Use Python script to run Asymptote.

Makefile

@@ -84,7 +84,7 @@ $(SCAD_STL_FILES): %.stl: %.scad $(GLOBAL_DEPS) | $(SCAD_ORDER_DEPS)
 
 # Rule to export an SVG file to an Asymptote file.
 $(ASY_PDF_FILES): %.pdf: %.asy $(GLOBAL_DEPS) $(COMPILED_SRC_FILES) $(SVG_ASY_FILES)
-	ASYMPTOTE_DIR=$$(dirname $@) $(ASYMPTOTE) -f pdf -o $@ $<
+	$(ASYMPTOTE_CMD) $*.asy $@
 
 # Rule for automaticaly generated OpenSCAD files.
 $(GENERATED_FILES): generate_sources.sh $(GLOBAL_DEPS)

support/asymptote/__main__.py

@@ -0,0 +1,24 @@
+import os, sys
+from lib import util
+
+
+def _asymptote(in_path, out_path, asymptote_dir):
+	util.command([os.environ['ASYMPTOTE'], '-f', 'pdf', '-o', out_path, in_path], set_env = { 'ASYMPTOTE_DIR': asymptote_dir })
+
+
+def main(in_path, out_path):
+	_, out_suffix = os.path.splitext(out_path)
+	
+	if out_suffix == '.pdf':
+		_asymptote(in_path, out_path, os.path.dirname(in_path))
+	else:
+		raise Exception('Unknown file type: {}'.format(out_suffix))
+
+
+try:
+	main(*sys.argv[1:])
+except util.UserError as e:
+	print 'Error:', e
+	sys.exit(1)
+except KeyboardInterrupt:
+	sys.exit(2)

support/lib/util.py

@@ -27,15 +27,14 @@ def TemporaryDirectory():
 		shutil.rmtree(dir)
 
 
-def command(args, remove_env = None):
-	if remove_env is None:
-		env = None
-	else:
-		env = dict(os.environ)
-		
-		for i in remove_env:
-			if i in env:
-				del env[i]
+def command(args, remove_env = [], set_env = { }):
+	env = dict(os.environ)
+	
+	for i in remove_env:
+		del env[i]
+	
+	for k, v in set_env.items():
+		env[k] = v
 	
 	process = subprocess.Popen(args, env = env)
 	process.wait()