Hello, I’m creating what I can best describe as a giant robot octopus.
I’d like to animate these instance meshes along a spline, How do I do that that?
I am using different segments, Mesh 1, and Mesh 2, alternating for the length of the “Arm”.
I have built these assembled in a Blueprint.
How do attach these meshes, already combined inside the Blueprint, to align to a spline that can be animated? Can I do this inside this blueprint?
This mesh assembly will be a lot longer in the end.
Any help or guidance or correct ways to approach would be appreciated! Thanks in advance.
I found this example, of kind of what I am trying to do, but he has every joint combined into one full static mesh.
I’m trying to have each joint, basically, a different instance mesh
He’s using MeshSpline in blueprint, If I could use effectively what would be a MeshBlueprint.
I appreciate it it illspiritx, The only issue with that is that it repeats the meshes. I think I am getting closer by attaching a MeshSpline to a Spline, and then getting the length and individually placing them and off setting them by their length. Still not quite working yet!
That tut shows how to set them by section length. So if you want to want to multiple “vertebrae” meshes, change code in the tut vid to use an array var of static meshes, and at the part of code where they do the for loop, use the index output of element to get a copy of mesh from that index of array. Only catch here is all the meshes in array should be same size (unless you want to make a struct with a mesh ref and an “x-offset” or whatever float, make an array of that and add each length offset to the find closest loc along spine logic in the loop). Well, the other downside is the bp might be kinda heavy if it has a whole stack of mesh hard refs in it. Although you can trim that down by only having 3 or 4 and use some extra math magic to select different indices in the loop based on whatever logic (or just random lol). Like if you just need a chunky “vertebrae” at the base and a hero "wrist " mesh at the end select index 0 of mesh array if loop index =0 and select wrist mesh if index = last index-1. It can look a bit noodley, but you can daisy chain bool selects to make the first bool select index 0 of mesh array or another select which picks generic middle mesh or wrist mesh at index 2 or whatevs.
Thank you illspiritx, you got me rolling in the right direction. Troubleshooting and the Unreal AI helped develop the final logic, which is pasted below.
To build a wall where a designer can pick a specific sequence of meshes (e.g., 01, 02, 01), we cannot use simple multiplication. Instead, we use a DistanceAccumulator variable that acts as a “playhead.” After placing each piece, we move the playhead forward by that specific piece’s length to find the start point for the next piece.
1. Asset & Variable Setup
Create the following variables in your Blueprint:
Designer_Order (Integer Array): Stores the sequence of choices (e.g., 0, 1, 0, 1).
Wall_Mesh_Array (Static Mesh Array): The library of available meshes.
Wall_Length_Array (Float Array): The lengths of the meshes in the library (must match indices).
DistanceAccumulator (Float): A local variable to track the current distance.
2. Construction Script Logic (The Flow)
Step A: Initialization
Set DistanceAccumulator: Set to 0.0. This resets the wall every time the actor is moved.
For Loop: Set the Last Index to the Length of your Designer_Order array minus 1.
Step B: Data Mapping (Loop Body)
Get Choice: Use the For Loop Index to Get an integer from Designer_Order.
Get Mesh: Use that integer to Get a Static Mesh from Wall_Mesh_Array.
Get Length: Use the same integer to Get a Float from Wall_Length_Array.
Length Safety: Plug the length into a Max (Float) node (A = Length, B = 10.0). This eliminates infinite loops by ensuring the accumulator always moves forward.
Step C: Tangent & Position Logic
Start Distance: Your current DistanceAccumulator value.
End Distance:DistanceAccumulator + SafeLength (from the Max node).
Samplers: Create two sets of Get Location at Distance and Get Tangent at Distance nodes (set to Local Space).
Set 1 (Start): Use DistanceAccumulator.
Set 2 (End): Use the End Distance calculation.
Tangent Clamping: Pass both Tangent outputs through a Clamp Vector Size node. Plug your SafeLength into the Max pin of the clamp to keep the curve proportional to the piece size.
Step D: Component Spawning
Add Spline Mesh Component: Set Manual Attachment to true.
Set Static Mesh: Plug in the mesh retrieved in Step B.
Set Forward Axis: Set to X (standard for most modular assets).
Set Start and End: Plug in the Location/Tangent vectors from Step C.
Step E: The Accumulator Update (Crucial)
After the Set Start and End node, use a Set DistanceAccumulator node.
Plug your End Distance value into this setter. This ensures the next loop iteration starts exactly where the current one finished.
3. Addressing Common Issues (UE 5.6 Best Practices)
Eliminating Nanite Flickering
In UE 5.4+, Nanite Spline Meshes can flicker if they are deformed.
Open the Static Mesh asset.
In Nanite Settings, set Max Edge Length Factor to a value between 0.02 and 0.05. This forces Nanite to maintain vertex density during deformation.
Eliminating Infinite Loop Crashes
Construction Scripts crash if the loop runs too many times or the distance doesn’t increase.
The Guard: Use a Branch at the start of the loop body to check if DistanceAccumulator is Less Than the Get Spline Length. If false, stop the loop.
