Practical -8 || Computer Graphics || Bezier Curve.cpp

#include <iostream.h>
#include <conio.h>
#include <math.h>
#include <stdlib.h>
#include <dos.h>
#include <graphics.h>

//Todo prototyping
void BezierThreePoints();
void BezierFourPoints();
// todo 3 Points Bezier
void BezierThreePoints()
{
    cout << "3 Points Bezier Curve";
    cout << "\n Enter the 3 points\n";
    int x1, y1, x2, y2, x3, y3;
    cin >> x1 >> y1;
    cin >> x2 >> y2;
    cin >> x3 >> y3;
    putpixel(x1, y1, WHITE);
    putpixel(x2, y2, WHITE);
    putpixel(x3, y3, WHITE);   
    //todo P = (1−t)2P1 + 2(1−t)tP2 + t2P3
    double x = 0.0, y = 0.0;
    for (double t = 0.0; t <= 1; t = t + 0.001)
    {
	x = (1 - t) * (1 - t) * x1 + 2 * (1 - t) * (t)*x2 + t * t * x3;
	y = (1 - t) * (1 - t) * y1 + 2 * (1 - t) * (t)*y2 + t * t * y3;	
	putpixel(x, y, YELLOW);
    }
}
//todo 4 Points Bezier
void BezierFourPoints()
{
    cout << "4 Points Bezier Curve";
    cout << "\n Enter the 4 points\n";
    int x1, y1, x2, y2, x3, y3, x4, y4;
    cin >> x1 >> y1;
    cin >> x2 >> y2;
    cin >> x3 >> y3;
    cin >> x4 >> y4;

    putpixel(x1, y1, WHITE);
    putpixel(x2, y2, WHITE);
    putpixel(x3, y3, WHITE);
    putpixel(x4, y4, WHITE);

    //todo P = (1−t)^3*P1 + 3(1−t)^2*t*P2 +3(1−t)t^2P3 + t^3P4

    double x = 0.0, y = 0.0;
    for (double t = 0.0; t <= 1; t = t + 0.001)
    {
        x = (1 - t) * (1 - t) * (1 - t) * x1 + 3 * (1 - t) * (1 - t) * (t)*x2 + 3 * (1 - t) * (t) * (t)*x3 + t * t * t * x4;
        y = (1 - t) * (1 - t) * (1 - t) * y1 + 3 * (1 - t) * (1 - t) * (t)*y2 + 3 * (1 - t) * (t) * (t)*y3 + t * t * t * y4;

        putpixel(x, y, YELLOW);
    }
}
void main()
{
    clrscr();
    int gd = DETECT, gm;
    initgraph(&gd, &gm, "C:\\TURBOC3\\BGI");
    cout << "BEZIER CURVE\n";
    cout << "\n1) 3 Point\n2) 4 Point \nEnter your options: \n";
    int option;
    cin >> option;
    switch (option)
    {
    case 1:
        BezierThreePoints();
        break;
    case 2:
        BezierFourPoints();
        break;
    default:
        cout << "\n Invalid option";
        break;
    }

    getch();
}