Bresenham's Line Algorithm

bresenhamLine.cpp

void bresenhamLine(int x0, int y0, int x1, int y1) {
    int dx = abs(x1 - x0);
    int dy = abs(y1 - y0);
    int x, y;

    if (dx >= dy) {
        int d = 2 * dy - dx;
        int ds = 2 * dy;
        int dt = 2 * (dy - dx);

        if (x0 < x1) {
            x = x0;
            y = y0;
        } else {
            x = x1;
            y = y1;
            x1 = x0;
            y1 = y0;
        }

        putPixel(x, y);

        while (x < x1) {
            if (d < 0) {
                d += ds;
            } else {
                if (y < y1) {
                    y++;
                    d += dt;
                } else {
                    y--;
                    d += dt;
                }
            }

            x++;
            putPixel(x, y);
        }
    } else {
        int d = 2 * dx - dy;
        int ds = 2 * dx;
        int dt = 2 * (dx - dy);
        
        if (y0 < y1) {
            x = x0;
            y = y0;
        } else {
            x = x1;
            y = y1;
            y1 = y0;
            x1 = x0;
        }

        putPixel(x, y);

        while (y < y1) {
            if (d < 0) {
                d += ds;
            } else {
                if (x < x1) {
                    x++;
                    d += dt;
                } else {
                    x--;
                    d += dt;
                }
            }
            
            y++;
            putPixel(x, y);
        }
    }
}