bloodstain improvements. work during pause for player, vastly more efficient

autoloads/stain_layer.gd

@@ -0,0 +1,17 @@
+extends Light2D
+
+
+onready var viewport: Viewport = $Viewport
+
+
+func _process(delta: float) -> void:
+	var main_viewport = get_viewport()
+	if viewport.canvas_transform != main_viewport.canvas_transform:
+		viewport.canvas_transform = main_viewport.canvas_transform
+		transform = main_viewport.canvas_transform.inverse()
+		viewport.render_target_update_mode = Viewport.UPDATE_ONCE
+
+
+func add_stain(stain: Node2D) -> void:
+	viewport.add_child(stain)
+	viewport.render_target_update_mode = Viewport.UPDATE_ONCE

autoloads/stain_layer.tscn

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+[gd_scene load_steps=3 format=2]
+
+[ext_resource path="res://autoloads/stain_layer.gd" type="Script" id=1]
+
+[sub_resource type="ViewportTexture" id=1]
+viewport_path = NodePath("Viewport")
+
+[node name="StainLight" type="Light2D" groups=["viewport_autoload"]]
+texture = SubResource( 1 )
+offset = Vector2( 128, 96 )
+mode = 2
+range_item_cull_mask = 2
+script = ExtResource( 1 )
+
+[node name="Viewport" type="Viewport" parent="."]
+size = Vector2( 256, 192 )
+transparent_bg = true
+disable_3d = true
+usage = 1
+render_target_v_flip = true
+render_target_update_mode = 1