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0a96e0bbc4
Implementation of classes BSplCLib_Cache and BSplSLib_Cache is revised: - Common functionality dealing with spans along one parametric direction is separated to new struct BSplCLib_CacheParams - Empty constructors are removed; copying is prohibited - Code reconsidering degree and other parameters on each call to BuildCache() is eliminated; curve parameters must be the same in constructor and all calls to BuildCache() - Extra call to BuildCache() from constructor is eliminated
107 lines
4.3 KiB
C++
107 lines
4.3 KiB
C++
// Copyright (c) 2018 OPEN CASCADE SAS
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//
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// This file is part of Open CASCADE Technology software library.
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//
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// This library is free software; you can redistribute it and/or modify it under
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// the terms of the GNU Lesser General Public License version 2.1 as published
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// by the Free Software Foundation, with special exception defined in the file
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// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
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// distribution for complete text of the license and disclaimer of any warranty.
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//
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// Alternatively, this file may be used under the terms of Open CASCADE
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// commercial license or contractual agreement.
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#ifndef _BSplCLib_CacheParams_Headerfile
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#define _BSplCLib_CacheParams_Headerfile
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#include <Standard_Real.hxx>
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#include <TColStd_Array1OfReal.hxx>
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#include <BSplCLib.hxx>
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//! Simple structure containing parameters describing parameterization
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//! of a B-spline curve or a surface in one direction (U or V),
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//! and data of the current span for its caching
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struct BSplCLib_CacheParams
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{
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const Standard_Integer Degree; ///< degree of Bezier/B-spline
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const Standard_Boolean IsPeriodic; ///< true of the B-spline is periodic
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const Standard_Real FirstParameter; ///< first valid parameter
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const Standard_Real LastParameter; ///< last valid parameter
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const Standard_Integer SpanIndexMin; ///< minimal index of span
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const Standard_Integer SpanIndexMax; ///< maximal index of span
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Standard_Real SpanStart; ///< parameter for the frst point of the span
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Standard_Real SpanLength; ///< length of the span
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Standard_Integer SpanIndex; ///< index of the span
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//! Constructor, prepares data structures for caching.
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//! \param theDegree degree of the B-spline (or Bezier)
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//! \param thePeriodic identify whether the B-spline is periodic
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//! \param theFlatKnots knots of Bezier / B-spline parameterization
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BSplCLib_CacheParams (Standard_Integer theDegree, Standard_Boolean thePeriodic,
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const TColStd_Array1OfReal& theFlatKnots)
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: Degree(theDegree),
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IsPeriodic(thePeriodic),
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FirstParameter(theFlatKnots.Value(theFlatKnots.Lower() + theDegree)),
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LastParameter(theFlatKnots.Value(theFlatKnots.Upper() - theDegree)),
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SpanIndexMin(theFlatKnots.Lower() + theDegree),
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SpanIndexMax(theFlatKnots.Upper() - theDegree - 1),
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SpanStart(0.),
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SpanLength(0.),
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SpanIndex(0)
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{}
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//! Normalizes the parameter for periodic B-splines
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//! \param theParameter the value to be normalized into the knots array
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Standard_Real PeriodicNormalization (Standard_Real theParameter) const
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{
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if (IsPeriodic)
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{
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if (theParameter < FirstParameter)
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{
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Standard_Real aPeriod = LastParameter - FirstParameter;
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Standard_Real aScale = IntegerPart ((FirstParameter - theParameter) / aPeriod);
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return theParameter + aPeriod * (aScale + 1.0);
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}
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if (theParameter > LastParameter)
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{
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Standard_Real aPeriod = LastParameter - FirstParameter;
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Standard_Real aScale = IntegerPart ((theParameter - LastParameter) / aPeriod);
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return theParameter - aPeriod * (aScale + 1.0);
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}
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}
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return theParameter;
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}
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//! Verifies validity of the cache using flat parameter of the point
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//! \param theParameter parameter of the point placed in the span
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Standard_Boolean IsCacheValid (Standard_Real theParameter) const
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{
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Standard_Real aNewParam = PeriodicNormalization (theParameter);
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Standard_Real aDelta = aNewParam - SpanStart;
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return ((aDelta >= 0.0 || SpanIndex == SpanIndexMin) &&
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(aDelta < SpanLength || SpanIndex == SpanIndexMax));
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}
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//! Computes span for the specified parameter
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//! \param theParameter parameter of the point placed in the span
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//! \param theFlatKnots knots of Bezier / B-spline parameterization
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void LocateParameter (Standard_Real& theParameter, const TColStd_Array1OfReal& theFlatKnots)
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{
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SpanIndex = 0;
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BSplCLib::LocateParameter (Degree, theFlatKnots, BSplCLib::NoMults(),
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theParameter, IsPeriodic, SpanIndex, theParameter);
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SpanStart = theFlatKnots.Value(SpanIndex);
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SpanLength = theFlatKnots.Value(SpanIndex + 1) - SpanStart;
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}
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private:
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// copying is prohibited
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BSplCLib_CacheParams (const BSplCLib_CacheParams&);
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void operator = (const BSplCLib_CacheParams&);
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};
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#endif
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