EDL Shader in Potree Viewer with orthographic mode

I have a problem with EDL Shader in Potree Viewer. While it works correct with perspective mode, I am in need to use orthographic mode in my project.
Please see the GIF and the example at the bottom.

There is a problem with EDL Renderer that does not work correctly with an orthographic mode. The problem appears when you zoom the point cloud. At some point, shadows disappear and we lose the depth perception.

You should be able to reproduce this on any public example. Just remember to set the orthographic mode from the Tools panel in the sidebar.

I would really appreciate any help.

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You can see how it looks like on this GIF: https://im.ezgif.com/tmp/ezgif-1-9e188b342d1c.gif

The example I used in GIF is available here: http://www.potree.org/potree/examples/lion_laz.html

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You can see Potree shaders here: https://github.com/potree/potree/tree/develop/src/materials/shaders

Also, navigation controls that manipulate position of the camera: https://github.com/potree/potree/blob/develop/src/navigation/OrbitControls.js

from EDL Shader in Potree Viewer with orthographic mode