double dx = x2 - x1;
        double dy = y2 - y1;

        //to prevent divide by 0 error
        if (dx == 0) {
            int x = x1;
            int y = y1;
            for (int i = 0; i < dy; i++) {
                y += 1;
                framebuffer.setPixel((int)Math.round(x), (int)Math.round(y), Vec3.one);
            }
        }
        else if (dy == 0) {
            int x = x1;
            int y = y1;
            for (int i = 0; i < dx; i++) {
                x += 1;
                framebuffer.setPixel((int)Math.round(x), (int)Math.round(y), Vec3.one);
            }
        }
        else {
            double m = (double)(dy / dx); //slope
            if ((m <= 1 && m > 0) || (m < 0 && m >= -1)) {
                double x = (double)x1;
                double y = (double)y1;
                for (int i = 0; i < Math.abs(dx); i++) {
                    x += 1;
                    y += m;
                    framebuffer.setPixel((int) Math.round(x), (int) Math.round(y), Vec3.one);
                }
            }
            else {
                double x = (double)x1;
                double y = (double)y1;

                if (y2 < y1) {
                    x = (double)x2;
                    y = (double)y2;
                }

                for (int i = 0; i < Math.abs(dy); i++) {
                    x += (double)(1 / m);
                    y += 1;
                    framebuffer.setPixel((int) Math.round(x), (int) Math.round(y), Vec3.one);
                }
            }
        }