Processing中shapes3d库的utils包中的Bezier2与Shape3D包中的BezShape类

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Processing中shapes3d库的utils包中的Bezier2D类的帮助文档是这样写的

This class is used to represent a single Bezier curve of degree >= 2 in 2D space.

这个类用来描述大于等于2 degree的Bezier 曲线
Note the degree of a Bezier curve equals the number of control points.

degree的值和控制点的值相等
Its primary purpose is to act as a convenience class to maintain a collection bezier controls points in 2 dimensions.

主要设计目的是保持一个2维空间的控制点集
In this library the Bezier2D object is used by the BezierShape class to create a 3D shape by rotating it about the Y axis [0,1,0].

这shapes3d库中主要是用来创建3D形状，方法是通过在xy平面上使用Bezier2D创建的曲线绕y轴旋转，得到一个3维形状

下面是degree与二维形状之间的对应关系

Degree Shape

2 straight line （直线）
3 quadratic bezier （二次bezier曲线）
4 cubic bezier （三次bezier曲线）
……

Bezier2D与BezShape结合实现了bezier曲线二维图形旋转建模

以下是本人写的一个示例程序：

import peasy.*;import shapes3d.*;import shapes3d.utils.*;PeasyCam cam;Bezier2D bz;PVector[] v;BezShape bzs;int slice, seg;void setup(){  cam=new PeasyCam(this, 500);  v=new PVector[]{    new PVector(0, 0, 0),     new PVector(100, 0, 0),     new PVector(200, 0, 0)  };  size(800, 600, P3D);}void draw(){  background(0);  lights();  bz=new Bezier2D(v, v.length);  bzs=new BezShape(this, bz, slice, seg);  bzs.stroke(color(255));  bzs.drawMode(BezShape.WIRE);  bzs.draw();}void mouseMoved(){  slice=int(map(mouseX, 0, width, 0, 100));  seg=int(map(mouseY, 0, width, 0, 100));}void keyPressed(){  if (keyCode%3==0)  {    v=new PVector[]{      new PVector(0, 0, 0),       new PVector(100, 0, 0),       new PVector(200, 0, 0)    };  }  if (keyCode%3==1)  {    v=new PVector[]{      new PVector(0, 0, 0),       new PVector(100, 100, 0),       new PVector(200, 0, 0)    };  }  if (keyCode%3==2)  {    v=new PVector[]{      new PVector(0, 0, 0),       new PVector(100, 100, 0),       new PVector(200, 0, 0),       new PVector(300, 100, 0)    };  }}

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