Path: chuka.playstation.co.uk!news
From: Jim <jim@micronetics.com>
Newsgroups: scea.yaroze.programming.2d_graphics
Subject: Re: Direct access to video memory?
Date: Tue, 20 May 1997 01:13:38 +0100
Organization: PlayStation Net Yaroze (SCEE)
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Message-ID: <3380ECB2.2A9004CC@micronetics.com>
References: <01bc6182$a4f9ac40$9591b8cd@mannynaj>
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Manny Najera wrote:
> 
> Are any of the SCEA engineers working on a demo that illustrates how to
> directly manipulate video memory, preferrably in assembler?  

I don't work for scea but I may still be able to help.

>There are a
> large number effects I want to try that can only be done pixel by >pixel.


There is a small demo I wrote recently available on my web page that
does exactly this.  

You can't directly access the video memory from your code (AFAIK), you
have to draw the image in host memory then send it to the screen via
LoadImage/StoreImage (One of them I think).  This is a non-blocking
function and uses dma, so while it is transmitting it you can start
creating the next screen.

It is in r3000 and when I wrote it, I could not get the preprocessor
working on the assembler, so all registers are accessed as $31 for
return address etc.. The registers are detailed in the manuals so it
should not be too tricky.

You can grab it from the SCEE web site at  
http://www.playstation.co.uk~/Sig1LL

Hope this is of some assistance.

Jim


> 
> Manny Najera