MapServer symbol with triangle

Question

I am looking for solution to style the symbol in MapServer; with polygon outlined with simple line along with filled triangle inward like below

; I tried creating symbol with following way

SYMBOL
  NAME "Inward line"
  TYPE vector
  POINTS
   0   0
    5  10
    10  0
        
    
  END # POINTS
  ANCHORPOINT 0.5 0
END # SYMBOL

with line symbols adding together,. but no luck,.

Answer 1

You should close the triangle adding the start point to the end. In your sample image the triangle is filled so you should add FILLED:

SYMBOL
  NAME "Inward_line"
  TYPE vector
  FILLED true
  POINTS
    0   0
    5  10
   10   0
    0   0    
  END # POINTS
  ANCHORPOINT 0.5 0
END # SYMBOL

In the layer definition:

LAYER
  STATUS DEFAULT
  TYPE LINE
  FEATURE
    POINTS     # sample rectangle
      10 10
      90 10
      90 60
      10 60
      10 10
    END # POINTS
  END # FEATURE
  CLASS
    STYLE                 # simple line
      COLOR 0 0 0
    STYLE                 # triangles
      SYMBOL "Inward_line"
      COLOR 0 0 0
      OFFSET 15 -99       # offset perpendicular to the line
      GAP -15              # distance from center to center, negative to rotate
    END # STYLE
  END # CLASS
END # LAYER

Be careful I didn't test it!