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RE: glClear(GL_DEPTH_BUFFER_BIT)

hello guys
im really stuck in here
i never worked with open gl
and or any advanced programming essue
and i have a dr who asked us to write a program using c++ and oen gl
that takes an image with 2 dimentions and convert it to 3 dimentions
can any one help ???




 

> Date: Sat, 24 Nov 2007 17:07:59 +0100
> From: email@hidden
> To: email@hidden
> CC: email@hidden
> Subject: Re: glClear(GL_DEPTH_BUFFER_BIT)
>
> Hi Daniel,
> true, if I disable the depth test I don't get the bad intersection.
> This works with the scrolling text which is a 2D object (Quad). But in case
> I draw a 3D object, I get a bad result. The surfaces get all drawn without
> depth. Any solution?
>
>
> Best Regards
> --
> Lorenzo
> email: email@hidden
>
> > From: Daniel Koch <email@hidden>
> > Date: Sat, 24 Nov 2007 10:08:33 -0500
> > To: Lorenzo <email@hidden>
> > Cc: email@hidden
> > Subject: Re: glClear(GL_DEPTH_BUFFER_BIT)
> >
> > Hi Lorenzo,
> >
> > If you just disable the depth test before drawing drawin g the scrolling
> > text, and enable it again afterwards you should be able to accomplish
> > what you want without loosing the contents of your depth buffer.
> >
> > Hope this helps,
> > Daniel
> >
> > Lorenzo wrote:
> >> Hi,
> >> I have to draw a cube in a 3D space using a perspective camera,
> >> then a scrolling text using an orthogonal camera. In some case, when the
> >> cube is too close, it intersects scrolling the text, even if I use 2
> >> cameras. So I used a trick: when I set the ortho camera, before I draw the
> >> scrolling text, I call again glClear(GL_DEPTH_BUFFER_BIT). It works very
> >> well. I do
> >>
> >> clear color buffer and depth buffer
> >> set camera 1 (perspective)
> >> draw the cube
> >> set camera 2 (ortho)
> >> clear depth buffe r
> >> draw the scrolling text
> >> draw other objects (?)
> >> flush
> >>
> >> The problem is that now I have not longer my depth buffer, so I can't
> >> properly draw any other 3D object, not even if I re-set the camera 1.
> >> I cannot change the drawing object order because I can't know in advance.
> >> Reading-Writing the z buffer is time consuming, so please have you a good
> >> idea to draw as on different layers?
> >>
> >>
> >>
> >> Best Regards
> >
> > --
> > Daniel Koch -+- Graphics Technology Lead -+- TransGaming Technologies
> > email@hidden +1 613.244.1111 x352 www.transgaming.com
>
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References: 
 >Re: glClear(GL_DEPTH_BUFFER_BIT) (From: Daniel Koch <email@hidden>)
 >Re: glClear(GL_DEPTH_BUFFER_BIT) (From: Lorenzo <email@hidden>)



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