3DDave
Aerospace
- May 23, 2013
- 10,810
I saw on another forum the claim that Creo layer rules depend directly on the way other layer rules are executed rather than the results of those rules. I think this is incorrect, but it might appear that way.
One of the difficulties is that layer rules don't have a defined order of execution; to the user it appears they should all be evaluated simultaneously, but that cannot be true.
For example:
Create Layer A
Rule for Layer B: Add items that are on layer A AND not on layer B
Add item(s) to layer A
At this point the item is not on B.
When the component is regenerated Creo should note that the item on A is not on B and add it to B.
When the component is regenerated again, it should note that the item on B is already on B and remove it.
The same should be seen by editing the layer rules for B and clicking on evaluate.
Whether the item is on layer B or not doesn't really depend on the rule (or lack of it) that put it on layer A, but it might be mistaken for doing so.
There was also some concept about creating layer rules and such. I recall that it's possible to save layers and their associated rules and import them, so that they don't have to be explicitly re-typed. Likewise, if there is some uncertainty about whether the layer rules are working correctly, they can be deleted from any particular model and the rules re-imported from a known good location.
My experience with layers and layer rules (which seem to use exactly the same search system as when one looks for any item with the Binocular icon) is that it is almost always the case that a failure to produce desired results is due to not understanding exactly how the NOT (!), AND, and OR operators work in typical programming. Users often manage to create rules they don't understand. The way to improve this is to create and save searches interactively from the Binocular icon and save that search as a file for import as a layer rule.
One of the difficulties is that layer rules don't have a defined order of execution; to the user it appears they should all be evaluated simultaneously, but that cannot be true.
For example:
Create Layer A
Rule for Layer B: Add items that are on layer A AND not on layer B
Add item(s) to layer A
At this point the item is not on B.
When the component is regenerated Creo should note that the item on A is not on B and add it to B.
When the component is regenerated again, it should note that the item on B is already on B and remove it.
The same should be seen by editing the layer rules for B and clicking on evaluate.
Whether the item is on layer B or not doesn't really depend on the rule (or lack of it) that put it on layer A, but it might be mistaken for doing so.
There was also some concept about creating layer rules and such. I recall that it's possible to save layers and their associated rules and import them, so that they don't have to be explicitly re-typed. Likewise, if there is some uncertainty about whether the layer rules are working correctly, they can be deleted from any particular model and the rules re-imported from a known good location.
My experience with layers and layer rules (which seem to use exactly the same search system as when one looks for any item with the Binocular icon) is that it is almost always the case that a failure to produce desired results is due to not understanding exactly how the NOT (!), AND, and OR operators work in typical programming. Users often manage to create rules they don't understand. The way to improve this is to create and save searches interactively from the Binocular icon and save that search as a file for import as a layer rule.