Why the hell is it not displaying?

OpenGL Development JOGL Development
#1

Hi everyone,
I don’t know whether i am blind or what but i have twice the same code to initialise a rendering in one class it works and in the other my Canvas desperately keeps being black.
I have spend nearly two days reading my code letter by letter but i really can not figure it out !!

Here is the one that works.

http://www.ccp4.ac.uk/fr45/jogl/HegeScene.java

and here the one that do not

http://www.ccp4.ac.uk/fr45/jogl/HegeArch.java

If anyone see something obvious please give me a shout, this is driving me nuts. I have the feeling it is something basic but I seem to be blind to it

#2

Got it ! ;D

I found the reason, but i am not really understanding why it does so. The fact is i place my “eye” at coordinate (x,y+20,z) and my look point at (x,y,z). Meaning that i look vertically downwards to my scene.

It seems that gluLookAt is suddenly very unhappy with it since my screen directly get black?

Even if i am thinking about how does the view Volume is built i do not know why it is behaving like that. Is it normal?

#3

What are you using as up vector? If you’re simply using (0, 1, 0), that’s the reason why things stop working. gluLookAt calculates the cross product of (center - eye) and up. If these two are parallel, the cross product is undefined resulting in a bogus modelview transformation matrix…

#4

Well sounds like you pointed out how blind I can be sometimes :stuck_out_tongue:

Thanks to point it out :wink: