C++ - finding entities in a scene

[AggrorJorn]

Does anybody know how to search entities that are loaded via map? LE2 LoadScene() gave back all entities but the current LoadMap function only returns a boolean.

[Mumbles]

I didn't think LE 2 load scene returned anything, but once done, you could then do CountChildren() on the scene (everything it loaded was a child) and then use GetChild for each of these children to access each entity (GetChild returned a TEntity type)

 

Obviously have no idea how this translates into Leadwerks 3 but in LE 2, LoadScene returned nothing. However there was a tutorial where it guided you through the process of writing a ProcessScene() function to get the children.

 

 

Edit: Actually no, I lie, You passed it a string, it returned a TScene object, which you then called CountChildren() on

[Rick]

I don't think we can at the moment, which is insane, but in another thread Josh was talking about ways of allowing this probably a week ago or so.

[shadmar]

If you know your boundries, ForEachEntityInAABBDo maybe be used to index them all.

[AggrorJorn]

Well I am looking in to the entire scene. Of course the bounding box could be set to 10000000. But that would be very clumsy in my opinion.

[shadmar]

Yeah I agree, Map should be an entity with loaded children.

[macklebee]

just looking at the LE3 documentation here, it appears a list is created for a world's entities... can you not access that list like how it was done in LE2?

LE2: fw.main.world.entities or fw.main.world.meshes or fw.main.world.emitters...etc...

[Rick]

After the map is loaded, the only thing I see under self.world is ambientlight (via the lua editor that shows the current state).

[AggrorJorn]

Hey Macklebee! good to see you again.

 

Yes we can access this list but there is nothing in there that can be used. In the image below I have loaded a scene which contains 1 csg brush and a directionalLight. If I iterate through this world list and try GetKeyName("DirectionalLight1") nothing is returned. Also note how the errors are displayed by the entity list.

 

[tjheldna]

Hi Aggror,

 

This may help you it iterates over the entities when the level is loaded. From there I can wrap the entities in classes and/or store them in a list...

 

void StoreWorldPointsCallBack(Entity* entity, Object* extra)
{        
       std::string text = entity->GetKeyValue("name");

       if(text.compare("playerSpawn") == 0)
       {
               TheGame->AddPlayerSpawnPoint(entity);
       }
}


//Load the map somewhere in your code
if(Map::Load((const char*)(path), StoreWorldPointsCallBack))
{
}

[Rick]

Woah! I guess that will teach us to look at the parameters section instead of the syntax section :/

 

http://www.leadwerks.com/werkspace/page/documentation/_/command-reference/map/mapload-r510

 

I'll have to test this with Lua.

[shadmar]

Rick, did you get this to work in lua?

[Josh]

Each scripted entity will have the Start() function, for Lua. That takes care of most usage.

[Rick]

That's if you choose to attach a script to it. I don't think being able to loop over all loaded entities is much to ask really. Pretty common task.

[shadmar]

Here's a way :

 

function Callback(entity)
  App.entities[entity] = entity
end

 

function App:Start()
  self.entities = {}
..
  --Load the starting map
  local mapfilename=System:GetProperty("map","Maps/start.map")
  if Map:Load(mapfilename,"Callback")==false then return false end

  -- Find camera from map
  for k, v in next, App.entities do
  if v:GetClass()==Object.CameraClass then
	 self.camera=v
  end
  end
...
end

[Rick]

Thx Shadmar

[AggrorJorn]

void StoreWorldPointsCallBack(Entity* entity, Object* extra)
{
std::string text = entity->GetKeyValue("name");

if(text.compare("playerSpawn") == 0)
{
TheGame->AddPlayerSpawnPoint(entity);
}
}


//Load the map somewhere in your code
if(Map::Load((const char*)(path), StoreWorldPointsCallBack))
{
}

 

Just a little detail for when you use a callback to iterate over all the entities loaded:

 

Lights and models trigger the callback, but CSG objects by default don't. So if you would want to save CSG objects in to a class then you either have to attach a script or set a mass.