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Graphics Programming
TVP4020
Programmers Reference Manual
110
C
f
= C
t
C
f
A
f
= A
t
A
f
where: C
f
is the fragment color, C
t
is the texture color , A
f
fragment
alpha and A
t
is the texture alpha.
Ramp Texture Application
This is referred to elsewhere as the Apple type of texture application
because of the approach adopted by QuickDraw3D. This type of texture
application is done three stages, where each stage can be
independently enabled or disabled. The first stage is decal, which does
the operation:
C
f
= C
t
A
t
+ C
f
(1-A
t
)
A
f
= A
f
If decal is not enabled then the following operation is done:
C
f
= C
t
A
f
= A
t
A
f
The next operation is modulate, which does:
C
f
= K
d
C
D
A
f
= K
d
A
D
where: C
f
is the fragment color, K
d
is an interpolated parameter which
represents the diffuse light intensity, A
t
is the texture alpha, C
D
is the
color after the decal operation and A
D
is the alpha value after the decal
operation.
The next operation is highlight:
C
f
= C
M
+K
s
A
f
= A
M
+K
s
where: C
f
is the fragment color, K
s
is an interpolated parameter which
represents the specular or highlight intensity, A
t
is the texture alpha, C
M
is the color after the modulate operation and A
M
is the alpha value after
the modulate operation.
5.12.2
Fog Application
The fog unit is used to combine the incoming fragment's color
(generated by the Color DDA unit, and potentially modified by the
texture unit) with a pre-defined fog color. Fogging can be used to
simulate atmospheric fogging, and also to depth-cue images.
Fog application has two stages; derivation of the fog index for a
fragment, and application of the fogging effect. The fog index is a value
Содержание TVP4020 PERMEDIA 2
Страница 1: ...Texas Instruments TVP4020 PERMEDIA 2 Programmer s Reference Manual Issue 4 ...
Страница 47: ...Memory I O and Organization TVP4020 Programmers Reference Manual 38 Texture address TextureBaseAddress T W S ...
Страница 284: ...TVP4020 Programmers Reference Manual A Gouraud Shaded Triangle 275 ...
Страница 292: ...TVP4020 Programmers Reference Manual Register Tables 283 ...
Страница 314: ...TVP4020 Programmers Reference Manual Index 305 ...
Страница 315: ...Index TVP4020 Programmers Reference Manual 306 Index ...
Страница 323: ...Index TVP4020 Programmers Reference Manual 314 ...