Sprite (computer graphics): Difference between revisions

Revision as of 15:20, 22 September 2005

Revision as of 03:16, 29 September 2005

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Separate locations in memory were used to hold the main display and the sprites, which were composited together into the display in two passes. This placed the sprites on the display without interferring with the "background" image, making them easy to move around the display. Examples of such systems include the [[Atari 8-bit]] machines (which referred to them as ''player/missile graphics'') and the [[Commodore 64]].

In contrast, [[bit blit]]ting (short for "bit block transfer") drew sprite-like figures into the same memory as the background, with the main display hardware rendering the entire image at once. Moving a bit blit object on the screen requires several steps; the orignaloriginal background to be painted over must be stored, the image drawn, then when it moves the original image painted back into the blit's ___location to "repair" the display and the process repeated for the new ___location. The upside to this approach is that there is no need for custom hardware and any number of images can be composited. The downside is that, in the era of severely limited processor performance, the time needed to repair the images and redraw them was considerably more expensive than using a sprite system.

Sprites are rare in most video hardware today. More commonly, bit blitting is employed or more complicated rendering algorithms are used. For extreme graphics performance, [[graphics processing unit|graphics accelerators]] now have a similar role.