2d camera defer_scroll option

2d cameras currently often give a frame delay between moving the camera and see the effects being updated. This PR adds an option to use a more optimized scroll_update (guaranteed no more than 1 per frame) which occurs after all other scene tree updates, removing the frame delay.
godotengine · Mar 1, 2021 · 7fe9aeb · 7fe9aeb
1 parent 7e2e96c
commit 7fe9aeb
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Showing 3 changed files with 62 additions and 3 deletions.
diff --git a/scene/2d/camera_2d.cpp b/scene/2d/camera_2d.cpp
@@ -35,8 +35,24 @@
 #include "scene/scene_string_names.h"
 #include "servers/visual_server.h"
 
+LocalVector<ObjectID> Camera2D::_pending_scroll_cameras;
+
+void Camera2D::flush_pending_scrolls() {
+	for (unsigned int n = 0; n < _pending_scroll_cameras.size(); n++) {
+		Camera2D *cam = Object::cast_to<Camera2D>(ObjectDB::get_instance(_pending_scroll_cameras[n]));
+
+		if (cam && cam->scroll_dirty) {
+			cam->_update_scroll();
+		}
+	}
+
+	_pending_scroll_cameras.clear();
+}
+
 void Camera2D::_update_scroll() {
 
+	scroll_dirty = false;
+
 	if (!is_inside_tree())
 		return;
 
@@ -226,13 +242,23 @@ void Camera2D::_notification(int p_what) {
 		case NOTIFICATION_INTERNAL_PROCESS:
 		case NOTIFICATION_INTERNAL_PHYSICS_PROCESS: {
 
-			_update_scroll();
+			// we can potentially switch off internal process if deferring scroll update? NYI
+			if (!defer_scroll_enabled) {
+				_update_scroll();
+			}
 
 		} break;
 		case NOTIFICATION_TRANSFORM_CHANGED: {
 
-			if (!is_processing_internal() && !is_physics_processing_internal())
-				_update_scroll();
+			if (defer_scroll_enabled) {
+				if (!scroll_dirty) {
+					scroll_dirty = true;
+					_pending_scroll_cameras.push_back(get_instance_id());
+				}
+			} else {
+				if (!is_processing_internal() && !is_physics_processing_internal())
+					_update_scroll();
+			}
 
 		} break;
 		case NOTIFICATION_ENTER_TREE: {
@@ -401,6 +427,14 @@ Camera2D::Camera2DProcessMode Camera2D::get_process_mode() const {
 	return process_mode;
 }
 
+void Camera2D::set_defer_scroll_enabled(bool p_enable) {
+	defer_scroll_enabled = p_enable;
+}
+
+bool Camera2D::get_defer_scroll_enabled() const {
+	return defer_scroll_enabled;
+}
+
 void Camera2D::_make_current(Object *p_which) {
 
 	if (p_which == this) {
@@ -689,6 +723,9 @@ void Camera2D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_process_mode", "mode"), &Camera2D::set_process_mode);
 	ClassDB::bind_method(D_METHOD("get_process_mode"), &Camera2D::get_process_mode);
 
+	ClassDB::bind_method(D_METHOD("set_defer_scroll_enabled", "enabled"), &Camera2D::set_defer_scroll_enabled);
+	ClassDB::bind_method(D_METHOD("get_defer_scroll_enabled"), &Camera2D::get_defer_scroll_enabled);
+
 	ClassDB::bind_method(D_METHOD("_set_current", "current"), &Camera2D::_set_current);
 	ClassDB::bind_method(D_METHOD("is_current"), &Camera2D::is_current);
 
@@ -750,6 +787,7 @@ void Camera2D::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "zoom"), "set_zoom", "get_zoom");
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "custom_viewport", PROPERTY_HINT_RESOURCE_TYPE, "Viewport", 0), "set_custom_viewport", "get_custom_viewport");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "process_mode", PROPERTY_HINT_ENUM, "Physics,Idle"), "set_process_mode", "get_process_mode");
+	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "defer_scroll"), "set_defer_scroll_enabled", "get_defer_scroll_enabled");
 
 	ADD_GROUP("Limit", "limit_");
 	ADD_PROPERTYI(PropertyInfo(Variant::INT, "limit_left"), "set_limit", "get_limit", MARGIN_LEFT);
@@ -808,6 +846,8 @@ Camera2D::Camera2D() {
 	custom_viewport = NULL;
 	custom_viewport_id = 0;
 	process_mode = CAMERA2D_PROCESS_IDLE;
+	defer_scroll_enabled = true;
+	scroll_dirty = true;
 
 	smoothing = 5.0;
 	zoom = Vector2(1, 1);

diff --git a/scene/2d/camera_2d.h b/scene/2d/camera_2d.h
@@ -31,6 +31,7 @@
 #ifndef CAMERA_2D_H
 #define CAMERA_2D_H
 
+#include "core/local_vector.h"
 #include "scene/2d/node_2d.h"
 #include "scene/main/viewport.h"
 
@@ -94,6 +95,9 @@ class Camera2D : public Node2D {
 	bool margin_drawing_enabled;
 
 	Camera2DProcessMode process_mode;
+	bool defer_scroll_enabled;
+
+	bool scroll_dirty;
 
 protected:
 	virtual Transform2D get_camera_transform();
@@ -140,6 +144,9 @@ class Camera2D : public Node2D {
 	void set_process_mode(Camera2DProcessMode p_mode);
 	Camera2DProcessMode get_process_mode() const;
 
+	void set_defer_scroll_enabled(bool p_enable);
+	bool get_defer_scroll_enabled() const;
+
 	void make_current();
 	void clear_current();
 	bool is_current() const;
@@ -167,6 +174,11 @@ class Camera2D : public Node2D {
 	bool is_margin_drawing_enabled() const;
 
 	Camera2D();
+
+	static void flush_pending_scrolls();
+
+private:
+	static LocalVector<ObjectID> _pending_scroll_cameras;
 };
 
 VARIANT_ENUM_CAST(Camera2D::AnchorMode);

diff --git a/scene/main/scene_tree.cpp b/scene/main/scene_tree.cpp
@@ -40,6 +40,7 @@
 #include "core/project_settings.h"
 #include "main/input_default.h"
 #include "node.h"
+#include "scene/2d/camera_2d.h"
 #include "scene/debugger/script_debugger_remote.h"
 #include "scene/resources/dynamic_font.h"
 #include "scene/resources/material.h"
@@ -576,6 +577,12 @@ bool SceneTree::idle(float p_time) {
 
 	flush_transform_notifications(); //additional transforms after timers update
 
+	// flush pending camera scrolls
+	Camera2D::flush_pending_scrolls();
+
+	// any further transform notifications
+	flush_transform_notifications();
+
 	_call_idle_callbacks();
 
 #ifdef TOOLS_ENABLED