Use shader for ColorSelect and add color similarity option

src/Shaders/ColorSelect.gdshader

@@ -0,0 +1,29 @@
+shader_type canvas_item;
+render_mode unshaded;
+
+uniform sampler2D selection : hint_black;
+uniform vec4 color;
+uniform float similarity_percent : hint_range(0.0, 100.0);
+uniform int operation = 0; // 0 = add, 1 = subtract, 2 = intersect
+
+void fragment() {
+	vec4 original_color = texture(TEXTURE, UV); 
+	float diff = distance(original_color, color);
+	float similarity = abs(2.0 - ((similarity_percent/100.0) * 2.0));
+	vec4 col = texture(selection, UV);
+	if (col.rgb == vec3(0.0))
+		col.a = 0.0;
+
+	if (diff <= similarity)
+	{
+		if (operation == 0)
+			col = vec4(1.0);
+		else if (operation == 1)
+			col = vec4(0.0);
+	}
+	else
+		if (operation == 2)
+			col = vec4(0.0);
+
+	COLOR = col;
+}

src/Tools/SelectionTools/ColorSelect.gd

@@ -1,5 +1,27 @@
 extends SelectionTool
 
+var shader: Shader = preload("res://src/Shaders/ColorSelect.gdshader")
+var _similarity := 100
+
+
+func get_config() -> Dictionary:
+	return {"similarity": _similarity}
+
+
+func set_config(config: Dictionary) -> void:
+	_similarity = config.get("similarity", _similarity)
+
+
+func update_config() -> void:
+	$Similarity/SimilaritySpinBox.value = _similarity
+	$Similarity/SimilaritySlider.value = _similarity
+
+
+func _on_Similarity_value_changed(value: float) -> void:
+	_similarity = value
+	update_config()
+	save_config()
+
 
 func apply_selection(position: Vector2) -> void:
 	var project: Project = Global.current_project
@@ -8,29 +30,28 @@ func apply_selection(position: Vector2) -> void:
 	if position.x > project.size.x - 1 or position.y > project.size.y - 1:
 		return
 
-	if !_add and !_subtract and !_intersect:
-		Global.canvas.selection.clear_selection()
-
-	var selection_map_copy := SelectionMap.new()
-	selection_map_copy.copy_from(project.selection_map)
-	if _intersect:
-		selection_map_copy.clear()
-
 	var cel_image := Image.new()
 	cel_image.copy_from(_get_draw_image())
 	cel_image.lock()
 	var color := cel_image.get_pixelv(position)
-	for x in cel_image.get_width():
-		for y in cel_image.get_height():
-			var pos := Vector2(x, y)
-			if color.is_equal_approx(cel_image.get_pixelv(pos)):
-				if _intersect:
-					var selected: bool = project.selection_map.is_pixel_selected(pos)
-					selection_map_copy.select_pixel(pos, selected)
-				else:
-					selection_map_copy.select_pixel(pos, !_subtract)
-
 	cel_image.unlock()
+	var operation := 0
+	if _subtract:
+		operation = 1
+	elif _intersect:
+		operation = 2
+
+	var params := {"color": color, "similarity_percent": _similarity, "operation": operation}
+	if _add or _subtract or _intersect:
+		var selection_tex := ImageTexture.new()
+		selection_tex.create_from_image(project.selection_map, 0)
+		params["selection"] = selection_tex
+	var gen := ShaderImageEffect.new()
+	gen.generate_image(cel_image, shader, params, project.size)
+	cel_image.convert(Image.FORMAT_LA8)
+
+	var selection_map_copy := SelectionMap.new()
+	selection_map_copy.copy_from(cel_image)
 	project.selection_map = selection_map_copy
 	Global.canvas.selection.big_bounding_rectangle = project.selection_map.get_used_rect()
 	Global.canvas.selection.commit_undo("Select", undo_data)

src/Tools/SelectionTools/ColorSelect.tscn

@@ -5,3 +5,50 @@
 
 [node name="ToolOptions" instance=ExtResource( 1 )]
 script = ExtResource( 2 )
+
+[node name="Similarity" type="VBoxContainer" parent="." index="8"]
+margin_top = 166.0
+margin_right = 116.0
+margin_bottom = 228.0
+alignment = 1
+
+[node name="Label" type="Label" parent="Similarity" index="0"]
+margin_left = 26.0
+margin_right = 90.0
+margin_bottom = 14.0
+size_flags_horizontal = 4
+text = "Similarity:"
+
+[node name="SimilaritySpinBox" type="SpinBox" parent="Similarity" index="1"]
+margin_left = 21.0
+margin_top = 18.0
+margin_right = 95.0
+margin_bottom = 42.0
+hint_tooltip = "How much two colors are Similar/Close together"
+mouse_default_cursor_shape = 2
+size_flags_horizontal = 4
+value = 100.0
+align = 1
+suffix = "%"
+__meta__ = {
+"_editor_description_": ""
+}
+
+[node name="SimilaritySlider" type="HSlider" parent="Similarity" index="2"]
+margin_left = 12.0
+margin_top = 46.0
+margin_right = 104.0
+margin_bottom = 62.0
+rect_min_size = Vector2( 92, 0 )
+hint_tooltip = "How much two colors are Similar/Close together"
+focus_mode = 0
+mouse_default_cursor_shape = 2
+size_flags_horizontal = 4
+size_flags_vertical = 1
+value = 100.0
+__meta__ = {
+"_editor_description_": ""
+}
+
+[connection signal="value_changed" from="Similarity/SimilaritySpinBox" to="." method="_on_Similarity_value_changed"]
+[connection signal="value_changed" from="Similarity/SimilaritySlider" to="." method="_on_Similarity_value_changed"]