Trapcode Particular

A cool feature of Trapcode Particular is being able to bounce particles on layers. Trapcode Particular supports bouncing particles on two 3D layers in the composition; the floor and wall. These two layers must be still in world space. By this, we mean that they cannot contain keyframes on rotation, scale or position properties. However, the camera can move freely in the scene as particles bounce on the layers.

Step-by-step instructions

Create a new comp (Ctrl/Cmd-N), make it 640*480 at 30 fps. 5 seconds long. Name it "Main". Create a new comp-sized solid (Ctrl/Cmd-Y), name it "Particles". Make sure to click "Make Comp Size" before OK. Apply Effect>Trapcode>Particular to the solid. In Particular, set: Emitter>Position XY to 320,100 (this will move the emitter upwards) Particle>Life to 5 (so particles live for 5 seconds) Particle>Color to Red Physics>Gravity to 300. A RAM preview gives this:

Now, let's add a floor so the particles have something to bounce on: Create a 200*200 grey solid and name it "Floor". Check the 3D switch on the Floor. Set Floors rotation X to -90. Notice that the blue orientation arrow of the Floor now points upwards. This is important later when we want particles to bounce on the layer. If we had set 90 degrees (no minus) the blue arrow would have pointed downwards and particles would not bounce on the surface (they would go through the layer and then bounce). Set Floors position to 320,400,0 To be able to navigate easily in the scene, we create a composition camera: Select Layer>New>Camera and use the 28mm preset. To let Particular know that we want to bounce particles on the floor: Set Physics>Physics Model to Bounce Set Physics>Bounce>Floor to floor. OK cool, but the floor seems to be obscuring all particles. To fix this: Move the Floor layer below the Particle layer in the TLW. OK, better, but now the particles are always in front of the floor. Here is the clever part, Trapcode Particular can use the floor to obscure particles that are behind it: Set Visibility>Also Obscure With to All. This means all layers that Particular know about will be used to obscure particles. Now try orbiting around the scene and see how particles are correctly obscured by the floor. OK, let's move on with the bouncing. Try a ram preview:

The particles bounce but they do not recognize the size of the floor. To fix this: Set Physics>Bounce>Floor Mode to Layer Size. OK, now let's add a text and make particles bounce off the text too. Create a new composition, 400*100 at 30fps, duration 5 seconds, name it "Bounce". Inside Bounce, use the Text tool and type "bounce" so it roughly fills the comp:

Go back to the Main comp and drag the Bounce comp into the comp window. Switch the Bounce layer to 3D. Set Bounce's position to 320,240,0 Set Bounce's X Rotation to -60 Set Bounce's Y Rotation to 20. Move the Bounce layer below the Particles layer in the TLW. Set Physics>Bounce>Wall Layer to Bounce Set Physics>Bounce>Wall Mode to Layer Alpha (so particles bounce only where there is alpha) Set up Emitter>Particles/sec to 1000 to get a more powerful effect:
Now, try clicking and playing in the preview window instead. The nice thing about playing in the Preview is that the camera can be orbited in real time. Also try shift-clicking in the preview to emit particles interactively with the mouse. Now, set Physics>Bounce>Collision Event to Stick and shift-click in the preview. See them particles sticking on the text and floor! Also try setting Physics>Bounce>Collision Event to Slide to make particles slide like on ice.