Re: pfDrawBin and pfDraw

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Rémi Arnaud (remi++at++remi.engr.sgi.com)
Tue, 19 May 1998 10:20:04 -0700 (PDT)

Mario Veraart wrote:
>
> Hello pfAll,
>
> I would like to implement a multipass algorithm and for this I have to
> draw the geometry in a certain order. For this I want to use the bins
> of a pfChannel. As an experiment I replaced the call of pfDraw with
> the following two lines
>
> pfDrawBin(PFSORT_OPAQUE_BIN);
> pfDrawBin(PFSORT_TRANSP_BIN);
>
> The result is that nothing gets drawn, only the sky and ground are
> drawn. If I set the bin number explicitly then only the geometry in
> the transparent bin is visible.
>
> My questions
>
> 1: What is pfDraw() doing besides calling pfDrawBin() in the order
> specified with setBinOrder()?

 pfDraw() draws everything that do not fall in a Bin, and then draw
 the bins.
 Since 2.2 you can use pfDrawBin(-1) to draw the objects that are
 not in a bin. Note, you have to use CULL separated from DRAW or
 CULL_DL_DRAW for the object not to be rendered immediately.
  
> 2: The programmers guide tells that it is possible to add more bins
> but does not tell you how. Is a call to setBinOrder() with an unkown
> bin number enough to create a new bin for this pfChannel?

 pfGeoSet::setDrawBin(b) will tell Performer to draw the geoset in
 the bin b. setBinOrder(b,order) will create the bin b and tell pfDraw
 in wich order to draw the bins.
 Note that each geoset has to have its own geostate for the bin mechanism
 to work. See 2.2 pfChannel man pages.

>
> 3: If I have to rely on pfDraw() to draw the geometry how can I set up
> the right GL calls to implement the wanted multipass algorithm?
 Since 2.2 you can use pfDrawScene(). pfDraw() may call an internal
 multipass (for pfLightSource).
>
> Any help to solve this problem is appreciated.
> I use Performer 2.0 on a REII. If Performer 2.2 is better on the point
> of using bins I will have to upgrade.

  A lot better, please upgrade.

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