[Interest] [qt3d] Batching optimization

[Sean Harmer]

Hi Xavier,

On 23/09/2016 17:13, Xavier Bigand wrote:
> Hi,
>
> Does qt3d backend capable to batch geometries to reduce the number of
> draw calls?
>
> In our case this optimization should improve performances a lot, because
> we generate dynamically geometries that doesn't change often and are
> created in world coordinates (no transformations applied).

Qt 3D does not yet do batching automatically. However we do support 
stuff that may help you.

* You can use instancing if you have GL 3.2 or newer
* You can do your own batching by putting such geometry into a single 
buffer, either

** to be rendered as a single entity if you don't need interaction with 
the individual parts or
** to be rendered as separate entities with GeometryRenderer's all 
referencing the same Buffer.

The latter doesn't reduce the draw call count but does minimise the 
state changes related to binding different buffers.

We hope to add automatic batching in the future but we're still looking 
into a nice API to expose this without reducing the control the user has 
over organising their data.

Cheers,

Sean

>
>
>
> --
> Xavier
>
>
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