Re: [Plib-users] ssgRoot node

[Steve B. <sjb...@ai...>]

Christopher S Horler wrote:

> Reading the plib docs and looking at the examples for plib 1.6 I'm under
> the impression that the scenegraph should all stem from the root node.
> and there should only be one root node.
> 
> Is this assumption correct?

That was the *original* intention when I wrote SSG - however, the system
works reasonably well when you have multiple roots and multiple calls to
ssgCullAndDraw in a single frame.

The thing you lose is the ability to sort by transparency.

Each call to ssgCullAndDraw sorts it's polygons into translucent and opaque
bins so that translucent surfaces can be rendered last.  If you have two
calls, then the translucent polygons in the first scene graph will be
drawn before the opaque polygons of the second.

This is sometimes a problem - but equally often useful.

> I ask this because flightgear would appear to have more than one ssgRoot
> node.  I don't think flightgear uses ssg to manage the very top of the
> scenegraph tree though - it appears to plug (for want of a better term)
> these root nodes into 'something else'.

Yes.

Some of my games do the same thing.

---------------------------- Steve Baker -------------------------
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