A swap chain is a series of framebuffers used to render an image before displaying it on a monitor. It eliminates timing conflicts and graphical artifacts, and creates smooth animations by rendering scenes in advance and swapping them during vertical retrace. It is also known as double or triple buffering and requires precise timing algorithms.
A swap chain is a series of framebuffers, or locations in computer memory, used to render an image before it is displayed on a real monitor or other device. There are always at least two framebuffers in a swap chain because the first, or active buffer, is usually identified as the one currently shown on the display. While one framebuffer is displayed, the next buffer can be rendered and prepared for display and then swapped to the device as needed. Using a swap chain can eliminate some of the problems that occur due to conflicts between hardware and software timings, as well as graphical artifacts that can appear due to rendering directly on the display device.
How an image is displayed on a monitor is really just a matter of placing the correct sequence of numbers into a specific area of memory. Anything in this memory area is drawn to the screen multiple times per second. A screen is drawn in horizontal lines from the upper left corner to the lower right corner. The moment when the screen begins the next frame, as it moves from the lower right corner of the screen to the upper left corner, is known as the vertical retrace.
Implementations of a swap buffer only draw to the screen during vertical retrace. If this timing is disabled, or if a program attempts to draw on a screen during periods when a frame is being rendered, a graphics anomaly known as tearing can appear. This occurs when the image in the display device’s memory suddenly changes in the middle of rendering, causing one side of the display to show the last frame and the rest of the screen to show the new one.
By rendering a scene in advance in a framebuffer, the next frame to be displayed is already prepared and can be quickly inserted into the display’s memory to be shown. While one image is displayed, the next one is drawn to the idle framebuffer, also called the back buffer. This creates smooth animations and visual effects that can be synchronized exactly to avoid tearing.
The term “swap chain” is more commonly known as double buffering or triple buffering, depending on the number of frames drawn before the active framebuffer. Using nanosecond or millisecond timing algorithms is an essential part of using a swap chain to ensure that the monitor’s maximum frame rate is not exceeded and that programs can adjust their processing and resources to a system. Using a swap chain, when implemented correctly, can produce smooth animation regardless of the properties of a display device or the amount of time it takes to render a single animation frame.
Protect your devices with Threat Protection by NordVPN
