Re: viewing matrix and pfDraw()

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Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Mon, 6 Nov 1995 18:33:11 +0100


On Nov 6, 11:03am, Greg Hock wrote:
> Subject:
> Hello,
>
> A couple of questions:
> 1). How does one position a pfGeoSet at multiple locations
> in the scene without having to recalculate the vertexes.
> Is there some way to use a transformation matrix on the
> GeoSet (or its Geode) to accomplish the task.

Just add it several times bellow pfDCS or pfSCS structures,
but make sure you don't call pfFlatten above the transformation.

You may also want to check out pfClone which can be used to copy
scene graphs without replicating geometry leafs.

>
> 2). How does one 'get a handle' on Multigen models when
> they are loaded. What I want to do (and yes I am aware of
> the associated graphics costs) is get at some of the
> model GeoSet vertexes and Group properties DURING RUN TIME!
> Basically I will try to toggle color and transparency.
> For example, I want to load a tank model and display it at
> say 25 different positions on a terrain, each having a
> slightly different color shading on one or more faces and
> different transparency overall.

Use pfGetChild calls to querry the graph, exactly how you do
this depends on what version of performer you use. Examples have
been posted. There is also the registerNode callback mechanisms
provided with the multigen loader, but I've never tried this.

Use draw callbacks to override material properties to modify the material
look at pfNodeTravFuncs(), pfOverride() & pfState. When multiply instancing
tanks of different colours you would probably want to use these at the level
of the pfDCS or pfSCS which positions them.

For vertex level tinkering you can view the old "atlantis" example of this
by Angus Henderson which is on the ftp site in:

~ftp/pup/Performer/RealityCentre

This querries the scene graph to vertex level (Performer 1.2).

>
> Thanks for the efforts,
>
> Gregg Hock
> (407) 726-7758
> ghock++at++gateway.grumman.com
>
>-- End of excerpt from Greg Hock

Good Luck,
Angus.

-- 
Angus Dorbie,
Silicon Graphics Ltd, UK
dorbie++at++reading.sgi.com

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