Particle

A

B

C

D

A

Attract

Combine

Repel

Combine

→ ←

← ←

← →

→ →

B

Combine

Repel

Combine

Attract

→ →

← →

← ←

→ ←

C

Repel

Combine

Attract

Combine

← →

→ →

→ ←

← ←

D

Combine

Attract

Combine

Repel

← ←

→ ←

→ →

← →