[Qgis-developer] Discussion: could Ice be used in Qgis ?

[Matthias Kuhn]

Hi

On 07/23/2015 10:22 AM, Hugo Mercier wrote:
> On 22/07/2015 21:26, Tim Sutton wrote:
>> Hi
>>
>>> On 22 Jul 2015, at 14:52, Paolo Cavallini <cavallini at faunalia.it
>>> <mailto:cavallini at faunalia.it>> wrote:
>>>
>>> Il 22/07/2015 11:48, Julien Michel ha scritto:
>>>> Hi Qgis developers,
>>>>
>>>> I wrote a small library called Ice which is able to render raster (and
>>> Hi all,
>>> I have seen ti in action during the recent FOSS4G, and I have been
>>> really impressed by its speed and capabilities. I think it would be a
>>> grat addition to QGIS, as either a main or alternative renderer.
>> As nice as the idea is, I think it will be quite a massive undertaking
>> and we would break all the beautiful (ok and ugly) cartography that
>> people have come up with using the rich array of rendering styles that
>> QGIS currently has.  I would also like to see a native OpenGL renderer
>> one day so that we can start to thing about native 3D support. Maybe it
>> would be nice to make a patch that lets you swap between Qt rendering
>> backend and Ice, but honestly its probably a lot of work and may just
>> fade away like the old mapnick renderer did…
>>
> I agree.
> To go toward OpenGL and then 3D support, we may start by finding a way
> to send 2D draw primitives to an OpenGL context. This way we would have
> all the current QGIS symbology support and it will be transparent for
> the end user.
> I may be wrong, but I think it will cost less than trying to integrate
> another library (like Ice).
>
>

The idea I have in mind for going towards OpenGL is to first send all
layers as rasterized images to it, so the only thing that OpenGL needs
to do is resize/translation for interactive zooming/panning and blending.

Then we could start to implement certain (simple) renderers directly in
OpenGL. This way we would still have the full-blown symbology for
complex layers and an increased UX while navigating with e.g. district
boundaries with simple symbology but rendered as vectors on the GPU from
a local cache.

I am not sure how much effort it would be to do that with Ice.
It looks amazing but I assume it was not developed with QGIS styling,
iterator and the rest of the QGIS API in mind. I imagine it will be
quite hard to re-wire all the internals of the two applications/libs to
play together nicely.

Kind regards
Matthias


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