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>

1 files changed, 5 insertions, 62 deletions

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);