FlockModifier

The Flock Modifier is a modifier object for the good old standard particle system in Cinema 4D. It allows to easily apply the behavior of flocks, swarms or schools to the particles.

The modifier uses a distributed behavioral model, as described by Craig Reynolds in his 1987 SIGGRAPH paper "Flocks, Herds, and Schools: A Distributed Behavioral Model". Several of the classic "Reynolds Rules" are implemented. Each particle will...

• ...keep a minimum distance to its neighbors
• ...try to stay in the center of the flock
• ...chase a target
• ...match the velocity and travel direction of its flockmates
• ...obey a certain minimum / maximum speed limit
• ...avoid collision with geometry
• ...fly level / avoid steep rising or falling
• ...apply a certain randomness to its movement

This plugin demonstrates the following C4D API aspects:

• Particle modifier plugins, derived from class ObjectData
• Working with the C4D standard particle system (which is not as lame as it sounds) using ObjectData::ModifyParticle()
• Ray intersections with class GeRayCollider
• Simple viewport drawing
• Aligning matrices to trajectories and directions