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TVP4020
Programmers Reference Manual
Graphics Programming
69
(X, Y)
Screen
Height
(SH)
Screen Width (SW)
Window Origin
(WX, WY)
User
Scissor
Min
User
Scissor
Max
Writeable Region
Scissor Region
Screen
Figure 5.9
Screen Scissor and User Scissor Tests
This test may reject fragments if some part of a window has been moved
off the screen. It will not reject fragments if part of a window is simply
overlapped by another window.
The screen scissor would normally be enabled. The most common
exception is during image upload.
5.4.3
Area Stippling
An 8 x 8 bit area stipple pattern can be applied to fragments. The least
significant 3 bits of the fragment's (X,Y) coordinates, index into a 2D
stipple pattern. If the selected bit in the pattern is set, then the fragment
passes the test, otherwise it is rejected. In addition the bit pattern can be
inverted or mirrored. Inverting the bit pattern has the effect of changing
the sense of the accept/reject test. If the mirror bit is set the most
significant bit of the pattern is towards the left of the window, the default
is the converse.
In some situations window relative stippling is required but coordinates
are only available screen relative. To allow window relative stippling, an
offset is available which is added to the coordinates before indexing the
stipple table. X and Y offsets can be controlled independently.
If the ForceBackgroundColor bit is set in the AreaStippleMode register,
fragments which fail the area stipple test are not discarded. Instead, the
contents of the Texel0 register are used in place of the normal color for
that pixel.
Area stippling is enabled using the AreaStippleMode register and must
be qualified by the AreaStippleEnable bit in the Render command
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 ...
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