OpenGL通过中点法绘制直线和圆
本文实例为大家分享了OpenGL绘制直线和圆的具体代码，供大家参考，具体内容如下
#include <gl/glut.h>
#include <math.h>
static int i=1;
void Initial(void)
{
glClearColor(1.0f, 1.0f, 1.0f, 1.0f); //设置窗口背景颜色为白色
glMatrixMode(GL_PROJECTION); //指定设置投影参数
gluOrtho2D(-200.0,200.0,-200.0,200.0); //设置投影参数 //指的是视图范围，如果(0,200,0,200)的话就只能在第一象限显示，就1/4圆，第1，3的参数是左下角坐标，第2，4的参数是右上角坐标
}
/*void Display(void)
{
glClear(GL_COLOR_BUFFER_BIT); //用当前背景色填充窗口
glColor3f(1.0f, 0.0f, 0.0f); //设置当前的绘图颜色为红色
glRectf(50.0f, 100.0f, 150.0f, 50.0f); //绘制一个矩形
glFlush(); //处理所有的OpenGL程序
}
*/
void DDALine(int x0,int y0,int x1,int y1)
{
//glVertex2f(10,10);
int dx,dy,epsl,k;
float x,y,xIncre,yIncre;
dx = x1 - x0;
dy = y1 - y0;
x = x0;
y = y0;
if(abs(dx)>abs(dy))
epsl=abs(dx);
else
epsl=abs(dy);
xIncre=(float)dx/(float)epsl;
yIncre=(float)dy/(float)epsl;
glPointSize(2);
glBegin(GL_POINTS);
for(k = 0;k <= epsl; k++)
{
glColor3f(1.0f, 0.0f, 0.0f);
glVertex2f(int(x+0.5),int(y+0.5));
x += xIncre;
y += yIncre;
}
glEnd();
}
void Mid_B(int x0,int y0,int x1,int y1)
{
int dx,dy,d,UpIncre,DownIncre,x,y;
if(x0 > x1)
{
x = x1;
x1 = x0;
x0 = x;
y = y1;
y1 = y0;
y0 = y;
}
x = x0;
y = y0;
dx = x1 - x0;
dy = y1 - y0;
d = dx - 2*dy;
UpIncre = 2*dx - 2*dy;
DownIncre =- 2*dy;
glPointSize(2);
glBegin(GL_POINTS);
while(x <= x1)
{
glColor3f(1.0f, 0.0f, 0.0f);
glVertex2f(x,y);
x++;
if(d < 0)
{
y++;
d += UpIncre;
}
else
d += DownIncre;
}
glEnd();
}
void G_B(int x0,int y0,int x1,int y1)
{
int x,y,dx,dy,e;
dx = x1 - x0;
dy = y1 - y0;
e =- dx;
x=x0;
y=y0;
glPointSize(2);
glBegin(GL_POINTS);
while(x <= x1)
{
glColor3f(1.0f, 0.0f, 0.0f);
glVertex2f(x,y);
x++;
e = e + 2*dy;
if(e > 0)
{
y++;
e = e - 2*dx;
}
}
glEnd();
}
void CirclePoint(int x, int y)
{
glPointSize(2);
glBegin(GL_POINTS);
glColor3f(1.0f, 0.0f, 0.0f);
glVertex2f(x,y);
glVertex2f(y,x);
glVertex2f(-y,x);
glVertex2f(-x,y);
glVertex2f(-x,-y);
glVertex2f(-y,-x);
glVertex2f(y,-x);
glVertex2f(x,-y);
glEnd();
}
void MidBresenhamCircle(int r)
{
int x = 0, y = r, d = 1-r;
//glPointSize(2);
//glBegin(GL_POINTS);
while(x <= y)
{
CirclePoint(x,y);
if(d < 0)
d += 2*x+3;
else
{
d += 2*(x-y)+5;
y--;
}
x++;
}
glEnd();
}
void ProcessMenu(int value)
{
i = value;
glutPostRedisplay();
}
void Display(void)
{
glClear(GL_COLOR_BUFFER_BIT); //用当前背景色填充窗口
glViewport(0,0,400,400); //前两个参数改变原点坐标，后两个参数改变图形长宽（放大缩小）
switch(i)
{
case 1:
DDALine(2,3,55,83);
break;
case 2:
Mid_B(2,3,55,83);
break;
case 3:
G_B(2,3,55,83);
break;
case 4:
MidBresenhamCircle(50);
break;
}
glFlush();
}
int main(int argc, char* argv[])
{
glutInit(&argc, argv); //初始化GLUT库,处理命令行参数
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); //初始化窗口的显示模式
glutInitWindowSize(400,400); //设置窗口的尺寸
glutInitWindowPosition(100,100); //设置窗口的位置
glutCreateWindow("直线"); //创建一个名为矩形的窗口
int MainMenu = glutCreateMenu(ProcessMenu); //创建主菜单
glutAddMenuEntry("DDA算法",1);
glutAddMenuEntry("中点Bresenham算法",2);
glutAddMenuEntry("改进的Bresenham算法",3);
glutAddMenuEntry("中点bresenham画圆",4);
glutAttachMenu(GLUT_RIGHT_BUTTON);
glutDisplayFunc(Display); //设置当前窗口的显示回调函数
Initial(); //完成窗口初始化
glutMainLoop(); //启动主GLUT事件处理循环
return 0;
}
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