/*Program to implement 2-D transformations */

#include <iostream.h>
#include <stdlib.h>
#include <graphics.h>
#include <stdio.h>
#include <math.h>
#include <conio.h>
#define PI 3.14

float cord[10][3];
int n;

void myclrscr()
{
	int gdriver = DETECT, gmode;
	initgraph(&gdriver, &gmode, "");
}

void getPoints()
{
	int i;
	printf("Enter the no of defining vertices: ");
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		printf("Enter coordinate %d: ",i+1);
		scanf("%f %f",&cord[i][0],&cord[i][1]);
		cord[i][2]=1;
	}
}

void drawPolygon()
{
	int i;
	for(i=0;i<n-1;i++)
			line(cord[i][0],cord[i][1],cord[i+1][0],cord[i+1][1]);
	line(cord[0][0],cord[0][1],cord[i][0],cord[i][1]);
}

void mul(float mat1[][3],float m1,int n,float mat2[][3],int m2,float ans[][3])
{
	int i,j,k;
	float sum;

	for(i=0;i<m1;i++)
		for(j=0;j<m2;j++)
		{
			sum=0;
			for(k=0;k<n;k++)
				sum+=mat1[i][k]*mat2[k][j];
			ans[i][j]=sum;
		}
}


void translate(int tx,int ty,int draw)
{
	int i;
	float tMat[3][3]={  1,0,0,
						0,1,0,
						0,0,1 };

	tMat[2][0]=tx;
	tMat[2][1]=ty;

	mul(cord,n,3,tMat,3,cord);

	if(draw) drawPolygon();
}

void scale(float sx,float sy,int xf,int yf)
{
	int i;
	float tMat[3][3]={1,0,0,
					  0,1,0,
					  0,0,1 };

	tMat[0][0]=sx;
	tMat[1][1]=sy;
	tMat[2][0]=xf-sx*xf;
	tMat[2][1]=yf-sy*yf;

	mul(cord,n,3,tMat,3,cord);

	drawPolygon();
}

void rotate(float angle,int xf,int yf)
{
	int i;
	float tMat[3][3]={1,0,0,
					  0,1,0,
					  0,0,1 };

	angle*=PI/180;
	translate(-xf,-yf,0);
	tMat[0][0]=cos(angle);
	tMat[0][1]=sin(angle);
	tMat[1][0]=-sin(angle);
	tMat[1][1]=cos(angle);

	mul(cord,n,3,tMat,3,cord);

	translate(xf,yf,0);
	drawPolygon();
}

void main()
{
	float xf,yf,sx,sy,tx,ty,r;
	int gdriver = DETECT, gmode;
	initgraph(&gdriver, &gmode, "e:\\proggy\\tc\\bgi");

	getPoints();
	drawPolygon();
	getch();
	myclrscr();
	cout<<"1- Translation"<<"\n";
	cout<<"2- Scaling"<<"\n";
	cout<<"3- Rotation "<<"\n";
	cout<<"0- Exit"<<"\n";
	int choice;
	while(1)
	{
		cout<<"Enter your choice: ";
		cin>>choice;
		switch(choice)
		{
			case 1 : printf("Enter the translating co-ordinates:");
					 scanf("%f %f",&tx,&ty);
					 myclrscr();
					 translate(tx,ty,1);
					 break;
			case 2 : printf("Enter the Scaling factors:");
					 scanf("%f %f",&sx,&sy);
					 printf("Enter the refrence co-ordinates: ");
					 scanf("%f %f",&xf,&yf);
					 myclrscr();
					 scale(sx,sy,xf,yf);
					 break;
			case 3:  printf("Enter the Rotating angle :");
					 scanf("%f",&r);
					 printf("Enter the refrence co-ordinates: ");
					 scanf("%f %f",&xf,&yf);
					 myclrscr();
					 rotate(r,xf,yf);
					 break;
			case 0 : exit(0);
			getch();
		}
	}
	getch();
}