This article explains double buffering in computer graphics, emphasizing its importance in preventing screen flickering and ensuring smooth, responsive application animations.
Alexander S. Ricciardi
August 25th, 2024
In computer graphic visualization, double buffering is a crucial technique that is used to address the issues of screen refresh rates and image rendering, particularly in applications where smooth animation and user interactions are essential.
Within a graphics system, images are generated in the framebuffer, and the framebuffer's content—the image—is shown on an output device, usually a screen, which is managed by the window system or, in the case of WebGL, by the browser. Moreover, in single-buffer models, there is only one buffer—the color buffer in the framebuffer—for rendering and display (Angel & Shreiner, 2020). However, an output device like a screen has a fixed refresh rate that is independent of how frequently the graphics system updates the framebuffer. Thus, an issue may arise between the screen refresh rate and the graphics system updating the framebuffer, particularly when repeatedly clearing and redrawing an area of the screen, an operation often performed in animations. In other words, there is no synchronization between when new images are drawn into the framebuffer and when the framebuffer is redisplayed by the hardware. This may lead to situations where only part of the image is displayed, depending on the screen refresh rate. In most cases, this translates into an image flickering issue.
Figure 1
Double Buffers
Note: From Platform Integration Aspects: Framebuffer Concepts by Embedded Wizard (n.d.)
Double buffering provides a solution to this problem by using two buffers. One buffer, called the front buffer, is used to display the current image, while the other, called the back buffer, is used to draw the next image. Once the image from the front buffer is displayed on the screen, the contents of the back buffer are transferred to the front buffer, and a new image is drawn in the back buffer, and so forth. This eliminates flickering and provides seamless animation.
One application that heavily relies on double buffering is Virtual Reality. In VR applications, the user’s experience needs to be deeply immersive to be effective. In this scenario, double buffering is crucial as it helps maintain application responsiveness by preventing flickering and ensuring that the display is updated seamlessly (Lenovo, n.d.). This is especially important when users interact with the GUI, such as dragging windows or scrolling through content. The smooth updates provided by double buffering enhance the overall responsiveness and usability of the interface—another application where double buffering is video games. The user can also experience screen flickering and incomplete scene rendering. For instance, in a first-person shooter game without double buffering implemented, an incomplete scene can be displayed when the screen refreshes, revealing, for example, an enemy hiding behind a wall because the wall was not yet drawn (Nerd First, 2015). Double buffering prevents such issues, ensuring smooth and fully rendered images and enhancing the player experience.
In conclusion, double buffering eliminates issues like flickering and incomplete scene rendering ensuring seamless animations. This technique is particularly vital in applications where user interaction is crucial, such as virtual reality and video games, where maintaining responsiveness and immersion is key to a successful interactive experience.
References:
Angel, E., & Shreiner, D. (2020). Chapter 3 interaction and animation. Interactive computer graphics. 8th edition. Pearson Education, Inc. ISBN: 9780135258262
Embedded Wizard (n.d.). Platform integration aspects: Framebuffer concepts. Embedded Wizard. https://doc.embedded-wizard.de/framebuffer-concepts
Lenovo (n.d). What is double buffering? Lenovo. https://www.lenovo.com/us/en/glossary/doublebuffering/?orgRef=https%253A%252F%252Fwww.perplexity.ai%252F
Nerd First (April 23, 2015). Double buffering - Friday Minis 103 [Video]. Youtube. https://www.youtube.com/watch?v=f3tO_gyyLmk
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