staged transitions

[gordonwoodhull]

staged transitions

[gordonwoodhull]

the new object stage would contradict #21, which i think i like better. after all, the new objects are often why other stuff has moved.

it's a question of whether to emphasize causality or separation of actions.

[gordonwoodhull]

Two different modes of staged transitions are now supported via .stageTransitions(mode)

1. Modify-insert (mode === 'modins'): first, old nodes and edges move to their new positions. Then inserted nodes and edges fade in. Node-node overlaps are mostly avoided during transitions because old nodes are in the correct positions before new nodes appear, and there is no superfluous movement. However, it can be confusing to see nodes move out of the way of something that is not yet there.
2. Insert-modify (mode === 'insmod'): first, new nodes and edges appear. Then old nodes and edges move to their new positions. This emphasizes causality because old nodes and edges move in response to both deletions and inserts. However, there may be temporary collisions if new nodes are inserted where old nodes used to be, and there is extra movement because old edges move twice.

No matter the staged transition mode, deletions always happen before layout calculation begins.