Why do some nodes have values without input sockets?

E.g. The glare node:

enter image description here

This may not be the most useful example, but there are instances where a plug might be useful, e.g. the dimensions of a blur node.

This can be easily worked around with a driver, proving that there is no technical limitation:

enter image description here

Is there any reason for certain values not having a node input?


The reason is that this is the way the node is written by the developer, Sometimes it makes sense for values to be adjusted per-pixel and sockets are used, other times its enough to have a setting on the node.

The are undoubtedly cases where you might want to adjust a setting per-pixel but there isn't a socket input. I guess you could call this a not-yet-implemented feature. There may be a good reason the developer chose not to do this, or it may be an oversight.


Currently, I bet all of them are specific types for some Filter and Matte nodes.

I think the possible reasons for that would be:

  • They are no more than numerical values, which indeed needn't any further tweaking by additional Value input.
  • To avoid wrong or inproper value input that cannot be handled at all, since these values are considered more as parameters rather than factors.
  • To limit parameter value to a certain interval, where minimum / maximum value required, which can hardly be determined by additional Value input.
  • Even though such demand exists (not quite often though), as you mentioned, drivers can do that.

The developers probably didn't think it was necessary.

You should report it as a feature request (http://lists.blender.org/mailman/listinfo/bf-funboard).

Describe what use cases warrant the interface change.

  • $\begingroup$ For reason for the change I would go for consistency. While most of the cycles material nodes have input sockets, the compositing nodes still have a lot without input sockets. $\endgroup$ – sambler Nov 22 '13 at 12:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.