Xref: utzoo comp.sys.amiga.tech:3826 comp.sys.amiga:29582
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ulowell!m2c!wpi!pawn
From: pawn@wpi.wpi.edu (Kevin Goroway)
Newsgroups: comp.sys.amiga.tech,comp.sys.amiga
Subject: Double Buffered Display
Message-ID: <938@wpi.wpi.edu>
Date: 21 Feb 89 03:42:43 GMT
Organization: Worcester Polytechnic Institute, Worcester, Mass.
Lines: 59

I hope someone can help me with this, because it is driving me crazy.
I'm trying to set up a double buffered display. It works fine, except for
one major point.  My second (first) BitMap just isn't there...

InitBitMap(&b[0],DEPTH,WIDTH,HEIGHT);   ;this sets up my two bitmaps
InitBitMap(&b[1],DEPTH,WIDTH,HEIGHT);

ri.BitMap=&b[0];		        ;this links the first into
					;my RasInfo...
vp.RasInfo=&ri;				;this links my RasInfo to my VPort

for(temp=0;temp<2;temp++)	        ;this allocates and clears
{					;my two bitmaps
 for(i=0;i<DEPTH;i++)
 {
	b[temp].Planes[i]=(PLANEPTR)AllocRaster(WIDTH,HEIGHT);
	if(b[temp].Planes[i]==NULL) exit(NOT_ENOUGH_MEMORY);
 }

 for(i=0;i<DEPTH;i++)
 {
	displaymem=(UBYTE *)b[temp].Planes[i];
	BltClear(displaymem,RASSIZE(WIDTH,HEIGHT),0);
 }
}

InitRastPort(&rp);			;this sets up my Rastport
rp.BitMap=&b[0];			;and points to my first Bitmap

ri.BitMap=&b[0];			;this was done already
MakeVPort(&v,&vp);			;begin setting up Double Buffer
MrgCop(&v);
LOF[0]=v.LOFCprList;
SHF[0]=v.SHFCprList;

ri.BitMap=&b[1];			;other bitmap
v.LOFCprList=NULL;
v.SHFCprList=NULL;

MakeVPort(&v,&vp);
MrgCop(&v);
LOF[1]=v.LOFCprList;			;ok, all done...but it doesn't work
SHF[1]=v.SHFCprList;

In a loop I say rp.Bitmap=&b[trigger], to alternate my bitmaps, but if
I set it to &b[0], to force drawing into bp[0], it doesn't display
squat, whereas &b[1] works fine...

I have tried many variations, such as setting up 2 RasInfos, setting up
two RastPorts, etc., but they all yield the same thing.  No bitmap.

I am sure that my LoadView(&v) works fine. (after I swap the LOF and SHF)
So I'm stuck. any ideas?
thanks!

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| Pawn@wpi.wpi.edu 		Worcester Polytechnic Institute, Mass, U.S.A. |
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