Getting normals for Custom Display Host?

[André Adam <a_adam(at)49games.de>]

Hi, this is a forward from one of our programmers. Anyone having a clue 
how to get this work?

Cheers!

   -André

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Hi,

we are developing a custom diplay host to display some geometry created 
with XSI in our inhouse-engine.

To convert the geometry from XSI to our own format we do the following:

- get the XSI::Geometry-object [xgeo] from the XSI::X3DObject to be 
converted
- get the count of vertices [ xgeo.GetPoints().GetCount(); ]
- get the count of facets    [ xgeo.GetFacets().GetCount); ]

Now we can build up a vertex-list and a facet-list. Per facet we'll get 
a list of points used and they deliver their index in the vertex-list by 
[point.GetIndex();].

Then we need the UV-sets. No problem:
- search for sample-clusters with "uvspace"-property
- build up the uv-coord-list [ 
clusterProperty.GetValues(uv[currentUVset]);]

The facet will deliver us a list of samples used and they can tell us 
their index in the uv-coord-list. [facet.GetSamples(); sample.GetIndex();]


And now finally our problem:
How to do something similar with the normals?
We want to create a list of normals and store the indices in our facet.
But there is no such thing like a normal-list to read from.
When we try to get the normals from the (XSI::)point from the 
[xgeo.GetPoints();] we get an averaged normal. (No surprise... one 
Position ... multiple normals ... access to get only one normal.)
We we try to get the normals from the point-list we get from the facet 
we get the same result. (Obviously the references used are the same 
which are in the "global"-pointlist so we called the same methods from 
the same objects.)

We tried to get them another way. We get a triangle-list by 
[xgeo.GetTriangle();]. And per triangle we get a list of three 
XSI::TriangleVertex-objects. The XSI::TriangleVertex 
<classXSI_1_1TriangleVertex.html> delivers the -correct- normal BUT 
there is no way to map the normal back to the lists we already have. 
Mainly because we don't know from which facet the triangle was generated.

You could say: Then forget the facets and points and just use the 
triangle-vertices. The problem is we need to map back to the samples 
(for getting multiple uv-coords for example) and this is not possible.

Do you know a solution for our problem?

Greetings
-Bjoern Gdanietz, 49Games-




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