A C++ program to show Window to Viewport coordinates transform.


# include <iostream>
# include <graphics.h>
# include <conio.h>
# include <math.h>
class RectangularCoordinates{
public:
float x_min, y_min, x_max, y_max;
RectangularCoordinates(const float x1,const float y1,const float x2,const
float y2){
x_min=x1;
y_min=y1;
x_max=x2;
y_max=y2;
}};
void apply_window_to_viewport_coordinate_transformation(const
RectangularCoordinates,const RectangularCoordinates,int &,int &);
void Rectangle(const int,const int,const int,const int);
void Line(const int,const int,const int,const int);
int main( ){
int driver=VGA;
int mode=VGAHI;
initgraph(&driver,&mode,”..\\Bgi”);
setcolor(15);
Line(90,150,90,390);
Line(50,350,320,350);
Line(400,150,400,390);
Line(360,350,580,350);
RectangularCoordinates WC(130,180,290,300);
RectangularCoordinates VC(440,230,550,300);
setcolor(15);
Line(90,180,95,180);
Line(90,300,95,300);
Line(130,345,130,350);
Line(290,345,290,350);
Line(400,230,405,230);
Line(400,300,405,300);
Line(440,345,440,350);
Line(550,345,550,350);
setcolor(15);
Rectangle(WC.x_min,WC.y_min,WC.x_max,WC.y_max);
Rectangle(VC.x_min,VC.y_min,VC.x_max,VC.y_max);
setcolor(15);
settextstyle(0,0,1);
outtextxy(50,175,”YW”);
outtextxy(50,295,”YW”);
outtextxy(110,360,”XW”);
outtextxy(280,360,”XW”);
outtextxy(360,225,”YV”);
outtextxy(360,295,”YV”);
outtextxy(420,360,”XV”);
outtextxy(530,360,”XV”);
outtextxy(182,170,”Window”);
outtextxy(140,390,”World Coordinates”);
outtextxy(462,220,”Viewport”);
outtextxy(420,390,”Device Coordinates”);
settextstyle(2,0,4);
outtextxy(67,175,”min”);
outtextxy(67,295,”max”);
outtextxy(127,360,”min”);
outtextxy(297,360,”max”);
outtextxy(377,225,”min”);
outtextxy(377,295,”max”);
outtextxy(437,360,”min”);
outtextxy(547,360,”max”);
int x=210;
int y=240;
putpixel(x,y,15);
setcolor(15);
settextstyle(2,0,4);
outtextxy((x-20),(y+3),”(XW,YW)”);
char Key=NULL;
do{
Key=getch( );}
while(Key!=’T’ && Key!=’t’);
settextstyle(0,0,1);
setcolor(0);
outtextxy(36,450,” Press ‘T’ to see the Window-to-Viewport Coordinate
Transformation. “);
setcolor(15);
outtextxy(38,450,”———————– ———————“);
setcolor(12);
outtextxy(222,450,” Press any Key to exit. “);
apply_window_to_viewport_coordinate_transformation(WC,VC,x,y);
putpixel(x,y,14);
setcolor(15);
settextstyle(2,0,4);
outtextxy((x-20),(y+3),”(XV,YV)”);
getch( );
return 0;
}
void apply_window_to_viewport_coordinate_transformation(const
RectangularCoordinates wc,const RectangularCoordinates vc,int &x,int &y)
{
float Sx=((vc.x_max-vc.x_min)/(wc.x_max-wc.x_min));
float Sy=((vc.y_max-vc.y_min)/(wc.y_max-wc.y_min));
float Tx=vc.x_min;
float Ty=vc.y_min;
x=(Tx+(Sx*(x-wc.x_min)));
y=(Ty+(Sy*(y-wc.y_min)));
}
void Rectangle(const int x_1,const int y_1,const int x_2,const int y_2)
{
Line(x_1,y_1,x_2,y_1);
Line(x_2,y_1,x_2,y_2);
Line(x_2,y_2,x_1,y_2);
Line(x_1,y_2,x_1,y_1);
}
void Line(const int x_1,const int y_1,const int x_2,const int y_2)
{
int color=getcolor( );
int x1=x_1;
int y1=y_1;
int x2=x_2;
int y2=y_2;
if(x_1>x_2)
{
x1=x_2;
y1=y_2;
x2=x_1;
y2=y_1;
}
int dx=abs(x2-x1);
int dy=abs(y2-y1);
int inc_dec=((y2>=y1)?1:-1);
if(dx>dy){
int two_dy=(2*dy);
int two_dy_dx=(2*(dy-dx));
int p=((2*dy)-dx);
int x=x1;
int y=y1;
putpixel(x,y,color);
while(x<x2){
x++;
if(p<0)
p+=two_dy;
else{
y+=inc_dec;
p+=two_dy_dx;}
putpixel(x,y,color);}}
else{
int two_dx=(2*dx);
int two_dx_dy=(2*(dx-dy));
int p=((2*dx)-dy);
int x=x1;
int y=y1;
putpixel(x,y,color);
while(y!=y2){
y+=inc_dec;
if(p<0)
p+=two_dx;
else{
x++;
p+=two_dx_dy;}
putpixel(x,y,color);}}}