option "Shadow only" under BGE ?

I’d like to have a plane with the shadow of my object, but i d’ont want to see the plane (only the shadow on the plane) because i use a background overlay.
Is it possible ? I dont’t know how “shadow only” is functionning… and if it is functionning under BGE. I’ve tested a lot of combinaisons, but … not terrible (alpha 0.5 to make the plane less visible…)
Any idea ?

im not really good at explaining things, “shadow only” option works by using shadows received by the plane as the plane alpha,so, the part of the plane that doesnt receive any shadow will have alpha set to 0 or transparent, and as far as i know,that option doesnt work in bge

“Shadow Only” has always worked fine for me. I’m not sure what could be the problem but it’s not BGE functionality or a bug.

This blendshould look like this:

what he wants is that the plane is not rendered, just the shadow cast on it. As a shadow catcher object, like when you tick ‘shadow only’ for internal renderer on a material.

Yes, it’s exactly that Morgoth Bauglyr !

Nobody has an idea to make that ?

I believe it might be impossible. This used to be possible by using Clip Alpha with the transparency set to 0, but I think it’s been fixed since then. If you want to cast a non 3D shape onto the ground, you could go with a light texture. In any case, though, it seems to be not possible currently. Maybe a dev will see this thread and expound on exactly what’s necessary to implement this feature.

I think you want the “Cast Only” option, and not the “Shadow Only.” Cast only isn’t currently supported in the BGE, but I whipped up a patch:

Unfortunately, we’re in BCon3, which means fixes only, so I cannot commit this to master right now.

Ah, dang, this is something I’ve been wanting too for quite awhile. Hope it doesn’t get forgotten about and eventually gets committed! In the meantime, I’ll build my version of Blender with it. Thanks a ton, Moguri!

That would look like a good fit for a larger commit containing the shadow work from Kupomen’s GSoC project, this will also benefit materials using light analysis via the light data node because its ‘shadow’ input only works to the extent of the BGE’s shadow functionality.

If we get both of those, then the lighting ability of the BGE will come close to many other commercial indie-level engines.

I didn’t know that Kupoman worked on point light shadows and other lighting things for the GSoC. I tried out the patch for point light shadows a few months ago, and it was pretty good, though it was slow then. Glad to see so much that he did - I certainly hope this stuff gets committed. I’m sure deferred rendering would be exceptionally helpful with larger numbers of lights, as well.