Glossary

The value representing the distance of a point from the Y-axis in the Cartesian coordinate system, measured along a line parallel to the X-axis. (Compare "Ordinate".)

A list of binding table entries which specifies the currently active textures within the rendering pipeline. All appropriate primitives will receive texture mapping effects sequentially evaluated from this list. Two separate lists exist for front- and backface distinguishing. (See PEXExtSetActiveTextures and PEXExtSetBFActiveTextures).

The operation of blending a source pixel color with a destination (frame buffer) pixel color according to some rule on alpha values.

An application of alpha blending to achieve the effect of transparent primitives; requires a multi-pass algorithm in order to generate realistic images.

A method for producing high-quality images using pixel coverage and blending techniques, most noticeable as smooth lines and polygon edges.

The horizontal angular distance from a fixed reference direction to a point.

A lookup table whose entries represent entire texture maps to the rendering pipeline. Each entry within the binding lookup table contains reference information for an X texture resource, texture coordinates for each primitive, color composition rules, and texture map sampling and quality controls. (See “Binding LUT ”).

When a texture coordinate accesses a texel outside of the texture map, texturing is discontinued and the primitive's existing color data is used. (See “Sampling LUT ”.)

When a texture coordinate accesses a texel outside of the texture map, texturing is discontinued and the "clamp col or" is applied. (See “Sampling LUT ”.)

When a texture coordinate accesses a texel out side of the texture map, sampling is reversed across the texture map. (See “Sampling LUT ”.)

When a texture coordinate accesses a texel out side of the texture map, sampling wraps back to the opposite texture border creating a "rubber stamp" effect. (See “Sampling LUT ”.)

A visualization technique, used with model clipping that re-closes a volume that has been clipped, making the object appear as though it had been cut away.

The colors in a colormap for PEXColorSpace which are expected to represent a "sampling" of the color space.

A lookup table with entries used to determine how texture map values will be applied to the current color of the rendering pipeline. Entries within this table control the blending and replacement rules for each texture-mapping operation. (See “Composition LUT ”.)

If alpha is not included in the texture map, the texture map color replaces the primitive's existing color. If, on the other hand, alpha is specified in the texture map, the following equation is used to determine the final blended color:

where C_{in} is the primitive's existing color, t_a is the texture map alpha and t_c is the texture map color.

(See “Composition LUT ”.)

The texture map color and alpha (if it exists) blend with the primitive's existing color and alpha. The texture color (alpha) is multiplied by the primitive's color (alpha) to determine the final result. (See “Composition LUT ”.)

The texture map color and alpha (if it exists) overwrite the primitive's existing color and alpha. (See “Composition LUT ”.)

A lookup table with entries used to determine how texture coordinates are to be derived for texture mapping. Texture coordinates are either explicitly stored with a vertex as floating point data or they are derived from other vertex data (point, color, normal). (See “Coordinate-Source LUT”.)

A technique for computing a displacement in model coordinates for each vertex of a primitive, based on data supplied with the vertex.

A method for visualizing and detecting inter-penetrating solids by highlighting overlapping caps within a clip plane.

The process used to determine the final color for a screen pixel when more than one screen pixel maps to one texture map texel. (See “Sampling LUT ”.)

The process used to determine the final color for a screen pixel when one screen pixel maps to more than one texture-map texel. (See “Sampling LUT ”.)

A pre-computed area-sampling mechanism which fixes the cost of approximating the average color over a large number of pixels in a texture image. A MIP map (and RIP map, which involves additional rectangular dimensions) is created as an image "pyramid" of down-sampled maps, or "levels." Traditionally, each pixel in a level n equals the average of four pixels beneath it at level n+1. Thus the resolution of each map becomes half of the preceding level until the top level is reached, which has one pixel representing the average color of the entire original base-level map.

See also “Discussion: MIP Map ”.

The value representing the distance of a point from the X-axis in the Cartesian coordinate system, measured along a line parallel to the Y-axis. (Compare "Abscissa".)

Display hardware often has two kinds of display planes, image and overlay. The image plane allows the hardware to help the graphics commands run faster and more efficiently. Overlay planes are graphics frame buffer planes that store pixel data that is independent of the image buffer. These planes can be used for alpha text, windows, cursors, or menus as well as graphics. They can be written to and turned on and off independently of the graphics, or image, planes.

A lookup table with entries used to determine how texture coordinates are to be derived for texture mapping. Texture coordinates are either explicitly stored with a vertex as floating-point data or they are derived from other vertex data (point, color, normal).

The data-processing phase before rendering where texture data are loaded and area primitives with data are "surface parameterized" with texture coordinates per vertex.

A standard volume used in calculation of texture coordinates. A primitive is conceptually placed at the center of a projection object and each of the primitive's vertices are projected onto the projection object. The intersections of the vertices with the projection object determine the texture coordinates. (See PEXExtCreateTMDescription and PEXExtTMCoord*) Spherical, cylindrical, and planar projection objects are possible objects.

A type of texture mapping that uses reflection vectors to calculate texture coordinates. The result is an object that reflects or mirrors the texture map much like a shiny Christmas tree ornament reflects its environment. See also Standard Mapping.

A lookup table with entries used to control texture map sampling (derivation of a color sample from an image) and rendering quality hints for each texture. (See “Sampling LUT ”.)

Standard texture mapping refers to the mapping of a texture onto an object much like a piece of wrapping paper is applied to a package. See also Reflection Mapping.

A mathematical projection of a 3D surface onto a 2D surface which, in effect, "ties" facet data to corresponding regions of a texture image map, thus orienting an image on the primitive. (See the texture parameterization utilities, such as PEXExtTMCoordFillAreaSetWithData.)

One texture map element. Texel is analogous to the term "pixel" — a texel is to a texture map as a pixel is to a bitmap. A texel may be a floating point value, an 8-bit integer, or in another for mat.

A 1D, 2D, or 3D data set consisting of "texels" (or texture elements). A 1D texture map is an array of values; a 2D texture map is a two-dimensional image, and a 3D texture map is a set of 2D texture maps. HP PEX supports 1D and 2D texture maps. (See texel.)

A rendering effect which enhances the surface detail of an area primitive for usually less cost than explicitly modeling the information. Texture mapping controls interior color and transparency through special "mapped" correspondences between texture images and area primitives during the rendering phase.

Texture mapping that changes with the position of the camera. If the camera (or point of view) changes, the orientation of the texture map on the texture-mapped object changes.

Texture mapping that does not change with the position of the camera. A texture map is fixed on an object and does not change even if the position of the camera or object changes. Describes the characteristics of a virtual colormap that has been or can be created for use on a particular screen.

Distinguishes between color or monochrome, whether the color map is read/write or read-only, and whether a pixel value provides a single index to the colormap or is decomposed into separate indices for red, green, or blue values.