Every rigid body, Dynamics clone, soft body and cloth in a comp shares one world. Its settings show in Properties under Dynamics World when nothing is selected. Geo Ops ▸ Dynamics ▸ World Settings (Gravity, Forces, Joints)… deselects everything to take you there.
World
| Name | What it does | Default/range |
|---|---|---|
| Gravity X / Y | Gravity direction and strength. | 0, −980 px/s² |
| Air Drag | Slows everything moving through the world. | 0, min 0 |
| Walls | 2D: Floor is the comp's bottom edge; Comp edges is all four sides; None. 3D: Floor is the studio floor; Comp edges is a room on it, the comp's width, up to its top edge, as deep as it is wide. | Floor |
| Start | When the simulation starts. | 0 s, min 0 |
| Iterations | Solver passes per step. More is steadier and slower. | 4, 1–32 |
Forces
Felt by every moving body and clone. Add one from + Force….
| Force | What it does | Default strength |
|---|---|---|
| Wind | A constant push in one direction. Has Direction. | 500 px/s² |
| Turbulence | A swirling noise field. Has Frequency (0.005), Evolution (0.5 /s) and Seed. | 1500 px/s² |
| Attract / Repel | Pulls toward its centre; negative pushes away. | 1500 px/s² |
| Vortex | Spins things around its centre; negative turns clockwise. | 1000 px/s² |
| Drag | Slows whatever moves through it. | 2 /s |
Every force also has an enable checkbox, Remove, Strength, Radius (0 = everywhere), Softness (when Radius is above 0), and a Center X / Y that can Follow a layer.
Joints
Anchors are in comp pixels, as the world starts. + Joint… adds one on the selected layer, at its position, to the comp.
| Joint | What it does | Extra settings |
|---|---|---|
| Pin | Free to turn about the anchor. | — |
| Hinge | A pin that can be limited and driven. | Axis (3D: Z facing, Y a door, X a lid), Limits (Min / Max °), Motor (°/s), Motor Force (100) |
| Weld | Locked together. | — |
| Spring | A damped spring between two ends. | Rest Length, Stiffness (50), Damping (1) |
| Rope | Can't get further apart than its length. | Length |
| Slider | Slides along an axis through the anchor. | Axis, Travel: Limit with From / To |
Every joint has Body (the rigid body it holds), To (another body or The comp), Anchor X / Y (or End A / End B for two-ended joints, plus Z in 3D) and Break at (in × weight).
Bake to Keyframes
Keys Position and Rotation on every frame for every simulated body in the comp (Position with Z and X / Y / Z Rotation in 3D), then switches the bodies off. Switch one back on to re-simulate. A replicator's copies can't take keys and are left simulating.
Tips
- In a 3D comp, forces push in X and Y and anchors carry depth. Clones, soft bodies and cloth simulate in their layer's plane.
- Joint handles can also be dragged in the viewer.