Tips & Tricks

Symptom: you drag a mesh into the palette, click to paint, and nothing spawns. Output Log shows the warning above.

Cause: the mesh's body setup has no AggGeom (no boxes, spheres, capsules, or convex). FT_Chaos refuses to spawn collision-less meshes because Chaos doesn't reliably simulate them.

Fix: open the mesh in the Static Mesh Editor. Collision menu → Add Box/Sphere/Capsule Simplified Collision OR Auto Convex Collision. Save the asset. Repaint.

Workaround: if you must paint without authoring collision (diagnostic only), turn off bSkipCollisionlessMeshes in Mode Settings. The mesh will spawn and fall forever; KillZ will eventually destroy it.

Symptom: you click, cubes appear briefly, then fall through the floor and disappear.

Cause 1: the floor mesh has no simple collision. The brush trace finds the floor (using complex collision), but spawned cubes can't collide with it.

Fix: add simple collision to the floor mesh. Same procedure as above.

Cause 2: the floor has simple collision but your cubes' simple collision is much larger than expected, causing initial penetration.

Fix: check the cube's collision in the Static Mesh Editor. The simple collision shape should be approximately the same size as the visual mesh. If a 10cm cube has a 100cm collision sphere, you'll get penetration.

Symptom: cubes are visibly at rest but the "simulating" count stays > 0 and they never become HISM instances.

Cause: the velocity thresholds in Settled Detection are too strict for the actual settling state.

Fix: raise LowLinearVelocityThresholdSq (try 5000 or 10000) and LowAngularVelocityThresholdSq (try 10 or 20). Or lower LowVelocityTicksToSettle (try 30 or 15) for faster baking.

Workaround: click Force Bake All to bake regardless of settled state.

Force Bake All leaves piles in mid-air

Symptom: clicked Force Bake All, but some cubes are floating in mid-air now.

Cause: Force Bake All bakes whatever transform the actor has at the moment of click — including mid-air positions if the cube hadn't actually landed.

Fix: undo (button) to delete the layer. Repaint. Wait for natural settling. Use Force Bake All only for cubes that are visibly at rest but failing the velocity threshold.

Symptom: during active paint, FPS drops noticeably.

Cause: spawning physics actors has a per-actor cost (UE actor construction + physics body init). Cluster Size × spacing-tick rate determines the spawn rate.

Fix: lower ClusterSize (fewer spawns per tick), raise StrokeSpacing (fewer ticks per drag distance), or paint shorter bursts and wait for bake before continuing.

Symptom: painting on a sloped surface, cubes immediately slide down and off.

Cause: gravity + insufficient friction.

Fix: raise FrictionMultiplier to 2.0–3.0. Confirm both your cube's and the slope's UPhysicalMaterial have non-trivial friction values (UE default is 0.7 - fine in most cases).

Symptom: the Layers section says "Layer 1: 47 instances" but the viewport shows no cubes.

Cause 1: the cubes are below the camera or beyond view distance. Press F (focus) on the manager actor in the outliner to find them.

Cause 2: the HISM is hidden. Click the manager actor in the outliner, find the HISM child component, ensure it's visible.

Cause 3: HISM has the right instances but at zero scale or NaN transforms (very rare; would indicate a corrupted bake). Inspect the HISM component's Instance List in details panel to verify.

Expected behavior. Mode Settings are session-scoped. They reset to defaults when you exit and re-enter the mode. The toolkit collapse states persist (across editor restarts), but settings values do not.

Workaround: memorize the values you like, or maintain a notes file with your preferred settings per project.

Symptom: you double-click a layer name to rename it, but the rename field closes immediately.

Cause: the layer's instance count is updating (cubes are still baking). Each count update refreshes the layer widget, which loses focus on the rename.

Fix: wait for all cubes to settle and bake before renaming. Or click Force Bake All first.