Intel 815 Manuel D’Utilisation

  

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The GC supports variable length vertex formats. These formats are determined, by enable bits contained 
in the variable length vertex format (VLVF) instructions. The following table specifies the attributes 
associated with each vertex. The order of the attributes must be strictly observed. 

For any attribute that is defined as not present, the value of the corresponding attribute from the last 
triangle of last packet will be used for the triangles in this packet. However, in the case of strip and fan 
primitives, the vertex numbers rotate from one primitive to the next primitive (e.g., the third vertex of 
one triangle will become the first vertex of the next triangle). Therefore, the re-used attribute value from 
the last primitive will not be guaranteed to be on the same vertex of the next primitive. In this case, 
undesired results may occur. It is recommended to turn off features that have the corresponding attributes 
disabled (e.g., if no texture coordinate is send, then turn off texture mapping feature). 

 

X Position 

Required for every vertex 

Triangle Edge V2–V0 Enable 

Required only on the first vertex of a triangle and on each new vertex, 
which defines a triangle when processing strips and fans. 

Triangle Edge V1–V2 Enable 

Required only on the first vertex of a triangle and on each new vertex, 
which defines a triangle when processing strips and fans. 

Triangle Edge V0–V1 Enable 

Required only on the first vertex of a triangle and on each new vertex, 
which defines a triangle when processing strips and fans. 

Y Position 

Required for every vertex 

Z Position 

Optional 

Z Bias 

Optional 

Reciprocal of W 

Optional 

Diffuse Color (Alpha, Red, Green and 
Blue) 

Optional 

Specular Color/Fog Factor 

Optional 

Texture Coordinate Set 0 

Optional 

Texture Coordinate Set 1 

Optional