Core: Fix BitMap RDP algorithm

doc/classes/BitMap.xml

@@ -69,13 +69,15 @@
 			<return type="PackedVector2Array[]" />
 			<param index="0" name="rect" type="Rect2i" />
 			<param index="1" name="epsilon" type="float" default="2.0" />
+			<param index="2" name="advanced_rdp" type="bool" default="false" />
 			<description>
 				Creates an [Array] of polygons covering a rectangular portion of the bitmap. It uses a marching squares algorithm, followed by Ramer-Douglas-Peucker (RDP) reduction of the number of vertices. Each polygon is described as a [PackedVector2Array] of its vertices.
 				To get polygons covering the whole bitmap, pass:
 				[codeblock]
 				Rect2(Vector2(), get_size())
 				[/codeblock]
 				[param epsilon] is passed to RDP to control how accurately the polygons cover the bitmap: a lower [param epsilon] corresponds to more points in the polygons.
+				If [param advanced_rdp] is [code]true[/code], uses a more advanced RDP algorithm that prevents self-intersections, but is considerably slower.
 			</description>
 		</method>
 		<method name="resize">

doc/classes/ResourceImporterTextureAtlas.xml

@@ -10,6 +10,10 @@
 	<tutorials>
 	</tutorials>
 	<members>
+		<member name="advanced_rdp" type="bool" setter="" getter="" default="false">
+			If [code]true[/code], a slower [url=https://en.wikipedia.org/wiki/Ramer%E2%80%93Douglas%E2%80%93Peucker_algorithm]Ramer Douglas Peuker Algorithm[/url] is used that does not self-intersect.
+			[b]Note:[/b] Only effective if [member import_mode] is [b]Mesh2D[/b].
+		</member>
 		<member name="atlas_file" type="String" setter="" getter="" default="&quot;&quot;">
 			Path to the atlas spritesheet. This [i]must[/i] be set to valid path to a PNG image. Otherwise, the atlas will fail to import.
 		</member>

editor/import/resource_importer_texture_atlas.cpp

@@ -67,6 +67,8 @@ bool ResourceImporterTextureAtlas::get_option_visibility(const String &p_path, c
 		return false;
 	} else if (p_option == "trim_alpha_border_from_region" && int(p_options["import_mode"]) != IMPORT_MODE_REGION) {
 		return false;
+	} else if (p_option == "advanced_rdp" && int(p_options["import_mode"]) != IMPORT_MODE_2D_MESH) {
+		return false;
 	}
 
 	return true;
@@ -85,6 +87,7 @@ void ResourceImporterTextureAtlas::get_import_options(const String &p_path, List
 	r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "import_mode", PROPERTY_HINT_ENUM, "Region,Mesh2D", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_UPDATE_ALL_IF_MODIFIED), 0));
 	r_options->push_back(ImportOption(PropertyInfo(Variant::BOOL, "crop_to_region"), false));
 	r_options->push_back(ImportOption(PropertyInfo(Variant::BOOL, "trim_alpha_border_from_region"), true));
+	r_options->push_back(ImportOption(PropertyInfo(Variant::BOOL, "advanced_rdp"), false));
 }
 
 String ResourceImporterTextureAtlas::get_option_group_file() const {
@@ -252,7 +255,7 @@ Error ResourceImporterTextureAtlas::import_group_file(const String &p_group_file
 			Ref<BitMap> bit_map;
 			bit_map.instantiate();
 			bit_map->create_from_image_alpha(image);
-			Vector<Vector<Vector2>> polygons = bit_map->clip_opaque_to_polygons(Rect2(Vector2(), image->get_size()));
+			Vector<Vector<Vector2>> polygons = bit_map->clip_opaque_to_polygons(Rect2(Vector2(), image->get_size()), 2.0, options["advanced_rdp"]);
 
 			for (int j = 0; j < polygons.size(); j++) {
 				EditorAtlasPacker::Chart chart;

editor/scene/2d/sprite_2d_editor_plugin.cpp

@@ -192,8 +192,9 @@ void Sprite2DEditor::_update_mesh_data() {
 	}
 
 	float epsilon = simplification->get_value();
+	bool advanced_rdp = enable_advanced_rdp->is_pressed();
 
-	Vector<Vector<Vector2>> lines = bm->clip_opaque_to_polygons(rect, epsilon);
+	Vector<Vector<Vector2>> lines = bm->clip_opaque_to_polygons(rect, epsilon, advanced_rdp);
 
 	uv_lines.clear();
 
@@ -711,6 +712,10 @@ Sprite2DEditor::Sprite2DEditor() {
 	grow_pixels->set_accessibility_name(TTRC("Grow (Pixels):"));
 	hb->add_child(grow_pixels);
 	hb->add_spacer();
+	hb->add_child(memnew(Label(TTRC("Enable Advanced RDP:"))));
+	enable_advanced_rdp = memnew(CheckBox);
+	hb->add_child(enable_advanced_rdp);
+	hb->add_spacer();
 	update_preview = memnew(Button);
 	update_preview->set_text(TTR("Update Preview"));
 	update_preview->connect(SceneStringName(pressed), callable_mp(this, &Sprite2DEditor::_update_mesh_data));

editor/scene/2d/sprite_2d_editor_plugin.h

@@ -42,6 +42,7 @@ class HBoxContainer;
 class MenuButton;
 class Panel;
 class ViewPanner;
+class CheckBox;
 
 class Sprite2DEditor : public Control {
 	GDCLASS(Sprite2DEditor, Control);
@@ -85,6 +86,7 @@ class Sprite2DEditor : public Control {
 	SpinBox *simplification = nullptr;
 	SpinBox *grow_pixels = nullptr;
 	SpinBox *shrink_pixels = nullptr;
+	CheckBox *enable_advanced_rdp = nullptr;
 	Button *update_preview = nullptr;
 
 	void _menu_option(int p_option);

misc/extension_api_validation/4.7-stable/GH-94602.txt

@@ -0,0 +1,5 @@
+GH-94602
+--------
+Validate extension JSON: Error: Field 'classes/BitMap/methods/opaque_to_polygons/arguments': size changed value in new API, from 2 to 3.
+
+Add an optional argument to use a star-region-restricted Ramer-Douglas-Peucker Algorithm. No adjustments should be necessary.

scene/resources/bit_map.compat.inc

@@ -0,0 +1,48 @@
+/**************************************************************************/
+/*  bit_map.compat.inc                                                    */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#ifndef DISABLE_DEPRECATED
+
+#include "core/object/class_db.h"
+#include "core/variant/typed_array.h"
+
+Vector<Vector<Vector2>> BitMap::_clip_opaque_to_polygons_bind_compat_94602(const Rect2i &p_rect, float p_epsilon) const {
+	return clip_opaque_to_polygons(p_rect, p_epsilon, false);
+}
+
+TypedArray<PackedVector2Array> BitMap::_opaque_to_polygons_bind_compat_94602(const Rect2i &p_rect, float p_epsilon) const {
+	return _opaque_to_polygons_bind(p_rect, p_epsilon, false);
+}
+
+void BitMap::_bind_compatibility_methods() {
+	ClassDB::bind_compatibility_method(D_METHOD("opaque_to_polygons", "rect", "epsilon"), &BitMap::_opaque_to_polygons_bind_compat_94602, DEFVAL(2.0));
+}
+
+#endif // DISABLE_DEPRECATED