Catmull_Rom算法的实现

2024-03-01 08:08

文章标签 算法实现 rom catmull

本文主要是介绍Catmull_Rom算法的实现，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

Catmull_Rom算法的具体原理在网络上都有，感兴趣的可以自己查找，此处只是它的代码实现，实现环境为OSG：

给定一堆离散点，将该离散点进行插值，绘制的曲线经过每一个离散点。

实现的代码：

//生成Catmull_Rom Spline算法顶点
osg::Vec3 Catmull_Rom_SplinePoint_new(float u, osg::ref_ptr<osg::Vec3Array> subconctrl_P)
{
   float f0, f1, f2, f3;
   osg::Vec3 vert;
   f0 = (-0.5)*pow(u, 3) + pow(u, 2) + (-0.5*u);
   f1 = 1.5*pow(u, 3) - 2.5*pow(u, 2) + 1;
   f2 = (-1.5)*pow(u, 3) + 2.0*pow(u, 2) + 0.5*u;
   f3 = 0.5*pow(u, 3) - 0.5*pow(u, 2);
   vert = subconctrl_P->at(0)*f0 + subconctrl_P->at(1)*f1 + subconctrl_P->at(2)*f2 + subconctrl_P->at(3)*f3;
   return vert;
}

//生成Catmull_Rom Spline样条线顶点,过端点
osg::ref_ptr<osg::Vec3Array> Catmull_Rom_SplinePoints_new(osg::ref_ptr<osg::Vec3Array> conctrl_P, int Unum = 10)
{
   osg::ref_ptr<osg::Vec3Array> C_Line_vertices = new osg::Vec3Array;
   osg::ref_ptr<osg::Vec3Array> New_conctrl_P = new osg::Vec3Array;
   auto pointsnum = conctrl_P->size();
   auto P0 = conctrl_P->at(0) * 2 - conctrl_P->at(1);
   New_conctrl_P->push_back(P0);
   auto Pn = conctrl_P->at(pointsnum - 1) * 2 - conctrl_P->at(pointsnum - 2);
   for (int i = 0; i < pointsnum; i++)
   {
       New_conctrl_P->push_back(conctrl_P->at(i));
   }
   New_conctrl_P->push_back(Pn);
   pointsnum += 2;
   for (int i = 0; i < pointsnum; i++)
   {
       if (i < pointsnum - 3)
       {
           osg::ref_ptr<osg::Vec3Array> subcontrl = new osg::Vec3Array;
           subcontrl->push_back(New_conctrl_P->at(i));
           subcontrl->push_back(New_conctrl_P->at(i + 1));
           subcontrl->push_back(New_conctrl_P->at(i + 2));
           subcontrl->push_back(New_conctrl_P->at(i + 3));
           float deltaU = 1.0 / float(Unum);
           for (int j = 0; j < Unum; j++)
           {
               auto Uu = j*deltaU;
               auto tempp = Catmull_Rom_SplinePoint_new(Uu, subcontrl);
               C_Line_vertices->push_back(tempp);
           }
       }

   }
   return C_Line_vertices;
}