Rework how the 3D editor viewport's resolution scale is changed

- Removed the Half Resolution per-viewport setting in favor of an
  editor setting that applies to all 3D viewports in all projects.
- Use an automatic rendering scale by default that's set to 100% on
  loDPI displays and 50% on hiDPI displays (editor scale >= 1.667).
- Add 25% and 33% scaling options in the Editor Settings.
  This is useful for low-end hardware with hiDPI displays
  (such as 4K laptops).

The rendering scale is updated when the editor setting changes,
so no restart is required to apply rendering scale changes (as before).

Author: Calinou

editor/editor_settings.cpp

@@ -641,6 +641,8 @@ void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 	hints["editors/3d/default_z_near"] = PropertyInfo(Variant::FLOAT, "editors/3d/default_z_near", PROPERTY_HINT_RANGE, "0.01,10,0.01,or_greater");
 	_initial_set("editors/3d/default_z_far", 4000.0);
 	hints["editors/3d/default_z_far"] = PropertyInfo(Variant::FLOAT, "editors/3d/default_z_far", PROPERTY_HINT_RANGE, "0.1,4000,0.1,or_greater");
+	_initial_set("editors/3d/viewport_resolution_scale", 0);
+	hints["editors/3d/viewport_resolution_scale"] = PropertyInfo(Variant::INT, "editors/3d/viewport_resolution_scale", PROPERTY_HINT_ENUM, "Auto (DPI-specific),Very Low (25%),Low (33%),Medium (50%),Full (100%)");
 
 	// 3D: Navigation
 	_initial_set("editors/3d/navigation/navigation_scheme", 0);

editor/plugins/node_3d_editor_plugin.cpp

@@ -2354,12 +2354,34 @@ void Node3DEditorViewport::_project_settings_changed() {
 	viewport->set_shadow_atlas_quadrant_subdiv(2, Viewport::ShadowAtlasQuadrantSubdiv(atlas_q2));
 	viewport->set_shadow_atlas_quadrant_subdiv(3, Viewport::ShadowAtlasQuadrantSubdiv(atlas_q3));
 
-	bool shrink = view_menu->get_popup()->is_item_checked(view_menu->get_popup()->get_item_index(VIEW_HALF_RESOLUTION));
-
-	if (shrink != (subviewport_container->get_stretch_shrink() > 1)) {
-		subviewport_container->set_stretch_shrink(shrink ? 2 : 1);
+	int shrink_factor;
+	switch (int(EDITOR_GET("editors/3d/viewport_resolution_scale"))) {
+		case 0:
+			// Auto (DPI-specific).
+			// Use 1:2 render scale on hiDPI displays to improve performance, especially on integrated graphics.
+			shrink_factor = EDSCALE >= 1.667 ? 2 : 1;
+			break;
+		case 1:
+			// Very Low (1:4).
+			shrink_factor = 4;
+			break;
+		case 2:
+			// Low (1:3).
+			shrink_factor = 3;
+			break;
+		case 3:
+			// Medium (1:2).
+			shrink_factor = 2;
+			break;
+		case 4:
+		default:
+			// Full (1:1).
+			shrink_factor = 1;
+			break;
 	}
 
+	subviewport_container->set_stretch_shrink(shrink_factor);
+
 	// Update MSAA, screen-space AA and debanding if changed
 
 	const int msaa_mode = ProjectSettings::get_singleton()->get("rendering/anti_aliasing/quality/msaa");
@@ -3034,12 +3056,6 @@ void Node3DEditorViewport::_menu_option(int p_option) {
 			view_menu->get_popup()->set_item_checked(idx, current);
 
 		} break;
-		case VIEW_HALF_RESOLUTION: {
-			int idx = view_menu->get_popup()->get_item_index(VIEW_HALF_RESOLUTION);
-			bool current = view_menu->get_popup()->is_item_checked(idx);
-			current = !current;
-			view_menu->get_popup()->set_item_checked(idx, current);
-		} break;
 		case VIEW_INFORMATION: {
 			int idx = view_menu->get_popup()->get_item_index(VIEW_INFORMATION);
 			bool current = view_menu->get_popup()->is_item_checked(idx);
@@ -3481,12 +3497,6 @@ void Node3DEditorViewport::set_state(const Dictionary &p_state) {
 			_menu_option(VIEW_FRAME_TIME);
 		}
 	}
-	if (p_state.has("half_res")) {
-		bool half_res = p_state["half_res"];
-
-		int idx = view_menu->get_popup()->get_item_index(VIEW_HALF_RESOLUTION);
-		view_menu->get_popup()->set_item_checked(idx, half_res);
-	}
 	if (p_state.has("cinematic_preview")) {
 		previewing_cinema = p_state["cinematic_preview"];
 
@@ -3537,7 +3547,6 @@ Dictionary Node3DEditorViewport::get_state() const {
 	d["gizmos"] = view_menu->get_popup()->is_item_checked(view_menu->get_popup()->get_item_index(VIEW_GIZMOS));
 	d["information"] = view_menu->get_popup()->is_item_checked(view_menu->get_popup()->get_item_index(VIEW_INFORMATION));
 	d["frame_time"] = view_menu->get_popup()->is_item_checked(view_menu->get_popup()->get_item_index(VIEW_FRAME_TIME));
-	d["half_res"] = subviewport_container->get_stretch_shrink() > 1;
 	d["cinematic_preview"] = view_menu->get_popup()->is_item_checked(view_menu->get_popup()->get_item_index(VIEW_CINEMATIC_PREVIEW));
 	if (previewing) {
 		d["previewing"] = EditorNode::get_singleton()->get_edited_scene()->get_path_to(previewing);
@@ -4066,8 +4075,6 @@ Node3DEditorViewport::Node3DEditorViewport(Node3DEditor *p_spatial_editor, Edito
 	view_menu->get_popup()->add_check_shortcut(ED_SHORTCUT("spatial_editor/view_fps", TTR("View Frame Time")), VIEW_FRAME_TIME);
 	view_menu->get_popup()->set_item_checked(view_menu->get_popup()->get_item_index(VIEW_ENVIRONMENT), true);
 	view_menu->get_popup()->add_separator();
-	view_menu->get_popup()->add_check_shortcut(ED_SHORTCUT("spatial_editor/view_half_resolution", TTR("Half Resolution")), VIEW_HALF_RESOLUTION);
-	view_menu->get_popup()->add_separator();
 	view_menu->get_popup()->add_check_shortcut(ED_SHORTCUT("spatial_editor/view_audio_listener", TTR("Audio Listener")), VIEW_AUDIO_LISTENER);
 	view_menu->get_popup()->add_check_shortcut(ED_SHORTCUT("spatial_editor/view_audio_doppler", TTR("Enable Doppler")), VIEW_AUDIO_DOPPLER);
 	view_menu->get_popup()->set_item_checked(view_menu->get_popup()->get_item_index(VIEW_GIZMOS), true);

editor/plugins/node_3d_editor_plugin.h

@@ -191,7 +191,6 @@ class Node3DEditorViewport : public Control {
 		VIEW_PERSPECTIVE,
 		VIEW_ENVIRONMENT,
 		VIEW_ORTHOGONAL,
-		VIEW_HALF_RESOLUTION,
 		VIEW_AUDIO_LISTENER,
 		VIEW_AUDIO_DOPPLER,
 		VIEW_GIZMOS,