[Robotics] Depth information from a camera

[Gilberto Echeverria]

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] 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
>> _______________________________________________
>> Robotics mailing list
>> Robotics at blender.org
>> http://lists.blender.org/mailman/listinfo/robo>  tics
>>
>>      
>
> _______________________________________________
> Robotics mailing list
> Robotics at blender.org
> http://lists.blender.org/mailman/listinfo/robotics
>