Dissapointing 'efficiency' of V-ray purge

[rene_rapati]

In this topic it was pointed out that I should use V-ray purge instead of Rhino purge to avoid v-ray assets to be accidentally purged from the model.
However I am now running into problems with the V-ray purge command NOT purging materials and geometries (belonging to a deleted block) that were 'tagged' and not in use anymore. This results in models with lots and lots of useless materials and v-ray geometries.

I can not believe this behavior is to be expected.

Steps to reproduce:

1. Open a new rhino model;
2. Draw a box;
3. Assign a v-ray material to the box
4. Assign a 'tag' to the v-ray material.
5. Save and close the model;
6. Open a new model;
7. Insert the model with the box from step 5;
8. The 'tagged' v-ray material should appear in the asset editor.
9. Delete the block;
10. Use the v-ray purge command in the asset editor --> the 'tagged' material is not purged from the drawing.

I have to use the Rhino purge command to get rid of all the clutter. But using the rhino purge has the annoying effect that sometimes v-ray assets that are still in use get purged from the model.

Why is it so hard for v-ray to work with rhino blocks?
I'm having a huge amount of trouble with lots of v-ray assets in combination with rhino blocks.
Working with groups instead of blocks avoids a lot of the problems, but is not a viable way of working with large models.
V-ray decals for instance do not work well on blocks. So to be able to use them correctly, I have to explode the block, and turn it into a group. This way the decals will work, but there is no easy way of updating the block that is now a group.

Please fix the annoying problems with blocks. I want to be able to use enmesh/lights/scatter/decals etc. in/on blocks. This will greatly speed up my workflow and save me hours and hours of troubleshooting problems I notice too late in the process.

[nikolay.bakalov]

Hello,

First, let me clear out that the V-Ray purge is not equivalent to Rhino purge in any aspect. It only clears unused V-Ray assets from the Asset Editor. It was initially designed for materials that were unassigned, but now it also includes some "assignable" assets like fur, displacement, etc.. The V-Ray purge will not purge any Rhino objects - block the least.
The second thing is that unused blocks are not really unused. There are blocks with zero instances, which Rhino gives the option to delete, but the are not unused, as they are part of the model. Deleting them is not something a plugin shall do. Each application shall maintain its own objects, and nothing more.
V-Ray does create some special geometry - proxies, infinite planes, lights, decals, etc. Only some of them are purgeable. And those are materials, furs, clippers, displacements, scatters, mesh lights and enmeshes. Those are all assignable modifiers. The rest are connected to an actual geometry, that must be first removed from the model (or from a block definition), and then if not automatically deleted, could be purged.
That being said, the only group of objects that are both purgeable Rhino and purgeable V-Ray objects are the materials. (obviously Rhino will not purge a V-Ray fur asset, because it doesn't "see" it). Thus in general, you should be using the Rhino purge command. If there are concerns of deleting V-Ray materials, that should not be deleted (like sub materials), just leave the materials checkbox unchecked in the Rhino purge dialog, and use the V-Ray purge afterwards.

There are known issues with the Rhino purge, that unintentionally purges V-Ray materials that are used - like Decal or proxy materials. This happens because when purging Rhino calls a plugin function to report the "used" content for a given set of objects. However Rhino supplies only the visible objects to the plugin. Basically Rhino asks us (or any other plugin) "What extra content that we don't see as 'assigned' you use for this given set of objects", and we give the respective answer. Now whether it is a bug or feature on the Rhino side, that it supplies the wrong set of objects - I can only speculate, but it is certainly not a V-Ray fault.

There is a ticket (still in development), that will prevent purging materials that are used by decals, proxies, etc, even if they are hidden, when Rhino's purge command is ongoing, but first we need to sort the things out with the McNeel developers.
However in any case, the V-Ray purge will never delete an asset used in a Rhino block definition no matter how many instances it has in the model.