion to move the ball in response to the Wiimote's
        % y-acceleration
        else
            yMove(ball, -0.4*yVel);
        end %if
        
        % for smoother animation
        redraw;
        pause(0.02);
        
    end %while
    
end

• lift.m