180 degree VGA image flip??

laser-vector

hello,

is there an easy way to flip the entire vga output 180 degrees? im using the supplied vga drivers from the parallax library and my screen orientation only allows for the monitor to fit upside down..

Grant

Rayman

I don't know about "easy" ways, but you could either modify the VGA driver at the assembly level or generate your own, upside-down, character set and modify the SPIN print routines...

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wjsteele

Can you simply read the video memory buffer backwards for each display line?

Rayman

I think that would be mirrored output. It sounds like he wants upside down...

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ericball

If we assume a 10x10 display the normal memory mapping would be:

00 -> 09
 V
90 -> 99

So if laser-vector has to mount his TV "upside down" then the bottom right corner becomes the top left:
[noparse][[/noparse]code]
99 -> 90
V
09 -> 00
[noparse][[/noparse]code]
which looks like a simple reversal of memory ordering. Unfortunately, for tiled displays each of the tiles would also need to be rotated which is considerably harder (accessed in reverse order & pixel reversed).

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potatohead

Any chance you could just modify the yoke on the CRT?

[noparse]:)[/noparse]

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