Re: Draw a node twice
Ran Yakir (rany++at++rtset.co.il)
Sun, 9 Feb 1997 18:43:26 +0000
On Feb 9, 1:03pm, Orad Hi-Tec Systems wrote:
> Subject: Re: Draw a node twice
> Angus Dorbie wrote:
> >
> > What about two channels and traversal masks?
>
>
> This way you would need to traverse all the non-leaf nodes twice.
>
> (from man pfChannel, pfNodeTravMask area:
>
> PFTRAV_DRAW
> Node is completely ignored. Both cull and draw
> traversals skip
> the node and its children.
>
> )
>
> Typically, there is a small number of multi-pass nodes (for special
> effects
> like multi-layered texture, bump-mapping), relative to a large and deep
> scene-graph. This would cause a large overhead. For example, all the DCS
> matrix calculations will be performed twice, all the culling
> calculations
> for non-leaf nodes will be performed twice, etc.
>
> Ran Yakir wrote:
> > Maybe this could be a nice addition to Performer's API. You could have a
> > pfNodeTravMode function of pfNodeMPassMode that will set the number of
> > passes for a specific node, and some parameters for the multipass (like,
> > when to draw the second pass - right after the node gets drawn, or at
> > the end of the normal scene).
> >
>
> and a user callback before every pass to change the GL state...
>
I'll vote for that.
Ran
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