How can I draw filled triangle line by line in C++ console? - c++

Question

I am creating an utility to display graphics in the console. I currently have a method that takes 2 coordinates and draws a line between those two points. Is it possible to create a method based on this that will take 3 coordinates and draw a filled triangle?
I was thinking of drawing 2 lines, and then drawing lines from each point of one line to each point of the other. However, I think that the time complexity of this method will be really bad.
Here is a method that I used to draw a line:
void drawLine(Line line)
{
const bool steep = (fabs(line.end.y - line.begin.y) > fabs(line.end.x - line.begin.x));
if (steep)
{
std::swap(line.begin.x, line.begin.y);
std::swap(line.end.x, line.end.y);
}
if (line.begin.x > line.end.x)
{
std::swap(line.begin, line.end);
}
const double dx = line.end.x - line.begin.x;
const double dy = fabs(line.end.y - line.begin.y);
const double zStepLength = fabs(fabs(line.end.z) - fabs(line.begin.z)) / dx;
double error = dx / 2.0;
const int ystep = (line.begin.y < line.end.y) ? 1 : -1;
const double zstep = (line.begin.z < line.end.z) ? zStepLength : -zStepLength;
for (double x = line.begin.x, z = line.begin.z; x <= line.end.x; x++, z += zstep)
{
if (steep)
{
setPixel({ line.begin.y, x, z }, line.color);
}
else
{
setPixel({ x, line.begin.y, z }, line.color);
}
error -= dy;
if (error < 0)
{
line.begin.y += ystep;
error += dx;
}
}
}