[Interest] Qt3D Multiple color targets not working

[Paul Lemire]

Hi Gil,

I'm pretty sure that's because you are using the PhongMaterial which
only writes to Depth and Color0. You'd need to have your own material
which writes to 3 different outputs to properly populate the 3 color
attachments.

Paul

On 8/1/19 7:42 PM, Gil H wrote:
>
> Hello everyone, I’m sure I’m doing something wrong here, but
> basically, I’m trying to render multiple frame graph subtrees into
> multiple texture targets, and then draw those as part of the final
> scene (kind of like seeing security camera feeds on a few textured
> quads).  Attached is my minimal test app which shows that only
> textures attached to Color0 seem to contain anything.  Is it because
> the surface is a QWindow?  I’ve tried a more complicated example with
> an offscreen render surface and an FBO with multiple color attachments
> added to it, but the textures I got back from that were still empty.
>
>  
>
> Tested this on Mac with Qt 5.13.0.
>
>  
>
> If anyone is curious about why you would want to do this, I need to
> render up to 3 different Qt3D scenes for integration into an external
> GL engine.  So different camera views and scene sub-trees need to be
> drawn onto separate textures each frame.
>
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-- 
Paul Lemire | paul.lemire at kdab.com | Senior Software Engineer
KDAB (France) S.A.S., a KDAB Group company
Tel: France +33 (0)4 90 84 08 53, http://www.kdab.fr
KDAB - The Qt, C++ and OpenGL Experts

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