Intel® 945G/945GZ/945GC/ 945P/945PL Express Chipset Family ...

Functional Description
10.5.3.4 Backface Culling
As part of the setup, the GMCH discards polygons from further processing, if they are facing
away from or towards the user’s viewpoint. This operation, referred to as “Backface Culling” is
accomplished based on the “clockwise” or “counter-clockwise” orientation of the vertices on a
primitive. This can be enabled or disabled by the driver.
10.5.3.5 Scan Converter
Working on a per-polygon basis, the scan converter uses the vertex and edge information to
identify all pixels affected by features being rendered.
10.5.3.6 Pixel Rasterization Rules
The GMCH supports both OpenGL and D3D pixel rasterization rules to determine whether a
pixel is filled by the triangle or line. For both D3D and OpenGL modes, a top-left filling
convention for filling geometry will be used. Pixel rasterization rule on rectangle primitive is also
supported using the top-left fill convention.
10.5.3.7 Pixel Pipeline
The pixel pipeline function combines, for each pixel, the interpolated vertex components from the
scan conversion function, texel values from the texture samplers, and the pixel’s current values
from the color and/or depth buffers. This combination is performed by a programmable pixel
shader engine, followed by a pipeline for optional pixel operations performed in a specific order.
The result of these operations can be written to the color and depth buffers.
10.5.3.8 Texture Samplers
A texture sampler takes a texture coordinate and its partial derivatives, access (samples) texture
maps, applies filtering and other operations to the texel samples, and feeds the resultant per-pixel
texel outputs to pixel shader registers. Sixteen texture samplers are supported.
10.5.3.9 2D Functionality
The stretch Block Level Transfer (BLT) function can stretch source data in the X and Y directions
to a destination larger or smaller than the source. Stretch BLT functionality expands a region of
memory into a larger or smaller region using replication and interpolation. The stretch BLT
function also provides format conversion and data alignment.
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