OpenGL

计算公式：

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运行结果：

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代码如下：

#include<gl/glut.h>#include<math.h>#include<windows.h>#include<vector>#include<algorithm>using namespace std;struct Point{    int x, y;    Point(){};    Point(int tx, int ty)    {        x = tx;        y = ty;    }};vector<Point> p;double getRatio(double t,double a,double b,double c,double d){    return a * pow(t, 3) + b * pow(t, 2) + c * t + d;}void Bezier(){    int n = 500;    double derta = 1.0 / n;    glPointSize(2);    glColor3d(0, 0, 0);    glBegin(GL_POINTS);    for (int i = 1; i < n; i++)    {        double t = derta * i;        double ratio[4];        ratio[0] = getRatio(t, -1, 3, -3, 1);        ratio[1] = getRatio(t, 3, -6, 3, 0);        ratio[2] = getRatio(t, -3, 3, 0, 0);        ratio[3] = getRatio(t, 1, 0, 0, 0);        double x=0, y=0;        for (int j = 0; j < 4; j++)        {            x += ratio[j] * p[j].x;            y += ratio[j] * p[j].y;        }        glVertex2d(x, y);    }    glEnd();}void myDisplay(){    glClear(GL_COLOR_BUFFER_BIT);    //清除颜色缓存和深度缓存    //画点    glPointSize(5);    glColor3d(1, 0, 0);    glBegin(GL_POINTS);    for (int i = 0; i < p.size(); i++)        glVertex2d(p[i].x, p[i].y);    glEnd();    //画线    glLineWidth(2);    glColor3d(0, 1, 0);    glBegin(GL_LINE_STRIP);    for (int i = 0; i < p.size(); i++)        glVertex2d(p[i].x, p[i].y);    glEnd();    if (p.size() == 4)        Bezier();    glFlush();}void mouse(int button, int state, int x, int y){    if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN && p.size() < 4)    {        Point t(x, y);        p.push_back(t);        glutPostRedisplay();    }}void Reshape(int w, int h)      //两个参数：窗口被移动后大小{    glViewport(0, 0, w, h);    glMatrixMode(GL_PROJECTION);    glLoadIdentity();    gluOrtho2D(0, w, h, 0);    glMatrixMode(GL_MODELVIEW);    glLoadIdentity();}void initWindow(int &argc, char *argv[], int width, int height, char *title)    //初始化并显示到屏幕中央{    glutInit(&argc, argv);    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);    glutInitWindowPosition((GetSystemMetrics(SM_CXSCREEN) - width) >> 1, (GetSystemMetrics(SM_CYSCREEN) - height) >> 1);       //指定窗口位置    glutInitWindowSize(width, height);       //指定窗口大小    glutCreateWindow(title);    glClearColor(1, 1, 1, 0);    glShadeModel(GL_FLAT);}int main(int argc, char *argv[]){    initWindow(argc, argv, 600, 600, "四点画Bezier曲线");    puts("\n\t鼠标在窗口点击四次后自动绘制出Bezier曲线");    glutDisplayFunc(myDisplay);    glutReshapeFunc(Reshape);    glutMouseFunc(mouse);    glutMainLoop();    return 0;}