void clip(int x1,int y1,int x2,int y2,int xmin,int ymin,int xmax1,int ymax1)
{
float u1=0.0,u2=1.0,dx=x2-x1,dy=y2-y1;
if(x1==x2&&y1==y2)
return;
if(cliptest(-dx,x1-xmin,&u1,&u2))
if(cliptest(dx,xmax1-x1,&u1,&u2))
if(cliptest(-dy,y1-ymin,&u1,&u2))
if(cliptest(dy,ymax1-y1,&u1,&u2))
{
if(u2<1.0)
{
x2=x1+u2*dx;
y2=y1+u2*dy;
}
if(u1>0.0)
{
x1+=u1*dx;
y1+=u1*dy;
}
array_line_entry2(round(x1),round(y1),round(x2),round(y2));
set_color(cur_color);
setdrawmode(COPY_MODE);
bresline(round(x1),round(y1),round(x2),round(y2),1);
}
}
void liang(double x0,double y0,double x1,double y1)
{
//arguments are endpoints of the line ie..p1(x0,y0) and p2(x1,y1)
double dx=x1-x0,dy=y1-y0,te=0.0,tl=1.0;//te and tl represent min(entry) and max(exit)
if(cliptest(-dx,x0-xmin,&te,&tl)) //inside test wrt left edge
if(cliptest(dx,xmax-x0,&te,&tl)) //inside test wrt Right edge
if(cliptest(-dy,y0-ymin,&te,&tl)) //inside test wrt Bottom edge
if(cliptest(dy,ymax-y0,&te,&tl)) //inside test wrt Top edge
{
if(tl<1.0) //means value of tl has been updated after calling cliptest
{
//new leaving point values ,i.e..p1
x1=x0+tl*dx;
y1=y0+tl*dy;
}
if(te>0.0)//te was updated
{
//new leaving point values ,i.e..p2
x0=x0+te*dx;
y0=y0+te*dy;
}
//Window to viewport mappings
//sx and sy is used to scale the line. it zooms the the clipping window
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;
// black colored viewport
glColor3f(0.0,0.0,0.0);
glBegin(GL_LINE_LOOP);
glVertex2f(xvmin,yvmin);
glVertex2f(xvmax,yvmin);
glVertex2f(xvmax,yvmax);
glVertex2f(xvmin,yvmax);
glEnd();
//blue clipped line
glColor3f(0.0,0.0,1.0);
glBegin(GL_LINES);
glVertex2d(vx0,vy0);
glVertex2d(vx1,vy1);
glEnd();
}
}
void lbc(double x0, double y0, double x1, double y1)
{
double dx = x1 - x0,
dy = y1 - y0,
te = 0.0,
tl = 1.0;
if(cliptest(-dx, x0 - xmin, &te, &tl))
if(cliptest(dx, xmax - x0, &te, &tl))
if(cliptest(-dy, y0 - ymin, &te, &tl))
if(cliptest(dy, ymax - y0, &te, &tl))
{
if(tl<1.0)
{
x1 = x0+tl*dx;
y1 = y0+tl*dy;
}
if(te>0.0)
{
x0 = x0+te*dx;
y0 = y0+te*dy;
}
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(1.0, 0.0, 0.0);
glBegin(GL_LINE_LOOP);
glVertex2f(xvmin,yvmin);
glVertex2f(xvmax,yvmin);
glVertex2f(xvmax,yvmax);
glVertex2f(xvmin,yvmax);
glEnd();
glColor3f(0.0,0.0,1.0);
glBegin(GL_LINES);
glVertex2d(vx0,vy0);
glVertex2d(vx1,vy1);
glEnd();
}
}
void LiangBarskyLineClipAndDraw (double x0, double y0,double x1, double y1)
{
double dx=x1-x0, dy=y1-y0, te=0.0, tl=1.0;
if(cliptest(-dx,x0-xmin,&te,&tl)) // inside test wrt left edge
if(cliptest(dx,xmax-x0,&te,&tl)) // inside test wrt right edge
if(cliptest(-dy,y0-ymin,&te,&tl)) // inside test wrt bottom edge
if(cliptest(dy,ymax-y0,&te,&tl)) // inside test wrt top edge
{
if( tl < 1.0 )
{
x1 = x0 + tl*dx;
y1 = y0 + tl*dy;
}
if( te > 0.0 )
{ x0 = x0 + te*dx;
y0 = y0 + te*dy;
}
// Window to viewport mappings
double sx=(xvmax-xvmin)/(xmax-xmin); // Scale parameters
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;
//draw a red colored viewport
glColor3f(1.0, 0.0, 0.0);
glBegin(GL_LINE_LOOP);
glVertex2f(xvmin, yvmin);
glVertex2f(xvmax, yvmin);
glVertex2f(xvmax, yvmax);
glVertex2f(xvmin, yvmax);
glEnd();
glColor3f(0.0,0.0,1.0); // draw blue colored clipped line
glBegin(GL_LINES);
glVertex2d (vx0, vy0);
glVertex2d (vx1, vy1);
glEnd();
}
}// end of line clipping
void Liang(double x0,double y0, double x1, double y1)
{
double dz=x1-x0,da=y1-y0,te=0.0,t1=1.0;
glColor3f(1.0,0.0,0.0);
glBegin(GL_LINE_LOOP);
glVertex2f(xvmin,yvmin);
glVertex2f(xvmax,yvmin);
glVertex2f(xvmax,yvmax);
glVertex2f(xvmin,yvmax);
glEnd();
if(cliptest(-dz,x0-xmin,&te,&t1))
if(cliptest(dz,xmax-x0,&te,&t1))
if(cliptest(-da,y0-ymin,&te,&t1))
if(cliptest(da,ymax-y0,&te,&t1))
{
if(t1<1.0)
{
x1=x0+t1*dz;
y1=y0+t1*da;
}
if(te>0.0)
{
x0=x0+te*dz;
y0=y0+te*da;
}
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_LINES);
glVertex2d(vx0,vy0);
glVertex2d(vx1,vy1);
glEnd();
}
}