def set_default_viewport(self):
<EOL>expected_height = int(self.buffer_width / self.aspect_ratio)<EOL>blank_space = self.buffer_height - expected_height<EOL>self.fbo.viewport = (<NUM_LIT:0>, blank_space // <NUM_LIT:2>, self.buffer_width, expected_height)<EOL>
Calculates the viewport based on the configured aspect ratio in settings.
Will add black borders if the window do not match the viewport.