VT8601 Via, VT8601 Datasheet - Page 129

• Manufacturer Part Number: VT8601
• Description: Slot-1 / Socket-370 PCI North Bridge
• Manufacturer: Via

Color Parameters
Color parameters are used for Gouraud shading. They consist
of starting values, incremental along the X and Y axis. In flat
color mode, this parameter only has the starting value.
DoubleWord 0 – Initial Values
DoubleWord 1 – X-Axis Blue Gradient
DoubleWord 2 – Y-Axis Blue Gradient
DoubleWord 3 – X-Axis Green Gradient
DoubleWord 4 – Y-Axis Green Gradient
DoubleWord 5 – X-Axis Red Gradient
DoubleWord 6 – Y-Axis Red Gradient
DoubleWord 7 – X-Axis Alpha Gradient
DoubleWord 8 – Y-Axis Alpha Gradient
Revision 1.3 September 8, 1999
31-24 Initial Alpha Value
23-16 Initial Red Value
15-8 Initial Green Value
31-0 X-Axis Blue Gradient
31-0 Y-Axis Blue Gradient
31-0 X-Axis Green Gradient
31-0 Y-Axis Green Gradient
31-0 X-Axis Red Gradient
31-0 Y-Axis Red Gradient
31-0 X-Axis Alpha Gradient
31-0 Y-Axis Alpha Gradient
7-0
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Initial Alpha value on main edge (left edge of
trapezoid or long edge of triangle). Unsigned integer.
Initial Red value on main edge (left edge of trapezoid
or long edge of triangle). Unsigned integer.
Initial Green value on main edge (left edge of
trapezoid or long edge of triangle). Unsigned integer.
Initial Blue Value
Initial Blue value on main edge (left edge of
trapezoid or long edge of triangle). Unsigned integer.
Gradient of Blue along the X axis over the primitive
surface. Signed 20.12 number.
Gradient of Blue along the Y axis over the primitive
surface. Signed 20.12 number.
Gradient of Green along the X axis over the primitive
surface. Signed 20.12 number.
Gradient of Green along the Y axis over the primitive
surface. Signed 20.12 number.
Gradient of Red along the X axis over the primitive
surface. Signed 20.12 number.
Gradient of Red along the Y axis over the primitive
surface. Signed 20.12 number.
Gradient of Alpha along the X axis over the primitive
surface. Signed 20.12 number.
Gradient of Alpha along the Y axis over the primitive
surface. Signed 20.12 number.
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Z Value Parameters
To the Rasterization Engine, the Z value is always a 25.8
signed integer internally regardless of Z buffer depth.
always passes a 24-bit unsigned integer to the Pixel Engine. It
is the Pixel Engine’s responsibility to scale Z to the depth of
the Z buffer.
information. Z values consist of starting values, incremental
along the X and Y axis.
DoubleWord 0 – Initial Z Value
DoubleWord 1 – X-Axis Z Gradient
DoubleWord 2 – Y-Axis Z Gradient
DoubleWord 3 – Minimum Z Threshold
DoubleWord 4 – Maximum Z Threshold
31-24 Reserved
31-24 Reserved
31-0 Initial Z Value
31-0 X-Axis Z Gradient
31-0 Y-Axis Z Gradient
23-0 Minimum Z Threshold
23-0 Maximum Z Threshold
Initial Z value on main edge (left edge of trapezoid or
long edge of triangle). Signed 25.7 integer.
Gradient of Z along the X axis over the primitive
surface. Signed 25.7 number.
Gradient of Z along the Y axis over the primitive
surface. Signed 25.7 number.
Minimum of Z threshold. Unsigned 24-bit integer.
Maximum of Z threshold. Unsigned 24-bit integer.
Z parameters are used to calculate depth
................................................... ignored
................................................... ignored
VT8601 Apollo ProMedia
3D Graphics Engine Registers
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