JG82852GMSL7VP Datasheet, PDF (127/176 Pages) Intel Corporation – Intel® 852GM/852GMV Chipset Intel® 852GM/852GMV Chipset Hub (GMCH)

Functional Description
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5.4.2.
5.4.2.1.
5.4.2.2.
5.4.2.3.
3D Engine
The 3D engine of the GMCH has been designed with a deeply pipelined architecture, where performance
is maximized by allowing each stage of the pipeline to simultaneously operate on different primitives or
portions of the same primitive. The GMCH supports the following:
Perspective-correct Texture Mapping,
Multitextures
Embossed and Dot-Product Bump-Mapping
Cubic Environment Maps
Bilinear, Trilinear, and Anisotropic MIP mapped filtering
Gouraud shading
Alpha-blending
Per-Vertex and Per- Pixel Fog
Z/W Buffering
These features are independently controlled via a set of 3D instructions. The 3D pipeline subsystem
performs the 3D rendering acceleration. The main blocks of the pipeline are the Setup Engine, Scan
Converter, Texture Pipeline, and Raster Pipeline. A typical programming sequence would be to send
instructions to set the state of the pipeline followed by rendering instructions containing 3D primitive
vertex data.
Setup Engine
The GMCH 3D setup engine takes the input data associated with each vertex of a 3D primitive and
computes the various parameters required for scan conversion. In formatting this data, the GMCH
maintains sub-pixel accuracy. The per-vertex data is converted into gradients that can be used to
interpolate the data at any pixel within a polygon (colors, alpha, Z or W depth, fog, and texture
coordinates). The pixels covered by a polygon are identified and per-pixel texture addresses are
calculated.
Viewport Transform and Perspective Divide
A 3D-geometry pipeline typically involves transformation of vertices from model space to clipping
space followed by clip test and clipping. Lighting can be performed during the transformation or at any
other point in the pipeline. After clipping, the next stage involves perspective divide followed by
transformation to the viewport or screen space. The GMCH can support Viewport Transform and
Perspective Divide portion of the 3D geometry pipeline in hardware.
3D Primitives and Data Formats Support
The 3D primitives rendered by the GMCH are points, lines, discrete triangles, line strips, triangle strips,
triangle fans, and polygons. In addition to this, the GMCH supports DirectX’s* Flexible Vertex Format*
(FVF), which enables the application to specify a variable length parameter list, obviating the need for
sending unused information to the hardware. Strips, Fans, and Indexed Vertices as well as FVF improves
delivered vertex rate to the setup engine significantly.
Intel^® 852GM/852GMV Chipset GMCH Datasheet
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