Set the physics engine through the component

[Diego Ferigo]

The upstream activities to implement new physics engine (bullet) is progressing. We should update the current logic to use the PhysicsEnginePlugin component to set the physics engine:

gym-ignition/cpp/scenario/plugins/Physics/Physics.cpp

Lines 546 to 552 in 50caccf

 // 1. Engine from component (from command line / ServerConfig) 
 auto engineComp = 
     _ecm.Component<ignition::gazebo::components::PhysicsEnginePlugin>( 
         _entity); 
 if (engineComp && !engineComp->Data().empty()) { 
     pluginLib = engineComp->Data(); 
 } 

gym-ignition/cpp/scenario/gazebo/src/World.cpp

Lines 273 to 291 in 50caccf

 bool World::setPhysicsEngine(const PhysicsEngine engine) 
 { 
     std::string libName; 
     std::string className; 
  
     switch (engine) { 
         case PhysicsEngine::Dart: 
             libName = "PhysicsSystem"; 
             className = "scenario::plugins::gazebo::Physics"; 
             break; 
     } 
  
     if (!this->insertWorldPlugin(libName, className)) { 
         sError << "Failed to insert the physics plugin" << std::endl; 
         return false; 
     } 
  
     return true; 
 } 

[Diego Ferigo]

Closed via #338