#include 
#include 
#include 
#include 

void draw (int r[][2])
{
    int i;
    setlinestyle (DOTTED_LINE, 0, 1);
    line (320, 0, 320, 480);
    line (0, 240, 640, 240);

    setlinestyle (SOLID_LINE, 0, 1);
    line (320+r[0][0], 240-r[0][1], 320+r[1][0], 240-r[1][1]);
    line (320+r[0][0], 240-r[0][1], 320+r[3][0], 240-r[3][1]);
    line (320+r[1][0], 240-r[1][1], 320+r[2][0], 240-r[2][1]);
    line (320+r[2][0], 240-r[2][1], 320+r[3][0], 240-r[3][1]);
}

void reset (int r[][2])
{
    int i;
    int val[4][2] = {
			{ 0, 0 },{ 100, 0 },{ 100, 50 },{ 0, 50 }
		    };
	for (i=0; i<4; i++)
    {
	r[i][0] = val[i][0];
	r[i][1] = val[i][1];
    }
}

void rotate (int r[][2], int angle)
{
    int i;
    double ang_rad = (angle * M_PI) / 180;
    for (i=0; i<4; i++)
    {
	double xnew, ynew;
	xnew = r[i][0] * cos (ang_rad) - r[i][1] * sin (ang_rad);
	ynew = r[i][0] * sin (ang_rad) + r[i][1] * cos (ang_rad);
	r[i][0] = xnew;
	r[i][1] = ynew;
    }
}

void shear (int r[][2], int sx, int sy)
{
    int i;
    for (i=0; i<4; i++)
    {
	int xnew, ynew;
	xnew = r[i][0] + r[i][1] * sx;
	ynew = r[i][1] + r[i][0] * sy;
	r[i][0] = xnew;
	r[i][1] = ynew;
    }
}

void translate (int r[][2], int dx, int dy)
{
    int i;
    for (i=0; i<4; i++)
    {
	r[i][0] += dx;
	r[i][1] += dy;
    }
}

void ini()
{
	int gd=DETECT,gm;
	initgraph(&gd,&gm,"..//bgi");
}
void main()
{

	int r[4][2],angle,dx,dy,x, y,choice;

	do
	{
		clrscr();
		printf("1.Rotation about the origin followed by translation\n");
		printf("2.Rotation about an arbitrary point\n");
		printf("3.Shear about the origin\n");
		printf("4.Exit\n\n");
		printf("Enter your choice: ");
		scanf("%d",&choice);
		switch(choice)
		{
			case 1: printf("Enter the rotation angle: ");
				scanf("%d", &angle);
				printf("Enter the x- and y-coordinates for translation: ");
				scanf("%d%d",&dx,&dy);
				ini();
				cleardevice();
				reset(r);
				draw(r);getch();
				rotate(r, angle);
				cleardevice();
				draw(r);getch();
				translate(r,dx,dy);
				cleardevice();
				draw(r);getch();
				closegraph();
				break;
			case 2: printf("Enter the rotation angle: ");
				scanf("%d",&angle);
				printf("Enter the x- and y-coordinates of the point: ");
				scanf("%d%d",&x,&y);
				ini();
				cleardevice();
				reset(r);
				translate(r,x,y);
				draw(r);
				putpixel(320+x,240-y,WHITE);
				getch();
				translate(r,-x,-y);
				draw(r);getch();
				rotate(r,angle);
				draw(r);getch();
				translate(r,x,y);
				cleardevice();
				draw(r);
				putpixel(320+x,240-y,WHITE);
				getch();
				closegraph();
				break;
			case 3: printf("Enter the x- and y-shears: ");
				scanf("%d%d",&x,&y);
				ini();
				reset(r);
				draw(r);getch();
				shear(r, x, y);
				cleardevice();
				draw (r);getch();
				closegraph();
				break;
			case 4: closegraph();
		}
	}while(choice!=4);
}

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