Sem 4‎ > ‎CG LAB‎ > ‎

Q13: WAP to perform reflection wrt to a line

posted Mar 12, 2012, 11:51 AM by Neil Mathew

SOURCE CODE:

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#include<iostream.h>
#include<conio.h>
#include<graphics.h>
#include<math.h>
#include<stdio.h>
 
 
 
int n;
double P[3][10];
double P2[3][10];
 
double S[3][3];
 
float m; int b;
 
 
 
void INPUT()
{
int ch;
cout<<"\n For Polygon where No of edges (>=3) = ";
cin>>n;
 
cout<<"\n Enter the coordinates of "<<n<<" sided Polygon: \n";
 
for(int i=0; i<n; i++)
{
cout<<" "<<i+1<<" Point (x,y) : ";
cin>>P[0][i]>>P[1][i];
P[2][i]=1;
}
 
cout<<"\n Enter the equation of line ( Y = m X + b) : ";
char ch1;
 
cin>>ch1;
cin>>ch1;
cin>>m;
cin>>ch1;
cin>>ch1;
cin>>b;
 
//cout<<"\n Slope = "<<m<<"\n Y Intercept = "<<b;
}
 
 
 
 
void ReflectPoint()
{
 
// S[3][3] : Reflect Transform MATRIX
// P[3][n] : 3 x n MATRIX
// P2[3][n] : Final MATRIX
 
//Reflect Transform Matrix:
//1st - making the identity Matrix
for(int i=0; i<3; i++)
{
for(int j=0; j<3; j++)
{
        if(i==j)     //DIAGONAL
        S[i][j] = 1;
        else
        S[i][j] = 0;
}
}
//2nd - making changes
S[0][0] = (1-m*m) / (m*m+1) ;
S[0][1] = (2*m) / (m*m+1) ;
S[0][2] = (-2*m*b) / (m*m+1) ;
S[1][0] = (2*m) / (m*m+1) ;
S[1][1] = (m*m-1) / (m*m+1) ;
S[1][2] =  (2*b) / (m*m+1);
 
 
// Matrix Multiplication
// S(3x3)  x  P(3xN)
 
for(i=0; i<3; i++)
{
for(int j=0; j<n; j++)
{
        P2[i][j]=0;
for(int k=0; k<3; k++)
{
P2[i][j]+=S[i][k]*P[k][j];
}
}
}
 
}
 
void Display_Matrix(double p[3][10])
{
 
for(int i=0; i<3; i++)
{
cout<<"\n |";
for(int j=0; j<n; j++)
cout<<"  "<<p[i][j];
cout<<"  |";
}
 
}
 
void DRAW(double p[3][10])
{
 
for(int i=0; i<n-1; i++)
{
line(getmaxx()*0.5+p[0][i], getmaxy()*0.5+p[1][i], 
               getmaxx()*0.5+p[0][i+1], getmaxy()*0.5+p[1][i+1]);
}
line(getmaxx()*0.5+p[0][n-1], getmaxy()*0.5+p[1][n-1], 
                    getmaxx()*0.5+p[0][0], getmaxy()*0.5+p[1][0]);
 
}
 
 
void main()
{
INPUT();
Display_Matrix(P);
cout<<endl;
 
ReflectPoint();
 
for(int i=0; i<3; i++)
{
cout<<"\n |";
for(int j=0; j<3; j++)
cout<<" "<<S[i][j];
cout<<" |";
}
cout<<endl;
 
Display_Matrix(P2);
 
cout<<"\n\n Press Enter to see Graphically? ";
getch();
 
int gdriver=DETECT,gmode;
initgraph(&gdriver,&gmode,"C:/TC/BGI");
 
 
setcolor(DARKGRAY);
//X AXIS
line(getmaxx()*0.5, 0, getmaxx()*0.5, getmaxy());
//Y AXIS
line(0, getmaxy()*0.5, getmaxx(), getmaxy()*0.5);
 
 
setcolor(CYAN);
DRAW(P);
setcolor(GREEN);
DRAW(P2);
 
getch();
closegraph();
 
}


OUTPUT:



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