draw relative to camera position

recently my boss told me to modify an opengl application. It uses gluLookAt to set the camera position. I'd have to draw a toolbar relative to that position so that the user could always see it.

I'm almost a complete beginner in openGL, so I don't really know what would be easier, doing all the translations and rotations myself so I could draw the 开发者_C百科object in camera sight, or using the projection and view matrices? I managed to get the projection and view matrices with the glGetFloatv command, but to be honest, I have no idea how to use them to make the desired transformations. I could just use the basic translation and rotation commands, but I think using those matrices would be easier.

I would be gratefull for any answer :)

What might be easier instead is to change the projection and modelview matrices after drawing the 3D scene. Change the projection matrix to a glOrtho2D, and the modelview so that it scales to fit the screen and then draw the toolbar. See the answers here for specifics:

Opengl drawing a 2d overlay on a 3d scene problem