Blender exporter and empties

[SeagullCZ]

Hello everyone,

I am creating an game which displays a map where I would like to mark some points (base on these points will be various models placed - it depends on data from backend). These points I am creating in the Blender by Plain Axes empty object. This objects appears also in exported *.babylon file in meshes part of file.  So far so good, but problem is that I need somehow mark these points, the Tag feature seems like good choice, but there isn't a Tag field in Blender UI like is for meshes. So my first question is: Do you know any way how to add tags at empty entity? And second one:  Do you know any other way how to mark such points? I was thinking about simple small circle but it seems like very ugly workaround for me. I was also thinking about using of entity name as a "tag", this solution seems like candidate for me, but delaing with multiple tags on one object will needs some ugly name/tag conversion.

 

Thank you for help

SeagullCZ

[Wingnut]

Hi Seagull, welcome to the forum!

I have some ideas for this... using a Blender "custom property" that you name 'metadata'.  It must be named metadata so that it arrives in BJS (imported) as the mesh.metadata property.

Note:  Lights and cameras ALSO carry the .metadata property, but let's ONLY talk about mesh.metadata, here/now.   [click here for forum-wide search for 'metadata']

In Blender, this mesh/object property VALUE could be set as a string value, and that string COULD BE a serialized JSON object.  After the .metadata string arrives into a BJS scene, it can be JSON parsed, and it will become an object.  That object COULD be a database of marker names, and each marker's worldspace position (x/y/z).

One problem.  Imagine you have 100 or more markers on a ground/floor.  The string you must edit/paste into the Property Value text-input field... (with each marker's name and position) will be long and ugly.

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We need to talk with @JCPalmer and other Blender exporter experts... for a moment.  Jeff/others... do you think it is possible to make the exporter... TRY to run a little "extra" user-written Python func.... during the exporting?

Objectives of the user-created Python func: 

  - Ignore the existence-of (don't export) ANY mesh named _marker_### (where ### = some number 000-999+)

  - Assemble a giant metadata string (serialized JSON) containing the names and positions of all _markers_.

  - Place that long string into parentMesh.metadata ... for export to BJS scene... where Seagull can use that _markers_ database.
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Then, Seagull, in your Blender scene... you could place little boxes or spheres at every _marker_ point, and if you named each...  _marker_xxx, then they would NOT be included in the scene export-from-Blender, but their names and positions WOULD be included... in someOtherMesh.metadata string.  A suitcase or traveling bag. 

Do you think this would work... for your needs, Seagull?  I don't know if it is possible, but, let's run it up the flagpole and see if anyone salutes it. 

Would that user-coded Python func be called an exporter pre-processor?  *shrug* 

My whole idea might be the wrong approach, as I'm not an export expert.  All ideas/comments welcome, always.

[JCPalmer]

Just use a plane mesh.  It only has 2 faces.  You can disable it right in the exporter Custom properties UI, which should perform identically to empties.  There is also a place to add tags which get exported.  No need to assign a material.

[V!nc3r]

I was just thinking about just a single verts, but it seems not convenient.

I took a look on the mesh.py addon file, but play with empties doest not appear easy (example, they aren't bpy.types.Empty - I could be wrong), so I don't success to show a Tags input box ?

By writing this, 'thought maybe the simpliest solution: create a custom mesh-empty without faces: