Scatter a flock with a timeline marker

Steps

1. Choose Help > Browse Demos..., type birds in the search box and open Life Birds Roofs. It plays at once: gulls circle the towers on loops above the streets, and now and then one glides down to rest on a roof edge.

   

2. Look along the timeline at the bottom of the window. A red flag named bang sits at 15 seconds. When the playhead reaches it, every gull takes off at once and scatters, and a few seconds later the flock settles back into its loops.

3. Move the bang. Right after the scatter, while the flag is still in view, right-click it and choose Edit marker....

   

4. In the Marker window, click Start, type 00:00:06:00 and press Enter, then close the window. The flag jumps back to six seconds.

   

5. Press stop and then play on the timeline. This time the gulls burst into the air six seconds in.

6. See how they hear it. Choose View > Frame All so the whole graph shows on the canvas below the viewport, and click the node named crowd, the tall one near the left with the most wires. The viewport switches to the gulls as dots, with the crowd's card on the right. On the card, click Open the behavior editor.

7. The editor draws the gulls' states as boxes, Fly, Approach, Perch, Takeoff and Scatter, with arrows that say when a gull moves on. A gull rests on its perch for 10 to 40 seconds, then takes off. Lower down, an arrow runs from From any state to Scatter when "bang" arrives: whatever a gull is doing, the bang sends it into Scatter, and 4 to 8 seconds later it is flying again.

   

8. Click the back arrow in the viewport's header (its tip reads Back to what you were looking at) to see the rendered city again.