3D Compositing with Action > Action: The Particle System > Bouncing Particles >
Bouncing Particles Off an Image

You can bounce particles off an image surface only. Particles will bounce off bilinear and bicubic surfaces, but only on the original flat surface and not on any changes in shape.

To create the bouncing particle effect, you start with a particle generator. When you determine the image off which you want to bounce particles, you must parent the particle generator to the image; otherwise, the particles will ignore the image. The following figure shows the schematic and the result of bouncing particles off an image using a light source as a generator.

To bounce particles off an image:

1. Add an image off which you want to bounce particles.
2. Create a particle generator using a light source, 3D object, or surface as a particle generator. See Generating Particles.
3. Parent the particle generator to the image's axis.
4. Select the image's axis and, in the Axis menu, enable Free.

   The parent-to-child relationship between the particle generator and the image is severed, allowing you to place the image in the scene more easily. Any transformations and animations from the particle generator are not passed to the image.

5. Move the image in the scene until the particle stream passes through it. To do this, you may have to switch views or orbit the camera.
6. In the schematic, select the image.
7. From the Node bin, double-click the Particle Bouncer node.

   A particle bouncer is added and parented by the image.

8. To access the Particle Bouncer menu, double-click the particle bouncer node in the schematic, or follow the tab population rules for the Object menu (see Populating Menu Tabs of Selected Objects).