Animation - Erasing a Sprite

Animation - Erasing a Sprite

Deus Ex Machina

Member #9,145

October 2007

Hi,

I was wondering if anybody could expain this:

To keep it simple, say I want to move a 10 x 20 rectangle around on the screen. If I try to erase it with a 10 x 20 rectangle of the background color, I get a "trail" in the path of motion.

I can deal with this okay by making the erasing rectangle a bit bigger, but it doesn't make sense to me logically. If I draw a rectangle of the background color of exactly the same size, in exactly the same place the moving rectangle was, shouldn't it obliterate it?

Thanks,

Jim

Paul whoknows

Member #5,081

September 2004

If my understanding is correct, a double buffer system is what you need.

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"The unlimited potential has been replaced by the concrete reality of what I programmed today." - Jordan Mechner.

Neil Black

Member #7,867

October 2006

Are you moving it before erasing? Make sure you're erasing the right spot.

Slartibartfast

Member #8,789

June 2007

Make sure you Erase->Move->Draw->Render.
Also, you're drawing and erasing to a single bitmap, right?
And if you can't fix it yourself, some code might help. (using [ code ] tags and showing only relevant code)

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"No man who has at least one good hand has to rape someone if he's horny and can't get any." - Neil Black
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Neil Black

Member #7,867

October 2006

Quote:

Make sure you Erase->Move->Draw->Render.

Yeah, that's what I was trying to say.