Sort vertices in STLs to make them diff nice

Author: gluap

Makefile

@@ -1,5 +1,6 @@
 OPENSCAD=/usr/bin/openscad
 OPENSCAD_OPTIONS=-q
+STL_SORTER=lib/sort_stl.py
 IMAGE_OPTIONS=--imgsize=1024,768 --colorscheme "Tomorrow Night" --render true -D orient_for_printing=false
 THUMBNAIL_OPTIONS=--imgsize=400,300 --colorscheme "Tomorrow Night" --render true -D fast=true -D orient_for_printing=false
 
@@ -28,6 +29,7 @@ clean:
 export/%.stl: src/%.scad
 	@mkdir -p $(shell dirname $@)
 	$(OPENSCAD) $(OPENSCAD_OPTIONS) -D orient_for_printing=true -o $@ $<
+	$(STL_SORTER) $@
 
 export-all : $(STLS)
 
@@ -55,7 +57,7 @@ define logo-part-rule
 export/logo/$(1)/$(shell basename $(2))-$(4)-$(3).stl: src/$(2).scad logo/$(1)/$(shell basename $(2)).svg export/$(2).stl
 	@mkdir -p $$(shell dirname $$@)
 	$$(OPENSCAD) $$(OPENSCAD_OPTIONS) -D orient_for_printing=true -D logo_enabled=true -D logo_use_prebuild=true -D 'logo_mode="$(4)"' -D 'logo_part="$(3)"' -D 'logo_name="$(1)"' -o $$@ $$<
-
+  $$(STL_SORTER) $$@
 logo-$1-$4: export/logo/$(1)/$(shell basename $(2))-$(4)-$(3).stl
 logo-$1: export/logo/$(1)/$(shell basename $(2))-$(4)-$(3).stl
 logos: logo-$1
@@ -86,6 +88,7 @@ define numbered-cover-rule
 export/Mounting/AttachmentCover_$(1).stl: src/Mounting/AttachmentCover.scad
 	@mkdir -p $$(shell dirname $$@)
 	$(OPENSCAD) $(OPENSCAD_OPTIONS) -D orient_for_printing=true -D attachment_cover_number_text=$(1) -o $$@ $$<
+	$(STL_SORTER) $@
 endef
 
 $(foreach number,$(shell seq 0 1 100), \

lib/sort_stl.py

@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+import argparse
+import re
+from pathlib import Path
+
+
+class Element():
+    def __init__(self, line):
+        self.startline = line
+        self.children = []
+        self.current_child = None
+        self.endline = None
+
+    def parse(self, line):
+
+        if self.current_child is None:
+            for Childtype in self._contains:
+                if Childtype._startswith.match(line):
+                    self.current_child = Childtype(line)
+                else:
+                    print(f"{Childtype} did not match {line} for {self.__class__}")
+            assert self.current_child is not None, f"should have found type for line {line}"
+        elif self.current_child._endswith.match(line):
+            self.current_child.endline = line
+            self.children.append(self.current_child)
+            self.current_child = None
+        else:
+            self.current_child.parse(line)
+
+    def __str__(self):
+        return self.startline + "".join(sorted([str(c) for c in self.children])) + self.endline
+
+
+class Loop(Element):
+    _startswith = re.compile("^\s+(?:outer|inner) loop$")
+    _endswith = re.compile("^\s+endloop$")
+    _footer = "endloop"
+
+    def parse(self, line):
+        self.children.append(line)
+
+    def __str__(self):
+        return self.startline + "".join(self.children) + self.endline
+
+
+class Facet(Element):
+    _startswith = re.compile("^\s+facet\s+(.*)$")
+    _endswith = re.compile("^\s+endfacet$")
+    _contains = (Loop,)
+
+
+class Model(Element):
+    _startswith = re.compile("^\s*solid\s+(.*)$")
+    _endswith = re.compile("^\s*endsolid\s+(.*)$")
+    _contains = (Facet,)
+
+
+class STL(Element):
+    _contains = (Model,)
+    endline = ""
+
+    def __init__(self, filename):
+        self.startline = ""
+        data = open(filename, "r").readlines()
+        self.children = []
+        self.current_child = None
+        self.read(data)
+
+    def read(self, data):
+        for line in data:
+            self.parse(line)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="stl sorter for deterministic diffing")
+    parser.add_argument('stlfile', metavar="STLFILE", type=Path, help="path of the STL to sort (in place)")
+    args = parser.parse_args()
+
+    s = STL(args.stlfile)
+    s_as_str = str(s)
+    open(args.stlfile, "w").write(s_as_str)