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Godot C# 自定义摄像机

news 来源：原创 2024/9/27 17:35:03

前言

说起来，Unity的社区环境跟插件支持确实要比Godot好很多，比如我们Unity最喜欢的Cinemachine插件，只需要动动手指就能轻松实现很多高级的摄像机动效。

所以一转到Godot就有一种力不从心的感觉，于是既然动不了手指我们就动手。自己做一个想要的摄像机。

Godot版本：4.3 mono

思路

其实没什么好说的，一开始只是想做一个能跟着某个节点移动的摄像机，至于为什么不直接把摄像机作为被跟随节点的子节点呢？因为Godot中的摄像机是按照节点树层次找到并展示最近的一个父级Viewport的，我觉得如果一个场景中有多个摄像机的情况，再加上被跟随节点自带的摄像机可能就不好管理了。还有用Unity习惯了，就这样考虑了。

人都是贪得无厌的，一开始还是只想做一个跟随就好了，结果为了满足自己的奇葩需求，索性就加了一些其他功能。

源码

using System.Collections;
using Godot;namespace GoDogKit
{/// <summary>/// A highly customizable camera that automatically follows a target./// </summary>public partial class AutoCamera2D : Camera2D{/// <summary>/// The target to follow./// </summary>[Export] public Node2D FollowTarget { get; set; } = null;/// <summary>/// Defines the maximum distance from the target to follow. Does not effect to the predict behaviour./// </summary>[Export] public float FollowClamp { get; set; } = 1.0f;/// <summary>/// Defines the camera's behaviour when following the target./// </summary>public enum BehaviourType{/// <summary>/// Follows the target normally. Results in global position copying./// </summary>Normal,/// <summary>/// Smoothly follows the target in a given duration. Results in global position interpolation./// </summary>            Inching,/// <summary>/// Follow the target with a constant speed. It can be faster or slower than the target's speed./// If the follow speed equals or exceeds the target's speed, results just like the Normal behaviour./// If the follow speed is slower than the target's speed, the camera will/// be clamped within a given distance from the target aka max distance./// </summary>            Slow,/// <summary>/// Follow the target with predictive behaviour./// It predicts the target's movement based on its last position./// And moves the camera towards the predicted position which /// determined by predict distance with a constant speed./// </summary>Predict}[Export] public BehaviourType Behaviour { get; set; } = BehaviourType.Normal;[ExportGroup("Inching Properties")][Export]public float InchingDuration{get => m_inchingDuration;set => m_inchingDuration = value;}private float m_inchingDuration = 1.0f;private float m_inchingTimer = 0.0f;[ExportGroup("Slow Properties")][Export] public float SlowFollowSpeed { get; set; } = 100.0f;[Export] public float SlowFollowMaxDistance { get; set; } = 100.0f;[ExportGroup("Predict Properties")][Export] public float PredictFollowSpeed { get; set; } = 100.0f;[Export] public float PredictDistance { get; set; } = 100.0f;private Vector2 m_targetLastPos = Vector2.Zero;public override void _Ready(){m_inchingTimer = m_inchingDuration;m_targetLastPos = Vector2.Zero;}private void NormalFollow(double delta){GlobalPosition = FollowTarget.GlobalPosition;}private void InchingFollow(double delta){float distance = GlobalPosition.DistanceTo(FollowTarget.GlobalPosition);// If the target is too close, stop inching.if (distance < FollowClamp){m_inchingTimer = m_inchingDuration;return;}m_inchingTimer -= (float)delta;// If the inching timer has reached 0, reset it and start inching again.float rate = m_inchingTimer <= 0.0f ? 1.0f : 1.0f - m_inchingTimer / m_inchingDuration;var _x = Mathf.Lerp(GlobalPosition.X, FollowTarget.GlobalPosition.X, rate);var _y = Mathf.Lerp(GlobalPosition.Y, FollowTarget.GlobalPosition.Y, rate);GlobalPosition = new Vector2(_x, _y);}private void SlowFollow(double delta){float distance = GlobalPosition.DistanceTo(FollowTarget.GlobalPosition);// If the target is too close, stop following.if (distance < FollowClamp){return;}// If the target is too far, move it to max distance position.if (distance > SlowFollowMaxDistance){Vector2 distanceVec = (FollowTarget.GlobalPosition - GlobalPosition).Normalized() * SlowFollowMaxDistance;GlobalPosition = FollowTarget.GlobalPosition - distanceVec;return;}var _x = Mathf.MoveToward(GlobalPosition.X, FollowTarget.GlobalPosition.X, (float)delta * SlowFollowSpeed);var _y = Mathf.MoveToward(GlobalPosition.Y, FollowTarget.GlobalPosition.Y, (float)delta * SlowFollowSpeed);GlobalPosition = new Vector2(_x, _y);}private void PredictFollow(double delta){// Predict the direction of the target based on its last position.Vector2 predictedDir = (FollowTarget.GlobalPosition - m_targetLastPos).Normalized();Vector2 predictedPos = FollowTarget.GlobalPosition + predictedDir * PredictDistance;var _x = Mathf.MoveToward(GlobalPosition.X, predictedPos.X, (float)delta * PredictFollowSpeed);var _y = Mathf.MoveToward(GlobalPosition.Y, predictedPos.Y, (float)delta * PredictFollowSpeed);GlobalPosition = new Vector2(_x, _y);// Record the last position of the target for the next prediction.m_targetLastPos = FollowTarget.GlobalPosition;}       public override void _PhysicsProcess(double delta){// If there is no target, do nothing.if (FollowTarget == null) return;switch (Behaviour){case BehaviourType.Normal: NormalFollow(delta); break;case BehaviourType.Inching: InchingFollow(delta); break;case BehaviourType.Slow: SlowFollow(delta); break;case BehaviourType.Predict: PredictFollow(delta); break;}}}
}

其实结构还是非常简单明了的（因为我也写不出很复杂的东西）。通过预设值决定摄像机的具体行为逻辑，就是这么简单。

哦对了，Godot的2D和3D的区别跟Unity不一样，Unity的2D是伪2D，而Godot的2D是真2D，

所以2D跟3D之间的沟壑可能比Unity大。所以我先做了2D的相机。

这个的操作方式应该跟Unity的差不多，就是调整数值还有选模式。主要这些模式都是我硬编的，其实我也不知道应该怎么为这些模式命名：

1.Normal，普通行为，就一直跟着，其实就是复制位置。

2.Inching，我管它叫缓动，从代码可以看出，这玩意跟时间有关，设计之初是想实现“在规定时间结束时，镜头恰好到达物体位置”，结构因为插值插的太快了，所以只能看出一点点效果，所以之后应该会大改或者直接砍掉；

3.Slow，慢跟随。其实也可以快，通过控制跟随速度营造出“镜头和物体相对运动的效果”。

实际上镜头跟随太慢会被限制在一个距离内，从而避免物体跑太快了以至于跑出镜头外。

// If the target is too far, move it to max distance position.

if (distance > SlowFollowMaxDistance)

{

Vector2 distanceVec = (FollowTarget.GlobalPosition - GlobalPosition).Normalized() * SlowFollowMaxDistance;

GlobalPosition = FollowTarget.GlobalPosition - distanceVec;

return;

}

限制手段就是这个：当相对距离超过限定距离时，根据等式关系减去偏移量。

为什么要单独拿出来记录呢？因为我之前写那个Untiy卡牌拖拽模型的时候，就是遇到了这种“锁定偏移量”的类似问题，当时还强调了一下，结果现在做开发的时候又又又错了。