What's the relationship between Blender coordinates and JME?

Troubleshooting import-assets
1

I’m importing a Blender model and trying to attach particle effects to specific places on the model node.

I took the coordinates of a vertex where I want it and they are
X -0.96
Y -0.95
Z 1.190

But creating the particle effect and moving it to that coordinate doesn’t get it where I want it in relation to the model. What am I doing wrong?

Are the coordinate systems related at all?

In which order does it make sense to

  1. load the model
  2. create the particle
  3. move the particle
  4. attachChild the particle to the model
  5. scale / move the model

Edit: I have done this successfully previously by trial and error but that takes a huge amount of time. Once it’s in place, it is really good and follows the model’s movement translation and rotation.

Trial and error isn’t a good way though since I make new models too often and have to re-do it.

2

You seem to read the coordinates wrong somehow in blender, maybe you scaled the object? Its 1:1 if you export your models with up-axis fixing. Also note the relationship of parent/child connections in jME:
https://wiki.jmonkeyengine.org/legacy/doku.php/jme3:scenegraph_for_dummies

1 Like
3

Why not place your particle emitter in the scene viewer in the sdk and save it with your j3o?
That’s what i do and it’s done in a breathe, and I don’t have to bother with the coordinates.

There are different coordinate spaces involved. I don’t know in which space the coordinates you picked are but they are obviously not in the on you think they are.

look at this doc https://wiki.jmonkeyengine.org/legacy/doku.php/jme3:advanced:jme3_shaders , it’s about shader, but there is an explanation of the different spaces. Look for “Spaces and Matrices”

1 Like
4

Thanks for the answers.
I didn’t know I could do that in the scene viewer, I’ll try to figure that out. Sounds great just like you say.

Here’s a pic of the two versions, the green (Y) axis is inverted from blender to jme, but X and Z are the same. In-game howerver translations don’t correspond to these directions either, but that may be another problem.

EDIT: found the scenecomposer and figured some of it. Thanks, it really helps for finding the right coordinates.
I’ll still use the code to create and add my particle since it’s currently easier to do so, but finding the coordinates was super quick.