Markers = Named frame numbers, and more!

A Blender-like Approach?

I've been thinking about what this would look like if it was implemented as a native feature in the most Blender-like way possible. I'm not making a proposal, just engaging in a thought experiment, but who knows, it might capture someone's imagination. Here's my fantasy, let me know what you guys think:

Temporal Parenting

Design a feature called "temporal parenting" (I'll abbreviate it as T-parenting ) which is analogous to Blender's existing parenting. T-parenting links an object relative to another object in the t dimension the same way that parenting links an object's transform relative to another's in 3D space.

Relevant objects are things like actions in the NLE, clips in the VSE, animation frame start/stop, simulation start/end. An exhaustive list would include some of the less obvious things like the start/offset of a camera's background image sequence, and the start/offset of a compositor image sequence node. Markers would be the equivalent of "empties", points in time with no functionality but still useful in T-parenting. As a special case, it should be possible to "hook" an object to an individual keyframe, analogous to hooking to a vertex.

As with regular parenting, if an object has a T-parent, you can still drag it around on the timeline (it's not "locked" in absolute time), but you'll be dragging it relative to its T-parent.

"Start" & "End" T-Parenting

One nuance is the relationship of "Start" and "End" T-parenting. In some cases (like Simulation Frame Start and Frame End) the start and ends should clearly have separate T-parents, so sim start is T-parented to a marker called Boom indicating the start of an explosion, and the end is T-parented with a marker called SmokeClears . But if you want the simulation length to always be 50 frames long even when it is moved relative to its T-parent, you could just T-parent the Simulation End to the Simulation Start ( +50 frames, for example).

An Action in the NLE would be the opposite - by default the End should be T-parented to the Start based on clip length, so that generally the Action might be moved relative to its T-parent, but the timing should not be changed. But it should be possible to T-parent the Action's start and end separately, so the timing of the action is slower or faster.

A very thorny detail is Image Sequence nodes in the Compositor and Shader Editor. What is the "start" of an image sequence? It's the first frame (for a PNG sequence, that could be frame 500 - the first file might not be 1 ). But what if some frames are later prepended to the PNG sequence (say, you start your simulation earlier in Houdini). Now what happens to the parenting? This would need some Deep Thought.

UI Elements

On the UI front I see two things needed, one small and one big:

• if an object is T-parented, any relevant fields (e.g. Frame Start ) would need an indicator, like a color, showing that the field is T-parented, and might contain the offset from the parent (so Frame Start: +25 or something like that)
• A new view called Universal Timeline, which shows all temporal objects (actions, VSE, markers, and everything else) on a multitrack grid. Dotted lines would indicate T-parenting relationships, similar to how a dotted line shows regular parenting relationships in the 3D viewer. In the Universal Timeline, selecting some objects and pressing p would establish a T-parenting relationship from the selected objects to the active object. This would make it easy for an animator to visually organize the timing of various elements in a hierarchy of relative relationships.

Feedback?

I think an approach like this would be immediately intuitive to Blender users. It would be very hard to implement, especially for things like image sequence nodes which have an unintuitive way to represent a position in time. But I enjoyed this thought experiment -- join me with your thoughts and let me know what you think.