Previous state/frame awareness
Being able to access previous frame info is a key part of other node-based workflows (looking at you houdini) - comparing current value with previous value has a number of practical applications : 1. making constraints more stable (solves the infamous copyrot flipping past 180 degrees) 2. creating simple dynamics through drivers (user can derive velocity from comparison between current and previous state and use that information in a rig, to make an automatic wiggling tail, or tentacles) 3. in the future, allows to create own simple solvers for simulations (in the context of object nodes, fluid sim or particle nodes, etc) Hadrien (added more obvious example cases)

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Fweeb · 4 months ago
Interesting feature. How would you envision it being implemented in Blender? How would users access this? Just via Python API, or would there be some form of GUI?
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hadriscus [OP] · 4 months ago (edited 4 months ago)

I would definitely see it as an API function, although it would be quite hidden in this form. Maybe it could be shown directly in the driver panel in the form of a checkbox “use value from previous frame” or “use value from current frame minus x”.
In the node context, it would probably have to be different - a sort of passthrough node able to replace the value fed into it by the one from the previous frame (or subframe) ? This is super vague speculation though…!

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