Xor line drawing

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4 total messages Started by Bobby Chawla Tue, 15 Dec 1992 14:19

#48

Author: Bobby Chawla
Date: Tue, 15 Dec 1992 14:19

10 lines
829 bytes

Could someone tell me how to draw a line on the SGI Indigos in 
Exclusive-Or mode?  

I would like to draw lines, and if the user does not require them,
then be able to erase them efficiently.

I was looking at the documentation and could not find it anywhere :-(.

Thanks
   Bobby Chawla

Re: Xor line drawing

#50

Author: Mark Solsman
Date: Tue, 15 Dec 1992 18:19

15 lines
1079 bytes

In article <BzB14n.5xJ@undergrad.math.waterloo.edu> bobbyc@surya.UWaterloo.CA (Bobby Chawla) writes:
>Could someone tell me how to draw a line on the SGI Indigos in 
>Exclusive-Or mode?  

I have an intresting question to this fact- 

3 months ago a professor at The Pennsylvania State University told me that
this method of line drawing was copyrighted.  (from the era where there
were no computer experts in Washington.)

was this bogus?
-- 
Mark Solsman                                 Building 1, Code 5160
United States Naval Research Laboratory      solsman@ra.nrl.navy.mil
Washington, DC                               (202) 767-5769

Re: Xor line drawing

#53

Author: Allan Schaffer
Date: Tue, 15 Dec 1992 21:08

25 lines
1064 bytes

bobbyc@surya.UWaterloo.CA (Bobby Chawla) said..
>Could someone tell me how to draw a line on the SGI Indigos in 
>Exclusive-Or mode?  
>
>I would like to draw lines, and if the user does not require them,
>then be able to erase them efficiently.
>
>I was looking at the documentation and could not find it anywhere :-(.

check the manpage for "logicop(3G)"

Something like this should work:

	logicop (LO_XOR);
	bgnline();
		v3f(..);
		v3f(..);
	endline();
	logicop (LO_SRC)   /* back to default */

Allan
-- 
Allan Schaffer
aschaffe@sgi.com
aschaffe@netcom.com

Re: Xor line drawing

#54

Author: Tom Benoist
Date: Tue, 15 Dec 1992 21:57

41 lines
1868 bytes

In article <BzB14n.5xJ@undergrad.math.waterloo.edu> bobbyc@surya.UWaterloo.CA 
(Bobby Chawla) writes:
> Could someone tell me how to draw a line on the SGI Indigos in 
> Exclusive-Or mode?  
>
> I would like to draw lines, and if the user does not require them,
> then be able to erase them efficiently.
>
> I was looking at the documentation and could not find it anywhere :-(.
>

Try:
logicop(LO_XOR);

As is usually the case with useful functions like logicop and pixmode
some machines just dont support it.  The Indigo is okay though.


[From logicop(3G)]

     This routine does not function on IRIS-4D B and G models, nor does it
     function on early serial numbers of the Personal Iris.  Use gversion to
     determine which type you have.

     Some IRIS-4D GT and GTX models do support this routine.  Use getgdesc to
     determine if logicop is supported.

BUGS
     Personal Iris models do not support logical operations in combination
     with non-solid patterns nor with zoomed pixel writes or copies.  When
     either of these features is selected, the default logical operation,
     LO_SRC, will be used regardless of the value passed to logicop.



Question:
Once OpenGL is implemented will more of these functions be supported
for ALL machines, or are the old GT's just gonna have to use old software?

-Tom Benoist
 benoist@netcom.com

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