sim (nodebox)

Simulation nodes: sim.spawn, sim.force, sim.collider, sim.scene_colliders, sim.particles and sim.shader, built on the runtime's g:state and g:step. sim.particles measures how far each source's points moved between presents, so a moving source births along its path and by the distance it travelled, and sim.flipbook writes the lanes a texture-sheet shader reads to play a sheet over each particle's age.