3D Glossary | Hardware Secrets

OpenGL: Is a programming interface (API). Games send command to the video card using this language and the video driver converts these commands into instructions that de video processor can understand.Using an API games don't need to have drivers for all video cards available at the market, as it happened in the past.
DirectX: Another programming interface (API), see explanation above.
Bump Mapping: Mapping technique used to create uneven surfaces like an orange skin, the asphalt on a street or a stone, for example.
Alpha Blending: Feature used to create partial transparency between objects. This technique is used in several effects in 3D games, in objects like water, glass, etc.
Dithering: It is possible to mix colors to obtain a color not available on the video card's color palette. This is done in order to not require you to increase the number of simultaneous colors used by the video card, what requires more video memory. The color mixture is done putting color pixels side by side in a way that from a distance your eyes make you believe that there is just one pixel from a different color. Nowadays video cards have enough video memory to run games with 4 billion simultaneous colors (32-bit color), so this feature isn't used by modern games - unless you reduce the number of simultaneous colors for any reason.
Frame buffer: 3D games usually divide the video memory into two blocks, called frame buffers, in order to increase the video performance. While one image is being shown, the video card starts drawing the next image on the second video memory block.. This technique is also called double buffering. Some video cards allow the use of three video memory blocks, feature called triple frame buffer, for cases where the video card is faster than the video monitor (while the video monitor is still drawing the first image and the video card has already finished the second image, the video card can be configured to start drawing the third image in the sequence, in order to not be idle, thus improving the video performance). Depending on the context, frame buffer can be s synonym for "video memory".
GPU (Graphics Processing Unit) or VPU (Visual Processing Unit): Name given to the video processor when it has lightining and transform (also known as L&T) functions integrated on the chip. A long time ago these steps, that are part of a group of tasks called geometric calculation, were done by the system processor. Starting with the GeForce 256 chip these steps moved from the system processor to the video processor. Since then the 3D video performance stopped being dependent on the system's math co-processor (FPU, Floating Point Unit) that is embbeded in the system's processor.
IGP (Integrated Graphics Processor): Is the name given to the motherboard's chipset when it has embbeded video capabilities, i.e., when it has on-board video.
Rendering: The process of creating tri-dimentional images is divided into two groups: geometric calculation and rendering. In the first step the objects to be shown on the screen are calculared. On the rendering step, they are actually drawn on the screen.
FPS: Frames per second, the most traditional way of measuring the video card's 3D performance. Also known as framerate, it measures the quantity of frames (full "screens") that the video card is capable of generating per second. For a game to be "playable" the video card has to be capable of generating at least 30 frames per second on this game.The highest this value, the better. As we explained on the previuos page, descreasing the image quality leads the number of frames per second to increase. It is very important to notice that due the different gaming tecnologies available on the market the video card can obtain a very high FPS number in one game and at the same time a very low FPS number in another game. For example, a GeForce FX 5200 can obtain a good scoring on Quake III which sets this card as "playable" for this game, but this same card will reach a very low FPS score on Doom 3, making it not so good for this other game. By the way, your video card should be chosen based on the games that you will run on your PC.