axmol/extensions/Particle3D/PU/CCPUSimpleSpline.cpp

/****************************************************************************
 Copyright (C) 2013 Henry van Merode. All rights reserved.
 Copyright (c) 2015-2016 Chukong Technologies Inc.
 Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.

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#include "CCPUSimpleSpline.h"
#include "base/ccMacros.h"

NS_AX_BEGIN
//---------------------------------------------------------------------
PUSimpleSpline::PUSimpleSpline()
{
    // Set up matrix
    // Hermite polynomial
    _coeffs.m[0]  = 2;
    _coeffs.m[1]  = -2;
    _coeffs.m[2]  = 1;
    _coeffs.m[3]  = 1;
    _coeffs.m[4]  = -3;
    _coeffs.m[5]  = 3;
    _coeffs.m[6]  = -2;
    _coeffs.m[7]  = -1;
    _coeffs.m[8]  = 0;
    _coeffs.m[9]  = 0;
    _coeffs.m[10] = 1;
    _coeffs.m[11] = 0;
    _coeffs.m[12] = 1;
    _coeffs.m[13] = 0;
    _coeffs.m[14] = 0;
    _coeffs.m[15] = 0;

    _autoCalc = true;
}
//---------------------------------------------------------------------
PUSimpleSpline::~PUSimpleSpline() {}
//---------------------------------------------------------------------
void PUSimpleSpline::addPoint(const Vec3& p)
{
    _points.emplace_back(p);
    if (_autoCalc)
    {
        recalcTangents();
    }
}
//---------------------------------------------------------------------
Vec3 PUSimpleSpline::interpolate(float t) const
{
    // Currently assumes points are evenly spaced, will cause velocity
    // change where this is not the case
    // TODO: base on arclength?

    // Work out which segment this is in
    float fSeg          = t * (_points.size() - 1);
    unsigned int segIdx = (unsigned int)fSeg;
    // Apportion t
    t = fSeg - segIdx;

    return interpolate(segIdx, t);
}
//---------------------------------------------------------------------
Vec3 PUSimpleSpline::interpolate(unsigned int fromIndex, float t) const
{
    // Bounds check
    AXASSERT(fromIndex < _points.size(), "fromIndex out of bounds");

    if ((fromIndex + 1) == _points.size())
    {
        // Duff request, cannot blend to nothing
        // Just return source
        return _points[fromIndex];
    }

    // Fast special cases
    if (t == 0.0f)
    {
        return _points[fromIndex];
    }
    else if (t == 1.0f)
    {
        return _points[fromIndex + 1];
    }

    // Real interpolation
    // Form a vector of powers of t
    float t2, t3;
    t2 = t * t;
    t3 = t2 * t;
    Vec4 powers(t3, t2, t, 1);

    // Algorithm is ret = powers * mCoeffs * Matrix4(point1, point2, tangent1, tangent2)
    const Vec3& point1 = _points[fromIndex];
    const Vec3& point2 = _points[fromIndex + 1];
    const Vec3& tan1   = _tangents[fromIndex];
    const Vec3& tan2   = _tangents[fromIndex + 1];
    Mat4 pt;

    pt.m[0]  = point1.x;
    pt.m[1]  = point1.y;
    pt.m[2]  = point1.z;
    pt.m[3]  = 1.0f;
    pt.m[4]  = point2.x;
    pt.m[5]  = point2.y;
    pt.m[6]  = point2.z;
    pt.m[7]  = 1.0f;
    pt.m[8]  = tan1.x;
    pt.m[9]  = tan1.y;
    pt.m[10] = tan1.z;
    pt.m[11] = 1.0f;
    pt.m[12] = tan2.x;
    pt.m[13] = tan2.y;
    pt.m[14] = tan2.z;
    pt.m[15] = 1.0f;

    Vec4 ret = pt * _coeffs * powers;

    return Vec3(ret.x, ret.y, ret.z);
}
//---------------------------------------------------------------------
void PUSimpleSpline::recalcTangents()
{
    // Catmull-Rom approach
    //
    // tangent[i] = 0.5 * (point[i+1] - point[i-1])
    //
    // Assume endpoint tangents are parallel with line with neighbour

    size_t i, numPoints;
    bool isClosed;

    numPoints = _points.size();
    if (numPoints < 2)
    {
        // Can't do anything yet
        return;
    }

    // Closed or open?
    if (_points[0] == _points[numPoints - 1])
    {
        isClosed = true;
    }
    else
    {
        isClosed = false;
    }

    _tangents.resize(numPoints);

    for (i = 0; i < numPoints; ++i)
    {
        if (i == 0)
        {
            // Special case start
            if (isClosed)
            {
                // Use numPoints-2 since numPoints-1 is the last point and == [0]
                _tangents[i] = 0.5 * (_points[1] - _points[numPoints - 2]);
            }
            else
            {
                _tangents[i] = 0.5 * (_points[1] - _points[0]);
            }
        }
        else if (i == numPoints - 1)
        {
            // Special case end
            if (isClosed)
            {
                // Use same tangent as already calculated for [0]
                _tangents[i] = _tangents[0];
            }
            else
            {
                _tangents[i] = 0.5 * (_points[i] - _points[i - 1]);
            }
        }
        else
        {
            _tangents[i] = 0.5 * (_points[i + 1] - _points[i - 1]);
        }
    }
}
//---------------------------------------------------------------------
const Vec3& PUSimpleSpline::getPoint(unsigned short index) const
{
    AXASSERT(index < _points.size(), "Point index is out of bounds!!");

    return _points[index];
}
//---------------------------------------------------------------------
unsigned short PUSimpleSpline::getNumPoints() const
{
    return (unsigned short)_points.size();
}
//---------------------------------------------------------------------
void PUSimpleSpline::clear()
{
    _points.clear();
    _tangents.clear();
}
//---------------------------------------------------------------------
void PUSimpleSpline::updatePoint(unsigned short index, const Vec3& value)
{
    AXASSERT(index < _points.size(), "Point index is out of bounds!!");

    _points[index] = value;
    if (_autoCalc)
    {
        recalcTangents();
    }
}
//---------------------------------------------------------------------
void PUSimpleSpline::setAutoCalculate(bool autoCalc)
{
    _autoCalc = autoCalc;
}
NS_AX_END