godot/modules/openxr/extensions/openxr_android_extension.cpp

/*************************************************************************/
/*  openxr_android_extension.cpp                                         */
/*************************************************************************/
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#include "openxr_android_extension.h"
#include "java_godot_wrapper.h"
#include "os_android.h"
#include "thread_jandroid.h"

#include <jni.h>
#include <modules/openxr/openxr_api.h>
#include <openxr/openxr.h>
#include <openxr/openxr_platform.h>

OpenXRAndroidExtension *OpenXRAndroidExtension::singleton = nullptr;

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

OpenXRAndroidExtension::OpenXRAndroidExtension(OpenXRAPI *p_openxr_api) :
		OpenXRExtensionWrapper(p_openxr_api) {
	singleton = this;
	request_extensions[XR_KHR_LOADER_INIT_ANDROID_EXTENSION_NAME] = &loader_init_extension_available;
	request_extensions[XR_KHR_ANDROID_CREATE_INSTANCE_EXTENSION_NAME] = &create_instance_extension_available;
}

void OpenXRAndroidExtension::on_before_instance_created() {
	if (!loader_init_extension_available) {
		print_line("OpenXR: XR_KHR_loader_init_android is not reported as available - trying to initialize anyway...");
	}

	EXT_INIT_XR_FUNC(xrInitializeLoaderKHR);

	JNIEnv *env = get_jni_env();
	JavaVM *vm;
	env->GetJavaVM(&vm);
	jobject activity_object = env->NewGlobalRef(static_cast<OS_Android *>(OS::get_singleton())->get_godot_java()->get_activity());

	XrLoaderInitInfoAndroidKHR loader_init_info_android = {
		.type = XR_TYPE_LOADER_INIT_INFO_ANDROID_KHR,
		.next = nullptr,
		.applicationVM = vm,
		.applicationContext = activity_object
	};
	XrResult result = xrInitializeLoaderKHR((const XrLoaderInitInfoBaseHeaderKHR *)&loader_init_info_android);
	ERR_FAIL_COND_MSG(XR_FAILED(result), "Failed to call xrInitializeLoaderKHR");
}

// We're keeping the Android create info struct here to avoid including openxr_platform.h in a header, which would break other extensions.
// This is reasonably safe as the struct is only used during intialization and the extension is a singleton.
static XrInstanceCreateInfoAndroidKHR instance_create_info;

void *OpenXRAndroidExtension::set_instance_create_info_and_get_next_pointer(void *p_next_pointer) {
	if (!create_instance_extension_available) {
		return nullptr;
	}

	JNIEnv *env = get_jni_env();
	JavaVM *vm;
	env->GetJavaVM(&vm);
	jobject activity_object = env->NewGlobalRef(static_cast<OS_Android *>(OS::get_singleton())->get_godot_java()->get_activity());

	instance_create_info = {
		.type = XR_TYPE_INSTANCE_CREATE_INFO_ANDROID_KHR,
		.next = p_next_pointer,
		.applicationVM = vm,
		.applicationActivity = activity_object
	};
	return &instance_create_info;
}

OpenXRAndroidExtension::~OpenXRAndroidExtension() {
	singleton = nullptr;
}