Radio Shack TRS-80 - Page 57

Computer Graphics Operation Manual
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Every viewport has absolute and relative coordinates and
graphic displays are drawn inside using the relative
coordinates. For example:
l~ VIEW (1~~,1~~)-(2~~,2~~),~,1
2~ LINE (3~,15)-(8~,6~),1
(3~ , 15 )
~ R.C.
R.C. ~
(8~,6~)
~ ----, (2~~,1~~) A.C.
(l~~,~) R.C.
(l~~,l~~) A.C.
(~,~) R.C.
(l~~,2~~) A.C.
(~,l~~) R.C.
(2~~,2~~) A.C.
(l~~ ,l~~) R.C.
Figure 18
Note: After each of the following examples, you'll have to
redefine the entire screen to VIEW(~,~)-(639,239) before
performing any other Graphics functions.
Examples
VIEW
(1~~,1~~)-(2~~,2~~),~,1
Draws
a black viewport
(pixels OFF)
that is outlined in
white
(border pixels ON).
VIEW
(1~~,1~~)-(2~~,2~~),1,1
Draws a
white viewport
(pixels ON)
that is outlined
in white
(border pixels ON).
VIEW
(5~,5~)-(1~~,1~~),1,~
Draws a
white viewport
(pixels ON)
that is
outlined in black
(border pixels OFF).
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