Hi Gil,
With an FBO with multiple textures attached each texture will still have
the same pixels rasterised. You can't draw different cameras and scenes
into each texture at the same time. Well something like that can be done
with some advanced use of the geometry shader but I don't think that's
the case here.
If you want to draw 3 different scenes into 3 different textures you
will need 3 different sub-trees in your framegraph. Each one will set
the camera to use, the filters to select the subset of the scene graph
to draw and the FBO with the target texture to render into.
Cheers,
Sean
On 01/08/2019 18:42, 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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