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AnimationBlender Utility class for transitions between animations

Cookbook » Snippets » Animation and Movement » AnimationBlender

Introduction
Source Code
- AnimationBlender.h
- AnimationBlender.cpp
AnimationBlender.cpp for Ogre 1.2 (minor changes)
Utilisation
Transition Bug

Introduction

To blend is to fade between two states. In the animation process it allows to create a transition between two animations. With this sample code, you can blend animations in 3 ways:

- BlendSwitch: just switch to the second/destination animation (stop the first/source and start the second).
- BlendWhileAnimating: cross-fade, blend source animation out while blending destination animation in.
- BlendThenAnimate: pick source's current frame and blend it with destination's first frame.

Here is a Mogre port: MOGRE AnimationBlender

Source Code

AnimationBlender.h

class AnimationBlender
 {
 public:
   enum BlendingTransition
   {
      BlendSwitch,         // stop source and start dest
      BlendWhileAnimating,   // cross fade, blend source animation out while blending destination animation in
      BlendThenAnimate      // blend source to first frame of dest, when done, start dest anim
   };
 
 private:
   Entity *mEntity;
   AnimationState *mSource;
   AnimationState *mTarget;
 
   BlendingTransition mTransition;
 
   bool loop;
 
   ~AnimationBlender() {}
 
 public: 
   Real mTimeleft, mDuration;
 
   bool complete;
 
   void blend( const String &animation, BlendingTransition transition, Real duration, bool l=true );
   void addTime( Real );
   Real getProgress() { return mTimeleft/ mDuration; }
   AnimationState *getSource() { return mSource; }
   AnimationState *getTarget() { return mTarget; }
   AnimationBlender( Entity *);
   void init( const String &animation, bool l=true );
 };

AnimationBlender.cpp

void AnimationBlender::init(const String &animation, bool l)
 {
   AnimationStateSet *set = mEntity->getAllAnimationStates();
   AnimationStateSet::iterator it = set->begin();
   while(it != set->end())
   {
      AnimationState &anim = it->second;
      anim.setEnabled(false);
      anim.setWeight(0);
      anim.setTimePosition(0);
      ++it;
   }
   mSource = mEntity->getAnimationState( animation );
   mSource->setEnabled(true);
   mSource->setWeight(1);
   mTimeleft = 0;
   mDuration = 1;
   mTarget = 0;
   complete = false;
   loop = l;
 } 
 
 void AnimationBlender::blend( const String &animation, BlendingTransition transition, Real duration, bool l )
 {
   loop = l;
 
   if( transition == AnimationBlender::BlendSwitch )
   {
      if( mSource != 0 )
         mSource->setEnabled(false);
      mSource = mEntity->getAnimationState( animation );
      mSource->setEnabled(true);
      mSource->setWeight(1);
      mSource->setTimePosition(0);
 
      mTimeleft = 0;
   } 
   else 
   { 
      AnimationState *newTarget = mEntity->getAnimationState( animation );
 
      if( mTimeleft > 0 )
      {
         // oops, weren't finished yet
         if( newTarget == mTarget )
         {
            // nothing to do! (ignoring duration here)
         }
         else if( newTarget == mSource )
         {
            // going back to the source state, so let's switch
            mSource = mTarget;
            mTarget = newTarget;
            mTimeleft = mDuration - mTimeleft; // i'm ignoring the new duration here
         }
         else
         {
            // ok, newTarget is really new, so either we simply replace the target with this one, or
            // we make the target the new source
            if( mTimeleft < mDuration * 0.5 )
            {
               // simply replace the target with this one
               mTarget->setEnabled(false);
               mTarget->setWeight(0);
            }
            else
            {
               // old target becomes new source
               mSource->setEnabled(false);
               mSource->setWeight(0);
               mSource = mTarget;
 
            } 
            mTarget = newTarget;
            mTarget->setEnabled(true);
            mTarget->setWeight( 1.0 - mTimeleft / mDuration );
            mTarget->setTimePosition(0);
         }
      }
      else
      {
         // assert( target == 0, "target should be 0 when not blending" )
         // mSource->setEnabled(true);
         // mSource->setWeight(1);
         mTransition = transition;
         mTimeleft = mDuration = duration;
         mTarget = newTarget;
         mTarget->setEnabled(true);
         mTarget->setWeight(0);
         mTarget->setTimePosition(0);
      }
   }
 }
 
 void AnimationBlender::addTime( Real time )
 {
   if( mSource != 0 )
   {
      if( mTimeleft > 0 )
      {
         mTimeleft -= time;
 
         if( mTimeleft < 0 )
         {
            // finish blending
            mSource->setEnabled(false);
            mSource->setWeight(0);
            mSource = mTarget;
            mSource->setEnabled(true);
            mSource->setWeight(1);
            mTarget = 0;
         }
         else
         {
            // still blending, advance weights
            mSource->setWeight(mTimeleft / mDuration);
            mTarget->setWeight(1.0 - mTimeleft / mDuration);
 
            if(mTransition == AnimationBlender::BlendWhileAnimating)
               mTarget->addTime(time);
         }
      }
 
      if (mSource->getTimePosition() >= mSource->getLength())
      {
         complete=true;
      }
      else
      {
        complete=false;
      }
 
      mSource->addTime(time);
      mSource->setLoop(loop);
   }
 }
 
 AnimationBlender::AnimationBlender( Entity *entity ) : mEntity(entity) 
 {
 }

AnimationBlender.cpp for Ogre 1.2 (minor changes)

void AnimationBlender::init(const String &animation, bool l)
 {
  AnimationStateSet *set = mEntity->getAllAnimationStates();
  AnimationStateIterator it = set->getAnimationStateIterator();
  while(it.hasMoreElements())
  {
     AnimationState *anim = it.getNext();
     anim->setEnabled(false);
     anim->setWeight(0);
     anim->setTimePosition(0);
  }
  mSource = mEntity->getAnimationState( animation );
  mSource->setEnabled(true);
  mSource->setWeight(1);
  mTimeleft = 0;
  mDuration = 1;
  mTarget = 0;
  complete = false;
  loop = l;
 } 
 void AnimationBlender::blend( const String &animation, BlendingTransition transition, Real duration, bool l )
 {
  loop = l;
  if( transition == AnimationBlender::BlendSwitch )
  {
     if( mSource != 0 )
     mSource->setEnabled(false);
     mSource = mEntity->getAnimationState( animation );
     mSource->setEnabled(true);
     mSource->setWeight(1);
     mSource->setTimePosition(0);
     mTimeleft = 0;
  } 
  else 
  { 
     AnimationState *newTarget = mEntity->getAnimationState( animation );
     if( mTimeleft > 0 )
     {
        // oops, weren't finished yet
        if( newTarget == mTarget )
        {
           // nothing to do! (ignoring duration here)
        }
        else if( newTarget == mSource )
        {
           // going back to the source state, so let's switch
           mSource = mTarget;
           mTarget = newTarget;
           mTimeleft = mDuration - mTimeleft; // i'm ignoring the new duration here
        }
        else
        {
           // ok, newTarget is really new, so either we simply replace the target with this one, or
           // we make the target the new source
           if( mTimeleft < mDuration * 0.5 )
           {
              // simply replace the target with this one
              mTarget->setEnabled(false);
              mTarget->setWeight(0);
           }
           else
           {
              // old target becomes new source
              mSource->setEnabled(false);
              mSource->setWeight(0);
              mSource = mTarget;
           } 
           mTarget = newTarget;
           mTarget->setEnabled(true);
           mTarget->setWeight( 1.0 - mTimeleft / mDuration );
           mTarget->setTimePosition(0);
        }
     }
     else
     {
        // assert( target == 0, "target should be 0 when not blending" )
        // mSource->setEnabled(true);
        // mSource->setWeight(1);
        mTransition = transition;
        mTimeleft = mDuration = duration;
        mTarget = newTarget;
        mTarget->setEnabled(true);
        mTarget->setWeight(0);
        mTarget->setTimePosition(0);
     }
  }
 }
 void AnimationBlender::addTime( Real time )
 {
  if( mSource != 0 )
  {
     if( mTimeleft > 0 )
     {
        mTimeleft -= time;
        if( mTimeleft < 0 )
        {
           // finish blending
           mSource->setEnabled(false);
           mSource->setWeight(0);
           mSource = mTarget;
           mSource->setEnabled(true);
           mSource->setWeight(1);
           mTarget = 0;
        }
        else
        {
           // still blending, advance weights
           mSource->setWeight(mTimeleft / mDuration);
           mTarget->setWeight(1.0 - mTimeleft / mDuration);
           if(mTransition == AnimationBlender::BlendWhileAnimating)
              mTarget->addTime(time);
        }
     }
     if (mSource->getTimePosition() >= mSource->getLength())
     {
        complete = true;
     }
     else
     {
       complete = false;
     }
     mSource->addTime(time);
     mSource->setLoop(loop);
  }
 }
 AnimationBlender::AnimationBlender( Entity *entity ) : mEntity(entity) 
 {
 }

Utilisation

To use the functions, you can do something like this:

If you want your character to walk for instance you could do this:

if (!walking)
 {
   thePlayer->mAnimationBlender->blend( "Walk",AnimationBlender::BlendWhileAnimating, 0.2, true );
   walking=true;
 }
 
 if (mInputDevice->isKeyDown( KC_SPACE ) && !jumping)
 {
   jumping=true;
   thePlayer->mAnimationBlender->blend("Jump",AnimationBlender::BlendWhileAnimating, 0.2, false );
 }
 
 if (jumping)
 {
   if (thePlayer->mAnimationBlender->complete)
   {
      thePlayer->mAnimationBlender->blend( "Idle1",AnimationBlender::BlendWhileAnimating, 0.02, true );
      jumping=false;
   }
 }

Transition Bug

Quote:

!!Bug in Animation Blender
I have noticed that the AnimationBlender dies/freezes (the animation not the application) when the blend function is called between the transition time of the last blend.
I am specifically talking about "BlendWhileAnimating" state here.

Work around posted here:
http://www.ogre3d.org/forums/viewtopic.php?f=2&t=53911&p=366582#p366582

Alias: Talk:AnimationBlender

Contributors to this page: pyritie , jacmoe and Danoli3 .
Page last modified on Monday 16 of January, 2012 14:11:29 GMT by pyritie .

The content on this page is licensed under the terms of the Creative Commons Attribution-ShareAlike License.
As an exception, any source code contributed within the content is released into the Public Domain.

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Table of contents

Introduction

Source Code

AnimationBlender.h

AnimationBlender.cpp

AnimationBlender.cpp for Ogre 1.2 (minor changes)

Utilisation

Transition Bug

Sidebar

Search by Tags

Last changes

Search box

Non Advanced Search or Natural Search

Advanced Search or Boolean Search

Default search behavior

Requiring terms

Excluding terms

Grouping terms

Finding phrases

Using wildcards

Reducing a term's value

Changing relevance value

Online users