[Qgis-developer] Z or M styling in QGIS

[kimaidou]

Hi all

This is indeed awesome !
Régis, you really should pass this kind of snippet to a broad audience (if
you have time, of course). I do not know if the new QGIS sharing tool is
the right target, or a quick blog post ?

Cheers,
Michaël

2017-01-03 11:31 GMT+01:00 Régis Haubourg <regis.haubourg at gmail.com>:

>
>
> 2017-01-03 5:44 GMT+01:00 Nyall Dawson <nyall.dawson at gmail.com>:
>
>>
>>
>> I'd say the preferred solution would be a 3d viewer using the Qt 3d
>> framework (http://doc.qt.io/qt-5/qt3d-examples.html). Then it could be
>> built in as core functionality instead of as a python plugin (or
>> relying on a js framework). We'd gain lots of benefits to this
>> approach, including:
>> - could be used with a multi-canvas view, with a mix of 2d/3d views
>> - could potentially reuse existing symbology as surface materials
>> - could do nifty things like embedding an interactive 3d view in a
>> composer
>> - could potentially replace the globe plugin
>
>
> Yes I forgot to mention Qt3D. That would be good to know if someone has
> already played with it.
>
>
>
>> So something like:
>> z(point_n($geometry, at geometry_point_num))
>
>
> Thanks for the pointer, That works with that expression on a Marker Line
> easily to draw vertical edges. See the screenshot here
> http://imgur.com/RPtOjMg
>
>
>
>>
>
> Throw that inside some type of data defined override and you can style
>> a geometry's nodes based on their z value.
>>
>> A geometry generator using  segments_to_lines and geometry_n can style
>> a geometries segments based on their z/m values too.
>>
>
> Wow I just realized that you can combine a geometry generator inside a
> marker line. Win!!!
>
> I used that expression, creating a line for each marker with a y
> translation using z value:
>
> make_line( translate(point_n(  $geometry,  @geometry_point_num ), 0 ,
> -z(point_n($geometry, at geometry_point_num)) ), translate( point_n(
>  $geometry,  @geometry_point_num +1  ), 0 , -z(point_n($geometry, at geometry_point_num+1))
> ) )
>
> See http://imgur.com/TlCN7zf
>
>
> and a video just to underline the immediate feedback when editing :)
>
> https://youtu.be/o_lAeKJhRkg
>
>
>
> Thanks again Nyall, QGIS always allows a lot more than we think. So
> great....
>
>
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