1. Intermediate Tutorial
OGRE Programming
Intermediate Tutorial

2. Use the mouse to select x and y coordinates on the terrain
Contents
Use RaySceneQueries to keep the camera from falling through the terrain
Use the mouse to select x and y coordinates on the terrain 2

3. Ray Scene Query Initialize the RaySceneQuery object:
RaySceneQuery *mRaySceneQuery =
mSceneMgr->createRayQuery ( Ray() );

4. Execution of Ray Scene Query
Setup the ray for the ray scene query
Execute the ray scene query
Retrieve intersection results
mRaySceneQuery->setRay(mRay);
// Perform the scene query
RaySceneQueryResult &result =
mRaySceneQuery->execute();
RaySceneQueryResult::iterator itr = result.begin();
// Get the results, set the camera height
// We are interested in the first intersection. It is ok to traverse all the results.
if (itr != result.end() && itr->worldFragment) { …… }

5. Mouse Ray // Setup the ray scene query, use CEGUI's mouse position
CEGUI::Point mousePos = CEGUI::MouseCursor::getSingleton().getPosition();
Ray mouseRay = mCamera->getCameraToViewportRay(
mousePos.d_x / float(arg.state.width),
mousePos.d_y / float(arg.state.height) );
Remark: e.g. in bool mouseMoved(const OIS::MouseEvent &arg),
arg.state.width and arg.state.height specify the viewport dimension 5

6. Mouse Ray
// Use TrayMgr
Ray mRay =mTrayMgr->getCursorRay(mCamera);

7. References: