Re: readback + tilesort

Joong Ho (Johann) Won wrote:
> Hi,
> 
> I'm testing a combination of readback and tilesort SPUs, of which the
> ultimate purpose is to let sort-last parallel apps be able to render on a
> DMX mural display. I wrote a simple test script for the first step, which is
> a very simple modification of simplemural.conf.
> Simplemural.conf uses a tilesort SPU to render an app in two seperate
> (possibly remote) windows.
> My intension is just to add a readback SPU on top of the tilesort SPU. At
> this stage, it has nothing to do with DMX.
> 
> What should be rendered must be the same as that of the original
> simplemural.conf, but it is not.
> SAME part of the application window is rendered on both of the crserver
> windows, i.e. the left half.
> 
> Configuration for readback is the simplest, as will be shown below.
> Mike Houston's guess is that there may be a bug in arguments for DrawPixels.
> Even worse is that when the 'extract_depth' option is turned on, nothing is
> drawn at all.
> 
> Below is my modified simplemural.conf script. Only a few lines related with
> readbackSPU are added and without these, everything works fine.
> 
> Thanks in advance for any comment.

I found the problem.  On the server side, the initial current raster 
position needs to be translated by the origin of the server's tile. 
Normally, the first call to glRasterPos/glWindowPos would set it 
correctly, but the tilesort SPU's state tracker was filtering out that 
state change.

Try applying this patch to crserverlib/server_context.c

-Brian

Index: server_context.c
===================================================================
RCS file: /cvsroot/chromium/cr/crserverlib/server_context.c,v
retrieving revision 1.11
diff -c -r1.11 server_context.c
*** server_context.c	7 May 2004 17:02:46 -0000	1.11
--- server_context.c	28 Jul 2004 21:51:53 -0000
***************
*** 158,163 ****
--- 158,172 ----
  		cr_server.firstCallMakeCurrent = GL_FALSE;
  		cr_server.currentWindow = window;
  		cr_server.currentNativeWindow = nativeWindow;
+ 
+ 		/* Set initial raster/window position for this context.
+ 		 * The position has to be biased by the tile origin.
+ 		 */
+ 		{
+ 			GLint x = -mural->extents[0].imagewindow.x1;
+ 			GLint y = -mural->extents[0].imagewindow.y1;
+ 			cr_server.head_spu->dispatch_table.WindowPos2iARB(x, y);
+ 		}
  	}
  
  	/* This used to be earlier, after crStateUpdateColorBits() call */