public com.google.protobuf.ExtensionRegistry assignDescriptors(
            com.google.protobuf.Descriptors.FileDescriptor root) {
          descriptor = root;
          internal_static_box2d_PbVec2_descriptor =
            getDescriptor().getMessageTypes().get(0);
          internal_static_box2d_PbVec2_fieldAccessorTable = new
            com.google.protobuf.GeneratedMessage.FieldAccessorTable(
              internal_static_box2d_PbVec2_descriptor,
              new java.lang.String[] { "X", "Y", },
              org.box2d.proto.Box2D.PbVec2.class,
              org.box2d.proto.Box2D.PbVec2.Builder.class);
          internal_static_box2d_PbFilter_descriptor =
            getDescriptor().getMessageTypes().get(1);
          internal_static_box2d_PbFilter_fieldAccessorTable = new
            com.google.protobuf.GeneratedMessage.FieldAccessorTable(
              internal_static_box2d_PbFilter_descriptor,
              new java.lang.String[] { "CategoryBits", "MaskBits", "GroupIndex", },
              org.box2d.proto.Box2D.PbFilter.class,
              org.box2d.proto.Box2D.PbFilter.Builder.class);
          internal_static_box2d_PbShape_descriptor =
            getDescriptor().getMessageTypes().get(2);
          internal_static_box2d_PbShape_fieldAccessorTable = new
            com.google.protobuf.GeneratedMessage.FieldAccessorTable(
              internal_static_box2d_PbShape_descriptor,
              new java.lang.String[] { "Tag", "Type", "Center", "Radius", "Points", "Normals", "Centroid", },
              org.box2d.proto.Box2D.PbShape.class,
              org.box2d.proto.Box2D.PbShape.Builder.class);
          internal_static_box2d_PbFixture_descriptor =
            getDescriptor().getMessageTypes().get(3);
          internal_static_box2d_PbFixture_fieldAccessorTable = new
            com.google.protobuf.GeneratedMessage.FieldAccessorTable(
              internal_static_box2d_PbFixture_descriptor,
              new java.lang.String[] { "Tag", "Restitution", "Friction", "Density", "Sensor", "Filter", "Shape", },
              org.box2d.proto.Box2D.PbFixture.class,
              org.box2d.proto.Box2D.PbFixture.Builder.class);
          internal_static_box2d_PbJoint_descriptor =
            getDescriptor().getMessageTypes().get(4);
          internal_static_box2d_PbJoint_fieldAccessorTable = new
            com.google.protobuf.GeneratedMessage.FieldAccessorTable(
              internal_static_box2d_PbJoint_descriptor,
              new java.lang.String[] { "Tag", "Type", "BodyA", "BodyB", "CollideConnected", "LocalAnchorA", "LocalAnchorB", "RefAngle", "EnableLimit", "LowerLimit", "UpperLimit", "EnableMotor", "MotorSpeed", "MaxMotorTorque", "LocalAxisA", "MaxMotorForce", "Length", "Frequency", "DampingRatio", "GroundAnchorA", "GroundAnchorB", "LengthA", "LengthB", "Ratio", "MaxLengthA", "MaxLengthB", "Target", "MaxForce", "Joint1", "Joint2", "SpringFrequency", "SpringDampingRatio", "MaxTorque", "MaxLength", "Bodies", "Joints", "TargetVolume", },
              org.box2d.proto.Box2D.PbJoint.class,
              org.box2d.proto.Box2D.PbJoint.Builder.class);
          internal_static_box2d_PbBody_descriptor =
            getDescriptor().getMessageTypes().get(5);
          internal_static_box2d_PbBody_fieldAccessorTable = new
            com.google.protobuf.GeneratedMessage.FieldAccessorTable(
              internal_static_box2d_PbBody_descriptor,
              new java.lang.String[] { "Tag", "Type", "Position", "Angle", "LinearVelocity", "AngularVelocity", "Force", "Torque", "Mass", "I", "LinearDamping", "AngularDamping", "GravityScale", "Bullet", "AllowSleep", "Awake", "Active", "FixedRotation", "Fixtures", },
              org.box2d.proto.Box2D.PbBody.class,
              org.box2d.proto.Box2D.PbBody.Builder.class);
          internal_static_box2d_PbWorld_descriptor =
            getDescriptor().getMessageTypes().get(6);
          internal_static_box2d_PbWorld_fieldAccessorTable = new
            com.google.protobuf.GeneratedMessage.FieldAccessorTable(
              internal_static_box2d_PbWorld_descriptor,
              new java.lang.String[] { "Tag", "Gravity", "AllowSleep", "AutoClearForces", "WarmStarting", "ContinuousPhysics", "SubStepping", "Bodies", "Joints", },
              org.box2d.proto.Box2D.PbWorld.class,
              org.box2d.proto.Box2D.PbWorld.Builder.class);
          return null;
        }