added a video player, added a GridContainer

AGUI.StackedUI/AGUI.Sorting/AGUIGridContainer.tscn

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+[gd_scene format=3 uid="uid://difktsmww6qlh"]
+
+[sub_resource type="GDScript" id="GDScript_mjcif"]
+resource_name = "AGUIContainer"
+script/source = "@tool
+extends Node3D
+
+## Number of items per row (X-axis)
+@export var columns: int = 2:
+	set(value):
+		columns = max(1, value)
+		_sort_3d_children()
+
+## Number of rows per layer (Z-axis)
+@export var rows: int = 2:
+	set(value):
+		rows = max(1, value)
+		_sort_3d_children()
+
+## Spacing between 3D objects in units
+@export var cell_size: Vector3 = Vector3(2.0, 2.0, 2.0):
+	set(value):
+		cell_size = value
+		_sort_3d_children()
+
+func _ready():
+	_sort_3d_children()
+	child_order_changed.connect(_sort_3d_children)
+
+func _sort_3d_children():
+	# 1. First pass: Gather valid Node3D children
+	var 3d_children: Array[Node3D] = []
+	for child in get_children():
+		if child is Node3D:
+			3d_children.append(child)
+			
+	var total_items = 3d_children.size()
+	if total_items == 0:
+		return
+
+	var items_per_layer = columns * rows
+
+	# 2. Calculate the actual dimensions used by the current number of items
+	# We use max(1, ...) to avoid multiplying by 0 if there's only 1 item
+	var active_columns = min(total_items, columns)
+	var active_rows = min(ceil(float(total_items) / columns), rows)
+	var active_layers = ceil(float(total_items) / items_per_layer)
+
+	# 3. Calculate the center offset
+	# (Total dimensions - 1) * cell_size / 2 gives us the exact mid-point
+	var offset = Vector3(
+		(active_columns - 1) * cell_size.x,
+		(active_layers - 1) * cell_size.y,
+		(active_rows - 1) * cell_size.z
+	) * 0.5
+
+	# 4. Second pass: Position children and subtract the offset
+	for index in range(total_items):
+		var layer = index / items_per_layer
+		var index_in_layer = index % items_per_layer
+		var col = index_in_layer % columns
+		var row = index_in_layer / columns
+		
+		var local_pos = Vector3(
+			col * cell_size.x,
+			layer * cell_size.y,
+			row * cell_size.z
+		)
+		
+		# Center the position relative to the parent Node3D's origin
+		3d_children[index].position = local_pos - offset
+"
+
+[node name="AguiGridContainer" type="Node3D" unique_id=1053523827]
+script = SubResource("GDScript_mjcif")
+columns = null
+rows = null
+cell_size = null