1 files changed, 47 insertions, 41 deletions

diff --git a/modules/openxr/extensions/openxr_extension_wrapper.h b/modules/openxr/extensions/openxr_extension_wrapper.h
index eed969d628..25383c12d6 100644
--- a/modules/openxr/extensions/openxr_extension_wrapper.h
+++ b/modules/openxr/extensions/openxr_extension_wrapper.h
@@ -42,19 +42,14 @@
 class OpenXRAPI;
 class OpenXRActionMap;
 
+// `OpenXRExtensionWrapper` allows us to implement OpenXR extensions.
 class OpenXRExtensionWrapper {
-protected:
-	OpenXRAPI *openxr_api = nullptr;
-
-	// Store extension we require.
-	// If bool pointer is a nullptr this means this extension is mandatory and initialisation will fail if it is not available
-	// If bool pointer is set, value will be set to true or false depending on whether extension is available
-	HashMap<String, bool *> request_extensions;
-
 public:
-	virtual HashMap<String, bool *> get_request_extensions() {
-		return request_extensions;
-	}
+	// `get_requested_extensions` should return a list of OpenXR extensions related to this extension.
+	// If the bool * is a nullptr this extension is mandatory
+	// If the bool * points to a boolean, the boolean will be updated
+	// to true if the extension is enabled.
+	virtual HashMap<String, bool *> get_requested_extensions() = 0;
 
 	// These functions allow an extension to add entries to a struct chain.
 	// `p_next_pointer` points to the last struct that was created for this chain
@@ -62,49 +57,60 @@ public:
 	// You should return the pointer to the last struct you define as your result.
 	// If you are not adding any structs, just return `p_next_pointer`.
 	// See existing extensions for examples of this implementation.
-	virtual void *set_system_properties_and_get_next_pointer(void *p_next_pointer) { return p_next_pointer; }
-	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 *set_instance_create_info_and_get_next_pointer(void *p_next_pointer) { return p_next_pointer; }
+	virtual void *set_system_properties_and_get_next_pointer(void *p_next_pointer) { return p_next_pointer; } // Add additional data structures when we interogate OpenXRS system abilities.
+	virtual void *set_instance_create_info_and_get_next_pointer(void *p_next_pointer) { return p_next_pointer; } // Add additional data structures when we create our OpenXR instance.
+	virtual void *set_session_create_and_get_next_pointer(void *p_next_pointer) { return p_next_pointer; } // Add additional data structures when we create our OpenXR session.
+	virtual void *set_swapchain_create_info_and_get_next_pointer(void *p_next_pointer) { return p_next_pointer; } // Add additional data structures when creating OpenXR swap chains.
 
-	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) {}
+	// `on_register_metadata` allows extensions to register additional controller metadata.
+	// This function is called even when OpenXRApi is not constructured as the metadata
+	// needs to be available to the editor.
+	// Also extensions should provide metadata regardless of whether they are supported
+	// on the host system as the controller data is used to setup action maps for users
+	// who may have access to the relevant hardware.
+	virtual void on_register_metadata() {}
+
+	virtual void on_before_instance_created() {} // `on_before_instance_created` is called before we create our OpenXR instance.
+	virtual void on_instance_created(const XrInstance p_instance) {} // `on_instance_created` is called right after we've successfully created our OpenXR instance.
+	virtual void on_instance_destroyed() {} // `on_instance_destroyed` is called right before we destroy our OpenXR instance.
+	virtual void on_session_created(const XrSession p_instance) {} // `on_session_created` is called right after we've successsfully created our OpenXR session.
+	virtual void on_session_destroyed() {} // `on_session_destroyed` is called right before we destroy our OpenXR session.
+
+	// `on_process` is called as part of our OpenXR process handling,
+	// this happens right before physics process and normal processing is run.
+	// This is when controller data is queried and made available to game logic.
 	virtual void on_process() {}
-	virtual void on_pre_render() {}
-	virtual void on_session_destroyed() {}
+	virtual void on_pre_render() {} // `on_pre_render` is called right before we start rendering our XR viewport.
 
-	virtual void on_state_idle() {}
-	virtual void on_state_ready() {}
-	virtual void on_state_synchronized() {}
-	virtual void on_state_visible() {}
-	virtual void on_state_focused() {}
-	virtual void on_state_stopping() {}
-	virtual void on_state_loss_pending() {}
-	virtual void on_state_exiting() {}
+	virtual void on_state_idle() {} // `on_state_idle` is called when the OpenXR session state is changed to idle.
+	virtual void on_state_ready() {} // `on_state_ready` is called when the OpenXR session state is changed to ready, this means OpenXR is ready to setup our session.
+	virtual void on_state_synchronized() {} // `on_state_synchronized` is called when the OpenXR session state is changed to synchronized, note that OpenXR also returns to this state when our application looses focus.
+	virtual void on_state_visible() {} // `on_state_visible` is called when the OpenXR session state is changed to visible, OpenXR is now ready to receive frames.
+	virtual void on_state_focused() {} // `on_state_focused` is called when the OpenXR session state is changed to focused, this state is the active state when our game runs.
+	virtual void on_state_stopping() {} // `on_state_stopping` is called when the OpenXR session state is changed to stopping.
+	virtual void on_state_loss_pending() {} // `on_state_loss_pending` is called when the OpenXR session state is changed to loss pending.
+	virtual void on_state_exiting() {} // `on_state_exiting` is called when the OpenXR session state is changed to exiting.
 
-	// Returns true if the event was handled, false otherwise.
+	// `on_event_polled` is called when there is an OpenXR event to process.
+	// Should return true if the event was handled, false otherwise.
 	virtual bool on_event_polled(const XrEventDataBuffer &event) {
 		return false;
 	}
 
-	OpenXRExtensionWrapper(OpenXRAPI *p_openxr_api) { openxr_api = p_openxr_api; };
+	OpenXRExtensionWrapper() = default;
 	virtual ~OpenXRExtensionWrapper() = default;
 };
 
+// `OpenXRGraphicsExtensionWrapper` implements specific logic for each supported graphics API.
 class OpenXRGraphicsExtensionWrapper : public OpenXRExtensionWrapper {
 public:
-	virtual void get_usable_swapchain_formats(Vector<int64_t> &p_usable_swap_chains) = 0;
-	virtual void get_usable_depth_formats(Vector<int64_t> &p_usable_swap_chains) = 0;
-	virtual String get_swapchain_format_name(int64_t p_swapchain_format) const = 0;
-	virtual bool get_swapchain_image_data(XrSwapchain p_swapchain, int64_t p_swapchain_format, uint32_t p_width, uint32_t p_height, uint32_t p_sample_count, uint32_t p_array_size, void **r_swapchain_graphics_data) = 0;
-	virtual void cleanup_swapchain_graphics_data(void **p_swapchain_graphics_data) = 0;
-	virtual bool create_projection_fov(const XrFovf p_fov, double p_z_near, double p_z_far, Projection &r_camera_matrix) = 0;
-	virtual RID get_texture(void *p_swapchain_graphics_data, int p_image_index) = 0;
-
-	OpenXRGraphicsExtensionWrapper(OpenXRAPI *p_openxr_api) :
-			OpenXRExtensionWrapper(p_openxr_api){};
+	virtual void get_usable_swapchain_formats(Vector<int64_t> &p_usable_swap_chains) = 0; // `get_usable_swapchain_formats` should return a list of usable color formats.
+	virtual void get_usable_depth_formats(Vector<int64_t> &p_usable_swap_chains) = 0; // `get_usable_depth_formats` should return a list of usable depth formats.
+	virtual String get_swapchain_format_name(int64_t p_swapchain_format) const = 0; // `get_swapchain_format_name` should return the constant name of a given format.
+	virtual bool get_swapchain_image_data(XrSwapchain p_swapchain, int64_t p_swapchain_format, uint32_t p_width, uint32_t p_height, uint32_t p_sample_count, uint32_t p_array_size, void **r_swapchain_graphics_data) = 0; // `get_swapchain_image_data` extracts image IDs for the swapchain images and stores there in an implementation dependent data structure.
+	virtual void cleanup_swapchain_graphics_data(void **p_swapchain_graphics_data) = 0; // `cleanup_swapchain_graphics_data` cleans up the data held in our implementation dependent data structure and should free up its memory.
+	virtual bool create_projection_fov(const XrFovf p_fov, double p_z_near, double p_z_far, Projection &r_camera_matrix) = 0; // `create_projection_fov` creates a proper projection matrix based on asymmetric FOV data provided by OpenXR.
+	virtual RID get_texture(void *p_swapchain_graphics_data, int p_image_index) = 0; // `get_texture` returns a Godot texture RID for the current active texture in our swapchain.
 };
 
 #endif // OPENXR_EXTENSION_WRAPPER_H