[Robotics] GE Geometry pt. 2

[Benoit Bolsee]

Hi Florian,

I tested the file and I don't see the problem in the GE, except that for
this model, all the normals are inverted, which makes it look strange in
the GE, but the geometry is correct.

There are two methods for parenting a mesh to an armature. The first
method is as you did: different objects parented to bones. In this case
the position and orientation of the bone is used as a base reference to
set the position and orientation of the objects. This method requires
that each element of the robot is a different object. It's a good (fast)
method and it works in the GE as long as you make sure that scaling is
uniform on all objects and armature: the GE has a different method of
computing the parent relationship and non-uniform scaling give bad
results in the GE.

The second method consists in having only one mesh object with different
vertex group for each part, named as the bones. You parent the object to
the armature and Blender will compute the deformation of each part. This
method is more CPU intensive but allows deformation, which is not the
case of the first method.

Mixing the two methods is possible but you have to be careful: a
deforming object does not move (only the vertices move) and if you
parent an object to it, it won't move either.

Hope this helps
/benoit

> -----Original Message-----
> From: robotics-bounces at blender.org 
> [mailto:robotics-bounces at blender.org] On Behalf Of Florian Lier
> Sent: mercredi 16 septembre 2009 18:25
> To: robotics at blender.org
> Subject: [Robotics] GE Geometry pt. 2
> 
> 
> Hey all,
> 
> thanks for the replies on the GE geometry topic.
> The face normals seem to be ok, maybe it's the way I "modell"...
> 
> At first I do the "constructing stuff" like adding cubes etc 
> etc ... Then I created parent child relationships for the objects. 
> Having created all relationships - I add armatures to the 
> model, then I attach the objects to the bones (select an 
> object + SHIFT + RMB on Armature  (now both are selected) go 
> to Posemode then STRG+P make parent to: Bone). No axis is 
> fixed yet - no constraint like IK is added, there are just 
> the armatures attached to the model. 
> 
> When starting the GE everything is messed up. As soon as I 
> remove the armature, the model looks fine again ... very weird..
> 
> 
> I've tested another .blend file which is part of a Blender 
> book (Das Blenderbuch). The Robot modelled in this file is 
> also messed up in the GE. Maybe you can test it by yourself.
> 
> You can find the file here: 
> http://www.blenderbuch.de/daten/Animation/iRob> ot09t.blend
> 
> Hm 
> what else could be wrong?
> 
> 
> 
> 
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