Updated node screenshot generation to make background transparent

Author: RodZill4

material_maker/panels/library/library.gd

@@ -232,6 +232,18 @@ func generate_screenshots(graph_edit : GraphEdit, parent_item : TreeItem = null)
 			var image = get_viewport().get_texture().get_image()
 			var csf = mm_globals.main_window.get_window().content_scale_factor
 			image = image.get_region(Rect2(csf*(new_nodes[0].global_position-Vector2(6, 6)),csf*(new_nodes[0].size+Vector2(14, 12))))
+			# Make background transparent
+			image.convert(Image.FORMAT_RGBA8)
+			var border_color : Color = image.get_pixel(0, 0)
+			for y : int in image.get_height():
+				for x : int in image.get_width():
+					if image.get_pixel(x, y) != border_color:
+						break
+					image.set_pixel(x, y, Color(0, 0, 0, 0))
+				for x : int in range(image.get_width()-1, 0, -1):
+					if image.get_pixel(x, y) != border_color:
+						break
+					image.set_pixel(x, y, Color(0, 0, 0, 0))
 			print(get_icon_name(get_item_path(item)))
 			image.resize(image.get_size().x/csf, image.get_size().y/csf, Image.INTERPOLATE_LANCZOS)
 			image.save_png("res://material_maker/doc/images/node_"+get_icon_name(get_item_path(item))+".png")