// Given a scene node for a terrain, find the manual object on that scene node and
// update the manual object with the heightmap passed. If  there is no manual object on
// the scene node, remove all it's attachments and add the manual object.
// The heightmap is passed in a 1D array ordered by width rows (for(width) {for(length) {hm[w,l]}})
// This must be called between frames since it touches the scene graph
// BETWEEN FRAME OPERATION
void Region::UpdateTerrain(const int hmWidth, const int hmLength, const float* hm) {
	Ogre::SceneNode* node = this->TerrainSceneNode;
	LG::Log("Region::UpdateTerrain: updating terrain for region %s", this->Name.c_str());

	if (node == NULL) {
		LG::Log("Region::UpdateTerrain: terrain scene node doesn't exist. Not updating terrain.");
		return;
	}

	// Find the movable object attached to the scene node. If not found remove all.
	if (node->numAttachedObjects() > 0) {
		Ogre::MovableObject* attached = node->getAttachedObject(0);
		if (attached->getMovableType() != "ManualObject") {
            // don't know why this would ever happen but clean out the odd stuff
            LG::Log("Found extra stuff on terrain scene node");
			node->detachAllObjects();
		}
	}
	// if there is not a manual object on the node, create a new one
	if (node->numAttachedObjects() == 0) {
		LG::Log("Region::UpdateTerrain: creating terrain ManualObject for region %s", this->Name.c_str());
        // if no attached objects, we add our dynamic ManualObject
		Ogre::ManualObject* mob = LG::RendererOgre::Instance()->m_sceneMgr->createManualObject("ManualObject/" + node->getName());
		mob->addQueryFlags(Ogre::SceneManager::WORLD_GEOMETRY_TYPE_MASK);
		mob->setDynamic(true);
		mob->setCastShadows(true);
		mob->setVisible(true);
		node->attachObject(mob);
		// m_visCalc->RecalculateVisibility();
	}

	Ogre::ManualObject* mo = (Ogre::ManualObject*)node->getAttachedObject(0);

	// stuff our heightmap information into the dynamic manual object
	mo->estimateVertexCount(hmWidth * hmLength);
	mo->estimateIndexCount(hmWidth * hmLength * 6);

	if (mo->getNumSections() == 0) {
		// if first time
		mo->begin(LG::GetParameter("Renderer.Ogre.DefaultTerrainMaterial"));
	}
	else {
		mo->beginUpdate(0);					// we've been here before
	}

	int loc = 0;
	for (int xx = 0; xx < hmWidth; xx++) {
		for (int yy = 0; yy < hmLength; yy++) {
			mo->position((Ogre::Real)xx, (Ogre::Real)yy, hm[loc++]);
			mo->textureCoord((float)xx / (float)hmWidth, (float)yy / (float)hmLength);
			mo->normal(0.0, 1.0, 0.0);	// always up (for the moment)
		}
	}

	for (int px = 0; px < hmLength-1; px++) {
		for (int py = 0; py < hmWidth-1; py++) {
			mo->quad(px      + py       * hmWidth,
					 px      + (py + 1) * hmWidth,
					(px + 1) + (py + 1) * hmWidth,
					(px + 1) + py       * hmWidth
					 );
		}
	}

	mo->end();

	return;
}