Largest object position inheritance for Prefabs

Our game places prefabs procedurally (say that fast!) and we often use prefabs as a way to create several instances of one object. Placing prefabs on the fly was giving us unnecessary headaches which this resource addresses.

This one object is usually the largest object which already has a place in the world. Such as a room or a building. The engine uses the center of the selection to position the prefab while it is probably more efficient to use the position of the largest object - which lets you position the object without having to poke into the prefab and extract its offset.

In gui/worldEditor/worldEditor.cpp change everything marked by the // >>> and // <<< comments.

// SimGroup we collect prefab objects into.
   SimGroup *group = new SimGroup();
   group->registerObject();

   // >>>
   // a small change to make prefabs use the center of the object with the largest bounding box
   SimObject *obj = NULL;
   SceneObject *sObj = NULL;

   Box3F largestBounds = Box3F::Zero;
   SceneObject* largest = NULL;
   for ( S32 i = 0; i < found.size(); i++ )
   {      
      obj = found[i];
      sObj = dynamic_cast< SceneObject* >( obj );
      if ( sObj )
      {
         if (largestBounds.getExtents().len() < sObj->getWorldBox().getExtents().len()) {
            largestBounds = sObj->getWorldBox();
            largest = sObj;
         }
      }
   }

   // Transform from World to Prefab space.
   MatrixF fabMat(true);
   fabMat.setPosition( largest ? largest->getPosition() : mSelected->getCentroid() );
   fabMat.inverse();

   MatrixF objMat;
   // <<<

   for ( S32 i = 0; i < found.size(); i++ )
   {

That's all there is to it. Next up - sometime next week I think - some optimized C++ AI pathfinding code based on Gabriel Notman's excellent resource. I just need some time to extract it from our game. ;)

@konradkiss
KonradKiss @ GitHub
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