天气系统

天气是飞行模拟器中最重要的挑战来源。顺风、逆风、侧风、湍流、低能见度降落——每一种天气都带来不同的飞行挑战。本章实现一个影响飞行物理的动态天气系统。

本章你将学到

• 风系统：风速风向如何影响飞机
• 湍流：随机颠簸的实现
• 云层与能见度：视觉和飞行的双重影响
• 天气动态变化：晴天→阴天→雨天的过渡
• 结冰：特定条件下飞机性能下降

风对飞行的影响

风是飞行中最基础也最重要的天气因素：

举例：飞机地速100km/h，正对20km/h顺风飞行，则空速=100-20=80km/h，升力减少；顶风飞行则空速=120km/h，升力增加，但地速减慢。

天气系统核心

GDScript

extends Node

## 天气系统 - 管理所有气象条件
class_name WeatherSystem

## 天气状态枚举
enum WeatherCondition { CLEAR, PARTLY_CLOUDY, OVERCAST, RAIN, STORM, FOG }

## 当前天气参数
var condition: WeatherCondition = WeatherCondition.CLEAR
var wind_direction: float = 270.0   ## 风从哪里来（度，270=从西来）
var wind_speed: float = 5.0         ## 风速（米/秒）
var turbulence_intensity: float = 0.0   ## 湍流强度（0~1）
var visibility: float = 10000.0     ## 能见度（米）
var cloud_base: float = 2000.0      ## 云底高度（米）

signal weather_changed(new_condition: WeatherCondition)

## 获取当前风速向量（3D空间中的风）
func get_wind_vector() -> Vector3:
    var wind_rad := deg_to_rad(wind_direction)
    ## 风向：气象上说的"北风"是从北吹来，所以向量朝南
    return Vector3(-sin(wind_rad), 0, -cos(wind_rad)) * wind_speed

## 获取随机湍流力（每帧调用，随机颠簸）
func get_turbulence_force(aircraft_mass: float) -> Vector3:
    if turbulence_intensity <= 0:
        return Vector3.ZERO
    var t := Time.get_ticks_msec() / 1000.0
    ## 用多个不同频率的正弦波叠加，产生不规则颠簸感
    var turbulence := Vector3(
        sin(t * 3.7) * cos(t * 2.3),
        sin(t * 2.1) * cos(t * 4.5) + sin(t * 7.3),
        sin(t * 4.1) * cos(t * 1.7)
    )
    return turbulence * turbulence_intensity * aircraft_mass * 2.0

## 随时间推移改变天气
func change_weather(new_condition: WeatherCondition, transition_time: float = 300.0) -> void:
    ## TODO: 用Tween平滑过渡天气参数
    condition = new_condition
    _apply_condition_parameters(new_condition)
    emit_signal("weather_changed", new_condition)

func _apply_condition_parameters(cond: WeatherCondition) -> void:
    match cond:
        WeatherCondition.CLEAR:
            visibility = 10000.0
            turbulence_intensity = 0.0
            cloud_base = 3000.0
        WeatherCondition.PARTLY_CLOUDY:
            visibility = 8000.0
            turbulence_intensity = 0.1
            cloud_base = 2000.0
        WeatherCondition.OVERCAST:
            visibility = 5000.0
            turbulence_intensity = 0.2
            cloud_base = 1000.0
        WeatherCondition.RAIN:
            visibility = 3000.0
            turbulence_intensity = 0.4
            cloud_base = 800.0
            wind_speed = maxf(wind_speed, 8.0)
        WeatherCondition.STORM:
            visibility = 500.0
            turbulence_intensity = 0.9
            cloud_base = 400.0
            wind_speed = maxf(wind_speed, 20.0)
        WeatherCondition.FOG:
            visibility = 200.0
            turbulence_intensity = 0.05
            cloud_base = 50.0

C

using Godot;

public partial class WeatherSystem : Node
{
    public enum WeatherCondition { Clear, PartlyCloudy, Overcast, Rain, Storm, Fog }

    public WeatherCondition Condition { get; private set; } = WeatherCondition.Clear;
    public float WindDirection { get; set; } = 270f;
    public float WindSpeed { get; set; } = 5f;
    public float TurbulenceIntensity { get; private set; } = 0f;
    public float Visibility { get; private set; } = 10000f;
    public float CloudBase { get; private set; } = 2000f;

    [Signal] public delegate void WeatherChangedEventHandler(int newCondition);

    public Vector3 GetWindVector()
    {
        float windRad = Mathf.DegToRad(WindDirection);
        return new Vector3(-Mathf.Sin(windRad), 0, -Mathf.Cos(windRad)) * WindSpeed;
    }

    public Vector3 GetTurbulenceForce(float aircraftMass)
    {
        if (TurbulenceIntensity <= 0) return Vector3.Zero;
        float t = Time.GetTicksMsec() / 1000f;
        var turbulence = new Vector3(
            Mathf.Sin(t * 3.7f) * Mathf.Cos(t * 2.3f),
            Mathf.Sin(t * 2.1f) * Mathf.Cos(t * 4.5f) + Mathf.Sin(t * 7.3f),
            Mathf.Sin(t * 4.1f) * Mathf.Cos(t * 1.7f)
        );
        return turbulence * TurbulenceIntensity * aircraftMass * 2f;
    }

    public void ChangeWeather(WeatherCondition newCondition)
    {
        Condition = newCondition;
        ApplyConditionParameters(newCondition);
        EmitSignal(SignalName.WeatherChanged, (int)newCondition);
    }

    private void ApplyConditionParameters(WeatherCondition cond)
    {
        switch (cond)
        {
            case WeatherCondition.Clear:
                Visibility = 10000f; TurbulenceIntensity = 0f; CloudBase = 3000f; break;
            case WeatherCondition.Rain:
                Visibility = 3000f; TurbulenceIntensity = 0.4f; CloudBase = 800f;
                WindSpeed = Mathf.Max(WindSpeed, 8f); break;
            case WeatherCondition.Storm:
                Visibility = 500f; TurbulenceIntensity = 0.9f; CloudBase = 400f;
                WindSpeed = Mathf.Max(WindSpeed, 20f); break;
            case WeatherCondition.Fog:
                Visibility = 200f; TurbulenceIntensity = 0.05f; CloudBase = 50f; break;
        }
    }
}

将风和湍流应用到飞机

在飞行物理控制器中接入天气系统：

GDScript

## 在 RealisticFlightController 的 _physics_process 中添加：

@onready var weather: WeatherSystem = get_node("/root/WeatherSystem")

func _apply_weather_effects() -> void:
    ## 风：把风速向量加到飞机受到的外力中
    var wind := weather.get_wind_vector()
    ## 注意：风影响的是"表观空速"，而非直接施加力
    ## 简化处理：把风看作在飞机逆着飞行方向施加的额外气动力
    var wind_effect := (wind - linear_velocity) * 0.01 * mass
    apply_central_force(wind_effect)

    ## 湍流：直接施加随机力
    var turbulence := weather.get_turbulence_force(mass)
    apply_central_force(turbulence)

C

// 在 RealisticFlightController._PhysicsProcess 中调用：
private WeatherSystem _weather;

public override void _Ready()
{
    _weather = GetNode<WeatherSystem>("/root/WeatherSystem");
}

private void ApplyWeatherEffects()
{
    var wind = _weather.GetWindVector();
    var windEffect = (wind - LinearVelocity) * 0.01f * Mass;
    ApplyCentralForce(windEffect);

    var turbulence = _weather.GetTurbulenceForce(Mass);
    ApplyCentralForce(turbulence);
}

云层视觉效果

云层既是视觉元素，也是影响飞行的功能性元素——进入云中能见度骤降：

飞行位置	视觉效果	操作影响
云层以下	正常视野，可见云底	无影响
云层中	白雾笼罩，能见度<100m	必须依靠仪表飞行
云层以上	晴朗蓝天，脚下云海	无法看到地面

下一步

天气系统完成后，实现 飞行建设系统——这是游戏的长线玩法核心。