How to set up a top view camera?

[Jami]

Hey guys,

Can someone tell me how can i set up top view camera for my scene? I've tried using gluLookAt() but i couldn't figure out the way i wanted. Any ideas with starting code would be really apperciated. Thanks in advance!! =]

[taymo2020]

Kinda Off Topic:

How did you start to learn OpenGL?

[Jami]

lol From Nehe tutorials . Well, i'm beginner don't know a lot

[Animatronic]

from google the gluLookat func is gluLookAt( eyeX,eyeY,eyeZ,centerX,centerY,centerZ,upX,upY,upZ).

eyeX,Y,Z is the position of your 'camera' e.g. (0,10,20),
centerX,Y,Z is a point where your camera is looking e.g. (0,0,0),
upX,Y,Z is the up vector for you camera, just keep it (0,1,0),

make sure you do this call at the beginning of your game loop, before rendering anything.

[Samuel]

Also Kinda Off Topic:

You cant really say that OpenGL has awesome graphics. 'Graphics' depend on the complexity of the game, like the poly count, antialliasing and other pretty things. Perhaps im being to picky

[devil_slayer]

The way i always used to to do it is first draw all the objects and then use glTranslate and glRotate to "move" the camera to the designated position.
This, of course, moves the scene, not the camera, but the effect is the same.

[Emery]

The way i always used to to do it is first draw all the objects and then use glTranslate and glRotate to "move" the camera to the designated position.
This, of course, moves the scene, not the camera, but the effect is the same.

gluLookAt is the correct way.

[devil_slayer]

Sure...

[Animatronic]

The way i always used to to do it is first draw all the objects and then use glTranslate and glRotate to "move" the camera to the designated position.
This, of course, moves the scene, not the camera, but the effect is the same.

I would be interested how this works?, I mean how do the camera transforms done at the end effect objects drawn before it ? Maybe I'm just mis-understanding your post.

[Emery]

The way i always used to to do it is first draw all the objects and then use glTranslate and glRotate to "move" the camera to the designated position.
This, of course, moves the scene, not the camera, but the effect is the same.

I would be interested how this works?, I mean how do the camera transforms done at the end effect objects drawn before it ? Maybe I'm just mis-understanding your post.

He's talking about moving the world around the camera rather than the camera around the world.

[devil_slayer]

I would be interested how this works?, I mean how do the camera transforms done at the end effect objects drawn before it ? Maybe I'm just mis-understanding your post.

Sry, you are right. This operation is meant to be done at the begining, before objects are drawn. The downside is that for drawing some objects you have to use glLoadIdentity() and in this approach you have to add the translation and rotation every time you do that also...

Anyways:

gluLookAt is equivalent to glMultMatrixf(M); glTranslated (-eyex, -eyey, -eyez);

[Animatronic]

if your using glLoadIdentity() to discard unwanted transforms (translations + rotations etc) then pushing / poping the matrix stack would be more appropriate, as then it would preserve the initial camera settings (be it gluLookAt or whatever)