From e7db7b552da163e172705fb0148efb9d6205f033 Mon Sep 17 00:00:00 2001
From: aXu-AP <1621768+aXu-AP@users.noreply.github.com>
Date: Tue, 23 Jan 2024 20:20:18 +0100
Subject: [PATCH] Fix UV editor not showing polygon correctly

Fix polygon not showing correctly if UVs have been moved around. Show the actual contents of the polygon instead.

(cherry picked from commit a45db4d6168d9b7074b1ff322ce2d04129f8c761)
---
 editor/plugins/polygon_2d_editor_plugin.cpp | 56 ++++++++++++++++-----
 editor/plugins/polygon_2d_editor_plugin.h   |  4 +-
 2 files changed, 47 insertions(+), 13 deletions(-)

diff --git a/editor/plugins/polygon_2d_editor_plugin.cpp b/editor/plugins/polygon_2d_editor_plugin.cpp
index 305351ed088..38ab1df1492 100644
--- a/editor/plugins/polygon_2d_editor_plugin.cpp
+++ b/editor/plugins/polygon_2d_editor_plugin.cpp
@@ -456,6 +456,7 @@ void Polygon2DEditor::_uv_mode(int p_mode) {
 	for (int i = 0; i < UV_MODE_MAX; i++) {
 		uv_button[i]->set_pressed(p_mode == i);
 	}
+	uv_edit_draw->queue_redraw();
 }
 
 void Polygon2DEditor::_uv_input(const Ref<InputEvent> &p_input) {
@@ -980,12 +981,36 @@ void Polygon2DEditor::_uv_draw() {
 	mtx.columns[2] = -uv_draw_ofs;
 	mtx.scale_basis(Vector2(uv_draw_zoom, uv_draw_zoom));
 
-	Transform2D texture_transform = Transform2D(node->get_texture_rotation(), node->get_texture_offset());
-	texture_transform.scale(node->get_texture_scale());
-	texture_transform.affine_invert();
-	RS::get_singleton()->canvas_item_add_set_transform(uv_edit_draw->get_canvas_item(), mtx * texture_transform);
-	uv_edit_draw->draw_texture(base_tex, Point2());
-	RS::get_singleton()->canvas_item_add_set_transform(uv_edit_draw->get_canvas_item(), Transform2D());
+	// Draw texture as a background if editing uvs or no uv mapping exist.
+	if (uv_edit_mode[0]->is_pressed() || uv_mode == UV_MODE_CREATE || node->get_polygon().is_empty() || node->get_uv().size() != node->get_polygon().size()) {
+		Transform2D texture_transform = Transform2D(node->get_texture_rotation(), node->get_texture_offset());
+		texture_transform.scale(node->get_texture_scale());
+		texture_transform.affine_invert();
+		RS::get_singleton()->canvas_item_add_set_transform(uv_edit_draw->get_canvas_item(), mtx * texture_transform);
+		uv_edit_draw->draw_texture(base_tex, Point2());
+		RS::get_singleton()->canvas_item_add_set_transform(uv_edit_draw->get_canvas_item(), Transform2D());
+		preview_polygon->hide();
+	} else {
+		preview_polygon->set_transform(mtx);
+		// Keep in sync with newly added Polygon2D properties (when relevant).
+		preview_polygon->set_texture(node->get_texture());
+		preview_polygon->set_texture_offset(node->get_texture_offset());
+		preview_polygon->set_texture_rotation(node->get_texture_rotation());
+		preview_polygon->set_texture_scale(node->get_texture_scale());
+		preview_polygon->set_texture_filter(node->get_texture_filter_in_tree());
+		preview_polygon->set_texture_repeat(node->get_texture_repeat_in_tree());
+		preview_polygon->set_polygon(node->get_polygon());
+		preview_polygon->set_uv(node->get_uv());
+		preview_polygon->set_invert(node->get_invert());
+		preview_polygon->set_invert_border(node->get_invert_border());
+		preview_polygon->set_internal_vertex_count(node->get_internal_vertex_count());
+		if (uv_mode == UV_MODE_ADD_POLYGON) {
+			preview_polygon->set_polygons(Array());
+		} else {
+			preview_polygon->set_polygons(node->get_polygons());
+		}
+		preview_polygon->show();
+	}
 
 	if (snap_show_grid) {
 		Color grid_color = Color(1.0, 1.0, 1.0, 0.15);
@@ -1350,10 +1375,19 @@ Polygon2DEditor::Polygon2DEditor() {
 	HSplitContainer *uv_main_hsc = memnew(HSplitContainer);
 	uv_main_vb->add_child(uv_main_hsc);
 	uv_main_hsc->set_v_size_flags(SIZE_EXPAND_FILL);
-	uv_edit_draw = memnew(Panel);
-	uv_main_hsc->add_child(uv_edit_draw);
-	uv_edit_draw->set_h_size_flags(SIZE_EXPAND_FILL);
-	uv_edit_draw->set_custom_minimum_size(Size2(200, 200) * EDSCALE);
+
+	uv_edit_background = memnew(Panel);
+	uv_main_hsc->add_child(uv_edit_background);
+	uv_edit_background->set_h_size_flags(SIZE_EXPAND_FILL);
+	uv_edit_background->set_custom_minimum_size(Size2(200, 200) * EDSCALE);
+	uv_edit_background->set_clip_contents(true);
+
+	preview_polygon = memnew(Polygon2D);
+	uv_edit_background->add_child(preview_polygon);
+
+	uv_edit_draw = memnew(Control);
+	uv_edit_background->add_child(uv_edit_draw);
+	uv_edit_draw->set_anchors_and_offsets_preset(Control::PRESET_FULL_RECT);
 
 	Control *space = memnew(Control);
 	uv_mode_hb->add_child(space);
@@ -1494,8 +1528,6 @@ Polygon2DEditor::Polygon2DEditor() {
 
 	error = memnew(AcceptDialog);
 	add_child(error);
-
-	uv_edit_draw->set_clip_contents(true);
 }
 
 Polygon2DEditorPlugin::Polygon2DEditorPlugin() :
diff --git a/editor/plugins/polygon_2d_editor_plugin.h b/editor/plugins/polygon_2d_editor_plugin.h
index 3547c031207..8c52984b593 100644
--- a/editor/plugins/polygon_2d_editor_plugin.h
+++ b/editor/plugins/polygon_2d_editor_plugin.h
@@ -82,7 +82,9 @@ class Polygon2DEditor : public AbstractPolygon2DEditor {
 	Button *uv_button[UV_MODE_MAX];
 	Button *b_snap_enable = nullptr;
 	Button *b_snap_grid = nullptr;
-	Panel *uv_edit_draw = nullptr;
+	Panel *uv_edit_background = nullptr;
+	Polygon2D *preview_polygon = nullptr;
+	Control *uv_edit_draw = nullptr;
 	HSlider *uv_zoom = nullptr;
 	SpinBox *uv_zoom_value = nullptr;
 	HScrollBar *uv_hscroll = nullptr;