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@jshorty

jshorty/snapshot_sprite.gd

Created April 5, 2020 08:29
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Sprite that "snapshots" a Polygon2D for rendering performance
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snapshot_sprite.gd
extends Sprite
# This dictates the size of the viewport used for the "snapshot".
export var source_image_size : Vector2
export var polygon : PoolVector2Array
func _ready():
var viewport_container = ViewportContainer.new()
viewport_container.set_size(source_image_size)
add_child(viewport_container)
# Additional optimizations can be made on the viewport's properties,
# depending on the use case.
var viewport = Viewport.new()
viewport.set_size(source_image_size)
viewport_container.add_child(viewport)
var polygon_2d = Polygon2D.new()
polygon_2d.set_polygon(polygon)
viewport.add_child(polygon_2d)
# Need to yield here when "snapshotting" the first frame of a scene.
# As described in issue https://github.com/godotengine/godot/issues/19239
yield(get_tree(), "idle_frame")
yield(get_tree(), "idle_frame")
var image = viewport.get_texture().get_data()
image.flip_y()
var texture = ImageTexture.new()
texture.create_from_image(image)
set_texture(texture)
# Don't need any of this any longer!
viewport_container.queue_free()
@jshorty
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jshorty commented Apr 17, 2020

Note that if the instance is freed while yielding, this will cause errors. An option to avoid this is to overload the definition of queue_free() and poll an instance variable, since the yield is just for a couple frames (not entirely sure how well this scales):

var is_yielding = false

func queue_free():
  if !is_yielding:
    .queue_free()
  else:
    queue_free()

func _ready():
  ...
  is_yielding = true
  yield(get_tree(), "idle_frame")
  yield(get_tree(), "idle_frame")
  is_yielding = false
  ...

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