Examples of jinngine.physics.constraint.contact.ContactConstraint

Package jinngine.physics.constraint.contact

Examples of jinngine.physics.constraint.contact.ContactConstraint

jinngine.physics.constraint.contact.ContactConstraint
A constraint the models contact region forces, acting between two bodies. A ContactConstraint acts like any other constraint/joint, for instance {@link BallInSocketJoint}. ContactConstraint uses one ore more {@link ContactGenerator} instances to supply contact points and contact normals of the involved geometries. When two bodies are subject to a contact constraint, a ContactGenerator for each interacting geometry pair is required. Determining and instantiating these ContactGenerators should be handled by the simulator itself, however, one can create new and possibly optimised ContactGenerators for certain geometry pairs. A trivial example would be a ContactGenerator for the Sphere-Sphere case, which is already implemented in Jinngine, see ( {@link SphereContactGenerator}).

//            bodypair = new Pair<Body>(b2,b1);
//            geometrypair = new Pair<Geometry>(inputpair.getSecond(), inputpair.getFirst());
//          }
          
          
          ContactConstraint contactConstraint = null;


          //a contact constraint already exists 
          if (contactConstraints.containsKey(bodypair)) {
            contactConstraint = contactConstraints.get(bodypair);
            
            // order the geometry pair to match the order of the contact constraint. 
            // this is necessary to keep normals pointing in the right direction when 
            // contact constraints have more than one contact generator
            Pair<Body> orderedpair = contactConstraint.getBodies();
            if (orderedpair.getFirst() == bodypair.getFirst()) {
              // same order
              geometrypair = inputpair;
            } else {
              // swap
              geometrypair = new Pair<Geometry>(inputpair.getSecond(),inputpair.getFirst());            
            }
            
                                
            //add a new contact generator to this contact constraint
            ContactGenerator generator = getContactGenerator(geometrypair);
            contactGenerators.put(geometrypair, generator);
            contactConstraint.addGenerator(generator);


          //no contact constraint is present
          } else {          
            //do not act if some other constraint(joint) is already present
            //in the contact graph
            if (constraintGraph.getEdge(bodypair) == null)  {
              //create a new contact generator
              ContactGenerator generator = getContactGenerator(inputpair);
              
              // try custom contact constraint generators
              for ( ContactConstraintCreator c : contactConstraintCreators) {
                contactConstraint = c.createContactConstraint(bodypair.getFirst(), bodypair.getSecond(), generator);
                if (contactConstraint != null)
                  break;
              }
              
              // if no contact constraint was obtained, use the default creator
              if ( contactConstraint == null) {
                contactConstraint = defaultcreator.createContactConstraint(bodypair.getFirst(), bodypair.getSecond(), generator);
              }
                  
              //insert into data structures
              contactConstraints.put(bodypair, contactConstraint);
              contactGenerators.put(inputpair, generator);
              constraintGraph.addEdge( bodypair, contactConstraint);
              
              // signal handlers
              for (Handler h: handlers) {
                h.contactConstraintCreated(bodypair, contactConstraint);
              }
              
            }
          }
        }
        
        @Override
        public final void separation(Pair<Geometry> geometrypair) {
          //retrieve the bodies associated with overlapping geometries
          Body a = geometrypair.getFirst().getBody();
          Body b = geometrypair.getSecond().getBody();
          Pair<Body> bodypair = new Pair<Body>(a,b);


          //ignore overlaps stemming from the same body        
          if ( a == b) return;
          //ignore overlaps for non-body geometries
          if ( a == null || b == null) return;
          //ignore overlaps of fixed bodies
          if ( a.isFixed() && b.isFixed() ) return;
          
          //if this geometry pair has an acting contact constraint,
          //we must remove the contact generator
          if (contactConstraints.containsKey(bodypair)) {
            //check that we have the generator (if not, something is very wrong)
            if (contactGenerators.containsKey(geometrypair)) {
          
              //remove the generator from the contact constraint
              ContactConstraint constraint = contactConstraints.get(bodypair);
              ContactGenerator cg = contactGenerators.get(geometrypair);
              
              //notify contact generator (for possible clean-up)
              cg.remove();
              
              // remove from contact constraint
              constraint.removeGenerator(cg);
              
              //remove the generator from our list
              contactGenerators.remove(geometrypair);


              //if the contact constraint has no more generators, also
              //remove the contact constraint
              if (constraint.getNumberOfGenerators() < 1 ) {
                contactConstraints.remove(bodypair);
                constraintGraph.removeEdge(bodypair);  
                
                // signal event handlers
                for (Handler h: handlers) {

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//    timestep = s.getTimestep();


    // see if the monitored constraints can trigger an event
    ListIterator<ContactConstraint> monitored = monitoredconstraints.listIterator(); 
    while ( monitored.hasNext() ) {
      ContactConstraint constraint = monitored.next();
      totalforce = 0;
      numberOfNcpConstraints = 0;


      // sum up the applied contact force
      Iterator<NCPConstraint> ncps = constraint.getNcpConstraints();
      while(ncps.hasNext()) {
        NCPConstraint ncp = ncps.next();
        totalforce += ncp.lambda;      
        numberOfNcpConstraints += 1;
      }


      // check condition
      if (totalforce > impulsethreshold) {  
        
        // move constraint to triggered list
        monitored.remove();
        triggeredconstraints.add(constraint);
        
        // perform trigger event callback
        Pair<Body> bodies =  constraint.getBodies();
        Body interacting = bodies.getFirst()==body? bodies.getSecond(): bodies.getFirst();
        callback.contactAboveThreshold(interacting, constraint);


      } // if force > forcethreshold
    } // for monitored constraints  
    
    // see if triggered constraints should be moved back to monitored
    ListIterator<ContactConstraint> triggered = triggeredconstraints.listIterator();
    while ( triggered.hasNext()) {


      ContactConstraint constraint = triggered.next();
      totalforce = 0;
      numberOfNcpConstraints = 0;


      // sum up the applied contact force
      Iterator<NCPConstraint> ncps = constraint.getNcpConstraints();
      while(ncps.hasNext()) {
        NCPConstraint ncp = ncps.next();
        totalforce += ncp.lambda;        
        numberOfNcpConstraints += 1;
      }


      // check condition
      if (totalforce < impulsethreshold) {  
        
        // move constraint to monitored list
        triggered.remove();
        monitoredconstraints.add(constraint);
        
        // perform trigger event callback
        Pair<Body> bodies =  constraint.getBodies();
        Body interacting = bodies.getFirst()==body? bodies.getSecond(): bodies.getFirst();
        callback.contactBelowThreshold(interacting, constraint);


      } // if force > forcethreshold
    } // for monitored constraints

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Related Classes of jinngine.physics.constraint.contact.ContactConstraint

jinngine.physics.constraint.contact.DefaultContactConstraintManager

jinngine.physics.ContactTrigger

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