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Encyclopedia > Double buffering

In computer graphics, double buffering (sometimes called ping-pong buffering) is a technique used to reduce or remove visible artifacts from the drawing process. It may be implemented in either software or hardware. Computer graphics (CG) is the field of visual computing, where one utilizes computers both to generate visual images synthetically and to integrate or alter visual and spatial information sampled from the real world. ...


Computer monitors constantly redraw the visible video page (at around 70 times a second), and so it is difficult to make changes to the video page (such as creation or movement of complex objects onscreen) without the monitor showing the results before the graphics operation is complete. This results in ugly artifacts such as flickering, tearing and shearing.


A software implementation of double buffering uses a video page stored in system RAM that all drawing operations are written to. When a drawing operation is considered complete, the whole page, or a portion of it, are copied into the video RAM (VRAM) in one operation. This is generally synchronised so that copy operation is ahead of the monitor's raster beam so that ideally (if the copy is faster than the video beam) artifacts are avoided. The software method is not always flawless, and has a higher overhead than the hardware method. To meet Wikipedias quality standards, this article or section may require cleanup. ... VRAM an acronym for Video RAM. Generally a term used in computers to describe RAM dedicated to the purpose of displaying bitmap graphics in raster graphics hardware. ... Suppose the smiley face in the top left corner is an RGB bitmap image. ...


The hardware method is also known as 'page flipping'. In this method, two graphics pages in VRAM are used. At any one time, one page is actively being displayed by the monitor, while the other, background page is being drawn. When drawing is complete, the roles of the two pages are switched, so that the previously shown page is now being modified, and the previously drawn page is now being shown. The hardware method guarantees artifacts will not be seen as long as the pages are switched over during the monitor's vertical blank period when no video data is being drawn. This method requires twice the amount of VRAM that is required for a single video page. VRAM an acronym for Video RAM. Generally a term used in computers to describe RAM dedicated to the purpose of displaying bitmap graphics in raster graphics hardware. ... VRAM an acronym for Video RAM. Generally a term used in computers to describe RAM dedicated to the purpose of displaying bitmap graphics in raster graphics hardware. ...


A variation of double buffering exists called triple buffering. In computer graphics, triple buffering is a variant on double buffering, a technique for drawing graphics that show no (or less) flicker, shearing, and tearing artifacts. ...


External Links

  • Double-Buffering in Java - Learn how to use a secondary buffer to eliminate flickering in your Java applications and applets.

  Results from FactBites:
 
Double Buffering and Page Flipping (The Java™ Tutorials > Bonus > Full-Screen Exclusive Mode API) (730 words)
Suppose you created a back buffer (in video memory) of the exact width, height, and bit depth of the screen, then drew to that buffer the same way as you would using double-buffering.
When a page flip occurs, the pointer to the old back buffer now points to the primary surface and the pointer to the old primary surface now points to the back buffer memory.
In a flip chain, the next available back buffer becomes the primary surface, etc., all the way down to the rearmost back buffer that is used for drawing.
Java(TM) Boutique - The Java Game Development Tutorial - Page 4 (1173 words)
So let's talk about the double buffering which is a really good and effective solution to avoid a flickering screen and the best of it all: You can use this method in every applet the same way as I do now, so you'll never have to worry about that problem again!
Double buffering means to paint all the things in the paint() method to an offscreen image.
The only disadvantage of the double buffering is, that it produces a large amount of data and every image is drawn two times (offscreen and when copying to the screen).
  More results at FactBites »


 
 

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