gluPerspective() after glOrtho

Post: #1
Hei Everybody!
I just started to study OpenGL and have some problems with perspective projection.
I have a program in which a cube bouncing on the screen. If I create my 3D space like


it works without any troubles. But if I change to


Either I can't see anything in my window or I can notice that my viewing-point is somewhere 'in the created space' and the cube can go 'behind me'.
How could I manage to see the same space just like with glOrtho?
Is it necessary to use gluLookAt(...) with glPerspective? What is the default viewing-point after creating a space with gluPerspective? Is there a process to calculate gluPerspective() from glOrtho?

Thx: tmgergo
Quote this message in a reply
Posts: 5,143
Joined: 2002.04
Post: #2
gluPerspective can't make the same view as Ortho, that's why there are two functions.

The eye will default to 0,0,0 looking at 0,0,1 (or is that 0,0,-1, I never remember) with a perspective.

You can change that however you like, but gluLookAt is one of the easiest ways to manage it.
Quote this message in a reply
Posts: 1,563
Joined: 2003.10
Post: #3
OneSadCookie Wrote:(or is that 0,0,-1, I never remember)

Yup, {0.0, 0.0, -1.0} is correct.

- Alex Diener
Quote this message in a reply
Post Reply 

Possibly Related Threads...
Thread: Author Replies: Views: Last Post
  Small error with glViewport and gluPerspective? cjcaufield 1 4,348 Sep 20, 2009 01:10 AM
Last Post: DoG
  HELP!!! Simple glOrtho problem! Marvin 3 5,071 Jun 27, 2007 10:23 AM
Last Post: Marvin
  OpenGL Texture in relation to GL orientation, and... glOrtho help. Jones 6 6,252 Jun 30, 2006 07:18 PM
Last Post: arekkusu
  glOrtho setup for rendering "impostors" into a texture. TomorrowPlusX 22 13,290 May 22, 2006 07:21 AM
Last Post: TomorrowPlusX
  picking glOrtho vs gluPerspective rhiannon 0 4,480 Jun 6, 2005 02:20 PM
Last Post: rhiannon