0 votes


I am hoping to use Node2D.drawpolygon() to draw in a nice overlay for a section of my screen. I am calculating an outline for an area, and feeding that set of points ([Vector2]) to the drawpolygon method. I have verified that the method gets the data correctly and that it looks like a complete shape, but I am getting a "Bad Polygon!" error from the engine.

Here is my code:

extends Node2D

var _outline_polygon = Vector2Array()
var _colors = ColorArray([Color(0,1,0,.5)])
var _drawing = false

func _ready():

func set_polygon(poly_path):
    #generate the polygon that represents this room
    _outline_polygon = poly_path
    print(get_name(), ": ", _outline_polygon)
#   _drawing = true

func _process(delta):

func _draw():
    if _drawing:
        draw_polygon(_outline_polygon, _colors)

Here is an example of the content of the outlinepolygon variable:

room_8: [(256, 448), (320, 448), (320, 448), (384, 448), (384, 448),
(384, 512), (384, 512), (384, 576), (384, 576), (320, 576), (320,
576), (256, 576), (256, 576), (256, 512), (256, 512), (256, 448)]

Here is the error I am getting - sorry about the image link, it is a screen shot. But basically says "Bad Polygon!" and seems to be coming from something called: visualserverraster.cpp in the back end.

Any ideas? What should I be passing into the function to get a nice polygon out on the other side?

in Engine by (41 points)
edited by

1 Answer

+3 votes
Best answer

Your polygon has duplicate points.
After experiencing a bit, I found draw_polygon will work only if those conditions are fulfilled:

  • There must be no duplicate points
  • The area must not be zero
  • The polygon must not fold onto itself
  • The number of points you provide must be the same as the number of colors (even if all colors are the same). The same rule applies to UVs if provided.
by (27,898 points)
selected by
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