From 49c603e1276b84f9b80414946429372f173bcbeb Mon Sep 17 00:00:00 2001
From: smix8 <52464204+smix8@users.noreply.github.com>
Date: Sat, 14 May 2022 18:25:45 +0200
Subject: [PATCH] Disable threaded NavigationMesh bake on unsupported OS

Automatically disables threaded NavigationMesh bake when OS does not support threads.
---
 doc/classes/NavigationRegion3D.xml | 2 +-
 scene/3d/navigation_region_3d.cpp  | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/doc/classes/NavigationRegion3D.xml b/doc/classes/NavigationRegion3D.xml
index 60f10202861..42f0e0c5d9c 100644
--- a/doc/classes/NavigationRegion3D.xml
+++ b/doc/classes/NavigationRegion3D.xml
@@ -14,7 +14,7 @@
 			<return type="void" />
 			<argument index="0" name="on_thread" type="bool" default="true" />
 			<description>
-				Bakes the [NavigationMesh]. If [code]on_thread[/code] is set to [code]true[/code] (default), the baking is done on a separate thread. Baking on separate thread is useful because navigation baking is not a cheap operation. When it is completed, it automatically sets the new [NavigationMesh]. Please note that baking on separate thread may be very slow if geometry is parsed from meshes as async access to each mesh involves heavy synchronization.
+				Bakes the [NavigationMesh]. If [code]on_thread[/code] is set to [code]true[/code] (default), the baking is done on a separate thread. Baking on separate thread is useful because navigation baking is not a cheap operation. When it is completed, it automatically sets the new [NavigationMesh]. Please note that baking on separate thread may be very slow if geometry is parsed from meshes as async access to each mesh involves heavy synchronization. Also, please note that baking on a separate thread is automatically disabled on operating systems that cannot use threads (such as HTML5 with threads disabled).
 			</description>
 		</method>
 		<method name="get_region_rid" qualifiers="const">
diff --git a/scene/3d/navigation_region_3d.cpp b/scene/3d/navigation_region_3d.cpp
index 80be770dfcf..64044326310 100644
--- a/scene/3d/navigation_region_3d.cpp
+++ b/scene/3d/navigation_region_3d.cpp
@@ -171,7 +171,12 @@ void NavigationRegion3D::bake_navigation_mesh(bool p_on_thread) {
 	BakeThreadsArgs *args = memnew(BakeThreadsArgs);
 	args->nav_region = this;
 
-	if (p_on_thread) {
+	if (p_on_thread && !OS::get_singleton()->can_use_threads()) {
+		WARN_PRINT("NavigationMesh bake 'on_thread' will be disabled as the current OS does not support multiple threads."
+				   "\nAs a fallback the navigation mesh will bake on the main thread which can cause framerate issues.");
+	}
+
+	if (p_on_thread && OS::get_singleton()->can_use_threads()) {
 		bake_thread.start(_bake_navigation_mesh, args);
 	} else {
 		_bake_navigation_mesh(args);