[Qgis-user] Understanding the rule-based renderer

[Andreas Neumann]

 It would make sense for very well-known datasets with a fixed 
 structure. Potential candidates are national survey datasets that are 
 widely used or OpenStreetMap data.

 In my case, the rendering rules are very specific to my own data 
 structure. It wouldn't make sense to share them.

 Andreas

 On Fri, 8 Apr 2011 05:37:52 -0700, Sam Vekemans wrote:
> Hi,
> Is their a list somewhere which shows all of the rendering rules 
> which
> people are using (the beginings of a standards system)?
>
>
> Thanks,
> Sam
>
> On 4/8/11, Martin Dobias <wonder.sk at gmail.com> wrote:
>> On Fri, Apr 8, 2011 at 11:36 AM, Andreas Neumann 
>> <a.neumann at carto.net>
>> wrote:
>>> Hi,
>>>
>>> I am trying to better understand the rule based renderer.
>>>
>>> Which version is correct?
>>>
>>> a) QGIS is rendering all features of the first rule, then the 
>>> second rule,
>>> etc, Features of the first rule are rendered first, features of the 
>>> second
>>> rule on top of features from the first rule
>>> b) QGIS is rendering each feature on by one and decides which rule
>>> applies.
>>>
>>> I hope it is not version b), I hoped it behaves like version a) but 
>>> it
>>> behaves a bit odd with my data. For my data it seems like the order 
>>> of the
>>> rule has no influence on the rendering order ;-(
>>
>> Hi Andreas
>>
>> the rule based renderer uses the b) option: it goes through the
>> features one by one and applies all matching rules (in the order in
>> which they appear). Mayeul Kaufmann has done some work in order to
>> support option a) by implementing support for symbol levels so that
>> the rendering order can be overridden.
>>
>> My ultimate goal is to only support the option a) in a way how SLD
>> specifies it: rules are grouped and these groups are rendered one
>> after each other.
>>
>> Regards
>> Martin
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>>

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 Andreas Neumann
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