Thanks Ken,

My suspicions are confirmed. I had a poke around with the ordered compositing 
code (vtkOrderedCompositeDistributor et al) and saw that the BSP cuts from the 
D3 filter are set to match those from the PKDTree internally. I notice that in 
the BSPcuts code it says
  // Description:
  //   Initialize the cuts with arrays of information.  This type of
  //   information would be obtained from a graph partitioning software
  //   package like Zoltan.

Do you know if there exists such an example. I am infact partitioning the data 
using Zoltan and have the exact bounds etc of the partitions, so I can work out 
what to pass into the BSPcuts  class and could potentially fool the IceT 
composiining into using my partitions. Can you point me to any crucial function 
that I must call. Is it sufficient to do a SetCuts on the compositing code - 
which class do I need to take control of?).

I shall create a custom representation to handle the depth sort. I've done the 
same some time ago for the point sprite renderer so I'll manage that ok, but 
I'll need to override the IceT compositing pass too as alluded to above , so 
any pointers welcome. (Could I somehow subclass on of the painters for the IceT 
pass and set the cuts to what I've got, then proceed as usual?)

Thanks

JB

From: Moreland, Kenneth [mailto:kmo...@sandia.gov]
Sent: 19 November 2012 16:13
To: Biddiscombe, John A.
Cc: paraview-develop...@paraview.org; paraview@paraview.org
Subject: Re: [Paraview-developers] (Ordered) Compositing question.

You are correct in that if you disable ordered composite it will disabled the 
distribution and the composite ordering. The problem is that the geometry 
distribution also creates a k-d tree structure that the compositing uses to 
determine the visibility order. So it would not be sufficient to simply have 
geometry that is in non-overlapping pieces. You would also have to provide some 
meta-structure that could be used to determine an appropriate ordering given a 
viewpoint. Even if you had that, there is no mechanism to feed that to the 
compositor in the view. I can't think of any way of doing that that would not 
be a huge hack.

As far as I know, there is no support for the DepthSortPolyData filter. You 
would probably have to create a custom representation to support that.

I believe the transparent lookup table for poly data is supported in 3.98, but 
to be honest I have not yet tried it.

-Ken

Sent from my iPad so blame autocorrect.

On Nov 19, 2012, at 3:46 AM, "Biddiscombe, John A." 
<biddi...@cscs.ch<mailto:biddi...@cscs.ch>> wrote:
I have geometry distributed into parallel pieces such that they are non 
overlapping and therefore compositing should only need to use a back to front 
sort last frame buffer operation with no redistribution of geometry.

I'm worried that when I turn on transparency, paraview will try to redistribute 
my data, even though I have already partitioned it nicely for this. I'd like to 
use ordered sort last compositing at the top level, and use DepthSortPolyData 
on each node (no depth peeling for now) to ensure I get a true image. What 
isn't clear to me is if I "disable ordered compositing" if this disables the 
transfer of geometry AND also disables the ordered compositing necessary for 
correct transparent blending (I may be confused here about the blend modes used 
or the term "ordered compositing" as used in the docs).

Is there written down anywhere a complete description of the pipelines used by 
the various rendering modes so that I can be sure the pipeline is doing what I 
want. I can create a custom representation which does what I want, but it'll 
take time and if the existing mechanism support it, I shouldn't need to.

Also, I specifically want to use a transparent lookuptable, does the newer 
paraview 3.98 have anything to support this. I thought I'd seen a thread about 
this recently, but cannot find it now.

In summary : For the rendering, I'd like Ordered sort-last compositing, no 
geometry redistribution, Depth sort of polygons on each node. Transparent 
lookup table.

What settings should I use :)

Thanks

JB

--
John Biddiscombe,                        email:biddisco @.at.@ 
cscs.ch<http://cscs.ch>
http://www.cscs.ch/
CSCS, Swiss National Supercomputing Centre  | Tel:  +41 (91) 610.82.07
Via Trevano 131, 6900 Lugano, Switzerland   | Fax:  +41 (91) 610.82.82

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