How the editor thinks
Object, frame, span, layer, parent, key - the six ideas the whole editor rests on
Once these six ideas are clear, the rest of the editor reads itself:
| Idea | In short |
|---|---|
| Object | a shape (what you see) and a collider (what hits you), two separate fields |
| Frame | a cell of time, not a moment |
| Span | an object's lifetime: a start and a duration, the end excluded |
| Layer | draw order, summed with the layers of all parents |
| Parent | passes transform, active state and lifetime down to its children |
| Key | a field's value on one frame, the game moves the value between keys by itself |
An unfamiliar word - Glossary
Object
An object is the thing that is drawn and the thing that hits. Those are two separate fields: a shape (what you see) and a collider (what hits you). A beam that glows but never touches you is an object with a shape and no collider. An invisible wall is the other way round
Frame and span
A frame is a cell of time, not a moment. Frame 30 occupies a stretch, not a point. The timeline counts from one. A level 900 frames long holds frames 1 to 900. The number 901 is the end boundary, not a frame
A span is an object's lifetime: a start and a duration. The end is not part of the span. So two objects placed back to back do not overlap on the frame they share
More - Frames, time and the length of a level
Layer and parent
A layer is draw order. It is relative: an object's layer is summed with the layers of all its parents
Dragging an object under a different parent changes its draw order even when you never touched the number
A parent passes its transform, active state and lifetime down to its children. A child's span has to lie inside its parent's
The editor never clips what you wrote. It keeps your value and computes the effective one separately. That is why shrinking a parent is reversible: widen it back and the child returns
Key
A key is a field's value on one frame. The game moves the value between two keys by itself. Every field has its own set of keys: position, rotation, scale, size, anchors and pivot
A field with no keys is not broken, it uses the default value. There is no need to key everything for the sake of tidiness
What a key stores and how the value travels between keys - Keyframes and easing
Compared with other editors
In Project Arrhythmia (Afterbeat) an object also lives on a stretch of time. But hierarchy and draw order are arranged differently there, so an import does not carry them over one to one
Just Shapes and Beats has no editor for players, so there is nothing to compare
Next: Frames, time and the length of a level, Keyframes and easing, Readability and fairness