WM: app-template command line override

Without this, there was no simple way to have
launchers for different app-templates.

Also allows force-disabling the app-template stored in the preferences.

source/blender/windowmanager/WM_api.h

@@ -72,6 +72,9 @@ struct wmNDOFMotionData;
 typedef struct wmJob wmJob;
 
 /* general API */
+void		WM_init_state_app_template_set(const char *app_template);
+const char *WM_init_state_app_template_get(void);
+
 void		WM_init_state_size_set		(int stax, int stay, int sizx, int sizy);
 void		WM_init_state_fullscreen_set(void);
 void		WM_init_state_normal_set(void);

source/blender/windowmanager/intern/wm_files.c

@@ -638,6 +638,33 @@ bool WM_file_read(bContext *C, const char *filepath, ReportList *reports)
 
 }
 
+struct {
+	char app_template[64];
+	bool override;
+} wm_init_state_app_template = {0};
+
+/**
+ * Used for setting app-template from the command line:
+ * - non-empty string: overrides.
+ * - empty string: override, using no app template.
+ * - NULL: clears override.
+ */
+void WM_init_state_app_template_set(const char *app_template)
+{
+	if (app_template) {
+		STRNCPY(wm_init_state_app_template.app_template, app_template);
+		wm_init_state_app_template.override = true;
+	}
+	else {
+		wm_init_state_app_template.app_template[0] = '\0';
+		wm_init_state_app_template.override = false;
+	}
+}
+
+const char *WM_init_state_app_template_get(void)
+{
+	return wm_init_state_app_template.override ? wm_init_state_app_template.app_template : NULL;
+}
 
 /**
  * Called on startup, (context entirely filled with NULLs)
@@ -1614,9 +1641,13 @@ static int wm_homefile_read_exec(bContext *C, wmOperator *op)
 
 		/* Always load preferences when switching templates. */
 		use_userdef = true;
+
+		/* Turn override off, since we're explicitly loading a different app-template. */
+		WM_init_state_app_template_set(NULL);
 	}
 	else {
-		app_template = NULL;
+		/* Normally NULL, only set when overriding from the command-line. */
+		app_template = WM_init_state_app_template_get();
 	}
 
 	if (wm_homefile_read(C, op->reports, use_factory_settings, use_empty_data, use_userdef, filepath, app_template)) {

source/blender/windowmanager/intern/wm_init_exit.c

@@ -195,8 +195,7 @@ void WM_init(bContext *C, int argc, const char **argv)
 	wm_init_reports(C);
 
 	/* get the default database, plus a wm */
-	wm_homefile_read(C, NULL, G.factory_startup, false, true, NULL, NULL);
-
+	wm_homefile_read(C, NULL, G.factory_startup, false, true, NULL, WM_init_state_app_template_get());
 
 	BLT_lang_set(NULL);
 

source/creator/creator_args.c

@@ -580,6 +580,7 @@ static int arg_handle_print_help(int UNUSED(argc), const char **UNUSED(argv), vo
 
 	printf("\n");
 	printf("Misc Options:\n");
+	BLI_argsPrintArgDoc(ba, "--app-template");
 	BLI_argsPrintArgDoc(ba, "--factory-startup");
 	printf("\n");
 	BLI_argsPrintArgDoc(ba, "--env-system-datafiles");
@@ -993,6 +994,22 @@ static int arg_handle_debug_fpe_set(int UNUSED(argc), const char **UNUSED(argv),
 	return 0;
 }
 
+static const char arg_handle_app_template_doc[] =
+"\n\tSet the application template, use 'default' for none."
+;
+static int arg_handle_app_template(int argc, const char **argv, void *UNUSED(data))
+{
+	if (argc > 1) {
+		const char *app_template = STREQ(argv[1], "default") ? "" : argv[1];
+		WM_init_state_app_template_set(app_template);
+		return 1;
+	}
+	else {
+		printf("\nError: App template must follow '--app-template'.\n");
+		return 0;
+	}
+}
+
 static const char arg_handle_factory_startup_set_doc[] =
 "\n\tSkip reading the " STRINGIFY(BLENDER_STARTUP_FILE) " in the users home directory."
 ;
@@ -2043,6 +2060,7 @@ void main_args_setup(bContext *C, bArgs *ba, SYS_SystemHandle *syshandle)
 
 	BLI_argsAdd(ba, 1, NULL, "--verbose", CB(arg_handle_verbosity_set), NULL);
 
+	BLI_argsAdd(ba, 1, NULL, "--app-template", CB(arg_handle_app_template), NULL);
 	BLI_argsAdd(ba, 1, NULL, "--factory-startup", CB(arg_handle_factory_startup_set), NULL);
 
 	/* TODO, add user env vars? */