[WebXR] Add support for getting and setting display refresh rate

modules/webxr/doc_classes/WebXRInterface.xml

@@ -93,6 +93,18 @@
 		<link title="How to make a VR game for WebXR with Godot 4">https://www.snopekgames.com/tutorial/2023/how-make-vr-game-webxr-godot-4</link>
 	</tutorials>
 	<methods>
+		<method name="get_available_display_refresh_rates" qualifiers="const">
+			<return type="Array" />
+			<description>
+				Returns display refresh rates supported by the current HMD. Only returned if this feature is supported by the web browser and after the interface has been initialized.
+			</description>
+		</method>
+		<method name="get_display_refresh_rate" qualifiers="const">
+			<return type="float" />
+			<description>
+				Returns the display refresh rate for the current HMD. Not supported on all HMDs and browsers. It may not report an accurate value until after using [method set_display_refresh_rate].
+			</description>
+		</method>
 		<method name="get_input_source_target_ray_mode" qualifiers="const">
 			<return type="int" enum="WebXRInterface.TargetRayMode" />
 			<param index="0" name="input_source_id" type="int" />
@@ -132,6 +144,13 @@
 				This method returns nothing, instead it emits the [signal session_supported] signal with the result.
 			</description>
 		</method>
+		<method name="set_display_refresh_rate">
+			<return type="void" />
+			<param index="0" name="refresh_rate" type="float" />
+			<description>
+				Sets the display refresh rate for the current HMD. Not supported on all HMDs and browsers. It won't take effect right away until after [signal display_refresh_rate_changed] is emitted.
+			</description>
+		</method>
 	</methods>
 	<members>
 		<member name="optional_features" type="String" setter="set_optional_features" getter="get_optional_features">
@@ -167,6 +186,11 @@
 		</member>
 	</members>
 	<signals>
+		<signal name="display_refresh_rate_changed">
+			<description>
+				Emitted after the display's refresh rate has changed.
+			</description>
+		</signal>
 		<signal name="reference_space_reset">
 			<description>
 				Emitted to indicate that the reference space has been reset or reconfigured.

modules/webxr/godot_webxr.h

@@ -90,6 +90,10 @@ extern bool godot_webxr_update_input_source(
 extern char *godot_webxr_get_visibility_state();
 extern int godot_webxr_get_bounds_geometry(float **r_points);
 
+extern float godot_webxr_get_frame_rate();
+extern void godot_webxr_update_target_frame_rate(float p_frame_rate);
+extern int godot_webxr_get_supported_frame_rates(float **r_frame_rates);
+
 #ifdef __cplusplus
 }
 #endif

modules/webxr/native/library_godot_webxr.js

@@ -42,6 +42,7 @@ const GodotWebXR = {
 		view_count: 1,
 		input_sources: new Array(16),
 		touches: new Array(5),
+		onsimpleevent: null,
 
 		// Monkey-patch the requestAnimationFrame() used by Emscripten for the main
 		// loop, so that we can swap it out for XRSession.requestAnimationFrame()
@@ -283,6 +284,9 @@ const GodotWebXR = {
 				GodotRuntime.free(c_str);
 			});
 
+			// Store onsimpleevent so we can use it later.
+			GodotWebXR.onsimpleevent = onsimpleevent;
+
 			const gl_context_handle = _emscripten_webgl_get_current_context(); // eslint-disable-line no-undef
 			const gl = GL.getContext(gl_context_handle).GLctx;
 			GodotWebXR.gl = gl;
@@ -368,6 +372,7 @@ const GodotWebXR = {
 		GodotWebXR.view_count = 1;
 		GodotWebXR.input_sources = new Array(16);
 		GodotWebXR.touches = new Array(5);
+		GodotWebXR.onsimpleevent = null;
 
 		// Disable the monkey-patched window.requestAnimationFrame() and
 		// pause/restart the main loop to activate it on all platforms.
@@ -595,6 +600,51 @@ const GodotWebXR = {
 
 		return point_count;
 	},
+
+	godot_webxr_get_frame_rate__proxy: 'sync',
+	godot_webxr_get_frame_rate__sig: 'i',
+	godot_webxr_get_frame_rate: function () {
+		if (!GodotWebXR.session || GodotWebXR.session.frameRate === undefined) {
+			return 0;
+		}
+		return GodotWebXR.session.frameRate;
+	},
+
+	godot_webxr_update_target_frame_rate__proxy: 'sync',
+	godot_webxr_update_target_frame_rate__sig: 'vi',
+	godot_webxr_update_target_frame_rate: function (p_frame_rate) {
+		if (!GodotWebXR.session || GodotWebXR.session.updateTargetFrameRate === undefined) {
+			return;
+		}
+
+		GodotWebXR.session.updateTargetFrameRate(p_frame_rate).then(() => {
+			const c_str = GodotRuntime.allocString('display_refresh_rate_changed');
+			GodotWebXR.onsimpleevent(c_str);
+			GodotRuntime.free(c_str);
+		});
+	},
+
+	godot_webxr_get_supported_frame_rates__proxy: 'sync',
+	godot_webxr_get_supported_frame_rates__sig: 'ii',
+	godot_webxr_get_supported_frame_rates: function (r_frame_rates) {
+		if (!GodotWebXR.session || GodotWebXR.session.supportedFrameRates === undefined) {
+			return 0;
+		}
+
+		const frame_rate_count = GodotWebXR.session.supportedFrameRates.length;
+		if (frame_rate_count === 0) {
+			return 0;
+		}
+
+		const buf = GodotRuntime.malloc(frame_rate_count * 4);
+		for (let i = 0; i < frame_rate_count; i++) {
+			GodotRuntime.setHeapValue(buf + (i * 4), GodotWebXR.session.supportedFrameRates[i], 'float');
+		}
+		GodotRuntime.setHeapValue(r_frame_rates, buf, 'i32');
+
+		return frame_rate_count;
+	},
+
 };
 
 autoAddDeps(GodotWebXR, '$GodotWebXR');

modules/webxr/native/webxr.externs.js

@@ -67,6 +67,16 @@ XRSession.prototype.inputSources;
  */
 XRSession.prototype.visibilityState;
 
+/**
+ * @type {?number}
+ */
+XRSession.prototype.frameRate;
+
+/**
+ * @type {?Float32Array}
+ */
+XRSession.prototype.supportedFrameRates;
+
 /**
  * @type {?function (Event)}
  */
@@ -141,6 +151,12 @@ XRSession.prototype.end = function () {};
  */
 XRSession.prototype.requestReferenceSpace = function (referenceSpaceType) {};
 
+/**
+ * @param {number} rate
+ * @return {Promise<undefined>}
+ */
+XRSession.prototype.updateTargetFrameRate = function (rate) {};
+
 /**
  * @typedef {function(number, XRFrame): undefined}
  */

modules/webxr/webxr_interface.cpp

@@ -46,6 +46,9 @@ void WebXRInterface::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_input_source_tracker", "input_source_id"), &WebXRInterface::get_input_source_tracker);
 	ClassDB::bind_method(D_METHOD("get_input_source_target_ray_mode", "input_source_id"), &WebXRInterface::get_input_source_target_ray_mode);
 	ClassDB::bind_method(D_METHOD("get_visibility_state"), &WebXRInterface::get_visibility_state);
+	ClassDB::bind_method(D_METHOD("get_display_refresh_rate"), &WebXRInterface::get_display_refresh_rate);
+	ClassDB::bind_method(D_METHOD("set_display_refresh_rate", "refresh_rate"), &WebXRInterface::set_display_refresh_rate);
+	ClassDB::bind_method(D_METHOD("get_available_display_refresh_rates"), &WebXRInterface::get_available_display_refresh_rates);
 
 	ADD_PROPERTY(PropertyInfo(Variant::STRING, "session_mode", PROPERTY_HINT_NONE), "set_session_mode", "get_session_mode");
 	ADD_PROPERTY(PropertyInfo(Variant::STRING, "required_features", PROPERTY_HINT_NONE), "set_required_features", "get_required_features");
@@ -68,6 +71,7 @@ void WebXRInterface::_bind_methods() {
 
 	ADD_SIGNAL(MethodInfo("visibility_state_changed"));
 	ADD_SIGNAL(MethodInfo("reference_space_reset"));
+	ADD_SIGNAL(MethodInfo("display_refresh_rate_changed"));
 
 	BIND_ENUM_CONSTANT(TARGET_RAY_MODE_UNKNOWN);
 	BIND_ENUM_CONSTANT(TARGET_RAY_MODE_GAZE);

modules/webxr/webxr_interface.h

@@ -66,6 +66,9 @@ class WebXRInterface : public XRInterface {
 	virtual Ref<XRPositionalTracker> get_input_source_tracker(int p_input_source_id) const = 0;
 	virtual TargetRayMode get_input_source_target_ray_mode(int p_input_source_id) const = 0;
 	virtual String get_visibility_state() const = 0;
+	virtual float get_display_refresh_rate() const = 0;
+	virtual void set_display_refresh_rate(float p_refresh_rate) = 0;
+	virtual Array get_available_display_refresh_rates() const = 0;
 };
 
 VARIANT_ENUM_CAST(WebXRInterface::TargetRayMode);

modules/webxr/webxr_interface_js.cpp

@@ -202,6 +202,30 @@ PackedVector3Array WebXRInterfaceJS::get_play_area() const {
 	return ret;
 }
 
+float WebXRInterfaceJS::get_display_refresh_rate() const {
+	return godot_webxr_get_frame_rate();
+}
+
+void WebXRInterfaceJS::set_display_refresh_rate(float p_refresh_rate) {
+	godot_webxr_update_target_frame_rate(p_refresh_rate);
+}
+
+Array WebXRInterfaceJS::get_available_display_refresh_rates() const {
+	Array ret;
+
+	float *rates;
+	int rate_count = godot_webxr_get_supported_frame_rates(&rates);
+	if (rate_count > 0) {
+		ret.resize(rate_count);
+		for (int i = 0; i < rate_count; i++) {
+			ret[i] = rates[i];
+		}
+		free(rates);
+	}
+
+	return ret;
+}
+
 StringName WebXRInterfaceJS::get_name() const {
 	return "WebXR";
 };

modules/webxr/webxr_interface_js.h

@@ -102,6 +102,10 @@ class WebXRInterfaceJS : public WebXRInterface {
 	virtual String get_visibility_state() const override;
 	virtual PackedVector3Array get_play_area() const override;
 
+	virtual float get_display_refresh_rate() const override;
+	virtual void set_display_refresh_rate(float p_refresh_rate) override;
+	virtual Array get_available_display_refresh_rates() const override;
+
 	virtual StringName get_name() const override;
 	virtual uint32_t get_capabilities() const override;