Model display and rotation

OpenGL OpenGL: Advanced Coding
1

I have a world coordinate model, which I read from a file (the positon can be anywhere) with me.

I am trying to do 2 things:

  1. To display the entire model.

  2. To rotate the model on it’s own centric axis (ie, rotate about the axis which passes thru the center of the model in any 3 directions).

  3. I have done first one by calling glOrtho()
    and glTranslatef() (this is tricky as i have to generalize any data).

  4. After displaying the model in window, when I try to rotate the model around it’s own axis, it rotates as if the origin is in the world coord.

one condition: The model rotates around it’s own axis after translating the model to the origin. But I don’t want to do that as it is expensive to transform all points of the data.

Thanks in advance,
R.B