Coverage Report

Created: 2025-07-11 06:33

/src/ogre/OgreMain/src/OgreSimpleSpline.cpp
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/*
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-----------------------------------------------------------------------------
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This source file is part of OGRE
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    (Object-oriented Graphics Rendering Engine)
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For the latest info, see http://www.ogre3d.org/
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Copyright (c) 2000-2014 Torus Knot Software Ltd
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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-----------------------------------------------------------------------------
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*/
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#include "OgreStableHeaders.h"
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namespace Ogre {
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    //---------------------------------------------------------------------
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    SimpleSpline::SimpleSpline()
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    {
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        mAutoCalc = true;
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    }
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    //---------------------------------------------------------------------
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    SimpleSpline::~SimpleSpline()
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    {
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    }
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    //---------------------------------------------------------------------
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    void SimpleSpline::addPoint(const Vector3& p)
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    {
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        mPoints.push_back(p);
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        if (mAutoCalc)
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        {
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            recalcTangents();
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        }
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    }
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    //---------------------------------------------------------------------
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    Vector3 SimpleSpline::interpolate(Real t) const
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    {
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        // Currently assumes points are evenly spaced, will cause velocity
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        // change where this is not the case
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        // TODO: base on arclength?
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        // Work out which segment this is in
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        Real fSeg = t * (mPoints.size() - 1);
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        unsigned int segIdx = (unsigned int)fSeg;
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        // Apportion t 
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        t = fSeg - segIdx;
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        return interpolate(segIdx, t);
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    }
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    //---------------------------------------------------------------------
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    Vector3 SimpleSpline::interpolate(unsigned int fromIndex, Real t) const
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    {
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        // Bounds check
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        assert (fromIndex < mPoints.size() &&
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            "fromIndex out of bounds");
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        if ((fromIndex + 1) == mPoints.size())
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        {
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            // Duff request, cannot blend to nothing
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            // Just return source
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            return mPoints[fromIndex];
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        }
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        // Fast special cases
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        if (t == 0.0f)
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        {
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            return mPoints[fromIndex];
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        }
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        else if(t == 1.0f)
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        {
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            return mPoints[fromIndex + 1];
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        }
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        // Set up matrix
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        // Hermite polynomial
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        static Matrix4 hCoeffs = {
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             2, -2,  1,  1,
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            -3,  3, -2, -1,
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             0,  0,  1,  0,
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             1,  0,  0,  0
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        };
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        // Real interpolation
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        // Form a vector of powers of t
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        Real t2, t3;
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        t2 = t * t;
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        t3 = t2 * t;
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        Vector4 powers(t3, t2, t, 1);
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        // Algorithm is ret = powers * hCoeffs * Matrix4(point1, point2, tangent1, tangent2)
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        const Vector3& point1 = mPoints[fromIndex];
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        const Vector3& point2 = mPoints[fromIndex+1];
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        const Vector3& tan1 = mTangents[fromIndex];
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        const Vector3& tan2 = mTangents[fromIndex+1];
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        Matrix4 pt;
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        pt[0][0] = point1.x;
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        pt[0][1] = point1.y;
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        pt[0][2] = point1.z;
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        pt[0][3] = 1.0f;
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        pt[1][0] = point2.x;
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        pt[1][1] = point2.y;
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        pt[1][2] = point2.z;
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        pt[1][3] = 1.0f;
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        pt[2][0] = tan1.x;
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        pt[2][1] = tan1.y;
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        pt[2][2] = tan1.z;
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        pt[2][3] = 1.0f;
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        pt[3][0] = tan2.x;
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        pt[3][1] = tan2.y;
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        pt[3][2] = tan2.z;
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        pt[3][3] = 1.0f;
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        Vector4 ret = powers * hCoeffs * pt;
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        return Vector3(ret.x, ret.y, ret.z);
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    }
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    //---------------------------------------------------------------------
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    void SimpleSpline::recalcTangents(void)
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    {
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        // Catmull-Rom approach
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        // 
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        // tangent[i] = 0.5 * (point[i+1] - point[i-1])
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        //
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        // Assume endpoint tangents are parallel with line with neighbour
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        size_t i, numPoints;
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        bool isClosed;
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        numPoints = mPoints.size();
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        if (numPoints < 2)
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        {
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            // Can't do anything yet
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            return;
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        }
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        // Closed or open?
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        if (mPoints[0] == mPoints[numPoints-1])
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        {
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            isClosed = true;
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        }
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        else
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        {
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            isClosed = false;
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        }
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        mTangents.resize(numPoints);
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        for(i = 0; i < numPoints; ++i)
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        {
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            if (i ==0)
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            {
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                // Special case start
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                if (isClosed)
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                {
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                    // Use numPoints-2 since numPoints-1 is the last point and == [0]
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                    mTangents[i] = 0.5 * (mPoints[1] - mPoints[numPoints-2]);
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                }
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                else
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                {
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                    mTangents[i] = 0.5 * (mPoints[1] - mPoints[0]);
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                }
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            }
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            else if (i == numPoints-1)
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            {
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                // Special case end
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                if (isClosed)
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                {
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                    // Use same tangent as already calculated for [0]
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                    mTangents[i] = mTangents[0];
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                }
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                else
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                {
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                    mTangents[i] = 0.5 * (mPoints[i] - mPoints[i-1]);
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                }
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            }
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            else
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            {
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                mTangents[i] = 0.5 * (mPoints[i+1] - mPoints[i-1]);
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            }
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        }
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    }
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    //---------------------------------------------------------------------
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    const Vector3& SimpleSpline::getPoint(unsigned short index) const
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    {
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        assert (index < mPoints.size() && "Point index is out of bounds!!");
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        return mPoints[index];
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    }
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    //---------------------------------------------------------------------
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    unsigned short SimpleSpline::getNumPoints(void) const
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    {
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        return (unsigned short)mPoints.size();
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    }
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    //---------------------------------------------------------------------
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    void SimpleSpline::clear(void)
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    {
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        mPoints.clear();
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        mTangents.clear();
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    }
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    //---------------------------------------------------------------------
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    void SimpleSpline::updatePoint(unsigned short index, const Vector3& value)
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    {
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        assert (index < mPoints.size() && "Point index is out of bounds!!");
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        mPoints[index] = value;
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        if (mAutoCalc)
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        {
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            recalcTangents();
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        }
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    }
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    //---------------------------------------------------------------------
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    void SimpleSpline::setAutoCalculate(bool autoCalc)
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    {
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        mAutoCalc = autoCalc;
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    }
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}
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