Take a look at my Bouncing Angry Bird example tweaked version from:
http://forum.processing.org/topic/wanna-change-direction-with-keypressed
After using scale(-1, 1); you have to use the negative of the x position of an image, plus its width!
http://forum.processing.org/topic/wanna-change-direction-with-keypressed
After using scale(-1, 1); you have to use the negative of the x position of an image, plus its width!