[Bf-cycles] Render to memory buffer

[Mohamed Sakr]

I did exactly as Brecht said above in Cycles4D to get the buffer.

On Sun, Mar 18, 2018 at 2:08 PM, Brecht Van Lommel <
brechtvanlommel at pandora.be> wrote:

> It seems unnecessarily complicated. If you call session->draw() that will
> mostly just pass the session->display buffer to draw_pixels on the
> device. So why not just get the pixels from that display buffer directly?
> Something like this:
>
> thread_scoped_lock display_lock(session->display_mutex);
> if(session->display->draw_ready()) {
>     uint width = session->display->draw_width;
>     uint height = session->display->draw_height;
>     uchar4 *pixels = session->display->rgba_byte.data();
>     ... do something ...
> }
>
> On Sun, Mar 18, 2018 at 11:43 AM, Guillaume Chéreau <
> guillaume.chereau at gmail.com> wrote:
>
>> OK after some more tests it seems to me that the easiest would be to
>> create my own CPUDevice subclass and overload the draw_pixels method
>> to render into my own texture, then somehow set this as the session
>> device.
>> Does that make sense, or am I going to run into some subtle bugs with
>> this approach?
>>
>> Regards,
>> - Gui
>>
>> On Sun, Mar 18, 2018 at 2:31 AM, Lukas Stockner
>> <lukas.stockner at freenet.de> wrote:
>> > Answers inline.
>> >
>> > On 17.03.2018 18:10, Guillaume Chéreau wrote:
>> >>
>> >> On Sat, Mar 17, 2018 at 11:01 PM, Lukas Stockner
>> >> <lukas.stockner at freenet.de> wrote:
>> >>>
>> >>> - Are you fine with getting a raw float buffer?
>> >>
>> >> Yes that's fine, I can easily do the conversion to RGB.
>> >
>> > Okay, that makes things easier because you can just process the
>> > RenderBuffers directly and don't have to mess around with the
>> film_convert
>> > kernels.
>> >>>
>> >>> - Are you using interactive rendering?
>> >>
>> >> Yes, I am looking for the same kind of rendering as in Blender, where
>> >> we start we a low res version and progressively improve it, if the
>> >> user changes the scene of the camera position, the rendering is reset.
>> >> It works more or less out of the box with the session->draw method,
>> >> but it is using OpenGL to do the rendering directly on screen. What -I
>> >> think- I want is to get the raw data and add put it into a dynamic
>> >> texture that I can integrate into goxel rendering.
>> >>
>> >>> - Do you want to support multiple devices?
>> >>
>> >> Not sure what that means.  I only want to render on screen, and also
>> >> into a file for export.
>> >
>> > I was referring to the MultiDevice functionality, which is currently
>> used
>> > for rendering on multiple GPUs at once (and might in the future be used
>> for
>> > network rendering). The problem with that is that each device has its
>> own
>> > memory space, so you can't just write all tiles into a single buffer -
>> you'd
>> > have to allocate per-tile buffers, copy them back to the host and then
>> > combine them there (which is what Blender does when doing a
>> non-interactve
>> > render).
>> >
>> > Technically it is possible to allocate a single large buffer (on every
>> > device), have them write into it and then copy the right parts from the
>> > right devices to assemble it directly without moving stuff around, but
>> since
>> > you can only copy back linear memory regions you'd have to modify
>> tiling to
>> > split the image into horizontal slices (one slice per device). In fact,
>> that
>> > is what Cycles currently does for viewport previews since OpenGL drawing
>> > also works better that way.
>> >>>
>> >>> The easiest approaches I can think of right now are either using a
>> shared
>> >>> RenderBuffer for all tiles (already sort of implemented in
>> session.cpp)
>> >>> or
>> >>> just copying the pixels from their buffers into your shared buffer
>> >>> similar
>> >>> to how Cycles for Blender does it in
>> >>> BlenderSession::do_write_update_render_result.
>> >>
>> >> OK thanks for the tips, I will have a look at that.
>> >> - Gui
>> >> _______________________________________________
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>> >> Bf-cycles at blender.org
>> >> https://lists.blender.org/mailman/listinfo/bf-cycles
>> >
>> >
>> > _______________________________________________
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>>
>>
>>
>> --
>> Guillaume
>> guillaume.chereau at gmail.com
>> +886 970422910
>> _______________________________________________
>> Bf-cycles mailing list
>> Bf-cycles at blender.org
>> https://lists.blender.org/mailman/listinfo/bf-cycles
>>
>
>
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