simplify my Makefile by writing the build stuff in Python

I'm going to move all of the .scad files into subdirectories and I
couldn't figure out how to recurse properly in make, so... do it the
easy way

make is hard, let's go shopping

Signed-off-by: Brian S. Stephan <bss@incorporeal.org>

Makefile

@@ -1,9 +1,5 @@
-EXCLUDES = components parameters
+all:
-OBJECTS := $(filter-out $(EXCLUDES),$(patsubst src/%.scad,%,$(wildcard src/*.scad)))
+	python build.py
-dir_guard=@mkdir -p ./build
-
-all:	$(OBJECTS)
-	$(dir_guard)
 	mkdir -p ./build/docs
 	cp ./docs/README-objects.md ./build/README.md
 	cp ./docs/assembly-and-tips.md ./build/docs/assembly-and-tips.md
@@ -11,9 +7,5 @@ all:	$(OBJECTS)
 	cp ./LICENSE ./build/LICENSE
 	pushd ./build; zip ./buildable-stick-system-`git describe --dirty`-stls.zip . -r; popd
 
-$(OBJECTS):
-	$(dir_guard)
-	openscad -o build/$@.stl src/$@.scad
-
 clean:
 	rm -rf ./build

build.py

@@ -0,0 +1,47 @@
+"""Compile all OpenSCAD files into a build directory and package it with docs.
+
+(a.k.a.: "make is hard"
+
+SPDX-FileCopyrightText: © 2024 Brian S. Stephan <bss@incorporeal.org>
+SPDX-License-Identifier: GPL-3.0-or-later
+"""
+import os
+import os.path
+import re
+import subprocess
+
+PROJECT_ROOT = os.path.abspath(os.getcwd())
+BUILD_DIR = os.path.join(PROJECT_ROOT, 'build/')
+SOURCE_DIR = os.path.join(PROJECT_ROOT, 'src/')
+
+EXCLUDES = ['components.scad', 'parameters.scad']
+
+# set up our environment to point openscad at the right stuff
+os.environ['OPENSCADPATH'] = SOURCE_DIR
+
+# track processes to wait on
+processes = []
+
+os.chdir(SOURCE_DIR)
+for root, dirs, files in os.walk('.'):
+    print(f"{root} {dirs} {files}")
+    # make the current directory so that openscad can write stuff into it
+    os.makedirs(os.path.join(BUILD_DIR, root))
+
+    input_dir = os.path.join(SOURCE_DIR, root)
+    output_dir = os.path.join(BUILD_DIR, root)
+    for file in files:
+        if not re.match(r'.*\.scad$', file):
+            continue
+        if file in EXCLUDES:
+            continue
+
+        stl_file = re.sub(r'\.scad$', '.stl', file)
+        input_ = os.path.join(input_dir, file)
+        output = os.path.join(output_dir, stl_file)
+        cmd = f'openscad -o {output} {input_}'
+        print(cmd)
+        processes.append(subprocess.Popen(cmd.split(' ')))
+
+for process in processes:
+    process.wait()