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# System prepended metadata

title: Nodes & Physics Workshop

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# Nodes & Physics Workshop

## Simulation Nodes
* Trying to define the initial MVP and what can come next
* 3.6 initial release milestone added to [#103032](https://projects.blender.org/blender/blender/issues/103032):
    * Simulation starts on scene start frame
    * Get sockets and anonymous attributes to work
    * Store simulation on disk (see #105251)
    * Bake simulation using render settings (i.e., "is viewport" is false)
    * Design document for when to free dynamic cache
    * Dynamic cache
    * Simulation (and loop) zone color
    * Documentation
* What happens next will be decided once this is merged in main
* Simulation Disk Cache Format [#105251](https://projects.blender.org/blender/blender/issues/105251)

## Real-time physics clock
* MVP UI/scope
* Specially in regards to cache/playback/reset/pause
* Design:
    * Settings are in the scene
    * Initially support only simulation nodes
    * When rendering or baking the real-time clock maps to the animation clock
    * Option (in timeline) to detach simulation from timeline
    * ![](https://i.imgur.com/XGLOORh.png)
    * If detached we can control the simulation indepedently of animation playback
    * Example of control: play/pause/stop/reset
* Follow-up:
    * Design on where the play/pause buttons are
* Plan of action

## Miscellaneous
* Cancel geometry-nodes execution
    * What to show in the Viewport
    * How to resume the execution
    * Conclusions:
        * Supporting Ctrl+Z as a way to immediatelly undo a heavy operation is enough
* Simulation region name
    * e.g., "Simulation Region", "Loop Region"
    * Concusion:
        * We will call it "zone" (simulation zone)
## Attribute editing
* There is no need for an exclusive editor until 4.0 (use mesh/curve edit mode for now)
* For 3.6 having node-based operators with access to active attribute is enough.
* For 4.0 we can try to have the initial MVP for Attribute Edit mode:
    * Selection tools
    * At least vertex, edge and face domains
    * Set attribute operators
    * Attribute overlay
    * Transform attributes (G: offset values; S: scale values)
    * Assign ID (e.g., Face is of type Door)
* A future milestone would be to support Technical Painting
    * Vertex paint obsolete/removed
    * Weight paint exclusive for rigging
## Node operator design
* Real-case examples:
    * Smooth operator
* Initial constraints:
    * Consider to support only Selection
    * Design should account for more inputs
    * The main discussion was between allowing or not nesting the mapping
* Findings:
    * There were two main scenarios considered:
        * I. Mapping as part of the node-tree
            *  The operator specific inputs are available as regular nodes
            *  The operator inputs always show up in the node-group as inputs
            *  Those inputs fallback to the same original inputs (e.g., selection)
        * II. Explicit separation between mapping and operation (logic)
            * Allow a node-tree to have different maps, for different usages
            * The mapping itself is not nestable
    