Thanks all for the tips about normals and volumes.
I already use the normals, and have menu entries to visualize the
orientation of surfaces with arrows and colors … and use the
information SAME1ST DIFF1ST provided by GiD in an external
C++ routine …
I was just looking for some way to automatise some tasks (and so
not risk any errors).
I know the sign of a scalar product can provide the reciprocal
orientation between two vectors or surface normals.
But I was asking if the surface points inside or outside a VOLUME,
not its orientation relative to another one.
What I don’t know is if in GiD there are some already build in
functions to avoid the use of computational geometry routines and
calculation of area around spherical angles
to detect if a free point
in space is inside or outside a volume (not easily the convex hull
defined from some of his points).
And since GiD is a solid modeller I was thinking of some of the
routines used in Boolean operation with volumes, or something
similar. May be in a future version it could be an information
provided, I dont know
The information SAME1ST DIFF1ST doesnt offer me what I was
looking for because it tells me only if the orientation of a surface is
consistent with an initial reciprocal orientation between the normal
of surface 1 and the z axis.
At the end so is still a human choice to say if a normal to a surface
is pointing inside or outside a volume.
Sorry for the long mail.
Thanks in any case.
Andrea Calaon
Ashurst Lodge, Ashurst
Southampton, Hampshire
SO40 7AA, UK
Tel. office: +44 23 80 293 223
Fax office: +44 23 80 292 853
Mobile: +44 7766 488 225
E-mail: andrea at beasy.com
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