void Plot( int x, int y, Pixel color, Surface* surf )
{
	// get a pointer to the screen pixels
	Pixel* buffer = surf->GetBuffer();
	// plot the pixel
	int pixelnr = x + y * surf->GetWidth();
	buffer[pixelnr] = color;
}

// get a pixel at a location
Pixel Get( int x, int y, Surface* surf )
{
	// get a pointer to the screen pixels
	Pixel* buffer = surf->GetBuffer();
	// get the pixel
	int pixelnr = x + y * surf->GetWidth();
	return buffer[pixelnr];
}