Use Period Marker to fill circles drawn using viscircles
Learn how to fill circles drawn with MATLABs viscircles function using the period marker! This tutorial provides a simple solution to customize your visualizat
Expert Answer
Prashant Kumar answered .
2025-07-04 12:21:23
viscircles draws two lines with the same coordinates but with different line widths (and potentially different colors). This is deliberate in order to draw an "edge" around the circle.
If you ask to plot more than one circle at a time, the coordinate lists are merged together separated by NaN. There is a NaN at the end of the coordinate list even if only one circle is drawn.
What this implies you can retrieve the XData and YData coordinates of the first child of the output of viscircles, get rid of the nan at the end, and fill()
h = viscircles(centers_nodeXY, radii_inf_range, 'color', 'r');
xd = h.Children(1).XData(1:end-1); %leave out the nan
yd = h.Chidren(1).YData(1:end-1);
fill(xd, yd, 'r');
Besides it being easier to get the coordinates correct, there is another reason to do this. When you plot a marker, the markersize you give is screen relative, pi*6^2 
where 
. As you zoom, the marker will stay the same size on the screen. Whereas if you fill() the area will change appropriately.
where . As you zoom, the marker will stay the same size on the screen. Whereas if you fill() the area will change appropriately.There is another approach you should consider for filled circles: use rectangle()
recangle([centers_nodeXY-radii_inf_range, 2*radii_inf_range, 2*radii_inf_range], 'Curvature', [1 1], 'FaceColor', 'r', 'EdgeColor', 'r');
The subtraction is because rectangle needs a lower left corner and a width and height, whereas viscircles() uses center and radius.
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