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c:/home/kevn/src/animaniac/ani/Dynamics/operators/GrowWithAgeOperator.h

Go to the documentation of this file.

#ifndef GROW_WITH_AGE_OPERATOR
#define GROW_WITH_AGE_OPERATOR

#include <vector>
#include <gmtl/Vec.h>
#include <gmtl/VecOps.h>

namespace ani
{
   // change size as it grows older
   template<class __EntityType>
   class GrowWithAgeOperator : public ani::Operator<__EntityType>
   {
   public:
      typedef boost::shared_ptr<__EntityType> EntityTypePtr;

   public:
      GrowWithAgeOperator() : ani::Operator<__EntityType>()
      {
         mSizeTransitions.push_back( 1.0f );
         mSizeTransitions.push_back( 0.75f );
         mSizeTransitions.push_back( 0.50f );
         mSizeTransitions.push_back( 0.0f );
      }
      virtual ~GrowWithAgeOperator() {}
      void setVolumes( std::vector<float> sizeTransitions ) { mSizeTransitions = sizeTransitions; }
      virtual void exec(  DynamicSystem<__EntityType>& ps, float timeDelta );

      std::vector<float> mSizeTransitions;
   };

   template <class __EntityType>
   void GrowWithAgeOperator<__EntityType>::exec(  DynamicSystem<__EntityType>& ps, float timeDelta )
   {
      std::vector<EntityTypePtr>::iterator it;
      for (it = ps.entities().begin(); it != ps.entities().end(); ++it)
      {
         EntityTypePtr p = *it;
         float age__zero_to_one = p->age() / p->ageOfDeath();

         // find the range that we'll examine... range = {0...(size-1)} so that we can always check i and i+1
         // NOTE: range will at least be 0, since size >= 1
         assert( mSizeTransitions.size() > 0 && "to use this operator, you must define some colors" );
         float range = (float)mSizeTransitions.size() - 1.0f; 

         // the indices of the two colors to interpolate between 
         float indexf = age__zero_to_one * range;
         int index = (int)indexf;
         int next_index = ((index+1) != (int)mSizeTransitions.size()) ? index+1 : (mSizeTransitions.size() - 1);
         assert( index >= 0 && next_index < (int)mSizeTransitions.size() && "out of bounds" );

         // find the value to interpolate this color with the next color (should be 0..1)
         float val = indexf - (float)index;

         float result;
         gmtl::Math::lerp( result, val, mSizeTransitions[index], mSizeTransitions[index+1] );

         p->setVolume( gmtl::Vec3f( result, result, result ) );
      }
   }

} // end namespace

#endif

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