#include

#include

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;

}