Home > Cpp Graphics > C++ Graphics – 19 – ROTATION of LINE, TRIANGLE and RECTANGLE w.r.t a Point

## C++ Graphics – 19 – ROTATION of LINE, TRIANGLE and RECTANGLE w.r.t a Point

ROTATION of LINE, TRIANGLE and RECTANGLE w.r.t a Point.

```#include <math.h>
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <graphics.h>

const int MAX = 5;
const double PI = 3.14;

void GetCords(float mat1[][MAX], float mat2[][MAX], int n){
int i, j;
for(i=0; i<n; i++){
printf("\n Enter Coordinate no %d:- \n", i+1);
for(j=0; j<2; j++){
scanf("%f", &mat1[j][i]);
}
}

for(i=0; i<n; i++){
mat2[0][i] = mat1[0][i];
mat1[0][i] = 320 + mat1[0][i];
mat2[1][i] = mat1[1][i];
mat1[1][i] = 240 - mat1[1][i];
}

setcolor(GREEN);
line(0, 240, 640, 240);
outtextxy(630, 245, "x");
line(320, 0, 320, 480);
outtextxy(310, 0, "y");
outtextxy(280, 245, "(0,0)");

setcolor(YELLOW);
moveto(mat1[0][0], mat1[1][0]);
for(i=0; i<n; i++){
lineto(mat1[0][i], mat1[1][i]);
moveto(mat1[0][i], mat1[1][i]);
}
lineto(mat1[0][0], mat1[1][0]);

}

void pointRotate(float mat2[][MAX], int n){
int ang, i, j, k;
float tmat[MAX][MAX], tot[MAX][MAX];
int px, py;

// Get a Point.
px = mat2[0][0];
py = mat2[1][0];

printf("\n Enter the Angle (in Degrees):- \n");
scanf("%d", &ang);

// Inv Translation to Origin.
for(i=0; i<n; i++){
mat2[0][i] -= px;
mat2[1][i] -= py;
}

// Rotation.
rad = (ang * PI) / 180;

for(i=0; i<2; i++){
for(j=0; j<n; j++){
tot[i][j] = 0;
for(k=0; k<2; k++){
tot[i][j] = tot[i][j] + (tmat[i][k] * mat2[k][j]);
}
}
}

// Trnaslate from the Origin.
for(i=0; i<n; i++){
tot[0][i] += px;
tot[1][i] += py;
}

for(i=0; i<n; i++){
tot[0][i] = 320 + tot[0][i];
tot[1][i] = 240 - tot[1][i];
}

setcolor(LIGHTRED);
moveto(tot[0][0], tot[1][0]);
for(i=0; i<n; i++){
lineto(tot[0][i], tot[1][i]);
moveto(tot[0][i], tot[1][i]);
}
lineto(tot[0][0], tot[1][0]);
}

void main(){
int gd=DETECT, gm;
initgraph(&gd, &gm,"\\tc");
float mat1[MAX][MAX], mat2[MAX][MAX];
int ch, n;
while(1){

clrscr();
cleardevice();
printf("\n ROTATION w.r.t a point");
printf("\n ~~~~~~~~~~~~~~~~~~~~~~\n");
printf("\n 1 -> LINE.");
printf("\n 2 -> TRIANGLE.");
printf("\n 3 -> RECTANGLE");
printf("\n 4 -> Exit.");
scanf("%d", &ch);
clrscr();
cleardevice();
switch(ch){
case 1:		// LINE.
n=2;
break;
case 2:		// TRIANGLE.
n=3;
break;
case 3:		// RECTANGLE.
n=4;
break;
default:
gotoxy(10, 10);
printf(" Dev. By: Manoj Pandey.");
gotoxy(15, 15);
printf("MCA 3d Sem.");
getch();
closegraph();
exit(1);
} // end of switch.
GetCords(mat1, mat2, n);	// Input of Coordinates.
pointRotate(mat2, n);	// Rotating and Displaying.
getch();
} // end of while.
} // end of main.
```
Categories: Cpp Graphics