# Scrawl-canvas v8 - Particles test 009

## Net particles: drag-and-drop functionality

### The yellow beads and the orange ball are draggable

Select filter

#### Test purpose

Be aware that applying a filter to a particle system can cause it to fail in interesting yet mysterious ways! In some browsers, the addition of a filter can also cause a significant degradation in canvas animation speeds

- Create a particle world object and a Net entity. Make all the particles in the top row static, and mark them as draggable.
- Create a Wheel entity, and a Force object that uses that entity's position and radius to create a repulsing force (simulating a collision effect). Make the Wheel entity draggable; and that particles appear above it when it is dragged.
- Check that particles respond to the gravity and Wheel forces appropriately.
- Check that all the particles can be dragged; that static particles remain where they are placed after drag completes, while other particles rebound back into their positions relative to other particles.
- Add a selection of Filter objects to the demo; check that applying a filter to the Net entity displays both on the entity's artefact and on its Spring connection lines.

Touch test: should work as expected. Known issue: moving the pins is inconsistent (because pins are too small on device screens?)

Annotated code