# Draws geometric shapes by moving forward and turning. Inspired by the LOGO

# language.

#

# Most function calls record vertices and update the turtle's state but don't

# draw directly.

#

# To draw the shapes, see [play_draw_animation]. Uses tween animation to animate

# the motion of the turtle and drawing.

#

# Snaps drawing coordinates to the nearest pixel.

class_name DrawingTurtle

extends Node2D

signal turtle_finished

var draw_speed := 400.0

var turn_speed_degrees := 260.0

# Increases the animation playback speed.

var speed_multiplier := 1.0

var _points := []

var _polygons := []

var _current_offset := Vector2.ZERO

# Keeps a list of commands the user registered. This allows us to animate the

# turtle afterwards.

var _command_stack := []

# Stores commands until closing a polygon, to insert commands to move the

# camera.

var _temp_command_stack = []

var _tween := Tween.new()

onready var _turn_degrees = rotation_degrees

onready var _pivot := $Pivot as Node2D

onready var _sprite := $Pivot/Sprite as Sprite

onready var _shadow := $Pivot/Shadow as Sprite

onready var _canvas := $Canvas as Node2D

onready var _camera := $Camera2D as Camera2D

func _ready() -> void:

add_child(_tween)

# Allows to have a camera follow the turtle when using it in practices,

# inside the GDQuestBoy.

if get_parent() is Viewport:

_camera.set_as_toplevel(true)

_camera.position = global_position

_camera.make_current()

# Virtually moves the turtle and records a new vertex.

func move_forward(distance: float) -> void:

var previous_point := Vector2.ZERO

if _points.empty():

_points.append(previous_point)

else:

previous_point = _points[-1]

var new_point := previous_point + Vector2.RIGHT.rotated(deg2rad(_turn_degrees)) * distance

new_point = new_point.snapped(Vector2.ONE)

_points.append(new_point)

_temp_command_stack.append(

{command = "move_to", target = new_point + position + _current_offset}

)

func turn_right(angle_degrees: float) -> void:

_turn_degrees = round(_turn_degrees + angle_degrees)

_temp_command_stack.append({command = "turn", angle = round(angle_degrees)})

func turn_left(angle_degrees: float) -> void:

_turn_degrees = round(_turn_degrees - angle_degrees)

_temp_command_stack.append({command = "turn", angle = round(-angle_degrees)})

# Completes the current polygon's drawing and virtually jumps the turtle to a

# new start position.

func jump(x: float, y: float) -> void:

var last_point := Vector2.ZERO

if not _points.empty():

last_point = _points[-1]

_close_polygon()

_points.append(Vector2.ZERO)

_current_offset += Vector2(x, y) + last_point

_command_stack.append({command = "jump", offset = Vector2(x, y)})

# Resets the turtle's state. Use it when testing a student's assignments to

# reset the object between runs.

func reset() -> void:

_command_stack.clear()

stop_animation()

rotation_degrees = 0.0

_turn_degrees = 0.0

_pivot.rotation_degrees = 0.0

_pivot.position = Vector2.ZERO

_camera.position = Vector2.ZERO

_points.clear()

_polygons.clear()

for child in _canvas.get_children():

child.queue_free()

_current_offset = Vector2.ZERO

_pivot.position = Vector2.ZERO

# Returns a copy of the polygons the turtle will draw.

func get_polygons() -> Array:

return _polygons.duplicate()

func stop_animation() -> void:

_tween.stop_all()

for line in _canvas.get_children():

line.stop()

# Queues all tweens required to animate the turtle drawing all the shapes and

# starts the tween animation.

func play_draw_animation() -> void:

_close_polygon()

# We queue all tweens at once, based on commands: moving the turtle, turning

# it, drawing lines...

var tween_start_time := 0.0

var turtle_position := position

var turtle_rotation_degrees := rotation_degrees

for command in _command_stack:

var duration := 1.0

match command.command:

"set_position":

turtle_position = command.target

_pivot.position = command.target

"move_camera":

# The callback never gets called if it has a delay of 0 seconds.

if is_equal_approx(tween_start_time, 0.0):

_move_camera(command.target)

else:

_tween.interpolate_callback(

self, tween_start_time, "_move_camera", command.target

)

"move_to":

duration = turtle_position.distance_to(command.target) / draw_speed / speed_multiplier

_tween.interpolate_property(

_pivot,

"position",

turtle_position - position,

command.target - position,

duration,

Tween.TRANS_LINEAR,

Tween.EASE_IN,

tween_start_time

)

var line := DrawingLine2D.new(

turtle_position - position,

command.target - position,

duration,

tween_start_time

)

_canvas.add_child(line)

turtle_position = command.target

tween_start_time += duration

"turn":

duration = abs(command.angle) / turn_speed_degrees / speed_multiplier

var target_angle: float = round(turtle_rotation_degrees + command.angle)

_tween.interpolate_property(

_pivot,

"rotation_degrees",

turtle_rotation_degrees,

target_angle,

duration,

Tween.TRANS_LINEAR,

Tween.EASE_IN,

tween_start_time

)

turtle_rotation_degrees = target_angle

tween_start_time += duration

"jump":

duration = 0.5 / speed_multiplier

_tween.interpolate_property(

_pivot,

"position",

turtle_position,

turtle_position + command.offset,

duration,

Tween.TRANS_LINEAR,

Tween.EASE_IN,

tween_start_time

)

_tween.interpolate_method(

self,

"_animate_jump",

0.0,

1.0,

duration,

Tween.TRANS_LINEAR,

Tween.EASE_IN,

tween_start_time

)

turtle_position += command.offset

tween_start_time += duration

_tween.start()

for line in _canvas.get_children():

line.start()

# Animates the turtle's height and shadow scale when jumping. Tween the progress

# value from 0 to 1.

func _animate_jump(progress: float) -> void:

var parabola := -pow(2.0 * progress - 1.0, 2.0) + 1.0

_sprite.position.y = -parabola * 100.0

var shadow_scale := (1.0 - parabola + 1.0) / 2.0

_shadow.scale = shadow_scale * Vector2.ONE

# Returns the total bounding rectangle enclosing all the turtle's drawn

# polygons.

func get_rect() -> Rect2:

var bounds := Rect2()

for polygon in _polygons:

var rect: Rect2 = polygon.get_rect()

rect.position += polygon.position

bounds = bounds.merge(rect)

return bounds

func _close_polygon() -> void:

if _points.empty():

return

var polygon := Polygon.new()

# We want to test shapes being drawn at the correct position using the

# position property. It works differently from jump() which offsets the

# turtle from its position.

polygon.position = position + _current_offset

polygon.points = PoolVector2Array(_points)

_polygons.append(polygon)

_points.clear()

if not position.is_equal_approx(Vector2.ZERO):

_command_stack.append({command = "set_position", target = position})

# We can't know exactly when and where to move the camera until completing a

# shape, as we want to center the camera on the shape.

_command_stack.append({command = "move_camera", target = polygon.get_center()})

for command in _temp_command_stack:

_command_stack.append(command)

_temp_command_stack.clear()

func _move_camera(target_global_position: Vector2) -> void:

_camera.position = target_global_position

# Polygon that can animate drawing its line.

class Polygon:

extends Node2D

var points := PoolVector2Array() setget , get_points

# Returns the local bounds of the polygon. That is to say, it only takes the

# point into account in local space, but not the polygon's `position`.

func get_rect() -> Rect2:

var top_left := Vector2.ZERO

var bottom_right := Vector2.ZERO

for p in points:

if p.x > bottom_right.x:

bottom_right.x = p.x

elif p.x < top_left.x:

top_left.x = p.x

if p.y > bottom_right.y:

bottom_right.y = p.y

elif p.y < top_left.y:

top_left.y = p.y

return Rect2(top_left, bottom_right - top_left)

func get_positioned_rect() -> Rect2:

var rect := get_rect()

rect.position += position

return rect

func get_center() -> Vector2:

var rect := get_rect()

return (rect.position + rect.end) / 2.0 + position

func get_global_center() -> Vector2:

var rect := get_rect()

return (rect.position + rect.end) / 2.0 + global_position

func get_points() -> PoolVector2Array:

return points

func is_empty():

return points.empty() or points == PoolVector2Array([Vector2.ZERO])

class DrawingLine2D:

extends Line2D

const LabelScene := preload("DrawingTurtleLabel.tscn")

const LINE_THICKNESS := 4.0

const DEFAULT_COLOR := Color.white

var _tween := Tween.new()

func _init(start: Vector2, end: Vector2, duration: float, start_time: float) -> void:

add_child(_tween)

width = LINE_THICKNESS

default_color = DEFAULT_COLOR

points = PoolVector2Array([start, start])

_tween.interpolate_callback(self, start_time, "_spawn_label")

_tween.interpolate_method(

self,

"_animate_drawing",

start,

end,

duration,

Tween.TRANS_LINEAR,

Tween.EASE_IN,

start_time

)

func start() -> void:

_tween.start()

func stop() -> void:

_tween.stop_all()

func _animate_drawing(point: Vector2) -> void:

points[-1] = point

func _spawn_label() -> void:

var label := LabelScene.instance() as PanelContainer

label.rect_position = points[0] - label.rect_size / 2

add_child(label)