# Scrawl-canvas v8 - Particles test 006

## Fixed number of particles in a field; preAction and postAction functionality

Particle count
Connection radius

#### Test purpose

- Create a Block entity to match the canvas dimensions, to act as a generation area for an Emitter with a set number of required particles.
- Create the Emitter alongside its World object, artefact entity and pre-, post- and stampAction functions.
- Check that the pre- and post- actions work as expected, displaying lines between close Particles, and between Particles and the mouse cursor. Check that the functions respond to changes in the World object's user-defined 'connectionRadius' attribute.
- Check that Particles that move beyond the canvas display are killed and replaced by new Particles.
- Check that the requested number of particles, and the actual number of particles displayed, match (with allowances for particle generation and natural particle culling).

Touch test: should work as expected

Annotated code