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Clearing the Screen

Started by pizza box Dec 13, 2001 at 7:02 PM 8 replies 700+ views

Original Post

Dec 13, 2001 at 7:02 PM

I''m programming a tetris-style game using Window''s GDI. Every time I draw a rectangle it stays on the screen when I draw the next one, so I would leave a trail of rectangles whenever I moved the block. To solve this, I drew a big black rectangle the size of the screen to clear it before drawing the next frame, but I was wondering if there was a faster way to clear the screen, or perhaps a function that I could use? Thanks

Badone

Dec 13, 2001 at 7:06 PM

Have you tried just drawing a black box over the tetris box? So you can use the same code that you used to draw the box but with black instead of your color.

Floppy

Dec 13, 2001 at 7:15 PM

Are you double buffering?

pizza box

Dec 13, 2001 at 7:16 PM

Thats what Ive been doing, but the box I draw is the entire screen so it clears out everything. The problem is that I can see the blocks flickering, so it is kind of slow. I was wondering if there are any built-in functions to solve this.

Dharma

Dec 13, 2001 at 7:20 PM

You dont have to draw a black box over the entire screen. Just a black one on same place and same size but black... Or double buffer. (drawing everything on a invisible area then copy it all to the screen.

/Mario

Mvh Mario..

Edited by - Dharma on December 13, 2001 8:21:03 PM

Floppy

Dec 13, 2001 at 7:21 PM

What API are you in? Doing double buffering by putting a black square over the screen is not double buffering. OpenGL uses this:

  
//  Swap the buffers (double-buffering)

SwapBuffers(window->hDC);

Dharma

Dec 13, 2001 at 7:23 PM

If you will stick to using GDI... Below you have a link describing this.

http://www.winprog.org/tutorial/references.html

Mvh Mario..

atcdevil

Dec 13, 2001 at 7:24 PM

Hey, try the function BitBlt

Dharma

Dec 13, 2001 at 7:27 PM

Sorry bad link.. this should work fine

http://www.winprog.org/tutorial-old/

Mvh Mario..

pizza box

Dec 13, 2001 at 7:44 PM

Thanks for the link. I wasn''t double buffering before, I had a late post. Hopefully things will run a little smoother now. Thanks

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