[Interest] How to improve Qt3D rendering for big mesh?

Sean Harmer sean.harmer at kdab.com
Thu Sep 10 10:19:33 CEST 2015

On Thursday 10 Sep 2015 04:15:15 Bin Chen wrote:
> Hi, guys, 
> I am testing Qt3D to render a big triangle mesh,  >1000,000 triangles.
> I put all triangles in one QAbstractMesh subclass and added to a QEntity,
> but it is very slow.
 Then I separate these triangles into a quadtree and
> map them into a QEntity hierarchy. It became even slower and doesn’t seem
> to cull nodes:( 
> I am wondering if I need to compute a QEntity's bounding box myself so the
> framework can cull nodes accordingly.

View frustum culling will land at some point. We know it's missing at present. 
first step is to re-enable calculation of bounding volumes that was 
temporarily disabled in the port to the new buffer API. Laszlo has a patch 
that starts this.

> Any thoughts? 

Do you have the option to use tessellation on your system? If so that's 
probably the best bet for now. Or some other form of level of detail.

If you feel like contributing a LOD system or helping get the culling in place 
in Qt3D then you're more than welcome to help out here. I don't think the 
culling is that difficult to get in place.



Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
KDAB (UK) Ltd, a KDAB Group company
Tel. +44 (0)1625 809908; Sweden (HQ) +46-563-540090
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KDAB - Qt Experts

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