利用OpenGL函数，画出n次Bezier曲线

下面是画出n次Bezier曲线的代码：

#include <GL/glut.h>
#include <vector>

// 控制点数量
const int kNumControlPoints = 4;

// 控制点坐标
std::vector<float> control_points = { 0.1, 0.1, 0.3, 0.5, 0.6, 0.7, 0.9, 0.3 };

// 递归计算Bezier曲线上的点
void compute_bezier_point(float t, float* point) {
  // 初始化中间点为控制点
  std::vector<float> mid_points(control_points.begin(), control_points.end());
  while (mid_points.size() > 2) {
    // 递归计算中间点
    std::vector<float> new_mid_points;
    for (int i = 0; i < mid_points.size() - 1; i += 2) {
      float x = (1 - t) * mid_points[i] + t * mid_points[i + 2];
      float y = (1 - t) * mid_points[i + 1] + t * mid_points[i + 3];
      new_mid_points.push_back(x);
      new_mid_points.push_back(y);
    }
    mid_points = new_mid_points;
  }
  // 计算Bezier曲线上的点
  point[0] = (1 - t) * mid_points[0] + t * mid_points[2];
  point[1] = (1 - t) * mid_points[1] + t * mid_points[3];
}

// 画Bezier曲线
void draw_bezier_curve() {
  float point[2];
  glBegin(GL_LINE_STRIP);
  for (int i = 0; i <= 100; ++i) {
    float t = i / 100.0f;
    compute_bezier_point(t, point);
    glVertex2f(point[0], point[1]);
  }
  glEnd();
}

// 画控制点
void draw_control_points() {
  glPointSize(5);
  glColor3f(1, 0, 0);
  glBegin(GL_POINTS);
  for (int i = 0; i < control_points.size(); i += 2) {
    glVertex2f(control_points[i], control_points[i + 1]);
  }
  glEnd();
}

// 显示回调函数
void display() {
  glClear(GL_COLOR_BUFFER_BIT);
  draw_bezier_curve();
  draw_control_points();
  glutSwapBuffers();
}

// 初始化函数
void init() {
  glClearColor(1, 1, 1, 1);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluOrtho2D(0, 1, 0, 1);
}

// 主函数
int main(int argc, char** argv) {
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
  glutInitWindowSize(400, 400);
  glutCreateWindow("Bezier Curve");
  glutDisplayFunc(display);
  init();
  glutMainLoop();
  return 0;
}

注：以上代码中只画了一个Bezier曲线，如果要画n次Bezier曲线，只需要将control_points数组中的坐标改为n次Bezier曲线的控制点即可。