- UBGraphicsScene calls UBGraphicsStroke::addPoint, which returns a list of points that can be drawn. It may be none (e.g we discard very small segments), one (if we do no interpolation) or several. - Added a UBInterpolator base, abstract class. Various interpolation methods can be added easily. - Current methods: Basic spline (custom), Catmull-Rom spline (based on alglib), and Bézier - Added a setting to toggle interpolation. Added this to the UI as wellpreferencesAboutTextFull
Craig Watson
9 years ago
parent
fb6bc855e9
commit
4491341a4d
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#include "UBInterpolator.h" |
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UBInterpolator::UBInterpolator() |
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{ |
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} |
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UBInterpolator::~UBInterpolator() |
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{ |
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} |
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UBSimpleSpline::UBSimpleSpline() |
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{ |
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} |
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void UBSimpleSpline::setPoints(QList<QPointF> points) |
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{ |
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setPoints(points[0], points[1], points[2]); |
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} |
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void UBSimpleSpline::setPoints(QPointF p0, QPointF p1, QPointF p2) |
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{ |
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/*
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p0 -= p0; |
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p1 -= p0; |
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p2 -= p0; |
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*/ |
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long double x0, x1, x2, y0, y1, y2; |
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x0 = p0.x(); |
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x1 = p1.x(); |
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x2 = p2.x(); |
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y0 = p0.y(); |
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y1 = p1.y(); |
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y2 = p2.y(); |
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long double k1 = (y2-y0)/(x2-x0); |
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m_a = (y1-y2-k1*(x1-x2))/(pow(x1,3) - pow(x2,3) - 3*x2*(pow(x1,2)-pow(x2,2)) - |
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3*(pow(x1,2) - 2*x1*x2)*(x1-x2)); |
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m_b = -3*m_a*x2; |
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m_c = k1 - 3*m_a*pow(x1,2) - 2*m_b*x1; |
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m_d = y1 - m_a*pow(x1,3) - m_b*pow(x1,2) - m_c*x1; |
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} |
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double UBSimpleSpline::y(double x) |
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{ |
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return m_a*pow(x, 3) + m_b*pow(x, 2) + m_c*x + m_d; |
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} |
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UBCatmullRomSpline::UBCatmullRomSpline() |
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{ |
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mInterpolant = 0; |
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} |
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UBCatmullRomSpline::~UBCatmullRomSpline() |
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{ |
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if (mInterpolant) |
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delete mInterpolant; |
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} |
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void UBCatmullRomSpline::setPoints(QList<QPointF> points) |
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{ |
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// todo : basis change to avoid crashing when several X's are equal
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mInterpolant = new alglib::spline1dinterpolant(); |
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// alglib arrays are defined as strings
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QString x = "["; |
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QString y = "["; |
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foreach(QPointF point, points) { |
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x += (QString::number(point.x()) + QString(",")); |
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y += (QString::number(point.y()) + QString(",")); |
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} |
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x.chop(1); |
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y.chop(1); |
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x+="]"; |
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y+="]"; |
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alglib::real_1d_array xArray = x.toLatin1().data(); |
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alglib::real_1d_array yArray = y.toLatin1().data(); |
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alglib::spline1dbuildcatmullrom(xArray, yArray, *mInterpolant); |
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} |
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double UBCatmullRomSpline::y(double x) |
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{ |
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return alglib::spline1dcalc(*mInterpolant, x); |
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} |
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UBQuadraticBezier::UBQuadraticBezier() |
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{ |
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mPath = 0; |
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} |
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UBQuadraticBezier::~UBQuadraticBezier() |
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{ |
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if (mPath) |
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delete mPath; |
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} |
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void UBQuadraticBezier::setPoints(QList<QPointF> points) |
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{ |
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setPoints(points[0], points[1], points[2]); |
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} |
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void UBQuadraticBezier::setPoints(QPointF start, QPointF control, QPointF end) |
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{ |
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mPath = new QPainterPath(start); |
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mPath->quadTo(control, end); |
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} |
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/**
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* @brief Return n points along the curve, including start and end points (thus n should be larger than or equal to 2). |
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* |
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* The higher n, the more accurate the result |
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*/ |
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QList<QPointF> UBQuadraticBezier::getPoints(int n) |
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{ |
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QList<QPointF> points; |
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if (n <= 1) |
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return points; |
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for (int i(0); i <= n; ++i) { |
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qreal percent = qreal(i)/qreal(n); |
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points << mPath->pointAtPercent(percent); |
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} |
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return points; |
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} |
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#ifndef UBINTERPOLATOR_H |
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#define UBINTERPOLATOR_H |
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#include <QtGui> |
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#include "spline.h" |
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#include "interpolation.h" |
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class UBInterpolator |
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{ |
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/* Abstract class representing an interpolator */ |
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public: |
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enum InterpolationMethod { |
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NoInterpolation, |
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SimpleSpline, |
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CatmullRom, |
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Bezier |
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}; |
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UBInterpolator(); |
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virtual ~UBInterpolator(); |
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virtual void setPoints(QList<QPointF> points) = 0; |
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virtual double y(double x) {} |
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}; |
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class UBSimpleSpline : public UBInterpolator |
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{ |
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/* A basic cubic spline interpolator, that requires only three
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* points to interpolate between the second and third one. |
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* To do so, the curvature at p2 is set to 0, so the resulting |
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* curve is not very smooth. |
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* However, it is better than linear interpolation and requires no |
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* "future" points, so it can be used seamlessly during drawing. |
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*/ |
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public: |
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UBSimpleSpline(); |
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virtual ~UBSimpleSpline() {} |
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virtual void setPoints(QList<QPointF> points); |
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void setPoints(QPointF p0, QPointF p1, QPointF p2); |
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virtual double y(double x); |
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private: |
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long double m_a, |
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m_b, |
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m_c, |
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m_d; |
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}; |
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class UBCatmullRomSpline : public UBInterpolator |
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{ |
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/* Catmull-Rom spline, using AlgLib as backend
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* |
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* This requires four points to interpolate between the middle two. |
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*/ |
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public: |
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UBCatmullRomSpline(); |
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virtual ~UBCatmullRomSpline(); |
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virtual void setPoints(QList<QPointF> points); |
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virtual double y(double x); |
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private: |
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alglib::spline1dinterpolant * mInterpolant; |
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}; |
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class UBQuadraticBezier : public UBInterpolator |
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{ |
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public: |
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UBQuadraticBezier(); |
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virtual ~UBQuadraticBezier(); |
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virtual void setPoints(QList<QPointF> points); |
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void setPoints(QPointF start, QPointF control, QPointF end); |
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//virtual double y(double x);
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QList<QPointF> getPoints(int n); |
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private: |
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QPainterPath* mPath; |
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}; |
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#endif // UBINTERPOLATOR_H
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