# 2D Transformations: Scaling

Levels of difficulty: / perform operation:

### Function:

void scale( int figure[], int edges, int dx, int dy, int cx, int cy ) {
for (int i=0; i < edges; i++) {
figure[2*i] = (figure[2*i] - cx) * dx + cx;
figure[2*i+1] = (figure[2*i+1] - cy) * dy + cy;
}
}

### C Program

#include<graphics.h>
#include<stdio.h>
#include<conio.h>
void scale( int figure[], int edges, int dx, int dy, int cx, int cy ) {
for (int i=0; i < edges; i++) {
figure[2*i] = (figure[2*i] - cx) * dx + cx;
figure[2*i+1] = (figure[2*i+1] - cy) * dy + cy;
}
}
void main() {
int figure[20], edges;
// A Figure with Max 10 edges.
int dx, dy, cx=0, cy=0;
int gd = DETECT, gm;
clrscr();
printf( "Number of edges: " );
scanf( "%d", &edges );
for (int i=0; i < edges; i++) {
printf( "Enter edge (x%d,y%d) : ", i , i );
scanf( "%d %d", &figure[2*i], &figure[2*i+1] );
}
figure[2*i] = figure[0];
figure[2*i+1] = figure[1];
edges += 1;
printf( "Enter dx: ");
scanf( "%d", &dx);
printf( "Enter dy: ");
scanf( "%d", &dy);
printf( "Enter the center of scaling: \n");
printf( "cx: ");
scanf( "%d", &cx);
printf( "cy: ");
scanf( "%d", &cy);
initgraph( &gd, &gm, "" );
cleardevice();
setbkcolor(WHITE);
setcolor(GREEN);
setlinestyle(SOLID_LINE, 0, 3);
drawpoly( edges, figure );
getch();
scale(figure,edges,dx,dy,cx,cy);
setcolor(RED);
drawpoly( edges, figure );
getch();
}