Shadow of a transparent object

Troubleshooting graphics
1

Hello. I was looking into the JME3 shadow renderer and filter.
I was wondering, are those classes able to cast shadows of a transparent or an object that is not rendered?

What I want to do is to cast a shadow from a directional light (the sun) from a mountain range. The shadow is dynamical because the directional light will change depending on the sun’s position over time. I was thinking that the easiest way is to create a mountain using the JME3 terrain and a heightmap. The shadow renderer/filter can cast a shadow from this terrain. But the terrain will be transparent so that it’s not shown (because I don’t want the mountain to be visible, just the shadow). The shadow is cast on a flat pane.

Something like this: rendering - How do I make an object cast shadows but be invisible in the render? - Blender Stack Exchange

I guess I need to set a custom shader for that?

2

I’m pretty sure if you just added a transparent object it would still cast a shadow because the shadow filter is a post process. I don’t think it distingishes any difference in material, thought I’m not entirely sure about the bucket it’s in.

3

Shadows will adhere to transparency by default which is why tree leaves and things will cast proper shadows. At least that’s my recollection.

Probably needs a custom shader.