MB86296 Datasheet, PDF (119/352 Pages) Fujitsu Component Limited. – PCI Graphics Controller Specification

FUJITSU LIMITED PRELIMINARY AND CONFIDENTIAL
10.4.4 Filtering
CORAL supports two texture filtering modes: point filtering, and bi-linear filtering.
Point filtering
This mode uses the texture pixel specified by the (S, T) coordinates as they are for drawing. The
nearest pixel in the texture pattern is chosen according to the calculated (S, T) coordinates.
0.5 1.0 1.5 2.0
0.0
0.5
1.0
1.5
2.0
Bi- linear filtering
The four nearest pixels specified with (S, T) coordinate are blended according to the distance from
specified point and used in drawing.
0.5 1.0 1.5 2.0
0.0
C00
C10
0.5
1.0
1.5
2.0
C01
C11
10.4.5 Perspective correction
This function corrects the distortion of the 3D perspective in the texture mapping. For this correction,
the ‘Q’ component of the texture coordinates (Q = 1/W) is set based on the W component of 3D
coordinates of the vertex.
When the texture coordinates are large values, the texture may not be drawn correctly when
perspective correction is performed. This phenomenon occurs due to the precision limitation of the
arithmetical unit for perspective correction. The coordinates for the texture that cannot be drawn
normally vary with the value of the Q component; as a guide, when this value is smaller than –2048 or
larger than 2048, normal drawing results are less likely to be obtained.
MB86296S <Coral-PA>
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Specification Manual Rev0.1