History: Manual mesh merging

            Hi, i`m glad to introduce to you a manual mesh merging into one entity.

Given: std::vector< MeshPtr > m_Meshes
Target: One entity, where each of subentity is mesh from a given vector.

Let`s begin. First of all, we need to create a base mesh and add a submeshes to him:

{CODE(wrap="1", colors="c++")}
std::string m_ModelId = "MergedMesh";
Ogre::MeshPtr m_BaseMesh = MeshManager::getSingleton().createManual( m_ModelId, ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME );
//Lets add some submeshes
std::vector< MeshPtr >::iterator itr = m_Meshes.begin();
std::vector< MeshPtr >::iterator itr_e = m_Meshes.end();
for( ; itr !=itr_e; ++itr )
{
      Mesh::SubMeshIterator mesh_itr = source->getSubMeshIterator();
		SubMesh *in = 0, *out = 0;
		VertexBoneAssignment vbass;
		while( mesh_itr.hasMoreElements())
		{
			in = mesh_itr.getNext();
			out = m_BaseMesh->createSubMesh();
			out->indexData = in->indexData->clone();
			out->mLodFaceList = in->mLodFaceList;
			out->operationType = in->operationType;
			out->parent = m_BaseMesh.get();
			out->useSharedVertices = false;
			out->vertexData = in->vertexData->clone();
			out->clearBoneAssignments();
			for( size_t i = 0; i < in->vertexData->vertexCount; ++i )
			{
				vbass.vertexIndex = i;
				vbass.weight = 1.0f;
				out->addBoneAssignment(vbass);
			}
		}
}
{CODE}

SubMeshes was added, but for correct raytracing and picking entity now we need to set a bounding box for it :

{CODE(wrap="1", colors="c++")}

//define a extreme boundary values
 Real max_x = -1e+8;
 Real min_x = 1e+8;
 Real max_y = -1e+8;
 Real min_y = 1e+8;
 Real max_z = -1e+8;
 Real min_z = +1e+8;
// Setting bounding box
Mesh::SubMeshIterator mesh_itr = m_BaseMesh->getSubMeshIterator();
		while( itr.hasMoreElements())
		{
			in = mesh_itr.getNext();
			VertexData *vertex_data = in->vertexData;
			const Ogre::VertexElement* posElem = vertex_data->vertexDeclaration->findElementBySemantic(Ogre::VES_POSITION);
			HardwareVertexBufferSharedPtr hwvb = in->vertexData->vertexBufferBinding->getBuffer( posElem->getSource() );
			unsigned char *hbuff = static_cast<unsigned char*>( hwvb->lock( HardwareBuffer::HBL_READ_ONLY ));
			Real *pValue;
			Real value;

			for( size_t idx = 0; idx < vertex_data->vertexCount; ++idx, hbuff += hwvb->getVertexSize()  )
			{
				posElem->baseVertexPointerToElement( hbuff, &pValue );
				value = (*pValue++);
				if( value > max_x )
					max_x = value;
				if( value < min_x )
					min_x = value;
				value = (*pValue++);

				if( value > max_y )
					max_y = value;
				if( value < min_y )
					min_y = value;
				value = (*pValue++);

				if( value > max_z )
					max_z = value;
				if( value < min_z )
					min_z = value;
			}
			hwvb->unlock();
		}
		m_BaseMesh->_setBounds( AxisAlignedBox( min_x, min_y, min_z, max_x, max_y, max_z ));
{CODE}

And last step is a retrieving an entitiy from a mesh:

{CODE(wrap="1", colors="c++")}
Entity* ent = m_pSceneManager->createEntity( "entName", m_BaseMesh->getName() );
{CODE}

Cleaning up:

{CODE(wrap="1", colors="c++")}MeshManager::getSingleton().remove( m_BaseMesh->getHandle());{CODE}

Now we have a one mesh which contains all of our submeshes.