diff --git a/addons/material_maker/engine/gen_base.gd b/addons/material_maker/engine/gen_base.gd
index 05e0beb..40b008e 100644
--- a/addons/material_maker/engine/gen_base.gd
+++ b/addons/material_maker/engine/gen_base.gd
@@ -1,4 +1,68 @@
+tool
 extends Node
 class_name MMGenBase
 
+class OutputPort:
+	var generator : MMGenBase = null
+	var output_index : int = 0
+	
+	func _init(g : MMGenBase, o : int):
+		generator = g
+		output_index = o
+	
+	func get_shader():
+		return generator.get_shader(output_index)
+	
+	func get_globals():
+		return generator.get_globals()
 
+var parameters = null
+
+func get_seed():
+	return 0
+
+func get_source(input_index : int):
+	return get_parent().get_port_source(name, input_index)
+
+func get_input_shader(input_index : int):
+	var source = get_source(input_index)
+	if source != null:
+		return source.get_shader()
+
+func get_shader(output_index : int):
+	return get_shader_code("UV", output_index);
+
+# this will need an output index for switch
+func get_globals():
+	var list = []
+	for i in range(10):
+		var source = get_source(i)
+		if source != null:
+			var source_list = source.get_globals()
+			for g in source_list:
+				if list.find(g) == -1:
+					list.append(g)
+	return list
+
+func get_shader_code(uv, slot = 0):
+	var rv
+	rv = _get_shader_code(uv, slot)
+	if !rv.has("f"):
+		if rv.has("rgb"):
+			rv.f = "(dot("+rv.rgb+", vec3(1.0))/3.0)"
+		elif rv.has("rgba"):
+			rv.f = "(dot("+rv.rgba+".rgb, vec3(1.0))/3.0)"
+		else:
+			rv.f = "0.0"
+	if !rv.has("rgb"):
+		if rv.has("rgba"):
+			rv.rgb = rv.rgba+".rgb"
+		else:
+			rv.rgb = "vec3("+rv.f+")"
+	if !rv.has("rgba"):
+		rv.rgba = "vec4("+rv.rgb+", 1.0)"
+	rv.globals = get_globals()
+	return rv
+
+func _get_shader_code(uv : String, output_index : int):
+	return null
diff --git a/addons/material_maker/engine/gen_graph.gd b/addons/material_maker/engine/gen_graph.gd
index a5caacc..af73b8d 100644
--- a/addons/material_maker/engine/gen_graph.gd
+++ b/addons/material_maker/engine/gen_graph.gd
@@ -1,2 +1,11 @@
+tool
 extends MMGenBase
 class_name MMGenGraph
+
+var connections = null
+
+func get_port_source(gen_name: String, input_index: int) -> OutputPort:
+	for c in connections:
+		if c.to == gen_name and c.to_port == input_index:
+			return OutputPort.new(get_node(c.from), c.from_port)
+	return null
diff --git a/addons/material_maker/engine/gen_material.gd b/addons/material_maker/engine/gen_material.gd
index 37f2e00..2853e2f 100644
--- a/addons/material_maker/engine/gen_material.gd
+++ b/addons/material_maker/engine/gen_material.gd
@@ -1,11 +1,122 @@
+tool
 extends MMGenBase
 class_name MMGenMaterial
 
+var texture_list
+
+var material
+var generated_textures = {}
+
+const TEXTURE_LIST = [
+	{ port=0, texture="albedo" },
+	{ port=1, texture="metallic" },
+	{ port=2, texture="roughness" },
+	{ port=3, texture="emission" },
+	{ port=4, texture="normal_map" },
+	{ port=5, texture="ambient_occlusion" },
+	{ port=6, texture="depth_map" }
+]
+
+const ADDON_TEXTURE_LIST = [
+	{ port=0, texture="albedo" },
+	{ port=3, texture="emission" },
+	{ port=4, texture="normal_map" },
+	{ ports=[1, 2, 5], default_values=["0.0", "1.0", "1.0"], texture="mrao" },
+	{ port=6, texture="depth_map" }
+]
+
+func _ready():
+	texture_list = TEXTURE_LIST
+	if Engine.editor_hint:
+		texture_list = ADDON_TEXTURE_LIST
+	for t in texture_list:
+		generated_textures[t.texture] = { shader=null, source=null, texture=null }
+	material = SpatialMaterial.new()
+
 func generate_material():
 	print("Generating material")
-	var material = SpatialMaterial.new()
+	print(get_source(0).get_shader())
 	return material
 
 func initialize(data: Dictionary):
 	if data.has("name"):
 		name = data.name
+
+func get_generated_texture(slot, file_prefix = null):
+	if file_prefix != null:
+		var file_name = "%s_%s.png" % [ file_prefix, slot ]
+		if File.new().file_exists(file_name):
+			return load(file_name)
+		else:
+			return null
+	else:
+		return generated_textures[slot].texture
+
+func update_spatial_material(m, file_prefix = null):
+	var texture
+	m.albedo_color = parameters.albedo_color
+	m.albedo_texture = get_generated_texture("albedo", file_prefix)
+	m.metallic = parameters.metallic
+	m.roughness = parameters.roughness
+	if Engine.editor_hint:
+		texture = get_generated_texture("mrao", file_prefix)
+		m.metallic_texture = texture 
+		m.metallic_texture_channel = SpatialMaterial.TEXTURE_CHANNEL_RED
+		m.roughness_texture = texture
+		m.roughness_texture_channel = SpatialMaterial.TEXTURE_CHANNEL_GREEN
+	else:
+		m.metallic_texture = get_generated_texture("metallic", file_prefix)
+		m.roughness_texture = get_generated_texture("roughness", file_prefix)
+	texture = get_generated_texture("emission", file_prefix)
+	if texture != null:
+		m.emission_enabled = true
+		m.emission_energy = parameters.emission_energy
+		m.emission_texture = texture
+	else:
+		m.emission_enabled = false
+	texture = get_generated_texture("normal_map", file_prefix)
+	if texture != null:
+		m.normal_enabled = true
+		m.normal_texture = texture
+	else:
+		m.normal_enabled = false
+	if Engine.editor_hint:
+		if (generated_textures.mrao.mask & (1 << 2)) != 0:
+			m.ao_enabled = true
+			m.ao_light_affect = parameters.ao_light_affect
+			m.ao_texture = m.metallic_texture
+			m.ao_texture_channel = SpatialMaterial.TEXTURE_CHANNEL_BLUE
+		else:
+			m.ao_enabled = false
+	else:
+		texture = get_generated_texture("ambient_occlusion", file_prefix)
+		if texture != null:
+			m.ao_enabled = true
+			m.ao_light_affect = parameters.ao_light_affect
+			m.ao_texture = texture
+		else:
+			m.ao_enabled = false
+	texture = get_generated_texture("depth_map", file_prefix)
+	if texture != null:
+		m.depth_enabled = true
+		m.depth_scale = parameters.depth_scale
+		m.depth_texture = texture
+	else:
+		m.depth_enabled = false
+
+func export_textures(prefix, size = null):
+	if size == null:
+		size = int(pow(2, 8+parameters.resolution))
+	for t in texture_list:
+		var texture = generated_textures[t.texture].texture
+		if texture != null:
+			var image = texture.get_data()
+			image.save_png("%s_%s.png" % [ prefix, t.texture ])
+	if Engine.editor_hint:
+		var resource_filesystem = get_parent().editor_interface.get_resource_filesystem()
+		resource_filesystem.scan()
+		yield(resource_filesystem, "filesystem_changed")
+		var new_material = SpatialMaterial.new()
+		update_spatial_material(new_material, prefix)
+		ResourceSaver.save("%s.tres" % [ prefix ], new_material)
+		resource_filesystem.scan()
diff --git a/addons/material_maker/engine/gen_shader.gd b/addons/material_maker/engine/gen_shader.gd
index 6607849..8c6c916 100644
--- a/addons/material_maker/engine/gen_shader.gd
+++ b/addons/material_maker/engine/gen_shader.gd
@@ -1,14 +1,136 @@
+tool
 extends MMGenBase
 class_name MMGenShader
 
-var config
-var parameters
+var model_data = null
+var generated_variants = []
 
-func configure(c: Dictionary):
-	config = c
+func set_model_data(data: Dictionary):
+	model_data = data
 
 func initialize(data: Dictionary):
 	if data.has("name"):
 		name = data.name
 	if data.has("parameters"):
 		parameters = data.parameters
+
+func find_keyword_call(string, keyword):
+	var search_string = "$%s(" % keyword
+	var position = string.find(search_string)
+	if position == -1:
+		return null
+	var parenthesis_level = 0
+	var parameter_begin = position+search_string.length()
+	var parameter_end = -1
+	for i in range(parameter_begin, string.length()):
+		if string[i] == '(':
+			parenthesis_level += 1
+		elif string[i] == ')':
+			if parenthesis_level == 0:
+				return string.substr(parameter_begin, i-parameter_begin)
+			parenthesis_level -= 1
+	return ""
+
+func replace_input(string, input, type, src, default):
+	var required_defs = ""
+	var required_code = ""
+	while true:
+		var uv = find_keyword_call(string, input)
+		if uv == null:
+			break
+		elif uv == "":
+			print("syntax error")
+			break
+		var src_code
+		if src == null:
+			src_code = subst(default, "(%s)" % uv)
+		else:
+			src_code = src.get_shader_code(uv)
+			src_code.string = src_code[type]
+		required_defs += src_code.defs
+		required_code += src_code.code
+		string = string.replace("$%s(%s)" % [ input, uv ], src_code.string)
+	return { string=string, defs=required_defs, code=required_code }
+
+func is_word_letter(l):
+	return "azertyuiopqsdfghjklmwxcvbnAZERTYUIOPQSDFGHJKLMWXCVBN1234567890_".find(l) != -1
+
+func replace_variable(string, variable, value):
+	string = string.replace("$(%s)" % variable, value)
+	var keyword_size = variable.length()+1
+	var new_string = ""
+	while !string.empty():
+		var pos = string.find("$"+variable)
+		if pos == -1:
+			new_string += string
+			break
+		new_string += string.left(pos)
+		string = string.right(pos)
+		if string.empty() or !is_word_letter(string[0]):
+			new_string += value
+		else:
+			new_string += "$"+variable
+		string = string.right(keyword_size)
+	return new_string
+
+func subst(string, uv = ""):
+	var required_defs = ""
+	var required_code = ""
+	string = replace_variable(string, "name", name)
+	string = replace_variable(string, "seed", str(get_seed()))
+	if uv != "":
+		string = replace_variable(string, "uv", "("+uv+")")
+	if model_data.has("parameters") and typeof(model_data.parameters) == TYPE_ARRAY:
+		for p in model_data.parameters:
+			if !p.has("name") or !p.has("type"):
+				continue
+			var value = parameters[p.name]
+			var value_string = null
+			if p.type == "float":
+				value_string = "%.9f" % value
+			elif p.type == "size":
+				value_string = "%.9f" % pow(2, value+p.first)
+			elif p.type == "enum":
+				value_string = p.values[value].value
+			elif p.type == "color":
+				value_string = "vec4(%.9f, %.9f, %.9f, %.9f)" % [ value.r, value.g, value.b, value.a ]
+			if value_string != null:
+				string = replace_variable(string, p.name, value_string)
+	if model_data.has("inputs") and typeof(model_data.inputs) == TYPE_ARRAY:
+		for i in range(model_data.inputs.size()):
+			var input = model_data.inputs[i]
+			var source = get_source(i)
+			var result = replace_input(string, input.name, input.type, source, input.default)
+			string = result.string
+			required_defs += result.defs
+			required_code += result.code
+	return { string=string, defs=required_defs, code=required_code }
+
+func _get_shader_code(uv, slot = 0):
+	var output_info = [ { field="rgba", type="vec4" }, { field="rgb", type="vec3" }, { field="f", type="float" } ]
+	var rv = { defs="", code="" }
+	var variant_string = uv+","+str(slot)
+	if model_data != null and model_data.has("outputs") and model_data.outputs.size() > slot:
+		var output = model_data.outputs[slot]
+		if model_data.has("instance") && generated_variants.empty():
+			rv.defs = subst(model_data.instance).string
+		var variant_index = generated_variants.find(variant_string)
+		if variant_index == -1:
+			variant_index = generated_variants.size()
+			generated_variants.append(variant_string)
+			for t in output_info:
+				if output.has(t.field):
+					var subst_output = subst(output[t.field], uv)
+					rv.defs += subst_output.defs
+					rv.code += subst_output.code
+					rv.code += "%s %s_%d_%d_%s = %s;\n" % [ t.type, name, slot, variant_index, t.field, subst_output.string ]
+		for t in output_info:
+			if output.has(t.field):
+				rv[t.field] = "%s_%d_%d_%s" % [ name, slot, variant_index, t.field ]
+	return rv
+
+func get_globals():
+	var list = .get_globals()
+	if typeof(model_data) == TYPE_DICTIONARY and model_data.has("global") and list.find(model_data.global) == -1:
+		list.append(model_data.global)
+	return list
diff --git a/addons/material_maker/engine/loader.gd b/addons/material_maker/engine/loader.gd
index b99f823..357c5cc 100644
--- a/addons/material_maker/engine/loader.gd
+++ b/addons/material_maker/engine/loader.gd
@@ -1,3 +1,4 @@
+tool
 extends Object
 class_name MMGenLoader
 
@@ -16,18 +17,22 @@ func create_gen(data) -> MMGenBase:
 			var g = create_gen(n)
 			if g != null:
 				generator.add_child(g)
+		generator.connections = data.connections
 	elif data.has("type"):
 		if data.type == "material":
 			generator = MMGenMaterial.new()
 		else:
 			generator = MMGenShader.new()
-			var file = File.new()
-			if file.open("res://addons/material_maker/nodes/"+data.type+".mmn", File.READ) == OK:
-				var config = parse_json(file.get_as_text())
-				print("loaded description "+data.type+".mmn")
-				generator.configure(config)
+			if data.type == "custom":
+				pass
 			else:
-				print("Cannot find description for "+data.type)
+				var file = File.new()
+				if file.open("res://addons/material_maker/nodes/"+data.type+".mmn", File.READ) == OK:
+					var model_data = parse_json(file.get_as_text())
+					print("loaded description "+data.type+".mmn")
+					generator.set_model_data(model_data)
+				else:
+					print("Cannot find description for "+data.type)
 	if generator != null and data.has("parameters"):
 		generator.initialize(data)
 	return generator
diff --git a/addons/material_maker/nodes/blur/blur.gd b/addons/material_maker/nodes/blur/blur.gd
index c2a8b49..e713b28 100644
--- a/addons/material_maker/nodes/blur/blur.gd
+++ b/addons/material_maker/nodes/blur/blur.gd
@@ -63,7 +63,7 @@ func get_textures():
 	list[name] = saved_texture
 	return list
 
-func _get_shader_code(uv):
+func _get_shader_code(uv, slot = 0):
 	var rv = { defs="", code="" }
 	var src = get_source()
 	if src == null:
diff --git a/addons/material_maker/plugin.gd b/addons/material_maker/plugin.gd
index 7af04c7..5260dc2 100644
--- a/addons/material_maker/plugin.gd
+++ b/addons/material_maker/plugin.gd
@@ -47,4 +47,5 @@ func generate_material(ptex_filename: String) -> Material:
 	var loader = MMGenLoader.new()
 	var generator = loader.load_gen(ptex_filename)
 	add_child(generator)
-	return generator.get_node("Material").generate_material()
+	var material = generator.get_node("Material")
+	return material.generate_material()