Exploring Graphics: Implementing Boundary Fill Algorithm in C++

Exploring Graphics: Implementing Boundary Fill Algorithm in C++

Introduction:

Graphics programming plays a crucial role in creating visually appealing applications and games. Understanding algorithms for filling regions with colors is fundamental to this field. One such algorithm is the Boundary Fill Algorithm, which efficiently fills a closed area with a specified color. In this blog post, we’ll delve into the implementation of the Boundary Fill Algorithm using C++.

What is the Boundary Fill Algorithm?

The Boundary Fill Algorithm is a seed-fill algorithm used in computer graphics to fill a closed area with a particular color. It starts from a seed point and recursively fills the neighboring pixels until a boundary color is encountered. The algorithm is particularly useful for coloring regions defined by a boundary.

Implementation in C++:

Let’s go through a simple implementation of the Boundary Fill Algorithm in C++. For this example, we’ll assume a 2D array representing a pixel grid and use a recursive approach.

#include<iostream>
#include<graphics.h>
using namespace std;

void boundaryFill(int x, int y, int fillColor, int boundaryColor) {
    if (getpixel(x, y) != boundaryColor && getpixel(x, y) != fillColor) {
        putpixel(x, y, fillColor);
        boundaryFill(x + 1, y, fillColor, boundaryColor);
        boundaryFill(x - 1, y, fillColor, boundaryColor);
        boundaryFill(x, y + 1, fillColor, boundaryColor);
        boundaryFill(x, y - 1, fillColor, boundaryColor);
    }
}

int main() {
    int gd = DETECT, gm;
    initgraph(&gd, &gm, "");

    // Assuming a 10x10 grid for demonstration
    rectangle(50, 50, 450, 450); // Drawing a boundary rectangle

    // Seed point for filling
    int seedX = 100, seedY = 100;

    // Fill color (RED in this case)
    int fillColor = RED;

    // Boundary color (WHITE in this case)
    int boundaryColor = WHITE;

    // Call the boundaryFill function
    boundaryFill(seedX, seedY, fillColor, boundaryColor);

    delay(5000); // Display the result for 5 seconds

    closegraph();
    return 0;
}

Explanation:

1. Include necessary header files, such as <iostream> for input/output and <graphics.h> for graphics functions.
2. Define the boundaryFill function to recursively fill the neighboring pixels.
3. In the main function, initialize the graphics system and draw a boundary (rectangle in this case) on the screen.
4. Specify the seed point (seedX and seedY), fill color (fillColor), and boundary color (boundaryColor).
5. Call the boundaryFill function with the specified parameters.
6. Display the result for a certain duration using the delay function.
7. Close the graphics system.

Conclusion:
The Boundary Fill Algorithm is a powerful tool in graphics programming for filling closed regions with colors. This implementation in C++ provides a starting point for understanding and experimenting with the algorithm. Feel free to modify and enhance the code for your specific needs in graphics applications. Happy coding!