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;
}
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