Hardware
- AGP (Accelerated Graphics Port) – Interface port that connects a video card to the motherboard.
- AGP Fast Writes – Technology that lets a program directly access a video card’s memory, resulting in faster performance.
- Core Clock / Core Frequency – The speed of a video card’s GPU or VPU, measured in megahertz (MHz).
- DDR (Double Data Rate) – A type of memory that transfers data twice each clock cycle.
- DDR-II – DDR memory that has been modified to run at higher clock speeds than DDR.
- Die – Refers to the size a chip. Die size is measured in square millimeters (mm2); a smaller die size means that more chips can fit on a sheet of silicon while consuming less power. Circuit size, measured in microns, is key to reducing the die size of a chip.
- Fab (short for “fabricate”) – Refers to the process of chip construction, e.g.: “That GPU was fabbed in Germany.” A chip is fabbed on a certain die size.
- GPU (Graphics Processing Unit) – The main chip attached to a 3D video card that performs most of the calculations required to display 3D images.
- PCI Express – A high-speed port that connects video cards and other peripherals to a motherboard. PCIe nearly doubles the performance potential of its predecessor, AGP.
- Pixel Shader – Unit of GPU responsible for the appearance of individual pixels. Pixel shaders are used in bump-mapping and reflective surfaces.
- T&L (Transform & Lighting) – The process of offloading transform (displaying 3D images on a 2D monitor) and lighting (providing multiple dynamic light sources) onto the GPU, leaving the CPU free to perform other game-related functions.
- RAMDAC (Random Access Memory Digital to Analog Converter) – Chips on a video card that convert digital information (received from the GPU) to analog, which can then be displayed on a monitor.
VPU (Visual Processing Unit) – An advanced, fully-programmable kind of GPU.
- Z-Buffer – The area of a video card’s memory used to store information about an object’s 3rd dimension (depth, or distance from the camera).
Creating a 3D Image
- API (Application Programming Interface) – A set of pre-defined instructions that allows programmers quick access to routine tasks. Since APIs automate certain functions, they become attractive to game programmers who have to program the same tasks to occur repeatedly.
- Direct3D – Microsoft’s API for rendering 3D graphics.
- DirectX – A collection of seven APIs (DirectDraw, Direct3D, DirectSound, DirectMusic, DirectInput, DirectPlay, DirectShow) produced and distributed by Microsoft.
- OpenGL – Another 3D API that competes with Direct3D. OpenGL differs from Direct3D in that OpenGL is not maintained by a corporation (as Direct3D is maintained by Microsoft) and, as such, updates and revisions to its code tend to come quicker. All 3D video cards made today support both OpenGL and Direct3D.
Displaying a 3D Image
- Aliasing – The tendency of a straight, diagonal line to form jagged “edges” on a computer monitor.
- Alpha Blending – Graphics technique that simulates transparency, such as in smoke or fog.
- Artifact – Distorted or otherwise undesirable video output such as tearing (gaps between textures), ghosting (blurring of images), erroneous pixels, or image flickering.
- Bump-Map – A 3D texture with “feel.” Imagine a cobblestone street: a regular texture would have 2D stones drawn onto a flat surface and shaded to give the impression of depth, but a bump-mapped texture would give a more realistic appearance of stones sticking out of the ground.
- Dynamic Lighting – Scene lighting that changes based on in-game actions; e.g., shooting a hanging light causes the light to swing, bouncing shadows all over the room.
- Frame Rate – The rate or speed at which 3D frames are rendered and displayed. The frame rate is measured in frames per second (fps). This number serves as an all-important benchmark for gamers who want their games to respond and play as quickly as possible, with 60fps being generally accepted as the most desired frame rate. The frame rate is closely tied to many options inside a game; enabling options that enhance image quality (such as anti-aliasing) will typically lower the frame rate because the video card has to work harder to display the same image.
- Resolution – The number of pixels displayed onscreen at any one point. For example, a resolution of 640x480 displays 307,200 pixels onscreen while a resolution of 1600x1200 displays 1,920,000 pixels onscreen. Increasing a game’s resolution will raise the image quality but tend to lower the frame rate because the video card has to work harder to display the same image.
- Render – The process of creating a 3D image.
Correcting a 3D Image – Aliasing
- Anti-aliasing – Technology that reduces or eliminates the jagged appearance of straight lines on a computer monitor, resulting in smoother images.
- FSAA (Full-screen anti-aliasing) – Applying the anti-aliasing process to the entire screen. Measured in “x” amounts: for example, 8x FSAA removes more aliasing than 4x FSAA.
- Multi-sampling – Anti-aliasing technique that fills in the extra pixels required to make a line appear straight.
- Super-sampling – Anti-aliasing technique that first renders a screen in high resolution and then scales the image down to the desired size. A very effective technique, but one that requires a lot of processing power.
Correcting a 3D Image – Textures
- Anisotropic Filtering – Filtering technique that automatically blends and corrects perspective. Preferable over, but slower than, bilinear or trilinear filtering.
- Bilinear Filtering – Filtering technique that blends adjacent textures. Provides less visual quality than trilinear or anisotropic filtering, albeit with more speed.
- Mip-mapping – The process of placing low-quality textures in the background of a 3D scene and moving high-quality textures to the front. As the player’s viewpoint shifts, these textures are shuffled in order to bring the highest-quality images to the front. Without filtering, mip-mapping can degrade image quality because of the seams that develop between the different quality textures.
- Texture – A “skin” applied over a 3D image to give it a distinct look.
- Texture Compression – The process of reducing the amount of memory a single texture occupies.
- Texture Filtering – The process of improving the image quality of textures.
- Trilinear Filtering – Filtering technique that compensates for the loss of quality during mip-mapping by blending the pixels on adjacent mip-maps. Intermediate visual quality between bilinear and anisotropic filtering.
Miscellaneous
- Floating Point – A number described with a decimal point (e.g., 5.76) to allow for more precise 3D images.
- Vsync (Vertical Sync) – An option in some 3D games that synchronizes the game’s frame rate with the monitor’s refresh rate, providing maximum stability. Turning Vsync off will result in a higher frame rate but might cause artifacts to appear.
