RG82865GV S L77X Intel, RG82865GV S L77X Datasheet - Page 167

• Manufacturer Part Number: RG82865GV S L77X
• Manufacturer: Intel

Specifications of RG82865GV S L77X

• Lead Free Status / Rohs Status: Not Compliant

Intel
®
82865G/82865GV GMCH Datasheet
Texture Formats and Storage
The GMCH supports up to 32 bits of color for textures.
Texture Decompression
DirectX supports Texture Compression to reduce the bandwidth required to deliver textures. As the
textures’ average sizes gets larger with higher color depth and multiple textures become the norm,
it becomes increasingly important to provide a mechanism to compress textures. Supported Texture
decompression formats include DXT1, DXT2, DXT3, DXT4, DXT5, and FXT1.
Texture ChromaKey
ChromaKey describes a method of removing a specific color or range of colors from a texture map
before it is applied to an object. For “nearest” texture filter modes, removing a color simply makes
those portions of the object transparent (the previous contents of the back buffer show through).
For “linear” texture filtering modes, the texture filter is modified if only the non-nearest neighbor
texels match the key (range).
Anti-Aliasing
Aliasing is one of the artifacts that degrade image quality. In its simplest manifestation, aliasing
causes the jagged staircase effects on sloped lines and polygon edges. Another artifact is the moiré
patterns that occur as a result of the fact that there is very small number of pixels available on
screen to contain the data of a high resolution texture map. More subtle effects are observed in
animation, where very small primitives blink in and out of view.
Texture Map Filtering
Many texture mapping modes are supported. Perspective correct mapping is always performed. As
the map is fitted across the polygon, the map can be tiled, mirrored in either the U or V directions,
or mapped up to the end of the texture and no longer placed on the object (this is known as clamp
mode). The way a texture is combined with other object attributes is also definable.
The GMCH supports up to 12 Levels-of-Detail (LODs) ranging in size from 2048x2048 to 1x1
texels. (A texel is defined as a texture map element). Textures need not be square. Included in the
texture processor is a texture cache, which provides efficient MIP-mapping.
The GMCH supports 7 types of texture filtering:
1. Nearest (aka Point Filtering): Texel with coordinates nearest to the desired pixel is used.
2. Linear (aka Bilinear Filtering): A weighted average of a 2x2 area of texels surrounding the
3. Nearest MIP Nearest (aka Point Filtering): This is used if many LODs are present. The nearest
4. Linear MIP Nearest (Bilinear MIP Mapping): This is used if many LODs are present. The
5. Nearest MIP Linear (Point MIP Mapping): This is used if many LODs are present. Two
(This is used if only one LOD is present).
desired pixel are used. (This is used if only one LOD is present).
LOD is chosen and the texel with coordinates nearest to the desired pixel are used.
nearest LOD is chosen and a weighted average of a 2x2 area of texels surrounding the desired
pixel are used (four texels). This is also referred to as Bilinear MIP Mapping.
appropriate LODs are selected and within each LOD the texel with coordinates nearest to the
desired pixel are selected. The Final texture value is generated by linear interpolation between
the two texels selected from each of the MIP Maps.
Functional Description
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