Hi Gil, You shouldn't have to actually modify the Material to add in more passes.
What you have to do is edit the fragment shader to have more than 1
color output:
e.g:
out vec4 fragColor1;
out vec4 fragColor2;
out vec4 fragColor3;
void main() {
fragColor1 = color;
fragColor2 = color;
fragColor3 = color;
}
By default the declaration order of the output maps to your attachments:
first output goes to ColorAttachment0, second output to ColorAttachment1 ...
On 8/6/19 6:14 PM, Gil H wrote:
>
> 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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>
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> --
> Paul Lemire | paul.lem...@kdab.com <mailto:paul.lem...@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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--
Paul Lemire | paul.lem...@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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