#include <OgreOverlayManager.h>

class ObjectTextDisplay {

public:
 ObjectTextDisplay(const Ogre::MovableObject* p, const Ogre::Camera* c) {
  m_p = p;
  m_c = c;
  m_enabled = false;
  m_text = "";

  // create an overlay that we can use for later
  m_pOverlay = Ogre::OverlayManager::getSingleton().create("shapeName");
  m_pContainer = static_cast<Ogre::OverlayContainer*>(Ogre::OverlayManager::getSingleton().createOverlayElement(
   "Panel", "container1"));

  m_pOverlay->add2D(m_pContainer);

  m_pText = Ogre::OverlayManager::getSingleton().createOverlayElement("TextArea", "shapeNameText");
  m_pText->setDimensions(1.0, 1.0);
  m_pText->setMetricsMode(Ogre::GMM_PIXELS);
  m_pText->setPosition(0, 0);

  m_pText->setParameter("font_name","BlueHighway");
  m_pText->setParameter("char_height", "16");
  m_pText->setParameter("horz_align", "center");
  m_pText->setColour(Ogre::ColourValue(0.0, 1.0, 0.0));

  m_pContainer->addChild(m_pText);
  m_pOverlay->show();
 }

 virtual ~ObjectTextDisplay() {

  // overlay cleanup -- Ogre would clean this up at app exit but if your app
  // tends to create and delete these objects often it's a good idea to do it here.

  m_pOverlay->hide();
  Ogre::OverlayManager *overlayManager = Ogre::OverlayManager::getSingletonPtr();
  m_pContainer->removeChild("shapeNameText");
  m_pOverlay->remove2D(m_pContainer);
  overlayManager->destroyOverlayElement(m_pText);
  overlayManager->destroyOverlayElement(m_pContainer);
  overlayManager->destroy(m_pOverlay);
 }

 void enable(bool enable) {
  m_enabled = enable;
  if (enable)
   m_pOverlay->show();
  else
   m_pOverlay->hide();
 }

 void setText(const Ogre::String& text) {
  m_text = text;
  m_pText->setCaption(m_text);
 }

 void update()
 {
  if (!m_enabled)
   return;

  // get the projection of the object's AABB into screen space
  const Ogre::AxisAlignedBox& bbox = m_p->getWorldBoundingBox(true);
  Ogre::Matrix4 mat = m_c->getViewMatrix();

  const Ogre::Vector3* corners = bbox.getAllCorners();

  float min_x = 1.0f, max_x = 0.0f, min_y = 1.0f, max_y = 0.0f;

  // expand the screen-space bounding-box so that it completely encloses
  // the object's AABB
  for (int i=0; i<8; i++) {
   Ogre::Vector3 corner = corners[i];

   // multiply the AABB corner vertex by the view matrix to
   // get a camera-space vertex
   corner = mat * corner;

   // make 2D relative/normalized coords from the view-space vertex
   // by dividing out the Z (depth) factor -- this is an approximation
   float x = corner.x / corner.z + 0.5;
   float y = corner.y / corner.z + 0.5;

   if (x < min_x)
    min_x = x;

   if (x > max_x)
    max_x = x;

   if (y < min_y)
    min_y = y;

   if (y > max_y)
    max_y = y;
  }

  // we now have relative screen-space coords for the object's bounding box; here
  // we need to center the text above the BB on the top edge. The line that defines
  // this top edge is (min_x, min_y) to (max_x, min_y)

  //m_pContainer->setPosition(min_x, min_y);
  m_pContainer->setPosition(1-max_x, min_y);  // Edited by alberts: This code works for me
  m_pContainer->setDimensions(max_x - min_x, 0.1); // 0.1, just "because"
 }

protected:
 const Ogre::MovableObject* m_p;
 const Ogre::Camera* m_c;
 bool m_enabled;
 Ogre::Overlay* m_pOverlay;
 Ogre::OverlayElement* m_pText;
 Ogre::OverlayContainer* m_pContainer;
 Ogre::String m_text;
};

调用：

ObjectTextDisplay * text = new ObjectTextDisplay(mBodyEnt, mCamera);
 text->enable(true);
 text->setText("name");

如上所示，然后直接调用即可，在ogre1.72版本中取消了对overlay的使用，所以如果想要使用overlay的话，只能将其资源添加回来，即去找到资源packs/OgreCore.zip,同时将overlays这个文件夹放入media中，最后再resources.cfg文件中添加FileSystem=http://www.cnblogs.com/media/overlays和Zip=http://www.cnblogs.com/media/packs/OgreCore.zip即可，这样即可使用overlay了，如果如上中找不到字体  m_pText->setParameter("font_name","BlueHighway");，即打开文件Shadows.overlay，找到element TextArea(Example/Shadows/Materials)查看字体名称。最后即可顺利将文字显示。