[Bf-committers] What an exporter should export... (about selections and presets)

[Gaia]

Hi.

I am running into the question which set of objects
shall actually be exported by an exporter under
which conditions. I refer to the Collada exporter here,
but maybe this can be seen in a more general context
like the "standard model for exporters".

If appreciated i can move this to a wiki page for
sorting out. And i could work on the Collada exporter
for proof of concept.


The Problem
===========

The current and most easy approach for an exporter's
behaviour is:

- When the exporter is opened without any options set,
   it exports everything
- When "selected only" is set it exports
   only the selected objects

This works as long as there is nothing more to select.
But we often have (and want) more export options:

- with armatures
- with lights
- with bone children
- with animations
- ...

So here is an example where i struggle:
what shall i export if i have selected

- only selected
- with armatures

Now shall i export all armatures ?
Only selected armatures ?
Only armatures who are parent of selected objects ?
...

So maybe this can be sorted out into a more general
approach. My intention is to get a better understanding
what makes sense, what an exporter should do.

this is just an attempt and it is not perfect.
But maybe someone can give me some feedback for
making this better (and maybe easier).


Proposal: "What an Exporter should export"
==========================================
Draft, first iteration, highly incomplete,
needs improvement... i know :)

Provided options/settings
-------------------------

- Export Categories:
   - Mesh
   - Curve
   - Surface
   - Metaball
   - Text
   - Armature
     - with animations
   - Lattice
   - Empty
   - Speaker
   - Camera
   - Lamp
   - Force field
   - Group Instance

Unsupported object types would not show up in this
list (or greyed out if planned for future support).

When the exporter is opened without any options set,
it should export no object at all.
When all categories are enabled, it should export
all supported objects.

- Scene options:
   - Scene Data (All scene data )

- Filter options
   - Current Scene only
   - selected only
      - all children (regardless of selection state)

- Misc:
   - Apply Modifiers
   - Use Object instantiation
   - Export for <Target> (very questionable)


Usage
-----

Now we could preset all export categories to enabled by default.
Hence this will export all objects with the default settings:

- File -> Export -> <exporter>
- then press the export button

We can add Presets for common cases

- Export model
- Export Rig
- Export Animations
...

or special cases

- Export for Second Life
...
==========================================
--- The End ---