Revert Parallax fixes from #12709 and #16795.

This reverts commits f5b6bfbbd1c826fcb8125d7e795d9d8974d64f7a and afccc72be3c150c7c02d7f56d8ce6efb6d45927b.

Reason: These commits seem to have caused a regression (#17764), so reverting
for now to get back to the same state as in 2.1.4-stable until a better
variant can be worked on and merged for 2.1.6.

Fixes #17764.

scene/2d/camera_2d.cpp

@@ -50,11 +50,7 @@ void Camera2D::_update_scroll() {
 		if (viewport) {
 			viewport->set_canvas_transform(xform);
 		}
-
-		Size2 screen_size = viewport->get_visible_rect().size;
-		Point2 screen_offset = (anchor_mode == ANCHOR_MODE_DRAG_CENTER ? (screen_size * 0.5) : Point2());
-
-		get_tree()->call_group(SceneTree::GROUP_CALL_REALTIME, group_name, "_camera_moved", xform, screen_offset);
+		get_tree()->call_group(SceneTree::GROUP_CALL_REALTIME, group_name, "_camera_moved", xform);
 	};
 }
 

scene/2d/parallax_background.cpp

@@ -47,12 +47,10 @@ void ParallaxBackground::_notification(int p_what) {
 	}
 }
 
-void ParallaxBackground::_camera_moved(const Matrix32 &p_transform, const Point2 &p_screen_offset) {
+void ParallaxBackground::_camera_moved(const Matrix32 &p_transform) {
 
-	screen_offset = p_screen_offset;
-
-	set_scroll_scale(p_transform.get_scale().dot(Vector2(0.5, 0.5)));
 	set_scroll_offset(p_transform.get_origin());
+	set_scroll_scale(p_transform.get_scale().dot(Vector2(0.5, 0.5)));
 }
 
 void ParallaxBackground::set_scroll_scale(float p_scale) {
@@ -108,9 +106,9 @@ void ParallaxBackground::_update_scroll() {
 			continue;
 
 		if (ignore_camera_zoom)
-			l->set_base_offset_and_scale(ofs, 1.0, screen_offset);
+			l->set_base_offset_and_scale(ofs, 1.0);
 		else
-			l->set_base_offset_and_scale(ofs, scale, screen_offset);
+			l->set_base_offset_and_scale(ofs, scale);
 	}
 }
 

scene/2d/parallax_background.h

@@ -42,7 +42,6 @@ class ParallaxBackground : public CanvasLayer {
 	float scale;
 	Point2 base_offset;
 	Point2 base_scale;
-	Point2 screen_offset;
 	String group_name;
 	Point2 limit_begin;
 	Point2 limit_end;
@@ -52,7 +51,7 @@ class ParallaxBackground : public CanvasLayer {
 	void _update_scroll();
 
 protected:
-	void _camera_moved(const Matrix32 &p_transform, const Point2 &p_screen_offset);
+	void _camera_moved(const Matrix32 &p_transform);
 
 	void _notification(int p_what);
 	static void _bind_methods();

scene/2d/parallax_layer.cpp

@@ -41,7 +41,7 @@ void ParallaxLayer::set_motion_scale(const Size2 &p_scale) {
 	if (is_inside_tree() && pb) {
 		Vector2 ofs = pb->get_final_offset();
 		float scale = pb->get_scroll_scale();
-		set_base_offset_and_scale(ofs, scale, screen_offset);
+		set_base_offset_and_scale(ofs, scale);
 	}
 }
 
@@ -61,7 +61,7 @@ void ParallaxLayer::set_motion_offset(const Size2 &p_offset) {
 	if (is_inside_tree() && pb) {
 		Vector2 ofs = pb->get_final_offset();
 		float scale = pb->get_scroll_scale();
-		set_base_offset_and_scale(ofs, scale, screen_offset);
+		set_base_offset_and_scale(ofs, scale);
 	}
 }
 
@@ -80,8 +80,7 @@ void ParallaxLayer::_update_mirroring() {
 
 		RID c = pb->get_world_2d()->get_canvas();
 		RID ci = get_canvas_item();
-		Point2 mirrorScale = mirroring * get_scale();
-		VisualServer::get_singleton()->canvas_set_item_mirroring(c, ci, mirrorScale);
+		VisualServer::get_singleton()->canvas_set_item_mirroring(c, ci, mirroring);
 	}
 }
 
@@ -114,21 +113,16 @@ void ParallaxLayer::_notification(int p_what) {
 	}
 }
 
-void ParallaxLayer::set_base_offset_and_scale(const Point2 &p_offset, float p_scale, const Point2 &p_screen_offset) {
-	screen_offset = p_screen_offset;
+void ParallaxLayer::set_base_offset_and_scale(const Point2 &p_offset, float p_scale) {
 
 	if (!is_inside_tree())
 		return;
 	if (get_tree()->is_editor_hint())
 		return;
-
-	Point2 new_ofs = (screen_offset + (p_offset - screen_offset) * motion_scale) + motion_offset * p_scale + orig_offset * p_scale;
-
-	Vector2 mirror = Vector2(1, 1);
+	Point2 new_ofs = ((orig_offset + p_offset) * motion_scale) * p_scale + motion_offset;
 
 	if (mirroring.x) {
 		double den = mirroring.x * p_scale;
-		double before = new_ofs.x;
 		new_ofs.x -= den * ceil(new_ofs.x / den);
 	}
 
@@ -138,9 +132,7 @@ void ParallaxLayer::set_base_offset_and_scale(const Point2 &p_offset, float p_sc
 	}
 
 	set_pos(new_ofs);
-	set_scale(Vector2(1, 1) * p_scale * orig_scale);
-
-	_update_mirroring();
+	set_scale(Vector2(1, 1) * p_scale);
 }
 
 String ParallaxLayer::get_configuration_warning() const {

scene/2d/parallax_layer.h

@@ -43,8 +43,6 @@ class ParallaxLayer : public Node2D {
 	Vector2 mirroring;
 	void _update_mirroring();
 
-	Point2 screen_offset;
-
 protected:
 	void _notification(int p_what);
 	static void _bind_methods();
@@ -59,7 +57,7 @@ public:
 	void set_mirroring(const Size2 &p_mirroring);
 	Size2 get_mirroring() const;
 
-	void set_base_offset_and_scale(const Point2 &p_offsetf, float p_scale, const Point2 &p_screen_offset);
+	void set_base_offset_and_scale(const Point2 &p_offsetf, float p_scale);
 
 	virtual String get_configuration_warning() const;
 	ParallaxLayer();