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c:/home/kevn/src/animaniac/gator/TireForceOperator.h

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#ifndef TIRE_FORCE_OPERATOR
#define TIRE_FORCE_OPERATOR
#include <vector>
#include <ani/Dynamics/Operator.h>
#include <ani/Dynamics/DynamicSystem.h>
#include <gator/Collision.h>
#include <gator/PlaneCollisionDetector.h>

namespace gator
{
   class TireForceOperator : public ani::Operator<ani::Body>
   {
   public:
      typedef boost::shared_ptr<ani::Body> EntityTypePtr;

   public:
      TireForceOperator( EntityTypePtr& e ) :
         ani::Operator<ani::Body>(),
         mUseTangentialForceAlways( false ), 
         mEnt( e )
      {
      }

      virtual ~TireForceOperator() 
      {
      }

      void setAirSteering( bool state )
      {
         mUseTangentialForceAlways = state;
      }   

      virtual void exec( ani::DynamicSystem<ani::Body>& ps, float timeDelta )
      {
         ani::Body& p = *mEnt;
         
         // replace this with a more generic polygon intersection
         gmtl::Vec3f polygonNormal;
         float dist = 0;
         bool collision_happened = mCollisionDetector->exec( p, dist, polygonNormal );

         // handle collision         
         // compute tangential forces (force from tires to keep car on the road while turning)
         if (collision_happened || mUseTangentialForceAlways)
         {         
            gmtl::Vec3f frictionForce, normalForce;
            gmtl::Matrix44f mat;
            gmtl::set( mat, p.rotation() );
            gmtl::Vec3f side_vec(1,0,0);
            side_vec = mat * side_vec;

            computeCollisionForces( side_vec, p.linearVelocity(), 0.1, 0, p.mass(), timeDelta, frictionForce, normalForce );
            p.applyForce( normalForce );
            p.applyForce( frictionForce );
            //std::cout<<normalForce<<" : "<<frictionForce<<"\n"<<std::flush;
//            std::cout<<"collide force: "<<normalForce + frictionForce<<"\n"<<std::flush;
         }
      }

      virtual void setCollisionDetector( CollisionDetectorPtr detect )
      {
         mCollisionDetector = detect;
      }

   private:
      bool mUseTangentialForceAlways; // true == steer in the air
      EntityTypePtr mEnt;
      CollisionDetectorPtr mCollisionDetector;
   };
} // end namespace gator

#endif

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