void cohenclipanddraw(double xz,double yz,double xo,double yo)
{
outcode outcode0,outcode1,outcodeout;
double sx,sy,vx0,vy0,vx1,vy1;
int accept=0,done=0;
outcode0=computecode(xz,yz);
outcode1=computecode(xo,yo);
do
{
if(!(outcode0|outcode1))
{
accept=1;
done=1;
}
else if(outcode0&outcode1)
done=1;
else
{
double x,y;
outcodeout=outcode0?outcode0:outcode1;
if(outcodeout&TOP)
{
x=xz+(xo-xz)*(ymax-yz)/(yo-yz);
y=ymax;
}
else if(outcodeout&BOTTOM)
{
x=xz+(xo-xz)*(ymin-yz)/(yo-yz);
y=ymin;
}
else if(outcodeout&RIGHT)
{
y=yz+(yo-yz)*(xmax-xz)/(xo-xz);
x=xmax;
}
else
{
y=yz+(yo-yz)*(xmin-xz)/(xo-xz);
x=xmin;
}
if(outcodeout==outcode0)
{
xz=x;yz=y;
outcode0=computecode(xz,yz);
}
else
{
xo=x;yo=y;
outcode1=computecode(xo,yo);
}
}
}
while(!done);
glColor3f(0.0,1.0,0.0);
glBegin(GL_LINE_LOOP);
glVertex2f(xvmin,yvmin);
glVertex2f(xvmax,yvmin);
glVertex2f(xvmax,yvmax);
glVertex2f(xvmin,yvmax);
glEnd();
if(accept)
{
sx=(xvmax-xvmin)/(xmax-xmin);
sy=(yvmax-yvmin)/(ymax-ymin);
vx0=xvmin+(xz-xmin)*sx;
vy0=yvmin+(yz-ymin)*sy;
vx1=xvmin+(xo-xmin)*sx;
vy1=yvmin+(yo-ymin)*sy;
glColor3f(1.0,0.0,0.0);
glBegin(GL_LINES);
glVertex2f(vx0,vy0);
glVertex2f(vx1,vy1);
glEnd();
}
}
void cohensutherland(double x0, double y0, double x1, double y1)
{
int o0,o1,out;
bool accept=false, done=false;
o0=computecode(x0,y0);
o1=computecode(x1,y1);
do
{
if(!(o0|o1))
{
accept=true;
done=true;
}
else if(o0&o1)
done=true;
else
{
double x,y;
out = o0?o0:o1;
if(out&RIGHT)
{
x=xmax;
y=y0+(y1-y0)*(xmax-x0)/(x1-x0);
}
else if(out&LEFT)
{
x=xmin;
y=y0+(y1-y0)*(xmin-x0)/(x1-x0);
}
else if(out&TOP)
{
y=ymax;
x=x0+(x1-x0)*(ymax-y0)/(y1-y0);
}
else
{
y=ymin;
x=x0+(x1-x0)*(ymin-y0)/(y1-y0);
}
if(out==o0)
{
x0=x;
y0=y;
o0=computecode(x0,y0);
}
else
{
x1=x;
y1=y;
o1=computecode(x1,y1);
}
}
}
while(!done);
if(accept)
{
double sx=(xvmax-xvmin)/(xmax-xmin);
double sy=(yvmax-yvmin)/(ymax-ymin);
double vx0=xvmin+(x0-xmin)*sx;
double vy0=yvmin+(y0-ymin)*sy;
double vx1=xvmin+(x1-xmin)*sx;
double vy1=yvmin+(y1-ymin)*sy;
glColor3f(0.0,0.0,1.0);
glBegin(GL_LINE_LOOP);
glVertex2f(xvmin,yvmin);
glVertex2f(xvmin,yvmax);
glVertex2f(xvmax,yvmax);
glVertex2f(xvmax,yvmin);
glEnd();
glColor3f(0.0,1.0,0.0);
glBegin(GL_LINES);
glVertex2d(vx0,vy0);
glVertex2d(vx1,vy1);
glEnd();
}
}
