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Action:
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Evaluates the cross curvature of a three-dimensional B-spline surface at a given
uv.
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Prototype:
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double bs3_surface_cross (
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SPApar_pos const& uv,
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// given parameter point
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SPAunit_vector const& dir,// object space tangent
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// direction
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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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Evaluates the cross curvature of a three-dimensional B-spline surface at a given
uv.
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This is equivalent to constructing a plane through the given point and perpendicular to the given direction, which must be tangent to the surface at the given point, and returning the curvature of the intersection curve between the plane and the surface at that point.
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If the intersection curve is convex when viewed from the outside of the surface (the side that the normal points toward), the sign of the result is negative. If the curve is is concave, the sign is positive. If there is a discontinuity in curvature at the given point, the value returned is for the left-hand side of the intersection curve as viewed in the given tangent direction with the surface normal upwards.
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Errors:
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Returns -1 if the input surface is null.
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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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