Computer-Graphics-Algorithms-Cpp/05_Implementation_of_ellipse_generating_Algorithm.cpp at main · Ronit049/Computer-Graphics-Algorithms-Cpp · GitHub

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#include <iostream>
#include <graphics.h>
#include <conio.h>

using namespace std;

// Function to plot four symmetric points
void plotEllipsePoints(int xc, int yc, int x, int y)
{
    putpixel(xc + x, yc + y, WHITE);
    putpixel(xc - x, yc + y, WHITE);
    putpixel(xc + x, yc - y, WHITE);
    putpixel(xc - x, yc - y, WHITE);
}

// Midpoint Ellipse Algorithm
void midpointEllipse(int xc, int yc, int rx, int ry)
{
    float dx, dy, d1, d2;
    int x = 0;
    int y = ry;

    // Initial decision parameter of Region 1
    d1 = (ry * ry) - (rx * rx * ry) +
         (0.25 * rx * rx);

    dx = 2 * ry * ry * x;
    dy = 2 * rx * rx * y;

    // Region 1
    while (dx < dy)
    {
        plotEllipsePoints(xc, yc, x, y);

        if (d1 < 0)
        {
            x++;
            dx = dx + (2 * ry * ry);
            d1 = d1 + dx + (ry * ry);
        }
        else
        {
            x++;
            y--;

            dx = dx + (2 * ry * ry);
            dy = dy - (2 * rx * rx);

            d1 = d1 + dx - dy + (ry * ry);
        }
    }

    // Decision parameter for Region 2
    d2 = ((ry * ry) * ((x + 0.5) * (x + 0.5))) +
         ((rx * rx) * ((y - 1) * (y - 1))) -
         (rx * rx * ry * ry);

    // Region 2
    while (y >= 0)
    {
        plotEllipsePoints(xc, yc, x, y);

        if (d2 > 0)
        {
            y--;
            dy = dy - (2 * rx * rx);
            d2 = d2 + (rx * rx) - dy;
        }
        else
        {
            y--;
            x++;

            dx = dx + (2 * ry * ry);
            dy = dy - (2 * rx * rx);

            d2 = d2 + dx - dy + (rx * rx);
        }
    }
}

int main()
{
    // Open graphics window
    initwindow(800, 600, "Midpoint Ellipse Algorithm");

    int xc, yc, rx, ry;

    cout << "Enter center coordinates (xc yc): ";
    cin >> xc >> yc;

    cout << "Enter X-axis radius (rx): ";
    cin >> rx;

    cout << "Enter Y-axis radius (ry): ";
    cin >> ry;

    // Draw ellipse
    midpointEllipse(xc, yc, rx, ry);

    getch();
    closegraph();

    return 0;
}