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Real-time stretch & squash shading for Unreal Engine 5.
TensionFX measures how much your mesh is stretching or squashing right now, every frame, on the GPU — and hands that value to your materials so they can react: wrinkles, blush, roughness shifts, color changes, detail normals, whatever you wire up.
Watch a trailer / tutorial here: TensionFX - Real-Time Strain Maps in Unreal Engine -- Trailer & Tutorial
Skin gets shiny and tight when you stretch it, and crinkly and dull when you squeeze it. TensionFX gives your shaders a live "how stretched is this spot" number so you can paint those reactions in.
Most "wrinkle" systems (including MetaHuman's built-in one) are animation-driven — someone has to rig each expression, and they only know about poses that were authored.
TensionFX is geometric. It looks at the actual deformed mesh and measures real edge-length change. It works on skeletal meshes (which have a rest pose to measure against), reacting to:
- Skeletal animation / skinning
- Morph targets & ARKit blendshapes
- ML Deformer output
No rigging of individual expressions. If the mesh deforms, TensionFX sees it.
Alembic / geometry caches are not supported — they ship pre-animated, with no rest pose for the solver to compare against.
Currently only available in the Fab Marketplace: TensionFX - Live Strain Maps
The solver writes a per-vertex value you read in your material:
| Mesh type | Stretch | Squash | Why |
|---|---|---|---|
| Standard meshes | Vertex Color Red | Vertex Color Green | Free RG channels |
| MetaHumans | Vertex Color Red | Vertex Color Alpha | Green & Blue are already in use (tangent-recompute mask), so squash moves to Alpha |
From there it's just material math — drive roughness, albedo, normals, etc.
Built and verified on UE 5.4, 5.5, 5.6, 5.7 (PC / DirectX 12, Shader Model 6).
Requires the Deformer Graph plugin
- Installation & Setup — add it from Fab, enable the Deformer Graph plugin, tour the folders.
- Quick Start: the Examples level — open one level, hit Play, see it working.
- Use it on your own mesh — the basic workflow on a normal skeletal mesh.
- MetaHumans — the (slightly more involved) MetaHuman workflow.
- Material Controls & Tuning — every knob and how to dial it in.
- How It Works — what's inside the Deformer Graphs.
- Troubleshooting & Known Issues — the quirks and fixes.