Animation & keyframes

Work from a fresh run

A keyframe changes Blender’s evaluated property value, but only controls sampled by the solver affect a running simulation. Saved frames play back as cached data. After editing keys, Reset and re-simulate or bake to a new cache path.

Keep the animated .blend file: point caches store simulation state, not Blender F-curves.

Controls sampled during simulation

These controls are sampled during newly simulated frames. Their systems must be enabled or configured where required:

• Motion: gravity strength/direction, Global Damping, Particle Friction, Dynamic Scale, Friction Variation, ground enable/friction/restitution, Smoothing Iterations, Rest Threshold and Mass Shock strength.
• Solver work: Substeps, Constraint Iterations, Collision Passes, Max Collision Speed, Velocity Margin and Collider Substeps. Samples Per Bond requires a glue network. Object Activation with animated colliders uses every solver substep for synchronized contact.
• Glue and attraction: Compliance, Break Distance and Break Variation on an existing glue network; Use Attraction, Attraction Weight and Search Scale. Changing these values does not create a new glue network.
• Plasticity: Shape Retention and the Advanced Plasticity controls, including Firmness, Set Speed, Bounce Back, Dent Limit, Plastic Damping, Bond Reach and Bond Breaking.
• Colliders: Friction, Restitution and Margin on existing entries. Geometry movement and deformation require Animated.
• Attachments: Compliance, Damping, Search Radius, Rest Length, Breakable and Break Distance on existing targets.
• Activation: Grains Active, configured emitter transforms/enabled state, Object Activation Surface Distance and empty activation ramp/falloff controls.
• Infection: Speed, Contagion Rate, Contact Slop, Contagious Travel, Release Aggressiveness and noise amount, feature size and crawl speed.
• Point Deform: inherited Velocity Scale and Max Velocity when Point Deform is configured.

Masks have their own sampling rules. Activation Mask is sampled each frame. Use Sample Every Frame for an animated Attraction Mask and Animated Mask for an attachment Break Mask. Configure attachment mask sampling before starting.

Animating infection

In Region and Both modes, Speed accumulates growth in scene units per second. Zero pauses growth; lowering Speed slows future growth without shrinking the region or reversing infection. Noise Crawl Speed controls the noise pattern’s motion; zero holds it still.

In Contagion mode, Contagion Rate controls transmission delay and Boundary Noise varies that delay across the material. A received transmission can complete after the source grain moves away. Fallen Grains Spread and Contagious Travel limit new transmissions.

To pause a spreading effect, account for contagion, noise and moving emitters as well as region Speed. After editing keys, Reset and re-simulate the sequence.

Keep fixed for a run

Choose fill geometry and packing, size and mass distribution, seeds, collider representation/SDF resolution, glue connectivity, attachment targets and Point Deform bindings before starting. Changing source topology, target identities or these initialization settings needs a fresh simulation.

Animating material values adjusts the existing setup; it does not rebuild connectivity or rebind the source. Configure spatial activation and mask sources before starting, then animate their supported controls.

For Record Render Motion, set the frame rate and centered shutter before simulation. Changing the recording switch, frame rate or shutter after initialization requires Reset and a fresh simulation.

Performance

Higher solver work settings increase calculation time. Continuously animated inputs can invalidate CUDA graph capture and use ordinary launches instead. Evaluate motion on a short sequence before committing to a full bake.