Model View Transformation
"Mohan Parthasarathy" <[email protected]> Tue, 14 Oct 2008 16:10:35 -0800
| Newsgroups | gmane.games.devel.opengl |
|---|---|
| Organization | Fat City Network Services, San Diego, California |
| Message-ID | <[email protected]> |
------=_Part_2630_17520956.1224025759100 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Hi, I am drawing a cube (2 units on all sides) that extends from -1 to 1 on Z axis. I have defined a view volume (parallel projection) that covers 3 units on all sides (glOrtho (-3.0, 3.0, -3.0,3.0,-3.0,3.0). The cube faces are differently colored so that i know what faces i am looking at. The camera by default is at (0,0,0). 1) glTranslate on Z axis with 0.0, 1.0 and 2.0, i see the front face. If i move greater than 2.0 units, i see the back face. I am unable to explain this. Isn't the camera pointing towards the -Z axis at the begninning ? Then why am i seeing the front face. Then when i cross 2 units, i see the back face. I am unable to understand this. To see the front face, don't i have to be in front of the cube i.e something like -1.1 ? Also, for seeing the back face, don't i have to move forward at least 1.1 and then turn around ? I am confused. 2) glTranslate on Z axis with values > 4.0 or -4.0, i don't see the cube. I can see that the camera/viewpoint is too far. What is too far ? How do i know that i have gone too far without trying different values ? Thanks for any help. mohan ------=_Part_2630_17520956.1224025759100 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline <div dir="ltr"><div>Hi,</div> <div> </div> <div>I am drawing a cube (2 units on all sides) that extends from -1 to 1 on Z axis. I have defined a view volume (parallel projection) that covers 3 units on all sides (glOrtho (-3.0, 3.0, -3.0,3.0,-3.0,3.0). The cube faces are differently colored so that i know what faces i am looking</div> <div>at. The camera by default is at (0,0,0).</div> <div> </div> <div>1) glTranslate on Z axis with 0.0, 1.0 and 2.0, i see the front face. If i move greater than 2.0 units, i see the back face. I am unable to explain this. Isn't the camera pointing towards the -Z axis at the begninning ? Then why am i seeing the front face. Then when i cross 2 units, i see the back face. I am unable to understand this. To see the front face, don't i have to be in front of the cube i.e something like -1.1 ? Also, for seeing the back face, don't i have to move forward at least 1.1 and then turn around ? I am confused.</div> <div> </div> <div>2) glTranslate on Z axis with values > 4.0 or -4.0, i don't see the cube. I can see that the camera/viewpoint is too far. What is too far ? How do i know that i have gone too far without trying different values ?</div> <div> </div> <div> </div> <div>Thanks for any help. </div> <div>mohan</div></div> ------=_Part_2630_17520956.1224025759100-- ----- FAQ and OpenGL Resources at: http://www.geocities.com/SiliconValley/Hills/9956/OpenGL -- Author: Mohan Parthasarathy INET: [email protected] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [email protected] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB OPENGL-GAMEDEV-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).