Click here to Skip to main content
15,860,859 members
Articles / Desktop Programming / MFC
Article

True OpenGL Zooming

Rate me:
Please Sign up or sign in to vote.
4.60/5 (17 votes)
11 Feb 2002 296.1K   9.8K   66   25
True zooming on a perspective view...

Sample Image - Zoom.jpg

Introduction

The topic of this article is focused around zooming in a perspective OpenGL view. I wrote this article because I found some examples of zooming in a OpenGL view using ortho projections. But the most advanced example that I found using perspective projections, don't implement a true zooming but simulate the zooming effect changing the view point or camera angle. The technique that I suggest implement a true zooming and not change camera angle or perspective parameters (view point, reference point clipping planes). I achieved this result using the function glFrustum instead of standard gluPerspective and manipulating (see function COGL::SetPerspective(const CRect &rcClient) in the class COGL) the scaling and translating parameters of projection matrix. Two normalized rectangles are maintained by the COGL class: one for the full size image, and one for the current zooming rectangle. The image presented by OpenGL is scaled by the ratio of the rectangles, adjusted according to the viewport aspect and translated to the center of current zooming rectangle.

Finally sorry for my poor English.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here


Written By
Italy Italy
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

Comments and Discussions

 
QuestionHow to run 2 different(or same) OpenGL objects in one DialogBox? Pin
werter13-May-04 21:10
werter13-May-04 21:10 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.