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Ogre3D Animation Help


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#1 TheComet   Crossbones+   -  Reputation: 1645

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Posted 21 May 2014 - 08:47 AM

Is there anyone here who has some experience with Ogre3D and animations?

 

My problem is simple. My animated model has multiple animations, but Ogre imports them all into a single animation track (called "Anim_1"), where one animation comes after the other. I want to split these animations up into separate animation tracks in software. (E.g. idle animation from 0-40, walk from 40-80, etc. should all have their own animation state).

 

How? How can I do this?

 

I thought it would be straight forward, where you could simply create a new animation and copy from an existing animation, but apparently there are no methods for copying one animation to another:

Ogre::Animation* idleAnim = m_OgreEntity->getSkeleton()->createAnimation("idle", 40);
// PROBLEM: How do I copy the existing animation "Anim_1" to my newly created animation?

The only trace of any form of "copy" method seems to be the clone() method, but then I face a new problem: There's no way to assign this new animation to a skeleton.

Ogre::Animation* idleAnim = m_OgreEntity->getSkeleton()->getAnimation("Anim_1")->clone("idle");
idleAnim->setLength(40);
// PROBLEM: How do I apply this "idleAnim" to my skeleton now? There is no method "addAnimation()"

Any help?

 


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#2 dlan   Members   -  Reputation: 481

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Posted 21 May 2014 - 12:10 PM

How do you export your model to Ogre3D format? The exporter usually create a mesh and skeleton file where you have all you animation separated. For me you got a problem with how you export your model.

 

In my case, the modeling software I used export the mesh / skeleton and animation definition in xml form that I later convert into Ogre mesh format with the Ogrexmlconverter tool.

 

I never tried to clone animations at runtime, but I suppose you can use getNodeTrackIterator() to get all the track for an animation (a track is associated to a bone, which is derived from a node), then iterate on each keyframes of a track to get it content (with getNodeKeyFrame of the nodetrack object) and use the getTime() function of the KeyFrame to filter out unneeded frames. After that, you will need to use CreateNodeTrack and CreateNodeKeyFrame on your node track to create your frames on your new animation.

 

 

Here's a sample of an animation xml file that can be converted to Ogre format, to give you an idea of the hierarchy used by Ogre:







<animations>
	<animation name="Idle" length="3.33333" >
	<tracks>
	<track bone="LeftHand" >
		<keyframes>
			<keyframe time="0" >
				<translate x="0" y="0" z="0" />
				<rotate angle="0" >
					<axis x="0" y="0" z="-1" />
				</rotate>
				<scale x="1" y="1" z="1" />
			</keyframe>
			<keyframe time="0.673401" >
				<translate x="0" y="0" z="0" />
				<rotate angle="0" >
					<axis x="0" y="0" z="-1" />
				</rotate>
				<scale x="1" y="1" z="1" />
			</keyframe>
			
		</keyframes>
	</track>
	<track bone="RightHand" >
		<keyframes>
			<keyframe time="0" >
				<translate x="0" y="0" z="0" />
				<rotate angle="0.0872659" >
					<axis x="0" y="0" z="1" />
				</rotate>
				<scale x="1" y="1" z="1" />
			</keyframe>
			<keyframe time="0.673401" >
				<translate x="0" y="0" z="0" />
				<rotate angle="0.0872659" >
					<axis x="0" y="0" z="1" />
				</rotate>
				<scale x="1" y="1" z="1" />
			</keyframe>
			
		</keyframes>
	</track>
	<tracks>
	</animation>
</animations>


#3 TheComet   Crossbones+   -  Reputation: 1645

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Posted 21 May 2014 - 12:27 PM

Hi dlan,

 

 

Thanks for the help. I don't have direct access to the original model file in question, what I do have is the skeleton.xml and mesh.xml, which, like you, I converted with OgreXMLConverter.

 

Looking at the XML file, it looks pretty simple to manipulate it in such a way that I would have separate animations when importing it into Ogre. I think I'll just write a small python script to handle that.

 

With that said, Ogre3D would be more complete if it supported a top-level interface to split animations up.


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#4 TheComet   Crossbones+   -  Reputation: 1645

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Posted 22 May 2014 - 12:57 PM

The solution is below, and turned out to be pretty simple. It will copy a section of one animation (specified by startTime and endTime) into a destination animation, scaling it to take up the length of the destination animation.

 

// ----------------------------------------------------------------------------
void Entity::extractAnimation(Ogre::Animation* source,
                              Ogre::Animation* dest,
                              Ogre::Real startTime,
                              Ogre::Real endTime)
{
    Ogre::Real timeScale = dest->getLength() / (endTime - startTime);
    dest->destroyAllTracks();


    // loop through all animation node tracks in source and copy them to destination
    for(Ogre::Animation::NodeTrackIterator srcNodeTrackIt = source->getNodeTrackIterator();
        srcNodeTrackIt.hasMoreElements()
        ;)
    {
        Ogre::NodeAnimationTrack* srcNodeTrack = srcNodeTrackIt.getNext();
        unsigned short trackHandle = srcNodeTrack->getHandle();
        Ogre::NodeAnimationTrack* destNodeTrack = dest->createNodeTrack(trackHandle);


        // loop through all transforms of current source track and copy them to destination
        // if they are within the time frame specified
        for(unsigned short keyFrameHandle = 0;
            keyFrameHandle != srcNodeTrack->getNumKeyFrames();
            ++keyFrameHandle)
        {
            Ogre::TransformKeyFrame* srcKeyFrame = srcNodeTrack->getNodeKeyFrame(keyFrameHandle);
            if(srcKeyFrame->getTime() < startTime || srcKeyFrame->getTime() > endTime)
                continue;


            Ogre::Real scaledTime = (srcKeyFrame->getTime()-startTime) * timeScale;
            Ogre::TransformKeyFrame* destKeyFrame = destNodeTrack->createNodeKeyFrame(scaledTime);


            destKeyFrame->setTranslate(srcKeyFrame->getTranslate());
            destKeyFrame->setRotation(srcKeyFrame->getRotation());
            destKeyFrame->setScale(srcKeyFrame->getScale());
        }
    }
}

Example usage:

    this->extractAnimation(
            m_OgreEntity->getSkeleton()->getAnimation("Anim_1"),
            m_OgreEntity->getSkeleton()->createAnimation("walk", 0.6f),
            41.0f,  // walk begin frame
            71.0f   // walk end frame
    );


    m_OgreEntity->refreshAvailableAnimationState();
    m_WalkAnimState = m_OgreEntity->getAnimationState("walk");

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