Rotating a symbol/layer drawn with PointObj

[Kasey Kirkham]

Hello,
 
Long, long ago, I posted to this forum asking for guidance on drawing a
point layer(
http://mapserver.gis.umn.edu/data2/wilma/mapserver-users/0403/msg00562.html
).  Thanks to the help of the folks on this list, I was able to get the
application working.  First off, I created a layer for each symbol I wanted
to use(in the mapfile, see below).  The php app which uses the mapfile will
create a new PointObj for each coordinate returned by a query,  look up the
name of the symbol layer associated with the gps source, then call
PointObj->draw with the layer as an argument(see my equally inscrutable code
fragment below).  This works nicely for drawing dots on the map, however
there is now a new twist.  I would like to use triangular symbols in my
layer, rotated relative to the point which follows.  For instance, if the
first coordinate was (1,1), and the second was (5,1), I would like to rotate
the first symbol to the right by 90 degrees so that it is "pointing" at the
second symbol.  I think labels support this with the "angle" attribute, but
I didn't find anything in the documentation indicating that points/symbols
could be rotated in the same way.  Any ideas?
 
A million thanks!
Kasey
 
# mapfile fragment: 
 
  # LAYER object
  LAYER
    NAME "point_mapping-red"
    TYPE POINT
    STATUS ON
    # CLASS object
    CLASS
      NAME "points_red"
      SYMBOL "gps_coordinate-red"
      COLOR 255 0 0
      # LABEL object
      LABEL
        POSITION CC
        SIZE TINY
        MINDISTANCE 400
        MINFEATURESIZE 5
        COLOR 255 255 255
        PARTIALS FALSE
      END
    END
  END
 
// php fragment:
    // retrieve associative array of gps coordinates
    $point_array = $currObjUnit->get_gps_coordinates();
    // loop through array
    foreach($point_array as $arPoints) {
        // get a new point object         
        $pointObj_coord1 = ms_newPointObj(); 

        // set the X and Y coords
        $pointObj_coord1->setXY($arPoints["longitude"],
$arPoints["latitude"]); 

        // $map is returned by ms_newMapObj()
        // $currObjUnit->get_unit_symbol retrieves the LAYER NAME attribute
for the layer indicated in the unit config(ie "point_mapping-red" in this
case)
        $layerObj_imageSymbol =
$map->getLayerByName($currObjUnit->get_unit_symbol());

        $class_index = 0;
        // draw the point
        // $map is a MapObj, $image is the image object returned by
$map->draw
        $pointObj_coord1->draw($map, $layerObj_imageSymbol, $image,
$class_index, '');     
    }
 
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