Thanks Paul.  My understanding of how to accomplish that would be to create an 
Effect with multiple RenderPasses and then in the framegraph specify a filter 
for each pass and the output surface for it.  Is that all?  I don’t see 
anything in the shaders that is specific to the attachment… is anything needed 
on that side of things?

 

Gil

 

 

From: Paul Lemire <paul.lem...@kdab.com>
Date: Monday, August 5, 2019 at 2:36 AM
To: Gil H <q...@tastytech.ca>, Qt Interest <interest@qt-project.org>
Subject: Re: [Interest] Qt3D Multiple color targets not working

 

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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