using the ShapeRenderer class, I can only fill rectangles.
As in the example of the shaperender
shapeRenderer.begin(ShapeType.Filled);
shapeRenderer.setColor(0, 1, 0, 1);
shapeRenderer.rect(x, y, width, height); // fills a rect
shapeRenderer.circle(x, y, radius);//<--- fills a circle
shapeRenderer.end();
should fill the circle. How to get a portion of a cicle i have no clue. Maybe create a mesh and fill it or such like that. Take a look at the shaperender there are differnet methods to fill parts. Just check if some of them fit.