Attention: Here be dragons

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游戏信息显示¶

我们的游戏最后还需要用户界面（User Interface，UI），显示分数、“游戏结束”信息、重启按钮。

创建新场景，然后添加一个 CanvasLayer 节点并命名为 HUD。“HUD”是“heads-up display”（游戏信息显示）的缩写，是覆盖在游戏视图上显示的信息。

CanvasLayer 节点可以让我们在游戏的其他部分的上一层绘制 UI 元素，这样它所显示的信息就不会被任何游戏元素（如玩家或敌人）所覆盖。

HUD 中需要显示以下信息：

得分，由 ScoreTimer 更改。
消息，例如“Game Over”或“Get Ready!”
“Start”按钮来开始游戏。

UI 元素的基本节点是 Control 。要创建 UI，我们需使用 Control 下的两种节点：Label 和 Button。

创建以下节点作为 HUD 的子节点：

名为分数标签 ScoreLabel 的 Label。
名为消息 Message 的 Label。
名为开始按钮 StartButton 的 Button。
名为信息计数器 MessageTimer 的 Timer。

点击 ScoreLabel 并在“检查器”的 Text 字段中键入一个数字。 Control 节点的默认字体很小，不能很好地缩放。游戏资产包中有一个叫作“Xolonium-Regular.ttf”的字体文件。使用此字体需要执行以下操作：

Under "Theme Overrides > Fonts", choose "Load" and select the "Xolonium-Regular.ttf" file.

../../_images/custom_font_load_font.webp

The font size is still too small, increase it to 64 under "Theme Overrides > Font Sizes". Once you've done this with the ScoreLabel, repeat the changes for the Message and StartButton nodes.

备注

Anchors: Control nodes have a position and size, but they also have anchors. Anchors define the origin - the reference point for the edges of the node.

Arrange the nodes as shown below. You can drag the nodes to place them manually, or for more precise placement, use "Anchor Presets".

ScoreLabel¶

Add the text 0.
Set the "Horizontal Alignment" and "Vertical Alignment" to Center.
Choose the "Anchor Preset" Center Top.

Message¶

Add the text Dodge the creeps!.
Set the "Horizontal Alignment" and "Vertical Alignment" to Center.
Set the "Autowrap Mode" to Word, otherwise the label will stay on one line.
Under "Control - Layout/Transform" set "Size X" to 480 to use the entire width of the screen.
Choose the "Anchor Preset" Center.

StartButton¶

Add the text Start.
Under "Control - Layout/Transform", set "Size X" to 200 and "Size Y" to 100 to add a little bit more padding between the border and text.
Choose the "Anchor Preset" Center Bottom.
Under "Control - Layout/Transform", set "Position Y" to 580.

在 MessageTimer 中，将 Wait Time 设置为 2 并将 One Shot 属性设置为“启用”。

现将这个脚本添加到 HUD：

extends CanvasLayer

# Notifies `Main` node that the button has been pressed
signal start_game

using Godot;

public partial class HUD : CanvasLayer
{
    // Don't forget to rebuild the project so the editor knows about the new signal.

    [Signal]
    public delegate void StartGameEventHandler();
}

// Copy `player.gdns` to `hud.gdns` and replace `Player` with `HUD`.
// Attach the `hud.gdns` file to the HUD node.

// Create two files `hud.cpp` and `hud.hpp` next to `entry.cpp` in `src`.
// This code goes in `hud.hpp`. We also define the methods we'll be using here.
#ifndef HUD_H
#define HUD_H

#include <Button.hpp>
#include <CanvasLayer.hpp>
#include <Godot.hpp>
#include <Label.hpp>
#include <Timer.hpp>

class HUD : public godot::CanvasLayer {
    GODOT_CLASS(HUD, godot::CanvasLayer)

    godot::Label *_score_label;
    godot::Label *_message_label;
    godot::Timer *_start_message_timer;
    godot::Timer *_get_ready_message_timer;
    godot::Button *_start_button;
    godot::Timer *_start_button_timer;

public:
    void _init() {}
    void _ready();
    void show_get_ready();
    void show_game_over();
    void update_score(const int score);
    void _on_StartButton_pressed();
    void _on_StartMessageTimer_timeout();
    void _on_GetReadyMessageTimer_timeout();

    static void _register_methods();
};

#endif // HUD_H

We now want to display a message temporarily, such as "Get Ready", so we add the following code

func show_message(text):
    $Message.text = text
    $Message.show()
    $MessageTimer.start()

public void ShowMessage(string text)
{
    var message = GetNode<Label>("Message");
    message.Text = text;
    message.Show();

    GetNode<Timer>("MessageTimer").Start();
}

// This code goes in `hud.cpp`.
#include "hud.hpp"

void HUD::_ready() {
    _score_label = get_node<godot::Label>("ScoreLabel");
    _message_label = get_node<godot::Label>("MessageLabel");
    _start_message_timer = get_node<godot::Timer>("StartMessageTimer");
    _get_ready_message_timer = get_node<godot::Timer>("GetReadyMessageTimer");
    _start_button = get_node<godot::Button>("StartButton");
    _start_button_timer = get_node<godot::Timer>("StartButtonTimer");
}

void HUD::_register_methods() {
    godot::register_method("_ready", &HUD::_ready);
    godot::register_method("show_get_ready", &HUD::show_get_ready);
    godot::register_method("show_game_over", &HUD::show_game_over);
    godot::register_method("update_score", &HUD::update_score);
    godot::register_method("_on_StartButton_pressed", &HUD::_on_StartButton_pressed);
    godot::register_method("_on_StartMessageTimer_timeout", &HUD::_on_StartMessageTimer_timeout);
    godot::register_method("_on_GetReadyMessageTimer_timeout", &HUD::_on_GetReadyMessageTimer_timeout);
    godot::register_signal<HUD>("start_game", godot::Dictionary());
}

We also need to process what happens when the player loses. The code below will show "Game Over" for 2 seconds, then return to the title screen and, after a brief pause, show the "Start" button.

func show_game_over():
    show_message("Game Over")
    # Wait until the MessageTimer has counted down.
    await $MessageTimer.timeout

    $Message.text = "Dodge the\nCreeps!"
    $Message.show()
    # Make a one-shot timer and wait for it to finish.
    await get_tree().create_timer(1.0).timeout
    $StartButton.show()

async public void ShowGameOver()
{
    ShowMessage("Game Over");

    var messageTimer = GetNode<Timer>("MessageTimer");
    await ToSignal(messageTimer, Timer.SignalName.Timeout);

    var message = GetNode<Label>("Message");
    message.Text = "Dodge the\nCreeps!";
    message.Show();

    await ToSignal(GetTree().CreateTimer(1.0), SceneTreeTimer.SignalName.Timeout);
    GetNode<Button>("StartButton").Show();
}

// This code goes in `hud.cpp`.
// There is no `yield` in GDExtension, so we need to have every
// step be its own method that is called on timer timeout.
void HUD::show_get_ready() {
    _message_label->set_text("Get Ready");
    _message_label->show();
    _get_ready_message_timer->start();
}

void HUD::show_game_over() {
    _message_label->set_text("Game Over");
    _message_label->show();
    _start_message_timer->start();
}

当玩家死亡时调用这个函数。将显示“Game Over”2 秒，然后返回标题屏幕并显示“Start”按钮。

备注

当您需要暂停片刻时，可以使用场景树的 get_tree().create_timer(2) 函数替代使用 Timer 节点。这对于延迟非常有用，例如在上述代码中，在这里我们需要在显示“开始”按钮前等待片刻。

Add the code below to HUD to update the score

func update_score(score):
    $ScoreLabel.text = str(score)

public void UpdateScore(int score)
{
    GetNode<Label>("ScoreLabel").Text = score.ToString();
}

// This code goes in `hud.cpp`.
void HUD::update_score(const int p_score) {
    _score_label->set_text(godot::Variant(p_score));
}

Connect the timeout() signal of MessageTimer and the pressed() signal of StartButton, and add the following code to the new functions:

func _on_start_button_pressed():
    $StartButton.hide()
    start_game.emit()

func _on_message_timer_timeout():
    $Message.hide()

private void OnStartButtonPressed()
{
    GetNode<Button>("StartButton").Hide();
    EmitSignal(SignalName.StartGame);
}

private void OnMessageTimerTimeout()
{
    GetNode<Label>("Message").Hide();
}

// This code goes in `hud.cpp`.
void HUD::_on_StartButton_pressed() {
    _start_button_timer->stop();
    _start_button->hide();
    emit_signal("start_game");
}

void HUD::_on_StartMessageTimer_timeout() {
    _message_label->set_text("Dodge the\nCreeps");
    _message_label->show();
    _start_button_timer->start();
}

void HUD::_on_GetReadyMessageTimer_timeout() {
    _message_label->hide();
}

将 HUD 场景连接到 Main 场景¶

现在我们完成了 HUD 场景，保存并返回 Main 场景。和 Player 场景的做法一样，在 Main 场景中实例化 HUD 场景。如果您没有错过任何东西，完整的场景树应该像这样：

现在我们需要将 HUD 功能与我们的 Main 脚本连接起来。这需要在 Main 场景中添加一些内容：

In the Node tab, connect the HUD's start_game signal to the new_game() function of the Main node by clicking the "Pick" button in the "Connect a Signal" window and selecting the new_game() method or type "new_game" below "Receiver Method" in the window. Verify that the green connection icon now appears next to func new_game() in the script.

Remember to remove the call to new_game() from _ready().

在 new_game() 函数中，更新分数显示并显示“Get Ready”消息：

$HUD.update_score(score)
$HUD.show_message("Get Ready")

var hud = GetNode<HUD>("HUD");
hud.UpdateScore(_score);
hud.ShowMessage("Get Ready!");

_hud->update_score(score);
_hud->show_get_ready();

在 game_over() 中我们需要调用相应的 HUD 函数：

$HUD.show_game_over()

GetNode<HUD>("HUD").ShowGameOver();

_hud->show_game_over();

Just a reminder: we don't want to start the new game automatically, so remove the call to new_game() in _ready() if you haven't yet.

Finally, add this to _on_score_timer_timeout() to keep the display in sync with the changing score:

$HUD.update_score(score)

GetNode<HUD>("HUD").UpdateScore(_score);

_hud->update_score(score);

Now you're ready to play! Click the "Play the Project" button. You will be asked to select a main scene, so choose main.tscn.

删除旧的小怪¶

如果你一直玩到“游戏结束”，然后重新开始新游戏，上局游戏的小怪仍然显示在屏幕上。更好的做法是在新游戏开始时清除它们。我们需要一个同时让所有小怪删除它自己的方法，为此可以使用“分组”功能。

在 Mob 场景中，选择根节点，然后单击检查器旁边的“节点”选项卡（在该位置可以找到节点的信号）。点击“信号”旁边的“分组”，然后可以输入新的组名称，点击“添加”。

现在，所有小怪都将属于“mobs”（小怪）分组。我们可以将以下行添加到 Main 中的 new_game() 函数中：

get_tree().call_group("mobs", "queue_free")

// Note that for calling Godot-provided methods with strings,
// we have to use the original Godot snake_case name.
GetTree().CallGroup("mobs", Node.MethodName.QueueFree);

get_tree()->call_group("mobs", "queue_free");

call_group() 函数调用组中每个节点上的删除函数——让每个怪物删除其自身。

游戏在这一点上大部分已经完成。在下一部分和最后一部分中，我们将通过添加背景，循环音乐和一些键盘快捷键来对其进行一些润色。