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Action:
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Evaluates the normal to a three-dimensional B-spline surface at a given (u,v).
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Prototype:
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SPAunit_vector bs3_surface_normal (
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SPApar_pos const& uv,
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// given parameter point
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bs3_surface bs
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// given surface
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);
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Includes:
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#include "kernel/acis.hxx"
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#include "baseutil/vector/param.hxx"
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#include "baseutil/vector/unitvec.hxx"
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#include "kernel/spline/bs3_srf/bs3surf.hxx"
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#include "kernel/spline/bs3_srf/sp3srtn.hxx"
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Description:
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This routine is often implemented as a call to
bs3_surface_eval to obtain the first derivatives, returning the cross product, suitably normalized, but special action may be required at parameter singularities. At a surface singularity, like the apex of a cone, the routine returns a unit vector with all its components zero.
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Library:
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kernel
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Filename:
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kern/kernel/spline/bs3_srf/sp3srtn.hxx
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Effect:
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Read-only
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