301467-005 Datasheet, PDF (243/426 Pages) Intel Corporation – Express Chipset

Functional Description
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12.6.4.10 Stencil Buffer
The Raster Engine provides 8-bit stencil buffer storage in 32-bit mode and the ability to perform
stencil testing. Stencil testing controls 3D drawing on a per pixel basis, conditionally eliminating
a pixel on the outcome of a comparison between a stencil reference value and the value in the
stencil buffer at the location of the source pixel being processed. They are typically used in
multipass algorithms to achieve special effects, such as decals, outlining, shadows and
constructive solid geometry rendering.
12.6.4.11 Projective Textures
The GMCH supports two simultaneous projective textures at full rate processing, and four
textures at half rate. These textures require three floating point texture coordinates to be included
in the Flexible Vertex Format (FVF). Projective textures enable special effects (such as projecting
spot light textures obliquely onto walls, etc.).
12.6.5
12.6.5.1
12.6.5.2
2D Engine
The GMCH contains BLT functionality, and an extensive set of 2D instructions. To take
advantage of the 3D drawing engine’s functionality, some BLT functions (such as Alpha BLTs,
arithmetic (bilinear) stretch BLTs, rotations, transposing pixel maps, limited color space
conversion, and DIBs) make use of the 3D renderer.
GMCH VGA Registers
The 2D registers are a combination of registers defined by IBM when the Video Graphics Array
(VGA) was first introduced and others that Intel has added to support graphics modes that have
color depths, resolutions, and hardware acceleration features that go beyond the original VGA
standard.
Logical 128-bit Fixed BLT and 256 Fill Engine
Use of this BLT engine accelerates the Graphical User Interface (GUI) of Microsoft Windows*
operating systems. The 128-bit GMCH BLT Engine provides hardware acceleration of block
transfers of pixel data for many common Windows operations. The term BLT refers to a block
transfer of pixel data between memory locations. The BLT engine can be used for the following:
• Move rectangular blocks of data between memory locations
• Data Alignment
• Perform logical operations (raster ops)
The rectangular block of data does not change as it is transferred between memory locations. The
allowable memory transfers are between: cacheable system memory and frame buffer memory,
frame buffer memory and frame buffer memory, and within system memory. Data to be
transferred can consist of regions of memory, patterns, or solid color fills. A pattern will always
be 8x8 pixels wide and may be 8, 16, or 32 bits per pixel.
The GMCH BLT engine has the ability to expand monochrome data into a color depth of 8, 16, or
32 bits. BLTs can be either opaque or transparent. Opaque transfers move the data specified to the
Datasheet
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