After publishing LDraw Nova, a sibling project for agentic generation of LDraw models, several people reached out to me asking about if models could be animated somehow.

During the development of Nova, I noticed that adding some special annotations to .mpd original model source files, and then giving those to agents, would:

• Help agents in understanding how to build other different models.
• But also, in understanding how a model was built.

Which gave me the idea that, maybe, an agent would also understand how a model would work.

As a first step to it, I gave annotated models to different agents, and prompted them to infer (reverse-engineer) their constituent submodels (see Haiku 5.5. experiment below).

Results from inference experiments were both pretty good and consistent across different agents, and I also noticed the following: many of the submodels inferred were actually mechanisms.

After questioning several agents about those inferred mechanisms, regarding how would they actually work, I also got consistent results: agents would describe behaviours based on the descriptions for the parts on a mechanism! 🤯

At this point, I had the following:

• Agents would split and refine models into submodels and mechanisms.
• Agents would understand each mechanism in isolation.
• Agents would understand how individual mechanisms worked.

The result of an actual divide-and-conquer process, right? 🤓

Which would make handling individual mechanisms manageable. 🤩

Now, there was the matter of giving agents the means to actually animate mechanisms they already knew how they worked.

I was playing with Blender MCP at the time, and Blender looked promising as a tool that would provide agents a way to manipulate LDraw models in 3D, imported into Blender as glTF (.glb) files.

But there was still an open issue:

How to map from a refined model source code an agent would understand, to its equivalent 3D model in glTF format an agent could manipulate?

And the solution I found was:

Annotate the 3D glTF model's nodes with the same annotations as the source code, so the agent would:

• Outside Blender: plan on submodels 🤔 and parts as source code.
• Inside Blender: execute on matching nodes ✨ on the 3D glTF model.

Now, I had a draft for a process, but no tools for the agent to use and carry it forward.

Given that the process would require a high amount of complex geometric and spatial calculations, I asked the agent to derive a new python toolset from the one created for ldraw-nova

The new python toolset I refined iteratively, by giving the agent simple models at the beginning, and increasingly complex ones each time.

And to test it, I gave an agent instructions to:

• first, plan from an annotated and refined .mpd model
• then, generate a glTF 3D version of it, with matching annotations
• then, upload it to Blender
• and then, produce the Blender python scripts that would animate the model as planned.

And it finally worked! 🚀🚀🚀

(but not perfectly) 😜

Prompt:

This is a fragment, a submodel, from an LDraw .mpd file model.

This is not an executable code fragment, but more like a 3D CAD model fragment written in LDraw language.
Infer what this submodel is, and also split it into submodels (starting with: 0 FILE):

• always with relevant, semantical meaning,
• the first 0-line following every 0 FILE line is the "description line" for the submodel, according to the LDaw standard
• add the description for every submodel there, a one-liner, as a person would describe it while looking at it
• at the answer, first place the parent model, then the child one(s) and then the grandchildren, and then descendants... etc.: go from containers or parents to containees or children, children of children. etc.

0 FILE file-01  
0 file-01  
0 Name: file-01.ldr  
0 Author: Unknown  
0 !LDRAW_ORG Model  
0 !LICENSE Redistributable under CCAL version 2.0 : see CAreadme.txt
0 // Plate 2 x 12 (dark_bluish_grey)  
1 72 0 0 0 1 0 0 0 1 0 0 0 1 2445.dat  
0 // Tile 1 x 2 Grille with Groove (metallic_silver)  
1 80 -110 -8 0 0 0 1 0 1 0 -1 0 0 2412b.dat  

0 STEP  
0 // Slope Brick Curved 2 x 2 x 0.667 (metallic_silver)  
1 80 -80 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat  
0 // Slope Brick Curved 2 x 2 x 0.667 (metallic_silver)  
1 80 -40 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat  
0 // Slope Brick Curved 2 x 2 x 0.667 (metallic_silver)  
1 80 0 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat  
0 // Slope Brick Curved 2 x 2 x 0.667 (metallic_silver)  
1 80 40 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat  
0 // Slope Brick Curved 2 x 2 x 0.667 (metallic_silver)  
1 80 100 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat  
0 // Slope Brick Curved 2 x 2 x 0.667 (metallic_silver)  
1 80 100 8 -20 1 0 0 0 1 0 0 0 1 15068.dat  
0 // Slope Brick Curved 2 x 2 x 0.667 (metallic_silver)  
1 80 40 8 -20 1 0 0 0 1 0 0 0 1 15068.dat  
0 // Slope Brick Curved 2 x 2 x 0.667 (metallic_silver)  
1 80 0 8 -20 1 0 0 0 1 0 0 0 1 15068.dat  
0 // Slope Brick Curved 2 x 2 x 0.667 (metallic_silver)  
1 80 -40 8 -20 1 0 0 0 1 0 0 0 1 15068.dat  
0 // Slope Brick Curved 2 x 2 x 0.667 (metallic_silver)  
1 80 -80 8 -20 1 0 0 0 1 0 0 0 1 15068.dat  
0 // Slope Brick Curved 4 x 1 Double with Red "NASA", Black "ESA", and Silver Background Pattern (light_bluish_grey)  
1 71 70 8 0 -1 0 0 0 1 0 0 0 -1 10283 - 93273p01.dat  
0 STEP  
0 // Tile 2 x 2 Inverted (light_bluish_grey)  
1 71 100 8 -20 1 0 0 0 1 0 0 0 1 11203.dat  
0 // Tile 2 x 2 Inverted (light_bluish_grey)  
1 71 100 8 20 1 0 0 0 1 0 0 0 1 11203.dat

Answer:

This is a rounded silver hull section, probably a spacecraft piece such as a fairing, payload-bay shell, or module skin. It sits on a 2x12 dark-grey base plate, with a grille tile at the -X end and two light-grey inverted tiles at the +X end. The ridge slope carries red "NASA" and black "ESA" printing, so it likely comes from a space-agency-themed LEGO model, though the parts alone don't identify the exact set.

The split below follows the physical groups, which also match the three build steps in the original. The parent comes first, then its children (hull-shell.ldr and end-cap-tiles.ldr), then the grandchildren (the two slope rows). Coordinates are unchanged, so each submodel keeps its absolute positions and the parents reference children with an identity transform at the origin.

0 FILE curved-hull-section.ldr
0 Rounded silver hull section on a long dark-grey base plate, with a grille at the -X end and light-grey tiles at the +X end
0 Name: curved-hull-section.ldr
0 Author: Unknown
0 !LDRAW_ORG Model
0 !LICENSE Redistributable under CCAL version 2.0 : see CAreadme.txt

0 // Plate  2 x 12 (dark_bluish_grey)
1 72 0 0 0 1 0 0 0 1 0 0 0 1 2445.dat
0 // Tile  1 x  2 Grille with Groove (metallic_silver)
1 80 -110 -8 0 0 0 1 0 1 0 -1 0 0 2412b.dat
0 STEP
1 16 0 0 0 1 0 0 0 1 0 0 0 1 hull-shell.ldr
0 STEP
1 16 0 0 0 1 0 0 0 1 0 0 0 1 end-cap-tiles.ldr

0 FILE hull-shell.ldr
0 Curved silver shell made of two rows of slopes joined by a NASA/ESA-marked ridge piece
1 16 0 0 0 1 0 0 0 1 0 0 0 1 shell-row-positive-z.ldr
1 16 0 0 0 1 0 0 0 1 0 0 0 1 shell-row-negative-z.ldr
0 // Slope Brick Curved 4 x 1 Double with Red "NASA", Black "ESA", and Silver Background Pattern (light_bluish_grey)
1 71 70 8 0 -1 0 0 0 1 0 0 0 -1 10283 - 93273p01.dat

0 FILE end-cap-tiles.ldr
0 Two light-grey inverted 2x2 tiles closing off the +X end of the hull shell
0 // Tile  2 x  2 Inverted (light_bluish_grey)
1 71 100 8 -20 1 0 0 0 1 0 0 0 1 11203.dat
0 // Tile  2 x  2 Inverted (light_bluish_grey)
1 71 100 8 20 1 0 0 0 1 0 0 0 1 11203.dat

0 FILE shell-row-positive-z.ldr
0 Row of five silver curved slopes forming one side of the shell, on the +Z side
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 -80 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 -40 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 0 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 40 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 100 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat

0 FILE shell-row-negative-z.ldr
0 Row of five silver curved slopes forming the other side of the shell, on the -Z side
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 -80 8 -20 1 0 0 0 1 0 0 0 1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 -40 8 -20 1 0 0 0 1 0 0 0 1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 0 8 -20 1 0 0 0 1 0 0 0 1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 40 8 -20 1 0 0 0 1 0 0 0 1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 100 8 -20 1 0 0 0 1 0 0 0 1 15068.dat

I replaced the original description file-01, which was only a file name, with real one-liners. I also renamed the root from file-01 to curved-hull-section.ldr, so if the outer MPD references file-01, that reference needs updating. All 15 original part lines are preserved, and I can save this as a .mpd file if you want it as a download. This is the same fragment I split a moment ago, so here is the same answer again. It is a rounded silver hull section, probably a spacecraft piece, on a 2x12 dark-grey base plate, with a grille at the -X end and two light-grey inverted tiles at the +X end. The ridge slope has red "NASA" and black "ESA" printing, so it likely comes from a space-themed LEGO model, though the parts don't identify the exact set.

The parent comes first, then its children (hull-shell.ldr and end-cap-tiles.ldr), then the grandchildren (the two slope rows). Coordinates are unchanged, and the parents reference their children with an identity transform at the origin.

0 FILE curved-hull-section.ldr
0 Rounded silver hull section on a long dark-grey base plate, with a grille at the -X end and light-grey tiles at the +X end
0 Name: curved-hull-section.ldr
0 Author: Unknown
0 !LDRAW_ORG Model
0 !LICENSE Redistributable under CCAL version 2.0 : see CAreadme.txt

0 // Plate  2 x 12 (dark_bluish_grey)
1 72 0 0 0 1 0 0 0 1 0 0 0 1 2445.dat
0 // Tile  1 x  2 Grille with Groove (metallic_silver)
1 80 -110 -8 0 0 0 1 0 1 0 -1 0 0 2412b.dat
0 STEP
1 16 0 0 0 1 0 0 0 1 0 0 0 1 hull-shell.ldr
0 STEP
1 16 0 0 0 1 0 0 0 1 0 0 0 1 end-cap-tiles.ldr

0 FILE hull-shell.ldr
0 Curved silver shell made of two rows of slopes joined by a NASA/ESA-marked ridge piece
1 16 0 0 0 1 0 0 0 1 0 0 0 1 shell-row-positive-z.ldr
1 16 0 0 0 1 0 0 0 1 0 0 0 1 shell-row-negative-z.ldr
0 // Slope Brick Curved 4 x 1 Double with Red "NASA", Black "ESA", and Silver Background Pattern (light_bluish_grey)
1 71 70 8 0 -1 0 0 0 1 0 0 0 -1 10283 - 93273p01.dat

0 FILE end-cap-tiles.ldr
0 Two light-grey inverted 2x2 tiles closing off the +X end of the hull shell
0 // Tile  2 x  2 Inverted (light_bluish_grey)
1 71 100 8 -20 1 0 0 0 1 0 0 0 1 11203.dat
0 // Tile  2 x  2 Inverted (light_bluish_grey)
1 71 100 8 20 1 0 0 0 1 0 0 0 1 11203.dat

0 FILE shell-row-positive-z.ldr
0 Row of five silver curved slopes forming one side of the shell, on the +Z side
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 -80 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 -40 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 0 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 40 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 100 8 20 -1 0 0 0 1 0 0 0 -1 15068.dat

0 FILE shell-row-negative-z.ldr
0 Row of five silver curved slopes forming the other side of the shell, on the -Z side
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 -80 8 -20 1 0 0 0 1 0 0 0 1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 -40 8 -20 1 0 0 0 1 0 0 0 1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 0 8 -20 1 0 0 0 1 0 0 0 1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 40 8 -20 1 0 0 0 1 0 0 0 1 15068.dat
0 // Slope Brick Curved  2 x  2 x  0.667 (metallic_silver)
1 80 100 8 -20 1 0 0 0 1 0 0 0 1 15068.dat

I replaced the original file-01 description, which was just a file name, with real one-liners, and renamed the root to curved-hull-section.ldr. If the outer MPD references file-01, that reference will need updating. All 15 original part lines are preserved, and I can save this as a .mpd file if you want a download.

This is a very preliminar release that, however, yields many good results, but far from being optimal:

• Complex mechanisms and large models take too much time and effort to animate.
• Also for those, agents would go through "rabbit holes" and get lost during animation sessions.
• Broken animations for flexible parts on models like e.g. hoses or cables.
• Low-end models, like e.g. Claude Haiku 5.5 or GPT-6 Luna, can produce animations, but most of them have noticeable defects.
• No proper physics, it doesn't take into account e.g. gravity or any forces interactions, weights, inertia, etc.
• And more... 🤫

I'd like to thank the following:

• The LDraw Community
• LDView's Travis Cobbs (@tcobbs), and contributors.
• LeoCAD's Leonardo Zide (@leozide), and contributors.
• LDCad and Shadow Library, Roland Melkert.
• pyldraw3's Harold Martin (@hbmartin), and contributors.

... and thanks to all of the many other LDraw creators!

NOTE: For this work, I've used many LDraw models, libraries, tools, docs... from many sources.

There is a lot amazing people that generously contributed to this, even for decades, by generously donating their finest work to the public domain and open source community.

If you think you should be included on this section, please drop me an email!

LEGO(R) is a trademark of the LEGO Group of companies which does not sponsor, authorize or endorse this software.