Although particles are usually simulated, you can also work with them as unsimulated point clouds. You can affect a point cloud in different ways depending on the region of the construction stack in which the ICETree and other operators reside: Simulation or Post-simulation (see ICE Simulation Regions and Nodes), Modeling, and Animation.
The Animation and Modeling regions are below the Simulation region which means that operators in these regions are not re-evaluated while the simulation environment is active. You must move to the first frame of the simulation (its default initial state) to see the effect of MoveComponent and other operators that are in these regions.
If the ICETree operator is in the Modeling or Animation region, it is unsimulated and you can use the point cloud as you can any other object: select, move, rotate, scale, or deform it. You can emit points to create a point cloud, or you could add points to the cloud, delete points from it, or create clusters of points.
If you're moving points and using proportional modelling, be aware that the Consider Neighborhood option is on by default. This option only works when points are connected, which they aren't when they're in a point cloud. Make sure to turn this option off to be able to use proportional modelling correctly.
You can also animate the unsimulated points in different ways. For example, you could emit particles in the Modeling or Animation region (see below), then use the Animated options in any of the Turbulize and Randomize compounds to animate the points. This can be useful if you want to animate unsimulated particle strands using the Strand Sine Wave and Turbulize Strand compounds. You can also apply dynamics on unsimulated strands to create movement. See ICE Particle Strands for more information.
If you create simulated particles, you can freeze the point cloud, then add a new ICE tree to control its movement, such as by deforming it. To freeze the point cloud, select it and click the Freeze button at the bottom of the MCP panel. This gets rid of all operators in all construction regions. The particles are no longer simulated and you can use them as regular points.
You could also freeze only the Modeling region or from an operator downward. See Freezing the Operator Stack for more information on freezing.
You can emit particles outside of the Simulation region. For example, you can emit a number of particles in the Modeling region and then freeze the point cloud. The particles are simply emitted, but they don't move because their positions are not being changed and updated at each frame (not simulated).
If you're doing this, you can emit particles as Total Number of Particles so that the number of particles you want are emitted at once at the first frame of emission instead of a certain amount emitted per second as is often done in a simulation (see ICE Particle Rate (Amount)).
You apply deformations to point clouds just like any other geometry, meaning that you can apply standard object-based deformations to them.
You can apply any of the standard deformation tools (such as lattices, cages, Push, Twist, or Taper) to point clouds. This is a powerful way of making complex particle systems, especially when combined with forces. For example, you could make a whirling tornado by containing a particle system within a twisted and tapered lattice and then applying a vortex force; or have a school of fish deform along a curve.
For information on deformations in general, refer to Deformations [Data Exchange].
Depending on the construction region in the point cloud's operation stack, there are different types of deformations you can use:
You can apply deformations such as lattices on top of particles while keeping the simulation active.
You can emit particles, then set the particle's initial state at a frame you want and freeze the point cloud. This way, all the particles needed for the deformation are available in the state you want by frame 1, and the number of particles in the cloud remains constant because there's no emission. You can then apply deformations to the point cloud to sculpt it, including shapes and envelopes.
As long as the point cloud doesn't have particles being added to it or removed from it, you can create clusters. If you create clusters, you can constrain objects to them and you can use deformations to modify them, as well as envelopes or shape animation. You can also animate the clusters individually by constraining them to an animated object, such as a null.
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