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Creating and Applying Forces to ICE Simulations

Each point cloud or deformed object can have multiple forces applied to it. As well, you can have the same force applied to a number of point clouds or objects in a scene.

You can use either ICE Force compounds or the non-ICE forces in the ICE tree. For information on the see Types of Forces [ Forces for Simulations ]

To create and apply a force to ICE simulations

1. Create a particle or deformation simulation.

2. Create a force in the ICE tree in one of these ways:

- In the ICE tree, click the Task tab and select Particles in the preset manager on the left. Drag any of the compounds from the Forces group into the ICE view.

or

- Choose Get > Force > force name from the Simulate toolbar or Get > Primitive > Control Object > force name from any other toolbar to create a force object in a viewport.

From an explorer, drag the force’s name into the ICE Tree to create a Get Data node for it.

3. In the ICE tree, drag the Add Forces compound from the Forces group into the ICE view. This compound is a hub for the forces in your ICE tree: it adds up and blends the effect of all forces that are plugged into it, then applies it to the simulated objects.

This compound can also add a force value to the simulation, even if there are no forces plugged into it. Just open its property editor and enter a force value in any XYZ direction.

4. Plug the Add Forces compound’s Execute output into a port on the ICE Tree node, above the Simulate Particles (or Simulate Rigid Bodies) node.

You can also plug this into a State compound’s Execute port, if you’re using a state system.

5. Plug each force node’s Force output into a Force port on the Add Forces compound. The force’s output is a 3D vector representing the force which is based on the PointPosition attribute of the element.

The order in which the forces are plugged into the Add Force compound is not important because they are simply added together.

You can continue to create and apply forces to a simulation in this way.

Applying Non-ICE Forces in a Group

You can create a group that includes several non-ICE forces, then bring the group’s node into the ICE tree and plug it into the Add Forces compound. This way, you can add forces to, or remove forces from, the group without needing to change any connections in the ICE tree: the group node remains connected and is updated by the Add Forces compound.

To apply forces in a group

1. Create and select several forces from the Get > Force menu on the Simulate toolbar (or from Get > Primitive > Control Object on any other toolbar)

2. Create a group (press Ctrl+G) that includes the forces you want to use in the ICE tree.

By default, there is a Forces group that is created in the current simulation environment. Standard forces are automatically added here when they are created. Select either the Environments or Curr. Envir. scope in the explorer to see the simulation environment. See The ICE Simulation Environment for information.

3. Drag the Forces group name from an explorer into the ICE tree to create a Get Data node for it.

4. In the ICE tree, click the Tool tab and drag the Get Array Sum node from the Array group into the ICE view.

You are adding this node because the output from the Forces Group node’s Value output is an array because it considers multiple objects, but the Add Forces compound can only take 3D vectors as an input. This node acts like a converter in that it takes the array value and outputs a single value, which can be a 3D vector.

5. Plug the Forces Group node’s Value output into the Get Array Sum’s Array port.

6. Plug the Get Array Sum’s Result output into a Force port on the Add Forces compound.

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