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Action:
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Creates a B-spline surface from a collection of control points and knot vectors.
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Prototype:
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bs3_surface bs3_surface_from_ctrlpts (
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int degree_u,
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// degree in u
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logical rational_u,
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// rational in u
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int form_u,
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// type in u
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int& pole_u,
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// pole in u
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int num_ctrlpts_u,
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// number of control
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// points in u
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int degree_v,
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// degree in v
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logical rational_v,
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// rational in v
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int form_v,
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// type in v
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int& pole_v,
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// pole in v
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int num_ctrlpts_v,
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// number of control
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// points in v
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const SPAposition
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// position control
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ctrlpts[],
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// points
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const double weights[],
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// weights
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double,
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// tolerance to determine
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// if two control points
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// are the same
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int num_knots_u,
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// number of knots in u
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const double knots_u[],
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// knots in u
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int num_knots_v,
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// number of knots in v
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const double knots_v[],
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// knots in v
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double knot_tol
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// tolerance to determine
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// if two knots are the
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// same
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);
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Includes:
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#include "kernel/acis.hxx"
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#include "baseutil/logical.h"
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#include "baseutil/vector/position.hxx"
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#include "kernel/spline/bs3_srf/bs3surf.hxx"
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#include "kernel/spline/sg_bs3s/sps3srtn.hxx"
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Description:
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The spline is defined by the given sequence of control points and knots. If the argument rational_u is TRUE, the surface is rational in the u parameter; if FALSE, it is not. Similarly, for rational_v.
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The argument form_u specifies whether the surface is open (0), closed (1), or periodic (2) in the u direction. Similarly for form_v.
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The argument pole_u indicates whether or not the surface has a singularity at the u-min or u-max parameter boundaries according to the following:
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0
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= No singularity at u-min or u-max boundary
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1
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= Has a singularity at the u-min boundary
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2
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= Has a singularity at the u-max boundary
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3
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= Has a singularity at both boundaries
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Similarly for pole_v.
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The control points are contained in an array of positions. The v index varies first. That is, a row of v control points for the first u value is found first. Then, the row of v control points for the next u value. If the surface is rational in either parameter, it is considered a rational surface and the associated weights are in the array of doubles. The values in this array are in the same sequential order as the control points.
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The point_tol tolerance value determines when two control points are identical and the knot_tol tolerance value performs the same function for the knot sequence.
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Limitations:
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The knots input have to be in an strictly increasing order.
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Library:
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kernel
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Filename:
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kern/kernel/spline/sg_bs3s/sp3srtn.hxx
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Effect:
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Changes model
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