[Robotics] GE Geometry pt. 3

[Florian Lier]

Hey all,

problem [SOLVED] !

The messed up GE visualisation has been caused by a wrong
parenting strategy ...

The way you should NOT do it:

1) Create a robot which consists of multiple objects.
2) Parent the objects "chainlike" to each other:  select multiple 
objects -> CTRL+P -> "make parent" then
select one of the recently parented objects (like the root node) and add 
it another parenting group ...

*This strategy causes loops which mess up the model in the GE but not in 
3D-View!

*The way you SHOULD do it:

1) Create a robot which consists of multiple objects.
2) Directly attach/parent all needed objects to the bones (select 
objects + select Armature -> CTRL + TAB -> Pose Mode -> select bone -> 
CTRL + P -> make parent to bone

Thats's it.

You can find the correclty drawn arms here: 
http://www.icram.de/files/ArmsBlenderGameEngine.png


Again thanks to all you guys.

Cheers, Florian

Florian Lier wrote:
> Hey,
>
> thank you very much! I'd to help my gf with her exam the last few hrs so
> I couldn't work on my problem :/
>
> I'll test it later on today. It's too late right now...
>
> You're the best!
>
> Cheers, Florian
>
> Benoit Bolsee wrote:
>> 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?
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Robotics mailing list
>>> Robotics at blender.org 
>>> http://lists.blender.org/mailman/listinfo/robo> tics
>>>
>>>     
>>
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>>   
>
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