Dynamic loading of OpenXR Loader on Android

This change implements dynamic loading of the OpenXR Loader library
on Android. If an OpenXR Loader library is not found,
Godot will still function with OpenXR disabled.

Also, on every platform, the OpenXR symbols are resolved at runtime
using xrGetInstanceProcAddr.

On Windows and Linux the OpenXR loader is included in the main
engine binary.

On Android, the OpenXR Loader is not built with the engine. Separately
distributed Android plugins will be provided with the correct loader
library for each device.

Co-authored-by: Gábor Pál Korom <gabor.p.korom@migeran.com>
Co-authored-by: Gábor Koncz <gabor.koncz@migeran.com>

5 files changed, 47 insertions, 84 deletions

diff --git a/modules/openxr/extensions/openxr_android_extension.cpp b/modules/openxr/extensions/openxr_android_extension.cpp
index 3bd4db169c..8f6d5c28db 100644
--- a/modules/openxr/extensions/openxr_android_extension.cpp
+++ b/modules/openxr/extensions/openxr_android_extension.cpp
@@ -29,7 +29,12 @@
 /*************************************************************************/
 
 #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>
 
@@ -42,19 +47,16 @@ OpenXRAndroidExtension *OpenXRAndroidExtension::get_singleton() {
 OpenXRAndroidExtension::OpenXRAndroidExtension(OpenXRAPI *p_openxr_api) :
 		OpenXRExtensionWrapper(p_openxr_api) {
 	singleton = this;
-
 	request_extensions[XR_KHR_ANDROID_THREAD_SETTINGS_EXTENSION_NAME] = nullptr; // must be available
+}
 
-	// Initialize the loader
-	PFN_xrInitializeLoaderKHR xrInitializeLoaderKHR;
-	result = xrGetInstanceProcAddr(XR_NULL_HANDLE, "xrInitializeLoaderKHR", (PFN_xrVoidFunction *)(&xrInitializeLoaderKHR));
-	ERR_FAIL_COND_MSG(XR_FAILED(result), "Failed to retrieve pointer to xrInitializeLoaderKHR");
+void OpenXRAndroidExtension::on_before_instance_created() {
+	EXT_INIT_XR_FUNC(xrInitializeLoaderKHR);
 
-	// TODO fix this code, this is still code from GDNative!
-	JNIEnv *env = android_api->godot_android_get_env();
+	JNIEnv *env = get_jni_env();
 	JavaVM *vm;
 	env->GetJavaVM(&vm);
-	jobject activity_object = env->NewGlobalRef(android_api->godot_android_get_activity());
+	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,
@@ -62,7 +64,7 @@ OpenXRAndroidExtension::OpenXRAndroidExtension(OpenXRAPI *p_openxr_api) :
 		.applicationVM = vm,
 		.applicationContext = activity_object
 	};
-	xrInitializeLoaderKHR((const XrLoaderInitInfoBaseHeaderKHR *)&loader_init_info_android);
+	XrResult result = xrInitializeLoaderKHR((const XrLoaderInitInfoBaseHeaderKHR *)&loader_init_info_android);
 	ERR_FAIL_COND_MSG(XR_FAILED(result), "Failed to call xrInitializeLoaderKHR");
 }
 
diff --git a/modules/openxr/extensions/openxr_android_extension.h b/modules/openxr/extensions/openxr_android_extension.h
index 88b0e310e7..eda7022064 100644
--- a/modules/openxr/extensions/openxr_android_extension.h
+++ b/modules/openxr/extensions/openxr_android_extension.h
@@ -31,6 +31,7 @@
 #ifndef OPENXR_ANDROID_EXTENSION_H
 #define OPENXR_ANDROID_EXTENSION_H
 
+#include "../util.h"
 #include "openxr_extension_wrapper.h"
 
 class OpenXRAndroidExtension : public OpenXRExtensionWrapper {
@@ -38,10 +39,16 @@ public:
 	static OpenXRAndroidExtension *get_singleton();
 
 	OpenXRAndroidExtension(OpenXRAPI *p_openxr_api);
+
+	virtual void on_before_instance_created() override;
+
 	virtual ~OpenXRAndroidExtension() override;
 
 private:
 	static OpenXRAndroidExtension *singleton;
+
+	// Initialize the loader
+	EXT_PROTO_XRRESULT_FUNC1(xrInitializeLoaderKHR, (const XrLoaderInitInfoBaseHeaderKHR *), loaderInitInfo)
 };
 
 #endif // OPENXR_ANDROID_EXTENSION_H
diff --git a/modules/openxr/extensions/openxr_extension_wrapper.h b/modules/openxr/extensions/openxr_extension_wrapper.h
index ecc6e0dd4e..0ed0155fc7 100644
--- a/modules/openxr/extensions/openxr_extension_wrapper.h
+++ b/modules/openxr/extensions/openxr_extension_wrapper.h
@@ -66,6 +66,7 @@ public:
 	virtual void *set_session_create_and_get_next_pointer(void *p_next_pointer) { return p_next_pointer; }
 	virtual void *set_swapchain_create_info_and_get_next_pointer(void *p_next_pointer) { return p_next_pointer; }
 
+	virtual void on_before_instance_created() {}
 	virtual void on_instance_created(const XrInstance p_instance) {}
 	virtual void on_instance_destroyed() {}
 	virtual void on_session_created(const XrSession p_instance) {}
diff --git a/modules/openxr/extensions/openxr_vulkan_extension.cpp b/modules/openxr/extensions/openxr_vulkan_extension.cpp
index 2608c4ac17..f9e771c934 100644
--- a/modules/openxr/extensions/openxr_vulkan_extension.cpp
+++ b/modules/openxr/extensions/openxr_vulkan_extension.cpp
@@ -31,30 +31,12 @@
 #include "core/string/print_string.h"
 
 #include "../extensions/openxr_vulkan_extension.h"
-#include "../openxr_api.h"
 #include "../openxr_util.h"
 #include "servers/rendering/renderer_rd/effects/copy_effects.h"
 #include "servers/rendering/renderer_rd/storage_rd/texture_storage.h"
 #include "servers/rendering/rendering_server_globals.h"
 #include "servers/rendering_server.h"
 
-// need to include Vulkan so we know of type definitions
-#define XR_USE_GRAPHICS_API_VULKAN
-
-#ifdef WINDOWS_ENABLED
-// Including windows.h here is absolutely evil, we shouldn't be doing this outside of platform
-// however due to the way the openxr headers are put together, we have no choice.
-#include <windows.h>
-#endif
-
-// include platform dependent structs
-#include <openxr/openxr_platform.h>
-
-PFN_xrGetVulkanGraphicsRequirements2KHR xrGetVulkanGraphicsRequirements2KHR_ptr = nullptr;
-PFN_xrCreateVulkanInstanceKHR xrCreateVulkanInstanceKHR_ptr = nullptr;
-PFN_xrGetVulkanGraphicsDevice2KHR xrGetVulkanGraphicsDevice2KHR_ptr = nullptr;
-PFN_xrCreateVulkanDeviceKHR xrCreateVulkanDeviceKHR_ptr = nullptr;
-
 OpenXRVulkanExtension::OpenXRVulkanExtension(OpenXRAPI *p_openxr_api) :
 		OpenXRGraphicsExtensionWrapper(p_openxr_api) {
 	VulkanContext::set_vulkan_hooks(this);
@@ -69,36 +51,15 @@ OpenXRVulkanExtension::~OpenXRVulkanExtension() {
 }
 
 void OpenXRVulkanExtension::on_instance_created(const XrInstance p_instance) {
-	XrResult result;
-
 	ERR_FAIL_NULL(openxr_api);
 
 	// Obtain pointers to functions we're accessing here, they are (not yet) part of core.
-	result = xrGetInstanceProcAddr(p_instance, "xrGetVulkanGraphicsRequirements2KHR", (PFN_xrVoidFunction *)&xrGetVulkanGraphicsRequirements2KHR_ptr);
-	if (XR_FAILED(result)) {
-		print_line("OpenXR: Failed to xrGetVulkanGraphicsRequirements2KHR entry point [", openxr_api->get_error_string(result), "]");
-	}
 
-	result = xrGetInstanceProcAddr(p_instance, "xrCreateVulkanInstanceKHR", (PFN_xrVoidFunction *)&xrCreateVulkanInstanceKHR_ptr);
-	if (XR_FAILED(result)) {
-		print_line("OpenXR: Failed to xrCreateVulkanInstanceKHR entry point [", openxr_api->get_error_string(result), "]");
-	}
-
-	result = xrGetInstanceProcAddr(p_instance, "xrGetVulkanGraphicsDevice2KHR", (PFN_xrVoidFunction *)&xrGetVulkanGraphicsDevice2KHR_ptr);
-	if (XR_FAILED(result)) {
-		print_line("OpenXR: Failed to xrGetVulkanGraphicsDevice2KHR entry point [", openxr_api->get_error_string(result), "]");
-	}
-
-	result = xrGetInstanceProcAddr(p_instance, "xrCreateVulkanDeviceKHR", (PFN_xrVoidFunction *)&xrCreateVulkanDeviceKHR_ptr);
-	if (XR_FAILED(result)) {
-		print_line("OpenXR: Failed to xrCreateVulkanDeviceKHR entry point [", openxr_api->get_error_string(result), "]");
-	}
-}
-
-XrResult OpenXRVulkanExtension::xrGetVulkanGraphicsRequirements2KHR(XrInstance p_instance, XrSystemId p_system_id, XrGraphicsRequirementsVulkanKHR *p_graphics_requirements) {
-	ERR_FAIL_NULL_V(xrGetVulkanGraphicsRequirements2KHR_ptr, XR_ERROR_HANDLE_INVALID);
-
-	return (*xrGetVulkanGraphicsRequirements2KHR_ptr)(p_instance, p_system_id, p_graphics_requirements);
+	EXT_INIT_XR_FUNC(xrGetVulkanGraphicsRequirements2KHR);
+	EXT_INIT_XR_FUNC(xrCreateVulkanInstanceKHR);
+	EXT_INIT_XR_FUNC(xrGetVulkanGraphicsDevice2KHR);
+	EXT_INIT_XR_FUNC(xrCreateVulkanDeviceKHR);
+	EXT_INIT_XR_FUNC(xrEnumerateSwapchainImages);
 }
 
 bool OpenXRVulkanExtension::check_graphics_api_support(XrVersion p_desired_version) {
@@ -141,12 +102,6 @@ bool OpenXRVulkanExtension::check_graphics_api_support(XrVersion p_desired_versi
 	return true;
 }
 
-XrResult OpenXRVulkanExtension::xrCreateVulkanInstanceKHR(XrInstance p_instance, const XrVulkanInstanceCreateInfoKHR *p_create_info, VkInstance *r_vulkan_instance, VkResult *r_vulkan_result) {
-	ERR_FAIL_NULL_V(xrCreateVulkanInstanceKHR_ptr, XR_ERROR_HANDLE_INVALID);
-
-	return (*xrCreateVulkanInstanceKHR_ptr)(p_instance, p_create_info, r_vulkan_instance, r_vulkan_result);
-}
-
 bool OpenXRVulkanExtension::create_vulkan_instance(const VkInstanceCreateInfo *p_vulkan_create_info, VkInstance *r_instance) {
 	// get the vulkan version we are creating
 	uint32_t vulkan_version = p_vulkan_create_info->pApplicationInfo->apiVersion;
@@ -195,12 +150,6 @@ bool OpenXRVulkanExtension::create_vulkan_instance(const VkInstanceCreateInfo *p
 	return true;
 }
 
-XrResult OpenXRVulkanExtension::xrGetVulkanGraphicsDevice2KHR(XrInstance p_instance, const XrVulkanGraphicsDeviceGetInfoKHR *p_get_info, VkPhysicalDevice *r_vulkan_physical_device) {
-	ERR_FAIL_NULL_V(xrGetVulkanGraphicsDevice2KHR_ptr, XR_ERROR_HANDLE_INVALID);
-
-	return (*xrGetVulkanGraphicsDevice2KHR_ptr)(p_instance, p_get_info, r_vulkan_physical_device);
-}
-
 bool OpenXRVulkanExtension::get_physical_device(VkPhysicalDevice *r_device) {
 	ERR_FAIL_NULL_V(openxr_api, false);
 
@@ -222,12 +171,6 @@ bool OpenXRVulkanExtension::get_physical_device(VkPhysicalDevice *r_device) {
 	return true;
 }
 
-XrResult OpenXRVulkanExtension::xrCreateVulkanDeviceKHR(XrInstance p_instance, const XrVulkanDeviceCreateInfoKHR *p_create_info, VkDevice *r_device, VkResult *r_result) {
-	ERR_FAIL_NULL_V(xrCreateVulkanDeviceKHR_ptr, XR_ERROR_HANDLE_INVALID);
-
-	return (*xrCreateVulkanDeviceKHR_ptr)(p_instance, p_create_info, r_device, r_result);
-}
-
 bool OpenXRVulkanExtension::create_vulkan_device(const VkDeviceCreateInfo *p_device_create_info, VkDevice *r_device) {
 	ERR_FAIL_NULL_V(openxr_api, false);
 
diff --git a/modules/openxr/extensions/openxr_vulkan_extension.h b/modules/openxr/extensions/openxr_vulkan_extension.h
index 5dddc4b9c9..d6e9917900 100644
--- a/modules/openxr/extensions/openxr_vulkan_extension.h
+++ b/modules/openxr/extensions/openxr_vulkan_extension.h
@@ -36,16 +36,25 @@
 
 #include "drivers/vulkan/vulkan_context.h"
 
-// Forward declare these so we don't need OpenXR headers where-ever this is included
-// Including OpenXR at this point gives loads and loads of compile issues especially
-// on Windows because windows.h is EVIL and really shouldn't be included outside of platform
-// but we really don't have a choice in the matter
+#include "../openxr_api.h"
+#include "../util.h"
 
-struct XrGraphicsRequirementsVulkanKHR;
-struct XrVulkanInstanceCreateInfoKHR;
-struct XrVulkanGraphicsDeviceGetInfoKHR;
-struct XrVulkanDeviceCreateInfoKHR;
-struct XrGraphicsBindingVulkanKHR;
+// need to include Vulkan so we know of type definitions
+#define XR_USE_GRAPHICS_API_VULKAN
+
+#ifdef WINDOWS_ENABLED
+// Including windows.h here is absolutely evil, we shouldn't be doing this outside of platform
+// however due to the way the openxr headers are put together, we have no choice.
+#include <windows.h>
+#endif
+
+#ifdef ANDROID_ENABLED
+// The jobject type from jni.h is used by openxr_platform.h on Android.
+#include <jni.h>
+#endif
+
+// include platform dependent structs
+#include <openxr/openxr_platform.h>
 
 class OpenXRVulkanExtension : public OpenXRGraphicsExtensionWrapper, VulkanHooks {
 public:
@@ -84,10 +93,11 @@ private:
 	uint32_t vulkan_queue_family_index = 0;
 	uint32_t vulkan_queue_index = 0;
 
-	XrResult xrGetVulkanGraphicsRequirements2KHR(XrInstance p_instance, XrSystemId p_system_id, XrGraphicsRequirementsVulkanKHR *p_graphics_requirements);
-	XrResult xrCreateVulkanInstanceKHR(XrInstance p_instance, const XrVulkanInstanceCreateInfoKHR *p_create_info, VkInstance *r_vulkan_instance, VkResult *r_vulkan_result);
-	XrResult xrGetVulkanGraphicsDevice2KHR(XrInstance p_instance, const XrVulkanGraphicsDeviceGetInfoKHR *p_get_info, VkPhysicalDevice *r_vulkan_physical_device);
-	XrResult xrCreateVulkanDeviceKHR(XrInstance p_instance, const XrVulkanDeviceCreateInfoKHR *p_create_info, VkDevice *r_device, VkResult *r_result);
+	EXT_PROTO_XRRESULT_FUNC3(xrGetVulkanGraphicsRequirements2KHR, (XrInstance), p_instance, (XrSystemId), p_system_id, (XrGraphicsRequirementsVulkanKHR *), p_graphics_requirements)
+	EXT_PROTO_XRRESULT_FUNC4(xrCreateVulkanInstanceKHR, (XrInstance), p_instance, (const XrVulkanInstanceCreateInfoKHR *), p_create_info, (VkInstance *), r_vulkan_instance, (VkResult *), r_vulkan_result)
+	EXT_PROTO_XRRESULT_FUNC3(xrGetVulkanGraphicsDevice2KHR, (XrInstance), p_instance, (const XrVulkanGraphicsDeviceGetInfoKHR *), p_get_info, (VkPhysicalDevice *), r_vulkan_physical_device)
+	EXT_PROTO_XRRESULT_FUNC4(xrCreateVulkanDeviceKHR, (XrInstance), p_instance, (const XrVulkanDeviceCreateInfoKHR *), p_create_info, (VkDevice *), r_device, (VkResult *), r_result)
+	EXT_PROTO_XRRESULT_FUNC4(xrEnumerateSwapchainImages, (XrSwapchain), p_swapchain, (uint32_t), p_image_capacity_input, (uint32_t *), p_image_count_output, (XrSwapchainImageBaseHeader *), p_images)
 };
 
 #endif // OPENXR_VULKAN_EXTENSION_H