No realtime feedback in the compositor

I may have inadvertently changed something, but I no longer getting real time feedback in the compositor.

Using nodes, if I change the value of the node, nothing changes. Re-rendering used the new value, and so clearly the new values are being read, but what has happened to stop the realtime adjustments?

version: 2.79 (sub 6), branch: blender2.8, commit date: 2018-08-08 22:14, hash: 3aee3bbac73, type: Release

Could it be that in the UV/image viewer, you are looking at the renderlayer and not compositor.
There is a menu next to slots, you can choose there renderlayer and compositor.
(From the top of my head).

No. I was testing an old(ish) plugin to ensure it’s still compatible, with a view to updating (spoiler alert, there are some failures now), which renders either 3 or 4 different images from the scene and composites them together. If I was looking at the non-composite image it would be glaringly obvious.

That said, the broken bits of the script need to be fixed to make it glaringly obvious, but c’est la vie.

I’m having one of those days where anything with the word “composite” in is causing me problems. Compositor in Blender, desktop compositor on Linux. Sigh!

Sometimes I find that I have to give Blender’s compositor a nudge by stepping to the next frame, As the frame buffer is stiff full from the last render it doesn’t have to redraw the 3D view, just the nodes.

That helps. Certainly faster than re-rendering, though it shouldn’t be necessary. But thank you.