Bresenham's line algorithm

main.cpp

// Example program
#include <iostream>
#include <string>
#include <cmath>

char buf[32][32];

void clearBuf()
{
    for (int i = 0; i < 32; i++)
        for (int j = 0; j < 32; j++)
        {
            buf[i][j] = '.';
        }
}

void drawLine(int y1, int x1, int y2, int x2) {
    const int deltaX = abs(x2 - x1);
    const int deltaY = abs(y2 - y1);
    const int signX = x1 < x2 ? 1 : -1;
    const int signY = y1 < y2 ? 1 : -1;
    //
    int error = deltaX - deltaY;
    //
    buf[x2][y2] = '#';
    while(x1 != x2 || y1 != y2) 
    {
        buf[x1][y1] = '#';
        const int error2 = error * 2;
        //
        if(error2 > -deltaY) 
        {
            error -= deltaY;
            x1 += signX;
        }
        if(error2 < deltaX) 
        {
            error += deltaX;
            y1 += signY;
        }
    }

}

void display()
{
    for (int i = 0; i < 32; i++)
    {
        for (int j = 0; j < 32; j++)
        {
            std::cout << buf[i][j] << " ";
        }
        std::cout << std::endl;
    }
}
int main()
{
    
    clearBuf();
    drawLine(0, 31, 31/2, 0);
    drawLine(31/2, 0, 31, 31);
    drawLine(31, 31, 0, 31);
    
    drawLine(8, 16, 23, 16);
    drawLine(8, 16, 31/2, 31);
    drawLine(23, 16, 32/2, 31);
    
    display();
}