[Robotics] Depth information from a camera

[Gilberto Echeverria]

On 01/11/2011 06:43 PM, Izaak Van Crombrugge wrote:
> There is indeed no bgl.buffer(), but there is bgl.Buffer(). (Capital 
> letter)
> When I can't find useful documentation, I try to figure it out in the 
> console in Blender with autocomplete.
> >>import bgl
> >>bgl. (ctrl+space)
> And you get the whole list.
>
> Maybe they aren't documented because they just map all these openGL 
> functions?
>
> Izaak
>
Thanks Izaak,

I didn't know about the autocomplete, but it can be very helpful.

Gilberto

> 2011/1/11 Gilberto Echeverria <gilberto.echeverria at laas.fr 
> <mailto:gilberto.echeverria at laas.fr>>
>
>     Hi Benoit,
>
>     I'm trying to get the zbuffer using the OpenGL functions, but I'm
>     running into a couple of problems.
>     First, I did some experiments and I can get the zbuffer using
>     bgl.glReadPixels, but specifying a section of the screen to read. How
>     can I change this to use the image from VideoTexture instead? I
>     thought
>     of using the glBindBuffer method, but that doesn't seem to be
>     implemented in bgl.
>
>     I also have the same problem with bgl.buffer(), where I get an error
>     saying that there is no attribute called 'buffer'. It seems to be
>     caused
>     by lack of support for some OpenGL functions within bgl. At least they
>     don't appear in the documentation of Blender 2.49, and for Blender
>     2.5 I
>     can't even find the bgl docs.
>
>     Thanks
>
>     Gilberto
>
>     On 01/11/2011 12:24 PM, Benoit Bolsee wrote:
>     > Hi Gilberto,
>     >
>     > The BGL module is still there in Blender 2.5. It is now called
>     'bgl' so
>     > you have to "import bgl" at the start of the module. The bgl
>     module is a
>     > wrapper around OpenGL, so you can call all OpenGL functions with
>     it. To
>     > get the Zbuffer, you will need to run a custom render from a camera
>     > using VideoTexture and then you can retrieve the Zbuffer using the
>     > appropriate OpenGL function.
>     >
>     > Void pointer parameters in OpenGL map to buffer objects that you
>     create
>     > with bgl.buffer() method.
>     > Unfortunately, the buffer objects returned by bgl.buffer() do not
>     > support the buffer protocol, which means that you cannot export the
>     > internal memory buffer to a C module. You can however access
>     individual
>     > elements of the buffer from python using sequence methods.
>     > Adding support for the buffer protocol to bgl.buffer object type
>     > shouldn't be difficult though.
>     >
>     > Hope this helps,
>     > Benoit
>     >
>     >
>     >> -----Original Message-----
>     >> From: robotics-bounces at blender.org
>     <mailto:robotics-bounces at blender.org>
>     >> [mailto:robotics-bounces at blender.org
>     <mailto:robotics-bounces at blender.org>] On Behalf Of Gilberto
>     Echeverria
>     >> Sent: mardi 11 janvier 2011 10:07
>     >> To: Blender and Robotics
>     >> Subject: [Robotics] Depth information from a camera
>     >>
>     >>
>     >> Hello everyone,
>     >>
>     >> For the MORSE simulator, we are trying to recreate laser
>     >> range scanners,
>     >> that provide depth information from a sensor on a robot. We are
>     >> currently doing this using ray tracing, but if we want to simulate
>     >> sensor with a lot of lasers, I fear ray tracing all of them
>     >> will be too
>     >> slow.
>     >> So my question is: Is there a way to get the depth information of a
>     >> scene in a faster way? We need something that can be used
>     >> from the Game
>     >> Engine of Blender 2.5
>     >> One possible method is to get the z-buffer from a camera.
>     Apparently
>     >> this was possible in Blender 2.49, using the BGL modules, but
>     >> that seems
>     >> to have disappeared from Blender 2.5.
>     >>
>     >> Any ideas will be greatly appreciated.
>     >> Cheers
>     >>
>     >> Gilberto
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>     >>
>     >>
>     >
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