godot/modules/openxr/extensions/openxr_fb_passthrough_extension_wrapper.cpp

/*************************************************************************/
/*  openxr_fb_passthrough_extension_wrapper.cpp                          */
/*************************************************************************/
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/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
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#include "openxr_fb_passthrough_extension_wrapper.h"

#include "core/os/os.h"
#include "scene/main/viewport.h"
#include "scene/main/window.h"

using namespace godot;

OpenXRFbPassthroughExtensionWrapper *OpenXRFbPassthroughExtensionWrapper::singleton = nullptr;

OpenXRFbPassthroughExtensionWrapper *OpenXRFbPassthroughExtensionWrapper::get_singleton() {
	return singleton;
}

OpenXRFbPassthroughExtensionWrapper::OpenXRFbPassthroughExtensionWrapper(OpenXRAPI *p_openxr_api) :
		OpenXRExtensionWrapper(p_openxr_api) {
	request_extensions[XR_FB_PASSTHROUGH_EXTENSION_NAME] = &fb_passthrough_ext;
	request_extensions[XR_FB_TRIANGLE_MESH_EXTENSION_NAME] = &fb_triangle_mesh_ext;
	singleton = this;
}

OpenXRFbPassthroughExtensionWrapper::~OpenXRFbPassthroughExtensionWrapper() {
	cleanup();
}

void OpenXRFbPassthroughExtensionWrapper::cleanup() {
	fb_passthrough_ext = false;
	fb_triangle_mesh_ext = false;
}

Viewport *OpenXRFbPassthroughExtensionWrapper::get_main_viewport() {
	MainLoop *main_loop = OS::get_singleton()->get_main_loop();
	if (!main_loop) {
		print_error("Unable to retrieve main loop");
		return nullptr;
	}

	auto *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 OpenXRFbPassthroughExtensionWrapper::on_instance_created(const XrInstance instance) {
	if (fb_passthrough_ext) {
		bool result = initialize_fb_passthrough_extension(instance);
		if (!result) {
			print_error("Failed to initialize fb_passthrough extension");
			fb_passthrough_ext = false;
		}
	}

	if (fb_triangle_mesh_ext) {
		bool result = initialize_fb_triangle_mesh_extension(instance);
		if (!result) {
			print_error("Failed to initialize fb_triangle_mesh extension");
			fb_triangle_mesh_ext = false;
		}
	}

	if (fb_passthrough_ext) {
		openxr_api->register_composition_layer_provider(this);
	}
}

bool OpenXRFbPassthroughExtensionWrapper::is_passthrough_enabled() {
	return fb_passthrough_ext && passthrough_handle != XR_NULL_HANDLE && passthrough_layer != XR_NULL_HANDLE;
}

bool OpenXRFbPassthroughExtensionWrapper::is_composition_passthrough_layer_ready() {
	return fb_passthrough_ext && passthrough_handle != XR_NULL_HANDLE && composition_passthrough_layer.layerHandle != XR_NULL_HANDLE;
}

bool OpenXRFbPassthroughExtensionWrapper::start_passthrough() {
	if (passthrough_handle == XR_NULL_HANDLE) {
		return false;
	}

	if (is_passthrough_enabled()) {
		return true;
	}

	// Start the passthrough feature
	XrResult result = xrPassthroughStartFB(passthrough_handle);
	if (!is_valid_passthrough_result(result, "Failed to start passthrough")) {
		stop_passthrough();
		return false;
	}

	// Create the passthrough layer
	result = xrCreatePassthroughLayerFB(openxr_api->get_session(), &passthrough_layer_config, &passthrough_layer);
	if (!is_valid_passthrough_result(result, "Failed to create the passthrough layer")) {
		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.");
	}

	composition_passthrough_layer.layerHandle = passthrough_layer;

	return true;
}

void OpenXRFbPassthroughExtensionWrapper::on_session_created(const XrSession session) {
	if (fb_passthrough_ext) {
		// Create the passthrough feature and start it.
		XrResult result = xrCreatePassthroughFB(openxr_api->get_session(), &passthrough_create_info, &passthrough_handle);
		if (!openxr_api->xr_result(result, "Failed to create passthrough")) {
			passthrough_handle = XR_NULL_HANDLE;
			return;
		}
	}
}

XrCompositionLayerBaseHeader *OpenXRFbPassthroughExtensionWrapper::get_composition_layer() {
	if (is_composition_passthrough_layer_ready()) {
		return (XrCompositionLayerBaseHeader *)&composition_passthrough_layer;
	} else {
		return nullptr;
	}
}

void OpenXRFbPassthroughExtensionWrapper::stop_passthrough() {
	if (!fb_passthrough_ext) {
		return;
	}

	composition_passthrough_layer.layerHandle = XR_NULL_HANDLE;

	XrResult result;
	if (passthrough_layer != XR_NULL_HANDLE) {
		// Destroy the layer
		result = xrDestroyPassthroughLayerFB(passthrough_layer);
		openxr_api->xr_result(result, "Unable to destroy passthrough layer");
		passthrough_layer = XR_NULL_HANDLE;
	}

	if (passthrough_handle != XR_NULL_HANDLE) {
		result = xrPassthroughPauseFB(passthrough_handle);
		openxr_api->xr_result(result, "Unable to stop passthrough feature");
	}
}

void OpenXRFbPassthroughExtensionWrapper::on_session_destroyed() {
	if (fb_passthrough_ext) {
		stop_passthrough();

		XrResult result;
		if (passthrough_handle != XR_NULL_HANDLE) {
			result = xrDestroyPassthroughFB(passthrough_handle);
			openxr_api->xr_result(result, "Unable to destroy passthrough feature");
			passthrough_handle = XR_NULL_HANDLE;
		}
	}
}

void OpenXRFbPassthroughExtensionWrapper::on_instance_destroyed() {
	if (fb_passthrough_ext) {
		openxr_api->unregister_composition_layer_provider(this);
	}
	cleanup();
}

bool OpenXRFbPassthroughExtensionWrapper::initialize_fb_passthrough_extension(const XrInstance p_instance) {
	ERR_FAIL_NULL_V(openxr_api, false);

	EXT_INIT_XR_FUNC_V(xrCreatePassthroughFB);
	EXT_INIT_XR_FUNC_V(xrDestroyPassthroughFB);
	EXT_INIT_XR_FUNC_V(xrPassthroughStartFB);
	EXT_INIT_XR_FUNC_V(xrPassthroughPauseFB);
	EXT_INIT_XR_FUNC_V(xrCreatePassthroughLayerFB);
	EXT_INIT_XR_FUNC_V(xrDestroyPassthroughLayerFB);
	EXT_INIT_XR_FUNC_V(xrPassthroughLayerPauseFB);
	EXT_INIT_XR_FUNC_V(xrPassthroughLayerResumeFB);
	EXT_INIT_XR_FUNC_V(xrPassthroughLayerSetStyleFB);
	EXT_INIT_XR_FUNC_V(xrCreateGeometryInstanceFB);
	EXT_INIT_XR_FUNC_V(xrDestroyGeometryInstanceFB);
	EXT_INIT_XR_FUNC_V(xrGeometryInstanceSetTransformFB);

	return true;
}

bool OpenXRFbPassthroughExtensionWrapper::initialize_fb_triangle_mesh_extension(const XrInstance p_instance) {
	ERR_FAIL_NULL_V(openxr_api, false);

	EXT_INIT_XR_FUNC_V(xrCreateTriangleMeshFB);
	EXT_INIT_XR_FUNC_V(xrDestroyTriangleMeshFB);
	EXT_INIT_XR_FUNC_V(xrTriangleMeshGetVertexBufferFB);
	EXT_INIT_XR_FUNC_V(xrTriangleMeshGetIndexBufferFB);
	EXT_INIT_XR_FUNC_V(xrTriangleMeshBeginUpdateFB);
	EXT_INIT_XR_FUNC_V(xrTriangleMeshEndUpdateFB);
	EXT_INIT_XR_FUNC_V(xrTriangleMeshBeginVertexBufferUpdateFB);
	EXT_INIT_XR_FUNC_V(xrTriangleMeshEndVertexBufferUpdateFB);

	return true;
}