Examples of correct inputs for draw_polygon

Question

Hello,

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:

#ROOM.GD
extends Node2D

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

func _ready():
    add_to_group("rooms")
    set_process(true)
    pass

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):
    update()

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?

Answer 1

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.