For those of you who didn't pick up the second issue of Voodoo magazine, I am putting the 3d Dictionary or as they called it the "3d Glossary". Either way it helps translate those tricky terms and abbreviations. Oh yeah, I must give credit where credit is due, all of these definitions were prepared for Voodoo Magazine by Dave Whittle and Chris Kramer. They did a good job of explaining fog so no one could understand it.

AGP- stands for "Accelerated Graphics Port." According to the AGP Implementors Forum ( www.agpforum.org ), AGP is "a new platform specification that enable high performance graphics capabilites, especially 3D, on PCs at mainstream price points." The AGP slot also runs at a faster speed than the older PCI bus: 66MHz versus 33MHz. As a way of processing graphics, AGP lets developers use the computer's main memory to cache larger texture maps, as well as handle z-buffering and alpha blending (AGP Voodoo 2 card will not take advantage of this, but it's likely that futre 3Dfx products will).

Aliasing-  Rendering artifacts that occur when a continuous function is discretely sampled or sub-sampled. Two common types of aliasing are polygonal aliasing and texture aliasing. Polygonal aliasing is a rendering artifact that occurs when rasterazation applies color to a pizel without considering how much of the pixel is coverd by the triangle. Along the edges of the triangle, only a portion of the pixel is likely to be coverd by the triangle. An aliased triangle will have jagged edges. Texture aliasing is a rendering artifact that occurs when a texture map is not sampled frequently enough, or when the texel area coverd by a pixel is not accounted for. Aliasing is evident in the "stair-step' effect you sometimes see on diagonal lines, or the stange moire patterns that crop up in games like Jedi Knight or Need for Speed 2 SE when you move past straight lines. See Anti-Aliasing.

Alpha Blending- The most common, and one of the most important, forms of blending (see Blending) in 3D accelerated games. Alpha Blending is used primarily to create visiual effects like transparency (water or glass), translucency (artifacts that partially obscure objects, such as smoke, clouds or explosions), lensflare and reflections.

Ambient Light- One of the components of a lighting model. Ambient light seems to come from all directions, rather than from a specific source. Back lighting in a room is an example - it scatters in all directions after striking a surface, as does diffuse light.

Animation- Generating and displaying a scene as the viewpoint and/or objects change postion to give the illusion of motion.

Anti-Aliasing- Techniques for elimination the stair-step jaggies on lines and edges (see aliasing). For polygonal aliasing, a rendering technique that accounts for fractional coverage of a pizel when assigning it a color, thereby reducing or eliminating the jagged edges that characterize an aliased rendering. For texture aliasing a rendering technique that accounts for the areas of texels covered by a pixel.

API- "Applications Programming Interface." An API is a set way of performing tasks for particular applications. The most prevalent API you'll see written about in Voodoo is DirectX (specifically the Direct3D component), which is the way Microsoft wants games to talk to it's Windows environment. There are many different APIs for different functions, such as Silicon Graphic's OpenGL or 3Dfx's Glide. See Glide, Direct3D and OpenGL.

Back-Face Culling- The process of elininating rear-facing triangles. A triangle has two sides, front and back, with only one side visible at a time. When you draw a three dimensional objects, there are portions of that object that are not directly visible on the screen. Back-face culling determines which side is visble, and eliminates the rear triangles before they are rendered, cutting down on processing time. Also known as. "polygon removal."

Banshee- The seconds generation 2D/3D Voodoo combination from 3Dfx interactive. Estimated release early '99. look for more information in future issues. (That means you will have to go out and spend a few dollars for Voodoo Magazine.)

Bi-Linear Filtering-A technique for choosing the texel color to apply to a pixel during texture mapping. The weighted average of the four texels nearest the pixel center is used, blending the colors togethers for a smoother appearance. The results is a slightly fuzzy blur. As you walk towards a wall in a game, bi-linear filtering smoothes it out, where in the software version, the textures would become chunky.

Blending- When two triangles overlap in screen space, a decision must be made about the color of the pixels in the overlapping area. Blending is a technique for reducing the two colors to one, usually as a linear interpolation of the two canidates. Alpha blending is the most common usage, allowing for explosions and transparentcies among other uses. See Alpha-Blending.

Bump Mapping- As simple as it sounds, Bump Mapping gives an objects a rough textured appearance. As light passes over this texture, different shadows and reflections appear across the surface, which shift according to the light's movements and placement. For example, if you look at a rug while you're standing, it appears smooth and solid, a single unified texture. If you get down on your hands and knees and look across the top of the rug, you notice ridges and bumps, crevasses and shadows. The 3Dfx Donut Demo is an excellent example of how bump mapping can be used.

Chipset- refers to the key components of your 3Dfx, ie. the little pieces of silicon that make the thing work. Another way of referring to your Voodoo Graphics, Voodoo Rush, or Voodoo 2 Card.

Chroma-Key- A technique for removing pixrls of a specific color, used to implement a "blue screen."

Clamp- Forcing a value to lie within a specified range of values. This keeps small textures from "tiling" across a larger polygonal sureface. Since clamped values are always set, a programmer cannot accidentally assign a strange value and freak out the Voodoo chipset. the reduces cracking in models if done correctly. On a techincal notem Voodoo clamps to 1/16 of a pixel.

Clock Speed- The internal rate fo data movement between computer chips.

Clipping- A visiual distortion when part of a 3D triangle goes outside the screen limites and the entire triangle disappears from the image.

D3D- see Direct3d.

Depth Buffering- Same as Z-Buffering.

Depth Complexity- How many times overlapping pixels are drawn. For instance, in Quake, when a monster stands in the hallway, the engine first draws the hallway, the draws the monster on top of it. In games, pixels are drawn three to four times.

Direct3D- A static API for 3D built into the Windows 95/98 DirectX systems designed to run with all hardware and software (as in the song from Everclear, "you try to be everything to everyone").

Dithering- A technique for increasing the percieved range of colors in an image by applying a pattern to surrounding pixels to modify their color values. When viewed from a distance, these colors appear to blend into an intermediate color that can;t be represented directly. Dithering may produce artifacts if not done properly. For example, when you fire a rocket down a hallway in Quake, you notice the dynamic lighting trail along the walls in banded, not an accurated lighting model - the is a dithering problem.

Double Buffering- This allows you to draw a second scene while viewing the first. Using two color buffers: a scene is prepared in one buffer while the previsouly renderd scene in the other buffer is displyed. When the redering is complete, the two buffers are swapped and the rendering of the next scene can begin in the buffer that is no longer being displayed. This prevents flickering or tearing. See Single Buffering, Triple Buffering, and Frame Buffer.

Draw In- An inferior game engine and/or video card will cause this visual degradation noted by not being able to display enough polygons on the screen at the same time. Also known as "pop-up".

Drop Out- When a game engine makes an error in calculations and drops or loses a polygon from the environment, usually resulting in a black space where the poly should have been.

Driver- a file, or series of files, that operate a piece of hardware in a computer.

Engine- A game's main program. When Voodoo Magazine (or any other magazine) refers to a game engine, we're talking about the underlying code that runs parts of the game, whether it is the physics model or 3D display.
 
Environment Mapping- The process of applying a reflection of the surrounding environment to a model. A shiny, reflective surface is applied across the polygons, which reacts to the environmental lighting. In Mad Trax, this produces the chromed appearance of the cars. In Ultimate R@ce Pro, environment mapping is used to reflect the clouds in the car's rear window. The shiny, metallic surface of the T-1000 from Terminator 2 was the most correct usage of environment mapping: as the T-1000 flows into the helicopter, the whole cockpit, including the pilot, is mapped into the T-1000's skin.

EDO DRAM- Extended-data-out dynamic random access memory. EDO DRAM is an older form of RAM used for memory, but is expensive. Chip manufacturers are attempting to incorporate SDRAM, which is cheaper, but less effective.

FBI- Frame buffer interface. This is where colors are stored before being sent to the monitor. The screen image is created in the FBI, which also handle trangle setup and gouraud shading.

Fog- A rendering technique that simulates atmospheric effects such as haze, fog, and smog by fading object colors to a background color based on distance from the viewer.

FPS- Frames per second. The number of times your monitor draws a screen. Often mistakenly referred to the speed of the game, it actually refers to the smoothness.

Frame Buffer- The memory used to hold pixels. In a Voodoo system, the frame buffer is accessed by the FBI chip and can be used for up to three color buffers. In single or double buffer mode, the auxiliary buffer can optionally be used as an alpha buffer or a depth buffer. The actual phyiscal location of the memory used by the FBI. Voodoo 2 cards can have either 2MBs of frame buffer or 4MB. The more memory you have in your frame buffer, the larger the size of the resolution you are able to display on your screen. See FBI.

Frame Rate- See FPS.

Fill Rate- How fast your system can place pixels on a screen. For instance, if your monitor is set for a resolution of 640x430, that means that your monitor will have to draw 307,200 pixels to fill the screen. You want all those pixels to move at 30fps to simulate movement, which means that your computer will have to generate and draw all those pixels thirty times before you can blink. Multiplying the number of displayed pixels by your desired frame rate gives you your fill rate - in this case, 9,216,000 pixels, which is usually referred to as 9 Mpixels. A Voodoo 2 card is capable of displaying up to 90 Mpixels per second. Redition, for example, can sustain 20 Mpixels, which means that a game like Quake will run around 20 fps.

Flat Shading- The most basic form of adding color to a polygon, a single color runs across the entire poly. Flat Shading is used in the first Virtua Fighter to add color to the models, which is why they appear so blocky and Lego-like. See Gouraud Shading, Phong Shading.

Glide- The 3D API native to Voodoo, which speaks directly and specifically to the 3Dfx chipset.

GLQuake- The OpenGL-accelerated version of Quake.

Gouraud Shading- Colors are assigned to the vertices of a triangle and linearly interpolated across the triangle to produce a smooth variation in color. This smoothes out the look of the polygons, producing a series of transitional colors across the face of the poly. Also called "smooth shading," it is the next step up from flat shading. Virtua Fighter 2 used Gouraud Shading to eliminate some of the boxy appearance of the fighters. See Flat Shading, Phong Shading.

Graphics Card- A device or devices in a computer that created the visual information for the monitor.

Graphic Interpolation- the process of scaling between low detail and high detail by interpreting the polygon parameters.

LOD- Level of Detail. The difference in textures when objects are at different distances or scales. LOD varies the detail of a texture according to the distance. See Mipmap.

Magnification- If a texture-mapped screen pixel is smaller than a texel, maginification techniques are used. See Mipmap and Minification.

Minification- If a texture-mapped screen pixel is larger than a texel, minification techniques are used. See Mipmap and Magnification.

MIPS- Millions of Instructions Per Second. A term, usually preceded by a number, used to denote how fast a piece of hardware is running.

Mini-GL- A nickname for the limited OpenGL driver used to run games based on the Quake engine for Voodoo cards.

Mipmap- A pyramidal organization of gradually smaller, filtered subtextures or an individual texture map within the set, that is used for anti-aliased texture mapping. For example, to simulate a plane approaching your point of view, an artist would start by drawing one small plane for the distant view, then a series of the same object, ending in a much larger and more detailed plane for the moment it passes you. Mipmapping swaps in the different-sized objects to simulate the movemnt towards you.

Multi-Texture- Method of combing two different textures to create special effects (projected textures, detail textures, shadow maps, etc.). The Voodoo 2 chipset is unique in that it can combine textures with no performance penalties due to the architecture's seond texture memory unit.

OpenGL- A non-proprietary API origally developed by Silicon Graphics Inc. for use with 3D hardware, which developers can easily build or add on to.

Overclocking- The process of turning the clockrate on a processor higher then the manufacturer's recommended setting. By over clocking a chipset, you can achieve faster speeds at the risk of overheating and damaging the chip.

PCI- The bus in a PC that connects the host CPU and the peripheral devices, including Voodoo boards.

Perspective Correcting- Syncing turning triangle and textures on top of those triangle in line and avoiding distorting the image. As you move closer to an uncorrected texture, the pixels become large and distored. Perspective Correcting makes sure that textures look the same at any viewing distance. Perspective correction reduces wearoing most noticeable in straight or parallel lines.

Phong Shading- The next level of shading above Gouraud. Phong shading lights certain parts of a polygon, applying light evenly across the sufrace of the texture. Phong shading is a very complex lighting model. See Flat Shading, Gouraud Shading.

Point Sampling- In the context of Voodoo texture mapping, choosing the texel nearest the pixel center. Taking a texture and applying to a polygon with no filtering.

Pop-Up- See Draw-In.

Rasterizing- The process of applying a texture to a polygon, the last step in rendering. more commonly referred to as "drawing."

Rendering- The process of converting triangles into bits in the frame buffer, applying texture mapping, alpha blending, depth buffering, etc. Redering is what Voodoo does. this is the entire process of drawing a screen on your monitor.

Resolution- The amount of pixels in a computer screen.

RGBA- Red, green, blue, and alpha. Individual colors blended together to form a whole screen.

Single Buffering- Rendering one scene at a time into the color buffer a sit is being displayed.

Scan-Line Interleave (SLI)- When you connect two Voodoo 2 cards in a single system, they split the work-load of drawing a screen between the two chipsets, one drawing all the even lines while the other draws the odd. This not only double frame rate by reducing the work load of the chipsets, but also doubles your fill rate, which means that higher resolutions can be achieved.

Specular Light- One of the components of a lighting model. Specualr light comes from a specific direction and bouces off surfaces in a preferred direction as well. It models the shininess of a surface. Think of it as "fake" Phong Shading, which lights only specific portions of a texture, like shining a flashlight on a surface. In Wing Commander" Prophecy, specualr lighting causes the sun ot gleam on the hull of the ships.

SST- The original project name for Voodoo. Taken from the first letters of the last names of 3Dfx founders: Smith, Sellers and Tarolli.

Strips and Fans- Ways to represent multiple polyogns with less data at a faster speed. By adding one single vertex to a polygon, you can quickyl create another.

Subpixel Correction- Adjusting the vertex parameter values (x, y, z, w, s, t, red, green, blue, and alpha) to lie at the center of the pixel rather than somewhere else. The result is very accurate rendering.

Texel- Texture element, one pixel of a texture.

Texture- A one- or two-dimensional image that is used to modify the color of a triangle and add realism to the scene. You might map a brick texture onto a set of triangles that represents a wall, for example.

Texture Mapping- The process of applying a texture to a triangle.

Texture Memory- Memory used for storing textures. On Voodoo graphics system, this memory is accessed by the TMU.

Texture Morphing- Allows animated textures or video textures to be applied to a 3D surface.

Texture Palette- Colors that go into a texture. 16-bit color means that 65,000 colors are available; 8-bit means that only 256 distinct colors can be used.

TMU- Texture Mapping Unit. This is the part of the chipset in which textures are applied, filtering takes place, chroma-key happens, and all the other effects that Voodoo produces. the chip take the data from the texture memory and then sticks it into the FBI. See FBI.

Triangle- The Voodoo system's rendering primitive. The most basic geometrical form, three connected points in space. With enough triangles, you can create an object, from a circle to a space ship.

Trilinear Filtering- A more advanced technique for blending texels between two levels of detail to avoid mipmap banding. See bi-linear Filtering.

Triple Buffering- One possible use of auxiliary buffer. Three drawing buffers are in use, one being displayed, one waiting to be displayed, and one being rendered into. Allows the software to store more textures.

Voodoo- 1) The best 3D gaming solution for your computer. 2) A kickasss gaming magazine from Dimension Publishing.

Voodoo Graphics- The first generation 3D-only Voodoo technology from 3Dfx Interactive.

Voodoo Rush- The first generation 2D/3D Voodoo combination from 3Dfx Interactive.

Voodoo 2- Second generation 3D-only Voodoo technology from 3Dfx Interactive.

Vertex- One of the corners of a triable. It has x- and y- coordinates and a set of attributes: an RCBA color, a z-value indicating depth, s and t coordinates for textre mapping, and a w-coordinate for perspective correction.

V-Synch- Synchronizing the number of frames frwan persecond with the refresh rate of a computer screen. this keeps that picture clearer with less tearing of textures. Turning off v-synch allows games to run much faster with the possibility of visual degredation.

W-Buffering- A much more precise way of storing depth values to redice the amount of pixels drawn on a screen. W-Buffering allows for decimal positions with the set values, aloowing fo rgreater accuracy in placing and drawing objects. Voodoo is one of the very few architectures that can process W-Buffering. See Z-Buffering.

Z-Buffering- Removing polygons from a scene that aren't visble to improve performance. Every object in a game is assigned a depth value, which is stored in the Z-buffer. By using z-buffering, the computer checks each object's value, then doesn't have to draw it if hidden from the camera viewpoint. There are 65,536 set on-screen positions for Z-buffering, which can only be whole numbers. Not as powerful as W-Buffering. See W-Buffering.