translucency & transparent shadows on opaque objects

Hi all,
in this thread some experiments were done trying to get opaque objects to show translucent shadows. I’ll continue my experiments in this forum because they are kind of off-topic in the original thread.

Basically I’m trying to get translucent but opaque objects with volume to do the following:

  • show translucent shadows on their back side (TraLu only does this for faces/planes).
  • cast transparent shadows, textures contribute to the shadows
  • no baking/UV mapping, so everything is animateable
  • shadows propagate to other objects and add upAfter a couple of days of experimenting I think I finally have a more or less working setup. It has become quite complicated, mostly because of workarounds for artifacts and the way renderlayers work.

For the impatient: Here’s the .blend :yes: and some result:

The ‘magic’ happens on scene layer 11. It contains clones of the to be translucent objects with a transparent & translucent material* and a very strong lamp, as well as all the opaque objects. Layer one contains the same objects, but lit normally and all objects have opaque materials.
(* the “clones with different materials” trick: Materials are assigned to objects, not meshes, and the translucent objects on layer 11 have constraints for loc, rot and scale linking them to their “originals” on layer 1 and share the mesh with them. This way I can model/animate on layer one, and the clones on layer 11 will inherit any changes but still have a different material.)

These two layers are fed to two render layers and then go into this enormous noodle soup:

The green part called “Method 1” is just an older experiment which I gave up due to artifacts that I could not get rid of. But it might serve as a source of inspiration, so it’s still there.

The rest basically is divided into three parts that control the brightness of the translucent objects (A), overall shadow intensity(B), shadow intensity on translucent objects © and finally shadow color (D), which means you can adjust each of these parameters independently. Nodes (E) work around some nasty color artifacts.

The results are not 100% artifact-free, but the best I got so far. There are some areas that need work, e.g. more control of the lighting of solid objects. And I’m sure the noodles are not optimal - maybe it’s even complete overkill and there’s a much simpler way that I just didn’t think of.

So, please feel free to experiment with this and share your thoughts :slight_smile:

Happy blending & happy holidays,

one question- why do you want them to cast transparent shadows? just wondering.

Sorry to butt in here, but can I just point out here that this is why people have trouble learning the new nodes system?

It’s a great setup, but just how are you supposed to logically approach setting all that up? :spin: :spin: :spin: :spin: :spin:

I just finished spending an hour trying to get a transparent png file to work as a transparent object in Blender. I messed around with nodes for 50 minutes before finding out it was easier and faster using the old layers system.

Not trying to bash or rubbish nodes, but sometimes it is just like trying to untangle noodle soup.