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Action:
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Creates an approximate spline surface to a procedurally defined surface.
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Prototype:
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bs3_surface bs3_surface_proc (
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SPAinterval& u_interval,
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// parameter range in u
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// over which approximate
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// surface is constructed
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SPAinterval& v_interval,
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// parameter range in v
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// over which approximate
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// surface is constructed
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pt_eval_fn_t pt_fn,
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// model space point
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// evaluator
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vec_eval_fn_t du_fn,
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// ds/du evaluator
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vec_eval_fn_t dv_fn,
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// ds/dv evaluator
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vec_eval_fn_t duv_fn,
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// ds2/dudv evaluator
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void* data,
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// data to be passed to
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// evaluators
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double res
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// fit resolution
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);
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Includes:
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#include "kernel/acis.hxx"
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#include "baseutil/vector/interval.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 surface is defined over a parametric interval in u and
v. Functions are supplied by the caller to calculate points on the surface, tangent vectors, and second derivatives. This information is evaluated and used to define a surface that is a fit to the evaluated data. If an error occurs, a
NULL surface is returned.
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The following are the type definitions of the evaluation functions used in
bs3_surface_proc.
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The
pt_fn evaluator function for the surface must return a point on the surface at a given (u,v) value:
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typedef logical
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(*pt_eval_fn_t) (
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// return of FALSE =>
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// evaluation failed
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double u,
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// u param of evaluation
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// point
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double v,
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// v param of evaluation
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// point
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void* data,
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// data you passed to
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// bs3_surface_proc
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SPAposition& pt
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// OUT: model space
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// position
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// at given uv location
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);
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The
du_fn evaluator function for the surface must return a
u-partial on the surface at a given (u,v) value. The
dv_fn evaluator function for the surface must return a
v-partial on the surface at a given (u,v) value. The
duv_fn evaluator function for the surface must return a
uv-partial on the surface at a given (u,v) value. All have the form:
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typedef logical
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(*vec_eval_fn_t) (
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// return of FALSE =>
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// evaluation failed
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double u,
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// u param of evaluation
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// point
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double v,
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// v param of evaluation
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// point
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void* data,
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// data you passed to
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// bs3_surface_proc
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SPAvector& vec);
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// OUT: vector at given uv
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// location
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);
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Limitations:
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Do not give too small a value for
res, because this can result in data explosion of the approximate surface. A
res value of 0.01 seems to work best.
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Library:
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kernel
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Filename:
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kern/kernel/spline/sg_bs3s/sps3srtn.hxx
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Effect:
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Changes model
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