ICE Particles Bouncing Off Obstacles
Using the Bounce Off Surface compound, you can make particles bounce off any number of obstacles upon collision. This is useful for creating ballistics, fragments, rain, or other debris bouncing off surfaces. The collision geometry that is used is the actual shape of the particle.
You can choose to use the Bounce Off Surface compound on its own or as part of a more extensive effect via a State system.
To make particles bounce off an obstacle
1. Create a particle emission—see Creating ICE Particle Emissions for information.
2. In the ICE tree’s preset manager, click the Task tab and select Particles.
3. Drag the Bounce Off Surface compound from the Surface Interaction group into the ICE view.
4. Plug this compound’s Execute output into a Port on the ICETree node.
5. Create one or more objects that you want to use as obstacles for the particles. These objects need to have geometric surfaces, such as polygon meshes or NURBS surface objects. Make sure that the particles will reach these obstacles at some point in the simulation.
6. Drag each obstacle’s name into the ICE Tree view to create a node for it.
7. Plug each obstacle’s Value output into a Surface port of the Bounce Off Surface compound.
8. In the Bounce Off Surface property editor, you can set the collision method (for deformed objects or static), use the particle size for the collision geometry or create an offset from the obstacle, set the offset and randomness angles, the maximum number of bounces per frame, the bounce factor (elasticity), and select off which sides of the collision object you want the particles to bounce (both, outer, or inner surfaces).
For obstacles that are enveloped or have animated deformations, make sure that the Collision Method is set to Continuous Animated Collisions so that the change in its shape is accounted for during the collision.
For more information on the parameters, click the ? icon in the property editor or see Bounce Off Surface.
9. Add forces, such as gravity, to make the particles move with force and bounce off the obstacles. See ICE Forces for information.
To use this compound with a state system
1. Create a particle emission—see Creating ICE Particle Emissions for information.
2. In the ICE Tree, set up a State Machine and State compounds as you like, as described in Workflow Overview of Creating a Particle State.
3. Plug the Bounce Off Surface compound’s Execute output into an Execute Every Frame port of a State compound.
4. Continue with creating the effect you want with the State compound.
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