Godot Best practices

Get direction Vector

## forward
transform.x
# 手动计算, 即：将x轴(1, 0)旋转rad度数后的向量
var rad = node.rotation
var forward = Vector2(cos(rad), sin(rad))
# 使用 Vector2.rotated(angle) 方法  
# 该方法得到指定向量按angle旋转后的向量, 所以
var forward = Vector2.right.rotated(rad)

## up, 由于 godot 中正y是朝下,通常需要取负
-transform.y
# 手动计算, 即：将y轴(0, 1)旋转rad度数后的向量
var up = -Vector2(-sin(rad), cos(rad))
# 或者
var up = Vector2(sin(rad), -cos(rad))
# or
var up = Vector2.up.rotated(rad)
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Await and Unity Style Coroutine

func coroutine(on_update: Callable, duration: float = 1):
	var elapse_time = 0
	while elapse_time < 1:
		elapse_time += get_process_delta_time() / duration
		on_update.call(elapse_time)
		await get_tree().process_frame # 等待下一帧

# normal call - 后续逻辑会在 while loop 执行一次后立刻执行
coroutine(func(): print("do coroutine"))
# test debug
start
do coroutine
end
do coroutine
do coroutine
...
# await call - 后续逻辑会等到 coroutine 执行完成之后才会执行
await coroutine(func(): print("do coroutine"))
# test debug
start
do coroutine
do coroutine
...
end
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Mouse input coordinates

func _input(event):
	if event is InputEventMouseButton:
	# 坐标为 viewport coordinates
	print("Mouse Click: ", event.position)
	# 和上面一样也是 viewport coordinates
	print("Mouse Click: ", get_viewport().get_mouse_position())
	# 坐标为 CanvasLayer coordinates 或者说是场景的世界坐标
	print("Mouse Click: ", get_global_mouse_position())
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