Any piece of CAD software can do this in “realtime” on thousands of parts which is running millions of polygons (yes, I’d consider 2fps realtime for reasons you’ll see below):
But in Blender, I just attempted to do this using Geometry nodes on a similar model as the one above (2210 objects, all with custom normals btw, with a little above a million polygons):
Aaand, let’s just say that after 10 minutes with the task manager looking like below, I had to kill Blender.
Searching on this forum led me to a Rightclickselect topic where someone claims that doing this in shader would have “terrible performance”, but I’d say it can’t possibly be worse than what I already experienced.
Now, apparently there’s is (or used to be) a Cycles way of doing this in materials, but nothing in Eevee?
(Note that the outline is not necessary! I’m just looking for a way to basically use a cube to turn parts of a large amount of geometry transparent so it can easily and quickly be animated.)
If you want CAD features, use a CAD program. If you want infinite ocean simulations, use a simulation program. Blender isn’t a magical answer to every problem, it’s a highly featured DCC program with corresponding strengths, weaknesses, and limitations.
That aside,
Couldn’t you simplify this at all? Reduce object and polygon count? If not, you could break up your scene into several view layers or collections, do this operation on one layer/collection at a time, and then composite them all together
For CAD it’s usual business to make cuts… so naturaly CAD-software is design to make them…
Polygon-modeling sofware usually is used to built what you will see in the endproduct and not for cutting it away.
Anyway: There was something like this:
… but it seems to this one isn’t working for nowadays blender…
Fantastic, thank you! I didn’t realize that the texture coordinate node behaved like that.
(Also, this thread is a duplicate of the one you linked, it seems. I must have missed it when I searched.)
EDIT: Blender quirk… material node groups can’t have object inputs, unlike geometry node groups… ho hum, this is going to be a bit difficult to make user friendly for the others…
EDIT: Another side effect, but really nitpicking now and it’s just an observation… “regular shadows” in Eevee still gets cast from the hidden objects, but contact shadows do not."
Would love to see a version which wont effect single side meshes. This current setup will show the emission side also on negative normal side for single side meshes. So in this case, when using tree models. The leaves will show issue with this cutaway method
