I'm looking for a 3-D Legos simulator. Some 3-D Library where I can programmatically generate a 3-D scene of legos, and generate animations of those legos moving. I have limited experience using 3-D libraries. Does anyone have any pointers to libs or software I should look at?

There's an official 3d creator called Lego Studio (made by Bricklink which was then bought by TLG). It can do realistic renders (not quite photo realistic but good), so you could certainly do an animation (painstakingly) with that.

Thank you! This looks like it could be exactly what I need, and the photo realistic renders look amazing!

Not gonna be helpful here (sorry) but you've triggered my OCD: it's "Lego", not "Legos"! 😄

Doh! I've only been saying it wrong for maybe 33 years.

If we're going full OCD, it's "LEGO" all caps. 🤓 And the pieces are called "LEGO bricks," which is, of course, ambiguous as a brick is also category of piece among others: plates, tiles, slopes, beams, pins, etc. Studio is my preferred CAD https://www.bricklink.com/v3/studio/download.page as it makes generating plans from models relatively easy. For a simulator, I don't know but would love to find out. I'm going to take a look at MecaBricks.

If you want to do it programmatically this might be a good option https://github.com/rienafairefr/python-ldraw#id6