[Nel] Sample MRM interfaces

[Cyril 'Hulud' Corvazier]

A new sample has been released to show how to setup MRM shapes with boundary
interfaces.
You can download this sample here :

http://www.nevrax.org/download/nel_mrm_interfaces_sample.zip

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This is a sample to explain how to use the MRM (multi resolution mesh)
interfaces NeL features.

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This sample is based on Ryzom production files that have been optimized (
destroyed :-) ) to be released as a sample.
Unzip the files in order to have a c:\database\ directory.

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If your model is composed of several shapes (arms, hands, head, upperbody,
lowerbody),
the MRM process will preoduce holes in the character. To correct this
artifact,
NeL needs to know what vertices belong the boundary interfaces in order to
not
optimize them.

To do this, you need to setup an extra .max file with a mesh for each
interface templates
(in this sample the file is called GE_HOM_interfaces_pantabottes.max). This
file won't
produce any shape.

In the main project with your meshes ready to be exported
(FY_HOM_armor00.max),
you have to add some info to each meshes:

* In "Node properties->Misc->Interface .max file" put the path to the file
with the interface templates.
* Set the "Node properties->Misc->Interface weld threshold". this is the
delta used to match the mesh vertices with the templates.
* The normal option flag (see after)

Your shapes are ready to be exported.
In the log.log file (where you export your shapes), you will have
info/warning about the interface export status.

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You have two choices to compute the normals at the boundary vertices :

1) Take the template tangent as normal for the boundary. (Don't check the
"Get interface normals from the scene" flag).
The advantages : the same vertices in two joined shapes will have the same
normal, so there won't be
lighting discontinuities.
The disadvantage : the computed normal can be far from the true normal.

2) Take the normals from the scene as normal for the boundary vertices.
(Check the "Get interface normals from the scene" flag).
For each boundary vertex, the process will average the normal of all welded
vertex at this position and export this normal.
The advantage : the normal is closer to the true normal.
The disadvantage : the shapes exported from another project using the same
interface will have different normals. So
lighting artifats may occured if you combine several shapes.

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Cyril 'Hulud' Corvazier.