Advanced Blender to Unity 3D model importer
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EdyJ Support for meshes without UVs
Thanks to Denis Opa for pointing it out!
Latest commit 9e8f284 Feb 16, 2016

Blender to Unity 3D importer

An advanced Blender model importer for Unity 3D

By Angel García "Edy"

Setting up

Copy the Editor folder to your project's Assets folder. No files will be touched by the Importer unless they are explictly configured to.

How to import models with the Importer

Rename the model to include the string [importer] in the name or path (case insensitive). Example:

Assets/Models/Scenery/Big House [importer].blend

The [importer] string can be used in a path. All contained 3D files are processed:

Assets/Models/Player Vehicles [IMPORTER]/Car1.blend

Right-click the file or folder, then choose Reimport to apply new settings after renaming.

How to use the advanced parameters

The [importer] string allows additional parameters as keywords separated by a dot (.):

[importer]					(use default settings)
[importer.opt.zreverse]		(optional parameters are applied)


IMPORTER		Use importer. Otherwise bypass the file and let Unity import without changes.
				This must be the first parameter. All others are optional.

OPT				Optimize mesh usage. Ensure that the identical meshes are instanced instead of 
				duplicated.	This optimization can also be applied later scene-wide (menu 
				GameObject > "Optimize mesh instances in this scene").
SKIPFIX			Do not fix the Blender file. This is automatically applied with any 3D format
				other than Blender. OPT and NOMODS can still be used separately in other 3D formats.
FORCEFIX		Forces to apply the fix even in non-Blender files. This is useful with FBX files
				exported from Blender.
ZREVERSE		Turn the model around 180º when importing so the Z axis points the opposite 
				direction. Use when the "forward" direction of the model points	backwards (-Z).
				"Forward" should be +Z in Unity (-Y in Blender).

NOMODS			Do not apply selective commands to meshes (see below).	
NOANIMFIX		Do not fix animation clips in .blend files when imported.
NOFLOATFIX		Do not fix floating point precision errors (i.e. rounding 0.9999998 to 1)
FORCEFIXROOT	Fixes an specific case of Blender file consisting on a single Empty object
				as root of all other objects. See Known Issues below for details.

Selective commands to meshes

Some keywords can be specified in the name of the objects in the hierarchy. They will trigger specific commands unless the NOMODS parameter is specified above.

Example object name:

collider_hull --norend--coll

All commands must be grouped together at the end of the name, starting by -- each, without any other character or separator.

Mesh commands:

NOREND			Remove the Mesh Renderer
COLL			Add a Mesh Collider
COLLCONV		Add a Mesh Collider and mark it as Convex

Hints & Tips

Parenting in Blender

Always use Ctrl-Shift-P for parenting objects instead of Ctrl-P. Parenting with Ctrl-P makes Blender to store two transforms per parenthood relationship, direct and inverse. Only the direct transform is imported by Unity.

Alt-P clears the parent's inverse transform in a children when the parenthood was established with Ctrl-P.

Please contact me if you have experience developing Blender Add-ons. I'd like add a function (maybe triggered by Shift-Alt-P?) for parenting objects like Unity does, without inverse transform.

Rotations and transforms

Unity applies Euler rotations in this order: ZXY

In Blender, the euler rotation mode that matches Unity is: "YXZ Euler" (Z and Y axis are exchanged). Still, you can use any rotation mode in Blender. The result of the rotation will be preserved, with the Euler angles in Unity adjusted accordingly.

All transformations (position, rotation, scale) will look in Unity exactly as seen in Blender, provided the parenthood relationships have been established as speficied above. Only the specific values will be different as result of the coordinate change (axis exchanged, etc).

Known issues

Rotations are incorrectly imported when the Blender file contains a single Empty object as root for all other objects. Use the FORCEFIXROOT option in this case.

Animation clips are processed when imported in "Legacy - Store in Root" mode.