Draft of HTC passthrough (XR_HTC_passthrough) support with OpenXR

modules/openxr/SCsub

@@ -108,6 +108,7 @@ env_openxr.add_source_files(module_obj, "extensions/openxr_palm_pose_extension.c
 env_openxr.add_source_files(module_obj, "extensions/openxr_composition_layer_depth_extension.cpp")
 env_openxr.add_source_files(module_obj, "extensions/openxr_eye_gaze_interaction.cpp")
 env_openxr.add_source_files(module_obj, "extensions/openxr_htc_controller_extension.cpp")
+env_openxr.add_source_files(module_obj, "extensions/openxr_htc_passthrough_extension.cpp")
 env_openxr.add_source_files(module_obj, "extensions/openxr_htc_vive_tracker_extension.cpp")
 env_openxr.add_source_files(module_obj, "extensions/openxr_huawei_controller_extension.cpp")
 env_openxr.add_source_files(module_obj, "extensions/openxr_hand_tracking_extension.cpp")

modules/openxr/extensions/openxr_htc_passthrough_extension.cpp

@@ -0,0 +1,193 @@
+/**************************************************************************/
+/*  openxr_htc_passthrough_extension.cpp                                  */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#include "openxr_htc_passthrough_extension.h"
+
+#include "core/os/os.h"
+#include "scene/main/viewport.h"
+#include "scene/main/window.h"
+
+using namespace godot;
+
+OpenXRHTCPassthroughExtension *OpenXRHTCPassthroughExtension::singleton = nullptr;
+
+OpenXRHTCPassthroughExtension *OpenXRHTCPassthroughExtension::get_singleton() {
+	return singleton;
+}
+
+OpenXRHTCPassthroughExtension::OpenXRHTCPassthroughExtension() {
+	singleton = this;
+}
+
+OpenXRHTCPassthroughExtension::~OpenXRHTCPassthroughExtension() {
+	cleanup();
+}
+
+HashMap<String, bool *> OpenXRHTCPassthroughExtension::get_requested_extensions() {
+	HashMap<String, bool *> request_extensions;
+
+	request_extensions[XR_HTC_PASSTHROUGH_EXTENSION_NAME] = &htc_passthrough_ext;
+
+	return request_extensions;
+}
+
+void OpenXRHTCPassthroughExtension::cleanup() {
+	htc_passthrough_ext = false;
+}
+
+Viewport *OpenXRHTCPassthroughExtension::get_main_viewport() {
+	MainLoop *main_loop = OS::get_singleton()->get_main_loop();
+	if (!main_loop) {
+		print_error("Unable to retrieve main loop");
+		return nullptr;
+	}
+
+	SceneTree *scene_tree = Object::cast_to<SceneTree>(main_loop);
+	if (!scene_tree) {
+		print_error("Unable to retrieve scene tree");
+		return nullptr;
+	}
+
+	Viewport *viewport = scene_tree->get_root()->get_viewport();
+	return viewport;
+}
+
+void OpenXRHTCPassthroughExtension::on_instance_created(const XrInstance instance) {
+	if (htc_passthrough_ext) {
+		bool result = initialize_htc_passthrough_extension(instance);
+		if (!result) {
+			print_error("Failed to initialize htc_passthrough extension");
+			htc_passthrough_ext = false;
+		}
+	}
+
+	if (htc_passthrough_ext) {
+		OpenXRAPI::get_singleton()->register_composition_layer_provider(this);
+	}
+}
+
+bool OpenXRHTCPassthroughExtension::is_passthrough_enabled() {
+	return htc_passthrough_ext && passthrough_handle != XR_NULL_HANDLE;
+}
+
+bool OpenXRHTCPassthroughExtension::start_passthrough() {
+	if (passthrough_handle == XR_NULL_HANDLE) {
+		return false;
+	}
+
+	if (is_passthrough_enabled()) {
+		return true;
+	}
+
+	const XrPassthroughCreateInfoHTC create_info = {
+		XR_TYPE_PASSTHROUGH_CREATE_INFO_HTC,
+		nullptr,
+		XR_PASSTHROUGH_FORM_PLANAR_HTC
+	};
+
+	XrResult result = xrCreatePassthroughHTC(OpenXRAPI::get_singleton()->get_session(),
+			&create_info,
+			&passthrough_handle);
+
+	if (result != XR_SUCCESS) {
+		stop_passthrough();
+		return false;
+	}
+
+	// Check if the the viewport has transparent background
+	Viewport *viewport = get_main_viewport();
+	if (viewport && !viewport->has_transparent_background()) {
+		print_error("Main viewport doesn't have transparent background! Passthrough may not properly render.");
+	}
+
+	// HACK: to behave similar to Meta Passthrough variant
+	set_alpha(1.0f);
+
+	return true;
+}
+
+void OpenXRHTCPassthroughExtension::on_session_created(const XrSession session) {
+	if (session && htc_passthrough_ext) {
+		start_passthrough();
+	}
+}
+
+XrCompositionLayerBaseHeader *OpenXRHTCPassthroughExtension::get_composition_layer() {
+	if (is_passthrough_enabled()) {
+		composition_passthrough_layer.passthrough = passthrough_handle;
+
+		return (XrCompositionLayerBaseHeader *)&composition_passthrough_layer;
+	} else {
+		return nullptr;
+	}
+}
+
+void OpenXRHTCPassthroughExtension::stop_passthrough() {
+	if (!htc_passthrough_ext) {
+		return;
+	}
+
+	if (passthrough_handle != XR_NULL_HANDLE) {
+		XrResult result = xrDestroyPassthroughHTC(passthrough_handle);
+		if (OpenXRAPI::get_singleton()->xr_result(result, "Unable to destroy passthrough feature")) {
+			passthrough_handle = XR_NULL_HANDLE;
+		}
+	}
+}
+
+void OpenXRHTCPassthroughExtension::on_session_destroyed() {
+	if (htc_passthrough_ext) {
+		stop_passthrough();
+	}
+}
+
+void OpenXRHTCPassthroughExtension::on_instance_destroyed() {
+	if (htc_passthrough_ext) {
+		OpenXRAPI::get_singleton()->unregister_composition_layer_provider(this);
+	}
+	cleanup();
+}
+
+void OpenXRHTCPassthroughExtension::set_alpha(float alpha) {
+	composition_passthrough_layer.color.alpha = std::clamp(alpha, 0.0f, 1.0f);
+}
+
+float OpenXRHTCPassthroughExtension::get_alpha() const {
+	return composition_passthrough_layer.color.alpha;
+}
+
+bool OpenXRHTCPassthroughExtension::initialize_htc_passthrough_extension(const XrInstance p_instance) {
+	ERR_FAIL_NULL_V(OpenXRAPI::get_singleton(), false);
+
+	EXT_INIT_XR_FUNC_V(xrCreatePassthroughHTC);
+	EXT_INIT_XR_FUNC_V(xrDestroyPassthroughHTC);
+
+	return true;
+}

modules/openxr/extensions/openxr_htc_passthrough_extension.h

@@ -0,0 +1,116 @@
+/**************************************************************************/
+/*  openxr_htc_passthrough_extension.h                                    */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#ifndef OPENXR_HTC_PASSTHROUGH_EXTENSION_H
+#define OPENXR_HTC_PASSTHROUGH_EXTENSION_H
+
+#include "../openxr_api.h"
+#include "../util.h"
+#include "openxr_composition_layer_provider.h"
+#include "openxr_extension_wrapper.h"
+
+#include <map>
+
+class Viewport;
+
+// Wrapper for the HTC XR passthrough extensions (extension #318).
+class OpenXRHTCPassthroughExtension : public OpenXRExtensionWrapper, public OpenXRCompositionLayerProvider {
+public:
+	OpenXRHTCPassthroughExtension();
+	~OpenXRHTCPassthroughExtension();
+
+	virtual HashMap<String, bool *> get_requested_extensions() override;
+
+	void on_instance_created(const XrInstance instance) override;
+
+	void on_session_created(const XrSession session) override;
+
+	void on_session_destroyed() override;
+
+	void on_instance_destroyed() override;
+
+	XrCompositionLayerBaseHeader *get_composition_layer() override;
+
+	bool is_passthrough_supported() {
+		return htc_passthrough_ext;
+	}
+
+	bool is_passthrough_enabled();
+
+	bool start_passthrough();
+
+	void stop_passthrough();
+
+	// set alpha of passthrough
+	void set_alpha(float alpha);
+
+	// get alpha of passthrough
+	float get_alpha() const;
+
+	static OpenXRHTCPassthroughExtension *get_singleton();
+
+private:
+	// Create a passthrough feature
+	EXT_PROTO_XRRESULT_FUNC3(xrCreatePassthroughHTC,
+			(XrSession), session,
+			(const XrPassthroughCreateInfoHTC *), create_info,
+			(XrPassthroughHTC *), feature_out)
+
+	// Destroy a previously created passthrough feature
+	EXT_PROTO_XRRESULT_FUNC1(xrDestroyPassthroughHTC, (XrPassthroughHTC), feature)
+
+	bool initialize_htc_passthrough_extension(const XrInstance instance);
+
+	void cleanup();
+
+	Viewport *get_main_viewport();
+
+	static OpenXRHTCPassthroughExtension *singleton;
+
+	bool htc_passthrough_ext = false; // required for any passthrough functionality
+
+	XrPassthroughHTC passthrough_handle = XR_NULL_HANDLE; // handle for passthrough
+
+	XrCompositionLayerPassthroughHTC composition_passthrough_layer = {
+		XR_TYPE_COMPOSITION_LAYER_PASSTHROUGH_HTC, // XrStructureType
+		nullptr, // next
+		XR_COMPOSITION_LAYER_BLEND_TEXTURE_SOURCE_ALPHA_BIT, //  XrCompositionLayerFlags
+		XR_NULL_HANDLE, // XrSpace
+		XR_NULL_HANDLE, // XrPassthroughHTC
+		{
+				// XrPassthroughColorHTC
+				XR_TYPE_PASSTHROUGH_COLOR_HTC, // XrStructureType
+				nullptr, // next
+				1.0f // alpha (preset to opaque)
+		}
+	};
+};
+
+#endif // OPENXR_HTC_PASSTHROUGH_EXTENSION_H

modules/openxr/openxr_interface.cpp

@@ -1112,20 +1112,40 @@ void OpenXRInterface::end_frame() {
 }
 
 bool OpenXRInterface::is_passthrough_supported() {
-	return passthrough_wrapper != nullptr && passthrough_wrapper->is_passthrough_supported();
+	if ((fb_passthrough_wrapper != nullptr) && (fb_passthrough_wrapper->is_passthrough_supported())) {
+		return true;
+	} else if ((htc_passthrough_wrapper != nullptr) && (htc_passthrough_wrapper->is_passthrough_supported())) {
+		return true;
+	} else {
+		return false;
+	}
 }
 
 bool OpenXRInterface::is_passthrough_enabled() {
-	return passthrough_wrapper != nullptr && passthrough_wrapper->is_passthrough_enabled();
+	if ((fb_passthrough_wrapper != nullptr) && (fb_passthrough_wrapper->is_passthrough_enabled())) {
+		return true;
+	} else if ((htc_passthrough_wrapper != nullptr) && (htc_passthrough_wrapper->is_passthrough_enabled())) {
+		return true;
+	} else {
+		return false;
+	}
 }
 
 bool OpenXRInterface::start_passthrough() {
-	return passthrough_wrapper != nullptr && passthrough_wrapper->start_passthrough();
+	if ((fb_passthrough_wrapper != nullptr) && (fb_passthrough_wrapper->start_passthrough())) {
+		return true;
+	} else if ((htc_passthrough_wrapper != nullptr) && (htc_passthrough_wrapper->start_passthrough())) {
+		return true;
+	} else {
+		return false;
+	}
 }
 
 void OpenXRInterface::stop_passthrough() {
-	if (passthrough_wrapper) {
-		passthrough_wrapper->stop_passthrough();
+	if (fb_passthrough_wrapper != nullptr) {
+		fb_passthrough_wrapper->stop_passthrough();
+	} else if (htc_passthrough_wrapper != nullptr) {
+		htc_passthrough_wrapper->stop_passthrough();
 	}
 }
 
@@ -1356,7 +1376,8 @@ OpenXRInterface::OpenXRInterface() {
 	_set_default_pos(transform_for_view[0], 1.0, 1);
 	_set_default_pos(transform_for_view[1], 1.0, 2);
 
-	passthrough_wrapper = OpenXRFbPassthroughExtensionWrapper::get_singleton();
+	fb_passthrough_wrapper = OpenXRFbPassthroughExtensionWrapper::get_singleton();
+	htc_passthrough_wrapper = OpenXRHTCPassthroughExtension::get_singleton();
 }
 
 OpenXRInterface::~OpenXRInterface() {

modules/openxr/openxr_interface.h

@@ -34,6 +34,7 @@
 #include "action_map/openxr_action_map.h"
 #include "extensions/openxr_fb_passthrough_extension_wrapper.h"
 #include "extensions/openxr_hand_tracking_extension.h"
+#include "extensions/openxr_htc_passthrough_extension.h"
 #include "openxr_api.h"
 
 #include "servers/xr/xr_interface.h"
@@ -49,7 +50,8 @@ class OpenXRInterface : public XRInterface {
 	OpenXRAPI *openxr_api = nullptr;
 	bool initialized = false;
 	XRInterface::TrackingStatus tracking_state;
-	OpenXRFbPassthroughExtensionWrapper *passthrough_wrapper = nullptr;
+	OpenXRFbPassthroughExtensionWrapper *fb_passthrough_wrapper = nullptr;
+	OpenXRHTCPassthroughExtension *htc_passthrough_wrapper = nullptr;
 
 	// At a minimum we need a tracker for our head
 	Ref<XRPositionalTracker> head;