Detect loops when connecting nodes and make sure Material cannot be deleted

addons/material_maker/engine/gen_base.gd

@@ -37,6 +37,9 @@ var parameters = {}
 func _ready():
 	init_parameters()
 
+func can_be_deleted() -> bool:
+	return true
+
 func init_parameters():
 	for p in get_parameter_defs():
 		if !parameters.has(p.name):
@@ -86,6 +89,13 @@ func get_source(input_index : int):
 func get_targets(output_index : int):
 	return get_parent().get_port_targets(name, output_index)
 
+# get the list of outputs that depend on the input whose index is passed as parameter
+func follow_input(input_index : int) -> Array:
+	var rv = []
+	for i in range(get_output_defs().size()):
+		rv.push_back(OutputPort.new(self, i))
+	return rv
+
 func get_input_shader(input_index : int):
 	var source = get_source(input_index)
 	if source != null:

addons/material_maker/engine/gen_graph.gd

@@ -49,7 +49,7 @@ func get_port_source(gen_name: String, input_index: int) -> OutputPort:
 					return OutputPort.new(src_gen, c.from_port)
 	return null
 
-func get_port_targets(gen_name: String, output_index: int) -> InputPort:
+func get_port_targets(gen_name: String, output_index: int) -> Array:
 	var rv = []
 	for c in connections:
 		if c.from == gen_name and c.from_port == output_index:
@@ -83,6 +83,15 @@ func replace_generator(old : MMGenBase, new : MMGenBase):
 	add_child(new)
 
 func connect_children(from, from_port : int, to, to_port : int):
+	# check the new connection does not create a loop
+	var spreadlist = [ InputPort.new(to, to_port) ]
+	while !spreadlist.empty():
+		var input : InputPort = spreadlist.pop_front()
+		for o in input.generator.follow_input(input.input_index):
+			if o.generator == from and o.output_index == from_port:
+				return false
+			for t in o.generator.get_parent().get_port_targets(o.generator.name, o.output_index):
+				spreadlist.push_back(t)
 	# disconnect target
 	while true:
 		var remove = -1
@@ -198,6 +207,6 @@ func create_subgraph(gens):
 	connections = my_new_connections
 	new_graph.connections = new_graph_connections
 	for g in generators:
-		if g is MMGenRemote:
+		if g.get_script() == load("res://addons/material_maker/engine/gen_remote.gd"):
 			g.name = "gen_parameters"
 			break

addons/material_maker/engine/gen_material.gd

@@ -21,6 +21,9 @@ func _ready():
 		generated_textures[t.texture] = null
 	material = SpatialMaterial.new()
 
+func can_be_deleted() -> bool:
+	return false
+
 func get_type():
 	return "material"
 

addons/material_maker/engine/loader.gd

@@ -31,7 +31,7 @@ static func add_to_gen_graph(gen_graph, generators, connections):
 		if gennames.has(c.from) and gennames.has(c.to):
 			c.from = gennames[c.from]
 			c.to = gennames[c.to]
-			gen_graph.connections.append(c)
+			if gen_graph.connect_children(gen_graph.get_node(c.from), c.from_port, gen_graph.get_node(c.to), c.to_port):
 				rv.connections.append(c)
 	return rv
 

addons/material_maker/main_window.tscn

@@ -41,35 +41,35 @@ margin_bottom = 20.0
 margin_right = 35.0
 margin_bottom = 20.0
 text = "File"
-items = [ "New material", null, 0, false, false, 0, 0, null, "", false, "Load material", null, 0, false, false, 1, 134217807, null, "", false, "", null, 0, false, false, -1, 0, null, "", true, "Save material", null, 0, false, false, 4, 134217811, null, "", false, "Save material as...", null, 0, false, false, 5, 167772243, null, "", false, "Save all materials...", null, 0, false, false, 6, 0, null, "", false, "", null, 0, false, false, -1, 0, null, "", true, "Export material", null, 0, false, false, 8, 134217797, null, "", false, "", null, 0, false, false, -1, 0, null, "", true, "Close material", null, 0, false, false, 10, 0, null, "", false, "Quit", null, 0, false, false, 11, 134217809, null, "", false ]
+items = [ "New material", null, 0, false, false, 0, 0, null, "", false, "Load material", null, 0, false, false, 1, 268435535, null, "", false, "", null, 0, false, false, -1, 0, null, "", true, "Save material", null, 0, false, false, 4, 268435539, null, "", false, "Save material as...", null, 0, false, false, 5, 301989971, null, "", false, "Save all materials...", null, 0, false, false, 6, 0, null, "", false, "", null, 0, false, false, -1, 0, null, "", true, "Export material", null, 0, false, false, 8, 268435525, null, "", false, "", null, 0, false, false, -1, 0, null, "", true, "Close material", null, 0, false, false, 10, 0, null, "", false, "Quit", null, 0, false, false, 11, 268435537, null, "", false ]
 
 [node name="Edit" type="MenuButton" parent="VBoxContainer/Menu"]
 margin_left = 39.0
 margin_right = 75.0
 margin_bottom = 20.0
 text = "Edit"
-items = [ "Cut", null, 0, false, false, 12, 134217816, null, "", false, "Copy", null, 0, false, false, 13, 134217795, null, "", false, "Paste", null, 0, false, false, 14, 134217814, null, "", false ]
+items = [ "Cut", null, 0, false, false, 12, 268435544, null, "", false, "Copy", null, 0, false, false, 13, 268435523, null, "", false, "Paste", null, 0, false, false, 14, 268435542, null, "", false ]
 
 [node name="View" type="MenuButton" parent="VBoxContainer/Menu"]
 margin_left = 79.0
 margin_right = 121.0
 margin_bottom = 20.0
 text = "View"
-items = [ "Cut", null, 0, false, false, 12, 134217816, null, "", false, "Copy", null, 0, false, false, 13, 134217795, null, "", false, "Paste", null, 0, false, false, 14, 134217814, null, "", false ]
+items = [ "Center view", null, 0, false, false, 15, 67, null, "", false, "Reset zoom", null, 0, false, false, 16, 268435504, null, "", false ]
 
 [node name="Tools" type="MenuButton" parent="VBoxContainer/Menu"]
 margin_left = 125.0
 margin_right = 171.0
 margin_bottom = 20.0
 text = "Tools"
-items = [ "Create", null, 0, false, false, -1, 0, null, "PopupMenu", false, "Create group", null, 0, false, false, 16, 134217799, null, "", false, "Make selected nodes editable", null, 0, false, false, 17, 134217798, null, "", false, "", null, 0, false, false, -1, 0, null, "", true, "Add selected node to user library", null, 0, false, false, 19, 0, null, "", false, "Save user library", null, 0, false, false, 20, 0, null, "", false ]
+items = [ "Create", null, 0, false, false, -1, 0, null, "PopupMenu", false, "Create group", null, 0, false, false, 18, 268435527, null, "", false, "Make selected nodes editable", null, 0, false, false, 19, 268435526, null, "", false, "", null, 0, false, false, -1, 0, null, "", true, "Add selected node to user library", null, 0, false, false, 21, 0, null, "", false, "Save user library", null, 0, false, false, 22, 0, null, "", false ]
 
 [node name="Help" type="MenuButton" parent="VBoxContainer/Menu"]
 margin_left = 175.0
 margin_right = 217.0
 margin_bottom = 20.0
 text = "Help"
-items = [ "User manual", null, 0, false, false, 21, 0, null, "", false, "Report a bug", null, 0, false, false, 22, 0, null, "", false, "", null, 0, false, false, -1, 0, null, "", true, "About", null, 0, false, false, 24, 0, null, "", false ]
+items = [ "User manual", null, 0, false, false, 23, 0, null, "", false, "Report a bug", null, 0, false, false, 24, 0, null, "", false, "", null, 0, false, false, -1, 0, null, "", true, "About", null, 0, false, false, 26, 0, null, "", false ]
 
 [node name="HBoxContainer" type="HSplitContainer" parent="VBoxContainer"]
 margin_top = 24.0

addons/material_maker/nodes/generic.gd

@@ -2,7 +2,7 @@ tool
 extends GraphNode
 class_name MMGraphNodeGeneric
 
-var generator = null setget set_generator
+var generator : MMGenBase = null setget set_generator
 
 var controls = {}
 var ignore_parameter_change = ""
@@ -152,6 +152,8 @@ func update_node():
 		remove_child(c)
 		c.free()
 	rect_size = Vector2(0, 0)
+	# Show or hide the close button
+	show_close = generator.can_be_deleted()
 	# Rebuild node
 	title = generator.get_type_name()
 	# Inputs