[mapserver-users] arrow head doesn't draw at the end

[Puneet Kishor]

On Sep 28, 2011, at 8:32 AM, Mr. Puneet Kishor wrote:

> 
>>>>>> ..
>>>>>> 
>>>>>> On 9/27/2011 4:12 AM, Puneet Kishor wrote:
>>>>>>> My arrows look like so -->-- instead of ---->  with declarations like so
>>>>>>> 
>>>>>>>   SYMBOL
>>>>>>>       NAME "vert-line"
>>>>>>>       TYPE vector
>>>>>>>       POINTS
>>>>>>>           0 1
>>>>>>>           0 0
>>>>>>>       END
>>>>>>>   END
>>>>>>> 
>>>>>>>    SYMBOL
>>>>>>>       NAME "up"
>>>>>>>       TYPE vector
>>>>>>>       POINTS
>>>>>>>           0 1
>>>>>>>           0.5 0
>>>>>>>           1 1
>>>>>>>       END
>>>>>>>   END
>>>>>>> 
>>>>>>>   CLASS
>>>>>>>       STYLE
>>>>>>>           SYMBOL 'vert-line'
>>>>>>>           ANGLE [az]
>>>>>>>           SIZE [rate]
>>>>>>>           COLOR 0 0 0
>>>>>>>           WIDTH 1
>>>>>>>       END
>>>>>>>       STYLE
>>>>>>>           SYMBOL "up"
>>>>>>>           ANGLE [az]
>>>>>>>           SIZE 5
>>>>>>>           GEOMTRANSFORM "end"
>>>>>>>           COLOR 0 0 0
>>>>>>>       END
>>>>>>>   END
>>>>>>> 
>>>>>>> But, at least the arrow heads are aligned correctly. Because, if I use
>>>>> "ANGLE auto" as prescribed in the docs instead of "ANGLE [az]" as shown
>>>>> above, my arrows draw like so --^--. The heads are always pointed up, and
>>>>> are in the middle.
>>>>>>> 
>>>>>>> Suggestions?
>>>>> 

Time to show my full hand --

- go to http://mumbai.geology.wisc.edu/geoplates/
- zoom out two clicks so the entire world is visible
- click on the round grey button with the arrow pointing NW in the top left 
  (just below the blue pan/zoom buttons)
- now click once on the map, say, on North America

The GPS readings load as arrow symbols. This is an OpenLayers vector layer, each point being drawn using an external graphic. The problem is speed. Not only does it take a perceptible time to load, when it has loaded, the entire map is very sluggish repainting as you pan and zoom.

Now, go to http://mumbai.geology.wisc.edu/test/gps_vecs.html where I have the same layer being loaded by MapServer. It is much quicker, but, most important, since these are images, the map is really responsive. Of course, the markers are no good. My style definition is as shown below.

Of course, I can use the same externalGraphic with MapServer as the one I used with OpenLayers. But that also doesn't produce much joy. The markers get drawn really tiny, for some reason.

--
Puneet Kishor