i''ve create a model with openGL and c++builder ,and i want my program can select any part of the model ,and zoom in or zoom out the selected part.But i don''t know how! would you like to give me some example or give me some advice waiting for your help!

glScalef() will do that Zoom-Trick, but if you want to select a part of a model you''ll have to write code to break the model apart, also take a took at the lesson 32 about picking

Use glulookat, first find the point on the model where the pointer will fall onto (gluunproject iirc), then feed in the start point and the end point (what you just got) to it, then change your field of vision to a lower setting with gluperspective and that should give you the effect you want.


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Cheers,