Toward a better exporting of particles systems (some first fixing attempts)

[JPfeP]

Hello,

I recently stumbled across various oddities while trying to export particles systems. After studying "converters/multimesh.py", it seems that the file was left in an unfinished state. It didn't take me long to fix some indentations preventing the export of several particles systems if the object has many.

Then I found a temporary fix by trial and errors for the particles transformations that were applied (location and angles). Because they were wrong for my usage. I don't understand everything happening with Blender right now because my fix for the orientation of the particles seems to work only when the particle systems is set to "Object Rotation" in its tab "Render/Object" . But at least I can achieve what I have in my mind, and get the proper escn in Godot (look at the 2 pictures). You can see my fixes here:

JPfeP@b2e597e

BTW, I have a strong problem with Godot 3.4.4 (was the same with previous versions). When I export from Blender in the "escn" format, I need not only to erase by hand the corresponding files in the .import directory, BUT i have to quit and restart the Godot editor (relaunching the project is not enough).

OS:

Linux

Godot version:

3.4.4

Blender version:

Blender 3.1

Issue description:

1. Particle export to MultiMesh was not able to handle several particles systems per object
2. Particles had a builtin translation of (0,0,1)
3. Rotation angles don't reflect the ones in Blender

Minimal reproduction project:
You can compare the behavior of the exporter by using the blend file provided, it contains 2 particles systems (cones and monkey on a Cube). The 2 pictures have been obtained with my fixes in my fork, it's just to show they work (2 Multimesh are created in the Godot project). With the current official repository you will get only one MultiMesh AND the particles will have wrong location/angles.

BTW, when you open the provided blendfile, at first the angles of the particles are wrong and as soon as you edit something in the parameters of the system, the orientations jump right to the one shown in the pictures. Another Blender oddity I am afraid... If someone know what's happening ? But after that everything is right.

test_export_particles.zip

In Blender:

In Godot: