Rotating Symbols

Mon May 29 11:33:07 EDT 2006

Blaise,

Is it possible - do you think - to create these fields on the fly? I 
don;t really want to have to require people to create a 'fake' point 
shapefile - just to use these symbols - I would prefer somehow to make a 
new point layer from the old one (whose source isn't always a shapefile) 
- and then perhaps dynamically add those values to it. The Mapscript API 
says that the 'values' array is read-only? is it possible to add new 
fields to the attribute table - especially if I have created the layer 
using ms_newLayerObj?

If not then I will definitely use your suggestion - and perhaps submit a 
bug report asking why the 'angle' property isn;t available - even tho in 
the API it says it should be!

Stu

Blaise wrote:
> Stu
> I've got symbols rotated :
> mapserver 4.8.3,
> point shapefile:"rotlabel", dbf with 2 fields : "ID" and "rotation"
> field rotation is numeric, 3 digits, no decimal (0->359)
> Layer definition in mapfile :
> LAYER
>   NAME rotlabel
>   TYPE POINT
>   STATUS ON
>   DATA rotlabel
>   CLASS
>     NAME "rotlabel"
>     STYLE
>       SYMBOL 'triangle'
>       ANGLEITEM "rotation"
>       SIZE 15
>       COLOR 255 0 255
>     END
>   END
> END 
>
> Triangle definition in symbol file (symbols.sym) :
> Symbol
> Name 'triangle'
> Type VECTOR
> Filled TRUE
> Points
> 0 1
> .5 0
> 1 1
> 0 1
> END
> END 
>
> No on-the-fly label drawing, just basic layer display. When updating data in 
> the "rotation" field of the dbf, triangles are rotating...
> One strange thing is with angle 90 and 180 : triangles don't display. 89, 91, 
> 179, 181 are ok, but not 90 and 180. 270 is ok as well.
> You should easily custom the triangle symbol into whatever you want (arrow or 
> else).
> Better check that your symbol is displayed for any angle (0->359). There must 
> be some kind of bug somewhere. Maybe you'll help discovering it.
> I hope this is what you were looking for.
> Regards
> Blaise
>
>
> Le Samedi 27 Mai 2006 17:47, Stuart Eve a écrit :
>   
>> Blaise
>>
>> I am working with shapefiles - but am going to need to do this with all
>> different types of layers (trying to abstract it out). I have just added
>> the 'angle' field to the dbf to try it out and I am still getting the
>> same error.
>>
>> It seems that the styleObj thinks it doesn't have the member of 'angle'
>> (or actualy 'angleitem') even though in my mapfile (which I
>> automatically output by using $map->save) it has written it like this:
>>
>>  STYLE
>>         ANGLE 360
>>         COLOR 0 0 0
>>         SIZE 8
>>         SYMBOL "rot_tri"
>>   END
>>
>> I am now trying to go through the process of automatically creating the
>> rotated symbol on the fly (but the logic of it makes my head hurt!).
>>
>> Thanks for your help so far!
>>
>> Stu
>>
>> Blaise wrote:
>>     
>>> Hi Stu
>>> What kind of layer do you use for your symbols, point or annotation ? I
>>> assume it's a shapefile (*.shp, *.shx, *.dbf) isn't it ? I don't remember
>>> exactly how annotation layers work but it must be the same as point. With
>>> point layers, you have to have an "angle" field (numeric, 3 digits
>>> without decimal, I believe, not sure) in your dbf file, or maybe better
>>> "ANGLE" to be able to set the angle. Do you have this field in the dbf
>>> and if not can you try adding it ?
>>> And do you have the right angle instructions in the layer section of your
>>> mapfile ? If not sure, post your mapfile layer section.
>>> Bravo for the work so far.
>>> Blaise
>>>
>>> Le Samedi 27 Mai 2006 16:58, Stuart Eve a écrit :
>>>       
>>>> Hi Blaise
>>>>
>>>> I have managed to get quite a long way down the road of extracting
>>>> points and placing them, etc.- and I think its all going to work -
>>>> however I have just been stumped by what seems to be to be a bug.
>>>>
>>>> I have managed to set up classes for each of the points that I wish to
>>>> draw - and now want to set their styles so that the symbol (a VECTOR)
>>>> symbol is rotated to the angle (which I have got from my geometry
>>>> function). However, whenever I try to access styleObj->set("angle",45)
>>>> it says that 'angle' doesn't exist in that object. However, I can dump
>>>> out the mapfile and it is there set as 360.
>>>>
>>>> Any ideas whats going on?
>>>>
>>>> Thanks
>>>>
>>>> Stu
>>>>
>>>> Blaise wrote:
>>>>         
>>>>> Stu
>>>>> I don't know what output you want exactly, but yes, using mapscript,
>>>>> you can easily put an arrow on each segment of a polyline with a loop
>>>>> something like :
>>>>> for each polyline
>>>>>  for each segment of polyline
>>>>>   get start and stop point of segment
>>>>>   calculate middle point of segment and angle
>>>>>   create new annotation arrow
>>>>>
>>>>> The geometry calculation is pretty straight forward, it's basic 2d
>>>>> geometry. Ask more if you need help on the mapscript functions and/or
>>>>> the geometry calculation.
>>>>> But maybe someone else on this list has got a better/different idea.
>>>>> Regards
>>>>> Blaise
>>>>>
>>>>> Le Vendredi 26 Mai 2006 16:41, vous avez écrit :
>>>>>           
>>>>>> Blaise
>>>>>>
>>>>>> Thanks for the reply. I presume that we could automatically create a
>>>>>> bunch of points along the line using mapscript or something - but then
>>>>>> how would we make sure that it was always at right angles to the line?
>>>>>> I guess we would have to do some fancy geometry to figure out what
>>>>>> angle that section of line was... sounds hard!
>>>>>>
>>>>>> Mind you it may be the only way - thanks for your help!
>>>>>>
>>>>>> Stu
>>>>>>
>>>>>> Blaise wrote:
>>>>>>             
>>>>>>> Le Vendredi 26 Mai 2006 16:23, Stuart Eve a écrit :
>>>>>>>               
>>>>>>>> Dear All,
>>>>>>>>
>>>>>>>> We have been trying to get symbols to rotate along a line in
>>>>>>>> mapserver (4.8.3). Basically we want to get a small triangle
>>>>>>>> pointing either 45 degrees or 270 degrees to a line.
>>>>>>>>
>>>>>>>> We firstly tried using PIXMAPs - but I don;t think its possible to
>>>>>>>> rotate these at all (is that true?) plus they do not seem to follow
>>>>>>>> the line and always just point 'up'.
>>>>>>>>
>>>>>>>> So we then tried using some truetype symbols - these follow the line
>>>>>>>> - but seem to be rather erratic as to which way they point. We are
>>>>>>>> using a small triangle from the webdings.ttf set - and sometimes it
>>>>>>>> will point up and sometimes it will point down (but even if its on
>>>>>>>> the same section of the line).
>>>>>>>>
>>>>>>>> Does anyone have any pointers?
>>>>>>>>
>>>>>>>> Thanks in advance
>>>>>>>>
>>>>>>>> Stu
>>>>>>>>                 
>>>>>>> Hi Stu
>>>>>>> Well, not sure about that, but sometimes it's hard to have the
>>>>>>> symbols exactly where you want. Perhaps you could create a special
>>>>>>> layer (point or annotation) to deal with your triangles. It should
>>>>>>> then be easier to manipulate. Of course it's extra data, extra code,
>>>>>>> extra mapfile parsing and so on but you'll have your symbols where
>>>>>>> you want and well rotated. Regards
>>>>>>> Blaise
>>>>>>>               
>
>
>
>   

-- 
Stuart Eve
L - P : Archaeology
stuarteve at lparchaeology.com 