[vtkusers] How to write into VTK vertex buffer object from an OpenCL kernel

[David E DeMarle]

You might be able to scrounge some ideas from Accelerators/Piston.
Back then we did the direct handoff from cuda to GL via glinterop.

See:
https://gitlab.kitware.com/vtk/vtk/blob/master/Accelerators/Piston/vtkPistonMapper.cu

Warning that project is long deprecated and won't build with anything
recent. In particular that was written before Rendering/OpenGL2 existed.

I expect that vtk-m will have an entirely revamped version of the concept
when it lands in VTK in a couple of months.



David E DeMarle
Kitware, Inc.
R&D Engineer
21 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4909

On Wed, Oct 26, 2016 at 12:21 PM, Ken Martin <ken.martin at kitware.com> wrote:

> The shaders can be updated ala http://www.vtk.org/Wiki/Shader_In_VTK
>
> In terms of getting the VBO I believe it has been done, not by me. I think
> you have to setup your data and render it to get the VBO built. Then you
> can get it's handle and pass that to cuda or something like that.
>
> setup input data with the right size, num points, even if the values are
> dummy positions
> polydatamapper->Render()
> vbo = polydatamapper->GetVBO()
> handle = vbo->GetHandle()
>
> would be nice to have an example.
>
>
> On Wed, Oct 26, 2016 at 10:27 AM, Reza Faieghi <mfaieghi at westerneng.ca>
> wrote:
>
>> Hello,
>>
>>
>>
>> My code generates a massive polygonal data through an openCL kernel. For
>> rendering purposes, this data copies from GPU memory to host memory.
>> Afterward, there are regular VTK codes to create an unstructured grid,
>> passing data into the renderer and display them. However, the data
>> transfers between device and host memories are time-consuming.
>>
>>
>> In order to speed up the code, I want to pass the polygonal data directly
>> from the openCL kernel to vertex buffer object. I am wondering is there any
>> way that I can bridge between openCL and openGL part of the VTK renderer?
>>
>> I assume that I will need to make few changes in openGL commands like
>> glDrawArrays. I also need to make a few changes in vertex shader just to
>> make sure that the renderer works fine with my data. Other than, the rest
>> of shaders should remain unchanged. Is it possible to access the shaders
>> and make the above changes?
>>
>>
>> I would really appreciate it if you could help me with this.
>>
>>
>>
>> Best Regards,
>>
>> Reza Faieghi
>>
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>
>
> --
> Ken Martin PhD
> Chairman & CFO
> Kitware Inc.
> 28 Corporate Drive
> Clifton Park NY 12065
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