Merge pull request #52952 from Calinou/cpu-lightmapper-num-threads-editor-setting

core/os/threaded_array_processor.h

@@ -64,8 +64,10 @@ void process_array_thread(void *ud) {
 	}
 }
 
+// p_num_threads is the number of logical CPU cores to use (0 = use all logical CPU cores available).
+// Negative values subtract from the total number of logical CPU cores available.
 template <class C, class M, class U>
-void thread_process_array(uint32_t p_elements, C *p_instance, M p_method, U p_userdata) {
+void thread_process_array(uint32_t p_elements, C *p_instance, M p_method, U p_userdata, int p_num_threads = 0) {
 	ThreadArrayProcessData<C, U> data;
 	data.method = p_method;
 	data.instance = p_instance;
@@ -74,7 +76,13 @@ void thread_process_array(uint32_t p_elements, C *p_instance, M p_method, U p_us
 	data.elements = p_elements;
 	data.process(0); //process first, let threads increment for next
 
-	int thread_count = OS::get_singleton()->get_processor_count();
+	int thread_count;
+	if (p_num_threads <= 0) {
+		thread_count = MAX(1, OS::get_singleton()->get_processor_count() + p_num_threads);
+	} else {
+		thread_count = p_num_threads;
+	}
+
 	Thread *threads = memnew_arr(Thread, thread_count);
 
 	for (int i = 0; i < thread_count; i++) {
@@ -89,8 +97,9 @@ void thread_process_array(uint32_t p_elements, C *p_instance, M p_method, U p_us
 
 #else
 
+// p_num_threads is intentionally unused when threads are disabled.
 template <class C, class M, class U>
-void thread_process_array(uint32_t p_elements, C *p_instance, M p_method, U p_userdata) {
+void thread_process_array(uint32_t p_elements, C *p_instance, M p_method, U p_userdata, int p_num_threads = 0) {
 	ThreadArrayProcessData<C, U> data;
 	data.method = p_method;
 	data.instance = p_instance;

editor/editor_settings.cpp

@@ -546,6 +546,9 @@ void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 	_initial_set("editors/3d/default_z_near", 0.05);
 	_initial_set("editors/3d/default_z_far", 500.0);
 
+	_initial_set("editors/3d/lightmap_baking_number_of_cpu_threads", 0);
+	hints["editors/3d/lightmap_baking_number_of_cpu_threads"] = PropertyInfo(Variant::INT, "editors/3d/lightmap_baking_number_of_cpu_threads", PROPERTY_HINT_RANGE, "-2,128,1", PROPERTY_USAGE_DEFAULT);
+
 	// 3D: Navigation
 	_initial_set("editors/3d/navigation/navigation_scheme", 0);
 	_initial_set("editors/3d/navigation/invert_y_axis", false);

modules/lightmapper_cpu/lightmapper_cpu.cpp

@@ -36,6 +36,10 @@
 #include "core/project_settings.h"
 #include "modules/raycast/lightmap_raycaster.h"
 
+#ifdef TOOLS_ENABLED
+#include "editor/editor_settings.h"
+#endif
+
 Error LightmapperCPU::_layout_atlas(int p_max_size, Vector2i *r_atlas_size, int *r_atlas_slices) {
 	Vector2i atlas_size;
 	for (unsigned int i = 0; i < mesh_instances.size(); i++) {
@@ -205,7 +209,12 @@ Error LightmapperCPU::_layout_atlas(int p_max_size, Vector2i *r_atlas_size, int
 
 void LightmapperCPU::_thread_func_callback(void *p_thread_data) {
 	ThreadData *thread_data = reinterpret_cast<ThreadData *>(p_thread_data);
-	thread_process_array(thread_data->count, thread_data->instance, &LightmapperCPU::_thread_func_wrapper, thread_data);
+#ifdef TOOLS_ENABLED
+	const int num_threads = EDITOR_GET("editors/3d/lightmap_baking_number_of_cpu_threads");
+#else
+	const int num_threads = 0;
+#endif
+	thread_process_array(thread_data->count, thread_data->instance, &LightmapperCPU::_thread_func_wrapper, thread_data, num_threads);
 }
 
 void LightmapperCPU::_thread_func_wrapper(uint32_t p_idx, ThreadData *p_thread_data) {