QG82945GSE S LB2R Intel, QG82945GSE S LB2R Datasheet - Page 367

• Manufacturer Part Number: QG82945GSE S LB2R
• Description: GRAPHICS AND MEM CNTRL HUB; No. of Pins: 998; Package / Case: FCBGA; Interface Type: PCI, SATA, USB
• Manufacturer: Intel

Functional Description
10.4.1.6.3
10.4.1.6.4
10.4.1.6.5
Datasheet
Texture Decompression
Texture Map Filtering
DirectX supports Texture Compression to reduce the bandwidth required to deliver
textures. As the textures’ average size gets larger with higher color depth and multiple
textures become the norm, it becomes increasingly important to provide a mechanism
for compressing textures. Texture decompression formats supported 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).
The Mobile Intel 945GM/GME/GMS/GU/GSE, 943/940GML and Intel 945GT Express
Chipsets support many texture mapping modes. 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 Mobile Intel 945GM/GME/GMS/GU/GSE, 943/940GML and Intel 945GT Express
Chipsets support up to 12 Levels-of-Detail (LODs) ranging in size from 2048x2048 to
1x1 texels. Textures need not be square. Included in the texture processor is a texture
cache, which provides efficient MIP-mapping.
The (G)MCH supports 9 types of texture filtering:
• Nearest (Point Filtering): Texel with coordinates nearest to the desired pixel is
• Linear (Bilinear Filtering): A weighted average of a 2x2 area of texels surrounding
• Nearest MIP Nearest (Point Filtering): This is used if many LODs are present. The
• Linear MIP Nearest (Bilinear MIP Mapping): This is used if many LODs are present.
• Nearest MIP Linear (Point MIP Mapping): This is used if many LODs are present.
• Linear MIP Linear (Trilinear MIP Mapping): This is used if many LODs are present.
• Anisotropic MIP Nearest (Anisotropic Filtering): This is used if many LODs are
used. (This is used if only one LOD is present).
the desired pixel is used. (This is used if only one LOD is present).
nearest LOD is chosen and the texel with coordinates nearest to the desired pixel is
used.
The nearest LOD is chosen and a weighted average of a 2x2 area of texels
surrounding the desired pixel is used (four texels). This is also referred to as
Bilinear MIP Mapping.
Two appropriate LODs are selected and within each LOD the texel with coordinates
nearest to the desired pixel is selected. The Final texture value is generated by
linear interpolation between the two texels selected from each of the MIP Maps.
Two appropriate LODs are selected and a weighted average of a 2x2 area of texels
surrounding the desired pixel in each MIP Map is generated (four texels per MIP
Map). The Final texture value is generated by linear interpolation between the two
texels generated for each of the MIP Maps. Trilinear MIP Mapping is used minimize
the visibility of LOD transitions across the polygon.
present. The nearest LOD is determined for up to each of 4 sub-samples for the
desired pixel. These four sub-samples are then bilinear filtered and averaged
together.
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