Intel 815 manual Gfxrenderstatemapcoordsets

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

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13.6.GFXRENDERSTATE_MAP_COORD_SETS

The Mapping Engine is capable of generating at most two map coordinate sets (u and v addresses) per pixel. Each output texel may be related to separate coordinate sets or to the same coordinate set, as shown below. The vertices of a GFXPRIMITIVE instruction may have 0, 1 or 2 map coordinate sets assigned with varying settings associated with each coordinate set.

A coordinate set may have normalized u/v coordinates or un-normalized coordinates. Normalized coordinates have been divided by the size of the map prior to delivery to the GC. This means that map addresses, which lie on the map, have a range of 0.0 to 1.0. 3D rendering utilized normalized coordinates. Un-normalized coordinates are in units of texels/pixels and have not been divided by the associated map’s height or width. Un-normalized coordinates allow the Motion Compensation and Arithmetic Stretch Blitter operations to be specified in pixels avoiding floating-point issues. Un- normalized coordinates are not usually specified outside of the map extents. These two coordinate sets may also have different wrap, clamp, and mirror settings.

Figure 32. State Variable Relationships

Coordinate Sets

Map Information

Texels

Blending Stages

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