Program:
#include<GL/glut.h>
// TBRL
int left = 1,right = 2, top = 8, bottom = 4;
int xmin = 100, xmax = 400, ymin = 100, ymax = 400;
int line_co_ordinate[4],i;
float x1=200, y1=250, x2=450,y2=450;
int c1,c2;
int flag = 1,clip_flag=0;
void myInit()
{
glClearColor(1.0, 1.0, 1.0, 0);
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(0.0, 0.0, 1.0);
gluOrtho2D(0, 500,0, 500);
glFlush();
}
int getCode(int x, int y)
{
int code = 0;
if(x < xmin)
{
code = code | left;
}
if(x > xmax)
{
code = code | right;
}
if(y < ymin)
{
code = code | bottom;
}
if(y > ymax)
{
code = code | top;
}
return code;
}
void clip()
{
int c;
float x,y;
float m = (y2-y1)/(x2-x1);
if(c1)
{
c = c1;
}
else
{
c = c2;
}
if( c & left)
{
x = xmin;
y = y1 + m*(xmin - x1) ;
}
if( c & right)
{
x = xmax;
y = m*(xmax - x1) + y1;
}
if( c & top)
{
y = ymax;
x = ((ymax - y1)/m) + x1;
}
if( c & bottom)
{
y = ymin;
x = ((ymin - y1)/m) + x1;
}
if(c == c1)
{
x1 = x;
y1 = y;
}
else
{
x2 = x;
y2 = y;
}
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT); //clearing buffer
glColor3f(1.0, 0.0, 0.0); //assigning color
glPointSize(4);
glBegin(GL_LINE_LOOP);
glVertex2f(xmin,ymin);
glVertex2f(xmax,ymin);
glVertex2f(xmax,ymax);
glVertex2f(xmin,ymax);
glEnd();
if(flag == 1)
{
glBegin(GL_LINES);
glVertex2f(x1,y1);
glVertex2f(x2,y2);
glEnd();
}
while(1 & clip_flag == 1)
{
c1 = getCode(x1,y1);
c2 = getCode(x2,y2);
// Line both point inside
if((c1 | c2)==0)
break;
// Line both point outside
else if((c1&c2) != 0)
{
flag = 0;
break;
}
else
{
clip();
}
}
glFlush();
}
// Keyboard Func
void Key(unsigned char ch,int x,int y)
{
if(ch=='c')
{
clip_flag = 1;
glutPostRedisplay();
}
}
// Mouse Func
void mouse_input(int button,int state,int x,int y)
{
if(button == GLUT_LEFT_BUTTON && state == GLUT_DOWN && i < 4)
{
line_co_ordinate[i] = x;
i=i+1;
line_co_ordinate[i] = 500-y;
i++;
}
if(i==4)
{
i=0;
x1 = line_co_ordinate[0];
y1 = line_co_ordinate[1];
x2 = line_co_ordinate[2];
y2 = line_co_ordinate[3];
display();
}
}
int main(int argc,char **argv)
{
glutInit(&argc,argv);
glutInitWindowPosition(100,100);
glutInitWindowSize(500,500);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutCreateWindow("Cohen Suderland");
myInit();
glutDisplayFunc(display);
glutKeyboardFunc(Key);
glutMouseFunc(mouse_input);
glutMainLoop();
return 0;
}
Output:
1) Before Clip:
2) After Clip
