Re: [Plib-users] plib, Scene Graphs and Demeter

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

mi...@st... wrote:
> 
> I'm looking for a scene graph library to use with the Demeter terrain engine. One
> option is plib, using either its simple scene graph (ssg), or something like Open
> Scene Graph.
> 
> How would these all work together? I'm sure I read somewhere that they could work
> together, with plib providing the OpenGL basics (i.e. window) and mouse and
> keyboard input, but how would I use ssg to insert and manipulate 3d modules?

PLIB doesn't cover window opening/resizing/whatever and it doesn't support
mouse/keyboard input - most PLIB users use GLUT (or something similar) to do
that.  However, I think SSG would be a good library to help out with rendering
whatever your terrain engine generates.

SSG handles the nastiness of culling to the view frustum and optimising
state changes - it also makes it easy to do things like adding man-made
structures like buildings, bridges, etc by loading them from one of a
dozen or so external file formats.

Open Scene Graph is another reasonable choice for that - it has similar
functionality to SSG but with a slightly different slant.  SSG is focussed
on realtime performance and also allows you fairly free access to OpenGL
functionality.  OpenSG is driven by a very strict view of 'correctness'
and (as I'm told) doesn't perform as quickly as a result.  It also doesn't
allow you access to OpenGL with things like callback functions.  If OpenSG
doesn't provide everything you need, you are screwed - with SSG, it's usually
possible to work around any limitations with callback functions or by
deriving new classes from those that SSG provides.

SSG is currently used by the FlightGear flight simulator - so you know it
can render terrain nicely.  Also, I come from a flight simulation background,
so you can expect that my design for SSG is well suited to terrain rendering.
OpenSG's main thrust has been towards the rendering of CAD models for the car
industry and other similar applications.

So, I believe that SSG would be a better choice than OpenSG.  But of course
I'm biassed.  This is the wonderful world of OpenSource where projects like
OpenSG and PLIB can co-exist and not feel the need to compete! There may well
be specific features of OpenSG that you may need for your application that
would make it a better choice than SSG.

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