OpenXR: Add refresh rate signal support

Author: BastiaanOlij

modules/openxr/doc_classes/OpenXRInterface.xml

@@ -152,6 +152,13 @@
 				Informs the user queued a recenter of the player position.
 			</description>
 		</signal>
+		<signal name="refresh_rate_changed">
+			<param index="0" name="refresh_rate" type="float" />
+			<description>
+				Informs the user the HMD refresh rate has changed.
+				[b]Node:[/b] Only emitted if XR runtime supports the refresh rate extension.
+			</description>
+		</signal>
 		<signal name="session_begun">
 			<description>
 				Informs our OpenXR session has been started.

modules/openxr/extensions/openxr_fb_display_refresh_rate_extension.cpp

@@ -29,6 +29,7 @@
 /**************************************************************************/
 
 #include "openxr_fb_display_refresh_rate_extension.h"
+#include "../openxr_interface.h"
 
 OpenXRDisplayRefreshRateExtension *OpenXRDisplayRefreshRateExtension::singleton = nullptr;
 
@@ -64,6 +65,23 @@ void OpenXRDisplayRefreshRateExtension::on_instance_destroyed() {
 	display_refresh_rate_ext = false;
 }
 
+bool OpenXRDisplayRefreshRateExtension::on_event_polled(const XrEventDataBuffer &event) {
+	switch (event.type) {
+		case XR_TYPE_EVENT_DATA_DISPLAY_REFRESH_RATE_CHANGED_FB: {
+			const XrEventDataDisplayRefreshRateChangedFB *event_fb = (XrEventDataDisplayRefreshRateChangedFB *)&event;
+
+			OpenXRInterface *xr_interface = OpenXRAPI::get_singleton()->get_xr_interface();
+			if (xr_interface) {
+				xr_interface->on_refresh_rate_changes(event_fb->toDisplayRefreshRate);
+			}
+
+			return true;
+		} break;
+		default:
+			return false;
+	}
+}
+
 float OpenXRDisplayRefreshRateExtension::get_refresh_rate() const {
 	float refresh_rate = 0.0;
 

modules/openxr/extensions/openxr_fb_display_refresh_rate_extension.h

@@ -51,6 +51,7 @@ class OpenXRDisplayRefreshRateExtension : public OpenXRExtensionWrapper {
 
 	virtual void on_instance_created(const XrInstance p_instance) override;
 	virtual void on_instance_destroyed() override;
+	virtual bool on_event_polled(const XrEventDataBuffer &event) override;
 
 	float get_refresh_rate() const;
 	void set_refresh_rate(float p_refresh_rate);

modules/openxr/openxr_api.h

@@ -336,6 +336,7 @@ class OpenXRAPI {
 	String get_error_string(XrResult result) const;
 	String get_swapchain_format_name(int64_t p_swapchain_format) const;
 
+	OpenXRInterface *get_xr_interface() const { return xr_interface; }
 	void set_xr_interface(OpenXRInterface *p_xr_interface);
 	static void register_extension_wrapper(OpenXRExtensionWrapper *p_extension_wrapper);
 	static void unregister_extension_wrapper(OpenXRExtensionWrapper *p_extension_wrapper);

modules/openxr/openxr_interface.cpp

@@ -43,6 +43,7 @@ void OpenXRInterface::_bind_methods() {
 	ADD_SIGNAL(MethodInfo("session_focussed"));
 	ADD_SIGNAL(MethodInfo("session_visible"));
 	ADD_SIGNAL(MethodInfo("pose_recentered"));
+	ADD_SIGNAL(MethodInfo("refresh_rate_changed", PropertyInfo(Variant::FLOAT, "refresh_rate")));
 
 	// Display refresh rate
 	ClassDB::bind_method(D_METHOD("get_display_refresh_rate"), &OpenXRInterface::get_display_refresh_rate);
@@ -1258,6 +1259,10 @@ void OpenXRInterface::on_pose_recentered() {
 	emit_signal(SNAME("pose_recentered"));
 }
 
+void OpenXRInterface::on_refresh_rate_changes(float p_new_rate) {
+	emit_signal(SNAME("refresh_rate_changed"), p_new_rate);
+}
+
 /** Hand tracking. */
 void OpenXRInterface::set_motion_range(const Hand p_hand, const HandMotionRange p_motion_range) {
 	ERR_FAIL_INDEX(p_hand, HAND_MAX);

modules/openxr/openxr_interface.h

@@ -174,6 +174,7 @@ class OpenXRInterface : public XRInterface {
 	void on_state_focused();
 	void on_state_stopping();
 	void on_pose_recentered();
+	void on_refresh_rate_changes(float p_new_rate);
 	void tracker_profile_changed(RID p_tracker, RID p_interaction_profile);
 
 	/** Hand tracking. */