Can you send the full program please? Thanks -- Matthias
On Oct 5, 2014, at 8:52 PM, Brian Craft wrote: > Hello -- Newbie here. I'm going through "Realm of Racket". I'm seeing an odd > effect when using this to-draw handler in big-bang: > > (define (draw-a-ufo-onto-an-empty-scene game) > (let ([pos (game-pos game)]) > (place-image IMAGE-of-UFO (round (vec-x pos)) (round (vec-y pos)) > (empty-scene WIDTH HEIGHT)))) > > vec is (struct vec (x y)) > > As the y coordinate approaches zero, IMAGE-of-UFO gets clipped on the top and > bottom, looking a bit like it's winking out of existence, rather than sliding > off the canvas. This doesn't happen on any other edge. It's only as y > approaches zero. It starts when the edge of the image meets the edge of the > scene. That is, if the image is 20px high, and y starts at 30, and decreases > by 1 on each tick, it will move up the canvas for 30..10, but from 10 on the > image will not change position, but will instead be clipped on the top & > bottom, until it disappears. > > This does not happen in the interactions window. If I call the above function > in the interactions window, it renders as expected, with the image moving > smoothly off the edge. > > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
