de Casteljau交互Bezier

#include <GL/glut.h>
#include <iostream>
#include <vector>
#include <cmath>
using namespace std;
const GLfloat wh=600;
struct point {
	float x;
	float y;
};
vector<point>V; 
vector<point> V1, V2; int  model = 0; bool dragging = false;
vector<point>& de_Casteljau(int n) {
    V1.resize(V.size()); V2.resize(0);
	for (float t = 0; t <= 1;t=t+0.02) {
		for (int j = 1; j < n; j++) {
			for (int k = 0; k < n - j;k++) {
				if (j == 1) { 
					V1[k].x = (1 - t) * V[k].x + t * V[k + 1].x;
					V1[k].y = (1 - t) * V[k].y + t * V[k + 1].y;
					
				}
				else {
					V1[k].x = (1 - t) * V1[k].x + t * V1[k + 1].x;
					V1[k].y = (1 - t) * V1[k].y + t * V1[k + 1].y;
					
				}
			}

		}
		cout << V1[0].x << " " << V1[0].y << endl;
		V2.push_back(V1[0]);
	}
	return V2;
}

int findnearest(float x,float y ) {
	float min = 1000000; int re=0;
	for (int i = 0; i < V.size(); i++) {
		float d = (V[i].x - x) * (V[i].x - x) + (V[i].y - y) * (V[i].y - y);
		if (d < min) {
			re = i; min = d;
		}
	}
	return re;
}
void draw() {
	glClear(GL_COLOR_BUFFER_BIT);
	glBegin(GL_LINE_STRIP);
	for (int i = 0; i < V.size(); i++) {
		point p = V[i];
		glVertex2f(p.x, p.y);
	}
	glEnd();
	glFlush();
	vector<point>re = de_Casteljau(V.size()); re.push_back(V.back());
	glBegin(GL_LINE_STRIP);
	for (int i = 0; i < re.size(); i++) {
		point p = re[i];

		glVertex2f(p.x, p.y);
	}
	glEnd();
	glFlush();
}

int id = 0;
void  mymouse(int button, int state, int x, int y) {
	y = wh - y; 
	if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
		if (model == 0) {
			point p; p.x = x; p.y = y;
			V.push_back(p);
			glBegin(GL_POINTS);
			glVertex2f(p.x, p.y);
			glEnd();
			glFlush();
		}
		else if (model == 1) {
			 id= findnearest(x, y);
			V.erase(V.begin() + id);
			if (V.size() > 1)draw();
			else { cout << "点数必须>=2" << endl; }
		}
		else if (model == 2) {
			 id = findnearest(x, y);
			cout << "点号" << id << endl;
			dragging = true;
		}
		else if (model == 3) {
			point p; p.x = x; p.y = y;
			V.push_back(p);
			glBegin(GL_POINTS);
			glVertex2f(p.x, p.y);
			glEnd();
			glFlush();
			draw();
		}
	}
	if (button == GLUT_LEFT_BUTTON && state == GLUT_UP) {
		if (dragging==true) {
			dragging = false;
			V[id].x = x; V[id].y = y;
			
			if (V.size() > 1)draw();
			return;
		}
	}
	
}
void keyboard(unsigned char key,int x,int y) {
	if (key == 32) {
		draw();
		 
	}
	
}
void Mymenu(int m) {
	model = m;
	if (model == 4) {
		exit(0);
	}
}
int main(int argc, char* argv[])
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RED);
	glutInitWindowPosition(50, 50);
	glutInitWindowSize(800, 600);
	glutCreateWindow("Bezier");
	cout << "。。。。" << endl;

	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0, 800, 0, 600);

	glClearColor(1, 1, 1, 1);
	glClear(GL_COLOR_BUFFER_BIT);

	glColor3f(160.0/255.0,82.0/255.0,45.0/255.0);
	glLineWidth(2.0f); glPointSize(5);


	glutMouseFunc(&mymouse);
	glutKeyboardFunc(&keyboard);

	glutCreateMenu(Mymenu);//注册菜单回调函数
	glutAddMenuEntry("Delete", 1);//添加菜单项
	glutAddMenuEntry("Move", 2);
	glutAddMenuEntry("Insert", 3);
	glutAddMenuEntry("Exit", 4);
	glutAttachMenu(GLUT_RIGHT_BUTTON);
	glutMainLoop();
	return 0;
}