Product specifications

VT8601A Apollo PLE133
Revision 1.82 October 22, 2001 -119 3D Graphics Engine Registers
Technologies, Inc.
Delivering Value
Delivering ValueDelivering Value
Delivering Value
GEbase + 30 – RE Primitive Attribute.............................RW
31 Z Parameter
0 Absent .................................................... default
1 Present (Rasterization Engine calculates Z
slope)
30 Texture Parameter
0 Absent .................................................... default
1 Present (RE calculates texture info)
29 Perspective Factor Parameter
0 Absent .................................................... default
1 Present (RE performs perspective correction)
28 Color Parameter
0 Absent .................................................... default
1 Present (RE calculates Gouraud color
(RGBA))
27 Specular Color Parameter
0 Absent .................................................... default
1 Present (RE calculates specular color)
26 Fog Parameter
0 Absent .................................................... default
1 Present (RE calculates fog)
25 Step Mode
0 Disable ................................................... default
1 Enable (RE will process the next primitive
only when it finishes the current primitive. No
parallelism exists between primitives)
24-20 Reserved .........................................always reads 0
19-15 LOD Adjust ...............................................default = 0
3.2 signed # to be added to calculate the LOD value
14-7 Reserved .........................................always reads 0
6 Z Normalization (Setup Engine Only)
0 Disable ....................................................default
1 Enable
5 Flat Mode (applies to diffuse color, alpha, specular
color, and fog)
0 Smooth color or no color........................default
1 Flat color. RE forces deltas to 0.
4 Full Vertex Info
0 Disable ....................................................default
1 Enable. Indicates that all vertex data are
needed for the triangle. Software still needs to
set bits 31-25. However in this case, the data
order in a vertex is: X, Y, Z, W, RGBA,
SrgbF, U, V. Even though the vertex actually
contains all the data, software doesn’t
necessarily set this bit. When this bit is not
set, hardware decodes vertex data as described
in the Vertex Register descriptions.
3 Sub-Pixel Precision (Rasterization Engine Only)
0 Disable ....................................................default
1 Enable
2 Anti-Aliasing (RE Only)
0 Disable (walk at pixel precision)............default
1 Enable (walk at sub-pixel precision)
1 Auto Direction for Scan Line Ends (RE Only)
0 Disable ....................................................default
1 Enable. Bits 31-2 must be 0. Scan order is
passed to the Pixel Engine based on the
comparison result of two end points instead of
the bit in the Primitive Type register.
Software should only use this bit for 2D
polygons with Bresenham edge walking.
0 Bresenham Edge Walking (RE Only)
0 Use DDA to walk through edges............default
1 Use Bresenham algorithm to walk through
edges
This register is decoded by the Setup Engine and passed to the
Rasterization Engine by the Setup Engine. This register and
its equivalent part in the Rasterization Engine are “partially”
pipelined in the sense that there are only two levels of pipe for
this register in both engines while there are many levels for
other data. The two levels are the decoding level and the
execution level. Both the Rasterization Engine and the Setup
Engine use this register to decide what kind of operation to
perform and what kind of data stream to expect. It must be set
before any parameter can be loaded.