grid multi mesh instance 3d

addons/nodot/mesh/GridMultiMeshInstance3D.gd

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+@tool
+class_name GridMultiMeshInstance3D extends MultiMeshInstance3D
+
+@export var source_mesh: MeshInstance3D: set = _set_source_mesh
+@export var rows: int = 10: set = _set_rows
+@export var columns: int = 10: set = _set_columns
+@export var depth: int = 1: set = _set_depth
+@export var spacing: float = 0.1: set = _set_spacing
+@export var mesh_scale: float = 1.0: set = _set_mesh_scale
+
+func _init():
+	multimesh = MultiMesh.new()
+
+	# Assuming each mesh is a 3D Vector (x, y, z)
+	multimesh.transform_format = MultiMesh.TRANSFORM_3D
+
+	recalculate_transforms()
+
+func _set_source_mesh(new_value: MeshInstance3D):
+	source_mesh = new_value
+	multimesh.mesh = source_mesh.mesh
+
+func _set_rows(new_value: int):
+	rows = new_value
+	calculate_instances()
+	recalculate_transforms()
+
+func _set_columns(new_value: int):
+	columns = new_value
+	calculate_instances()
+	recalculate_transforms()
+
+func _set_depth(new_value: int):
+	depth = new_value
+	calculate_instances()
+	recalculate_transforms()
+
+func _set_spacing(new_value: float):
+	spacing = new_value
+	recalculate_transforms()
+
+func _set_mesh_scale(new_value: float):
+	mesh_scale = new_value
+	recalculate_transforms()
+
+func calculate_instances():
+	multimesh.instance_count = rows * columns * depth
+
+func recalculate_transforms():
+	# Create a PackedFloat32Array for positions
+	var transforms := PackedFloat32Array()
+
+	var offset_x = -(columns - 1) * spacing / 2
+	var offset_y = -(depth - 1) * spacing / 2  # Offset for depth
+	var offset_z = -(rows - 1) * spacing / 2
+
+	# Calculate positions and add them to the array
+	for depth_level in range(depth):
+		for row in range(rows):
+			for column in range(columns):
+				var x: float = column * spacing + offset_x
+				var y: float = depth_level * spacing + offset_y  # Position along the y-axis
+				var z: float = row * spacing + offset_z
+
+				# Manually construct the array for the transform
+				var transform_array: Array[float] = [
+					mesh_scale, 0.0, 0.0, x,  # First column with scaling and x translation
+					0.0, mesh_scale, 0.0, y,  # Second column with scaling and y translation
+					0.0, 0.0, mesh_scale, z   # Third column with scaling and z translation
+				]
+
+				transforms.append_array(transform_array)
+
+	# Assign the transforms to the multimesh
+	multimesh.buffer = transforms
+