OpenGL绘制三次Bezier曲线

本文实例为大家分享了OpenGL绘制三次Bezier曲线的具体代码，供大家参考，具体内容如下

计算公式：

运行结果：

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;
}

来源：https://blog.csdn.net/wyg1997/article/details/78277040