User's Manual

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0
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13.10. GFXRENDERSTATE_MAP_LOD_CONTROL
The Level-of-Detail dither weight and bias can be associated with each map using the following
instruction.
Figure 37. State Variable Relationships
Coordinate Sets Map Information
Blending Stages
Texels
Dword Bit Description
0 31:29 Client : 03h – Rendering Engine
28:24 3DState16 : 1Ch
23:19 Opcode : 4h
18:17 Reserved: 00h (Additional Maps)
16 Update Map Index : The valid range is 0–1.
15:11 Reserved: 00h
10 Texture LOD Dither Weight Mask : 0 = Do not update; 1 = Update
9:8 Texture LOD Dither Weight: A 4-bit dither value can be added to the computed and
biased LOD which softens the transitions between mip-maps. The position or weight of
the dither value is specified as follows:
00 = Full dither weight (the dither value has a range of 0.0 – 0.9375)
01 = ½ dither weight (the dither value has a range of 0.0 – 0.4375)
10 = ¼ dither weight (the dither value has a range of 0.0 – 0.1875)
11 =
1
/
8
dither weight (the dither value has a range of 0.0 – 0.0625)
7 Texture LOD Bias Mask : 0 = Do not update; 1 = Update
6:0 Texture LOD Bias : This is a signed value that is added to the LOD when the LOD is
determined at a textured pixel. This 2’s complement fixed point value has 2 integer bits
and 4 fractional bits and is signed extended before being added to the LOD. Valid data
value range from -4.0 to 3.9375. (S2.4) The default value is 0.