Post 5: The Armature – Building the Metal Skeleton
Day 14 of the Bit Reactor live brief. We are closing out Week 2, and the pillar is really starting to come together.
I have the beautifully warped outer stones and the jagged inner core, but there is still a massive piece missing. When ancient pillars crumble, they don't just break into clean rocks; they reveal the internal structure holding them together. To really sell the stylised, heavy destruction from Radu Cius's references, I needed to build the internal metal armature—the exposed rebar.
Step 1: The Base Armature (Setting the Height)
Before generating any dense wire meshes, I had to build the main structural frame. This is the backbone of the armature system.
Bringing in a reference to my base mesh, I used a combination of Line and Tube primitives. The Line nodes are critical here—they act as the master controllers for the height of the metal skeleton. By using Match Size and Copy to Points, I instanced the tubes along these lines to create the thick outer brackets of the cage.
Because the lines dynamically reference the height of the overall pillar blockout, this ensures that if I make the pillar 20 feet taller, the metal skeleton scales up perfectly with it.
Step 2: The Inner Armature (The Wire Mesh)
Once the main structural frame and height were locked in, I needed to fill the void inside it with a dense, intersecting wire grid.
Building this by hand would take hours. Procedurally, using native Houdini SOPs, it took a handful of nodes. I generated a bounding box based on the structural space, then used a Divide node to slice that box into a 3D grid of lines.
Instead of manually extruding cylinders along all those intersecting lines, I dropped down a pair of Wire nodes. Instantly, every single line in that grid was given a physical thickness, turning a basic wireframe into a solid metal mesh.
With the inner mesh and base armature merged together into one solid cage, I needed to ensure it was ready for texturing. Doing UVs procedurally sounds intimidating, but I wanted to keep the tool logic as clean as possible without relying on black-box tools.
I set up my UVs using Houdini's native UV Flatten and UV Layout nodes. By flattening the geometry and packing it procedurally, I ensure that no matter how much the initial pillar dimensions change, the rebar UVs will automatically repack themselves perfectly every single time.
Step 4: Deforming the Metal
A perfectly straight metal grid sticking out of a ruined pillar looks completely fake. If the stone around it exploded, that metal needs to be warped and twisted.
To achieve this non-destructively, I used a combination of a Point Jitter and a Lattice node.
First, I created a bounding box around the armature and used the Point Jitter to randomly scramble the points of that box.
Then, I plugged that scrambled box into a Lattice node alongside my metal armature.
The Lattice node forced the perfect metal grid to warp and bend to match the scrambled box. A final Bend node gave it some macro-level bowing. The result is jagged, chaotic rebar that looks like it has survived a siege.
Prepping for Unreal Engine 5
The final and most important step of the day was getting this ready for the engine. This is a Technical Environment brief, meaning the asset needs to be plug-and-play.
At the very end of the armature setup, I dropped down a Attribute Create node specifically to set up the unreal_material string. By tagging this metal geometry with the exact path to my rust material in UE 5.6, I am guaranteeing that when I eventually export this digital asset, Unreal Engine will automatically recognise the metal bits and assign the correct shader.
Next up: We have all the physical pieces—the stones, the core, and the metal. Next week, it’s time to clean up the geometry, combine everything, and get this asset ready for the bridge into Unreal Engine.
