294 lines
10 KiB
C#
294 lines
10 KiB
C#
using System;
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using System.Collections.Generic;
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using UnityEngine;
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/// <summary>
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/// 多点采样浮力：考虑形状(采样点分布)、重心(Rigidbody.centerOfMass)、扭矩(在点上施力)。
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/// 适合小物体（0.01m级），避免“任何形状都一样直直往下/往上顶飞”
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/// </summary>
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[DisallowMultipleComponent]
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[RequireComponent(typeof(Rigidbody))]
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public class BuoyancyBody : MonoBehaviour
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{
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[Header("Water")]
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[Tooltip("如果不填则使用简单水面：y = WaterLevel")]
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public MonoBehaviour waterProviderBehaviour;
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private IWaterProvider waterProvider;
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[Tooltip("简单水面模式：水面高度（y）")]
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public float waterLevel = 0f;
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[Header("Buoyancy (Physical)")]
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[Tooltip("水密度 kg/m^3。淡水约1000，海水约1025")]
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public float waterDensity = 1000f;
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[Tooltip("物体密度 kg/m^3。决定浮沉：< waterDensity 更容易浮，> waterDensity 更容易沉")]
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public float objectDensity = 300f;
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[Tooltip("如果 > 0 则强制使用该体积(m^3)，否则按 mass/objectDensity 推体积")]
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public float overrideVolume = 0f;
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[Tooltip("浮力强度缩放（调手感用），1为物理值")]
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public float buoyancyScale = 1f;
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[Header("Stabilization / Damping")]
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[Tooltip("水中线性阻尼（越大越不弹、越“粘水”）")]
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public float linearDamping = 2.5f;
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[Tooltip("水中角阻尼（越大越稳定立漂）")]
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public float angularDamping = 2.0f;
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[Tooltip("入水/出水过渡平滑厚度（m）。越大越不弹，但边界更“软”】【0.01~0.05常用】")]
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public float surfaceSmoothing = 0.02f;
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[Tooltip("限制单个采样点最大浮力加速度（m/s^2），防止轻小物体从高处落下冲天")]
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public float maxBuoyantAccelPerPoint = 50f;
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[Header("Center of Mass")]
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[Tooltip("本地空间重心偏移（m）。可用来模拟胶囊体配重，让浮漂能站起来")]
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public Vector3 centerOfMassOffset = Vector3.zero;
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[Header("Sampling (Shape matters!)")]
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[Tooltip("每个Collider生成的采样点数量（越大越精确，越耗性能）。浮漂建议 12~40")]
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[Range(4, 200)] public int pointsPerCollider = 24;
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[Tooltip("采样点是否只保留在Collider内部（对非凸MeshCollider不可靠；浮漂建议用Capsule/Box/Sphere）")]
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public bool keepPointsInsideCollider = true;
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[Tooltip("运行时显示采样点(编辑器Gizmos)")]
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public bool drawGizmos = true;
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[Tooltip("只对这些Collider算浮力（为空则自动抓取子物体所有Collider）")]
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public Collider[] colliders;
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private Rigidbody rb;
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private readonly List<SamplePoint> samplePoints = new();
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private struct SamplePoint
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{
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public Collider col;
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public Vector3 localPos; // 相对 collider.transform 的本地
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}
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void Awake()
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{
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rb = GetComponent<Rigidbody>();
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ApplyCOM();
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waterProvider = waterProviderBehaviour as IWaterProvider;
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BuildSamplePoints();
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}
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void OnValidate()
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{
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if (!rb) rb = GetComponent<Rigidbody>();
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ApplyCOM();
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// 在编辑器里改参数时重建采样点
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if (Application.isPlaying == false)
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{
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// 避免在Prefab编辑等情况下报错
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}
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}
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void Reset()
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{
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rb = GetComponent<Rigidbody>();
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rb.useGravity = true;
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rb.interpolation = RigidbodyInterpolation.Interpolate;
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rb.collisionDetectionMode = CollisionDetectionMode.Continuous;
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if (colliders == null || colliders.Length == 0)
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colliders = GetComponentsInChildren<Collider>();
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}
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private void ApplyCOM()
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{
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if (!rb) return;
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rb.centerOfMass = centerOfMassOffset;
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}
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/// <summary>手动调用：当你运行时增减Collider或缩放后，建议调用一次</summary>
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public void Rebuild()
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{
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waterProvider = waterProviderBehaviour as IWaterProvider;
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ApplyCOM();
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BuildSamplePoints();
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}
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private void BuildSamplePoints()
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{
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samplePoints.Clear();
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Collider[] cols = colliders;
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if (cols == null || cols.Length == 0)
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cols = GetComponentsInChildren<Collider>();
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foreach (var col in cols)
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{
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if (!col || !col.enabled) continue;
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// 用 bounds 做快速采样，再可选筛内部点
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var b = col.bounds;
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int n = Mathf.Max(4, pointsPerCollider);
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// 使用“分层网格+抖动”的方式，保证不同形状/尺寸采样分布不同
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int dim = Mathf.CeilToInt(Mathf.Pow(n, 1f / 3f));
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dim = Mathf.Max(2, dim);
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Vector3 size = b.size;
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Vector3 step = new Vector3(
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size.x / (dim - 1),
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size.y / (dim - 1),
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size.z / (dim - 1)
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);
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// 为了让小物体也稳定：如果某轴极小，step可能很小，没关系
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int added = 0;
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for (int ix = 0; ix < dim && added < n; ix++)
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for (int iy = 0; iy < dim && added < n; iy++)
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for (int iz = 0; iz < dim && added < n; iz++)
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{
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// 0..1
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float fx = (dim == 1) ? 0.5f : (float)ix / (dim - 1);
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float fy = (dim == 1) ? 0.5f : (float)iy / (dim - 1);
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float fz = (dim == 1) ? 0.5f : (float)iz / (dim - 1);
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// 抖动（避免规则网格导致“锁姿态”）
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Vector3 jitter = new Vector3(
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(UnityEngine.Random.value - 0.5f) * step.x * 0.25f,
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(UnityEngine.Random.value - 0.5f) * step.y * 0.25f,
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(UnityEngine.Random.value - 0.5f) * step.z * 0.25f
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);
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Vector3 world = new Vector3(
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b.min.x + size.x * fx,
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b.min.y + size.y * fy,
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b.min.z + size.z * fz
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) + jitter;
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if (keepPointsInsideCollider)
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{
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// 对凸Collider通常可靠：如果点在内部，ClosestPoint会返回点本身
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Vector3 cp = col.ClosestPoint(world);
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if ((cp - world).sqrMagnitude > 1e-8f)
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continue;
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}
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// 转到 collider.transform 本地存储
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Vector3 local = col.transform.InverseTransformPoint(world);
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samplePoints.Add(new SamplePoint { col = col, localPos = local });
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added++;
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}
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// 如果内部点太少，至少补一点：用 collider.transform.position 周围
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if (added < 4)
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{
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for (int i = added; i < 4; i++)
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{
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Vector3 world = col.bounds.center + UnityEngine.Random.insideUnitSphere * (col.bounds.extents.magnitude * 0.25f);
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Vector3 local = col.transform.InverseTransformPoint(world);
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samplePoints.Add(new SamplePoint { col = col, localPos = local });
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}
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}
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}
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}
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void FixedUpdate()
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{
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if (samplePoints.Count == 0) BuildSamplePoints();
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// 体积估计：V = m / rho_object
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float volume = overrideVolume > 0f ? overrideVolume : (rb.mass / Mathf.Max(1e-6f, objectDensity));
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volume = Mathf.Max(1e-9f, volume);
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int count = samplePoints.Count;
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float volPerPoint = volume / count;
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Vector3 gravity = Physics.gravity; // 通常 (0,-9.81,0)
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float gMag = gravity.magnitude;
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// 如果重力为0就不算了
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if (gMag < 1e-6f) return;
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// 逐点施加：浮力 + 阻尼
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for (int i = 0; i < count; i++)
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{
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var sp = samplePoints[i];
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if (!sp.col || !sp.col.enabled) continue;
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Vector3 worldPos = sp.col.transform.TransformPoint(sp.localPos);
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float waterH = waterProvider?.GetWaterHeight(worldPos) ?? waterLevel;
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float depth = waterH - worldPos.y; // >0 表示点在水下
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if (depth <= 0f) continue;
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// 入水过渡：在水面附近用平滑厚度做0..1
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float submergence01 = (surfaceSmoothing <= 1e-6f)
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? 1f
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: Mathf.Clamp01(depth / surfaceSmoothing);
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// 该点产生的“排水质量”：m_displaced = rho_water * V_point * submergence
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float displacedMass = waterDensity * volPerPoint * submergence01;
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// 浮力 = -g * m_displaced
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Vector3 buoyancy = -gravity * displacedMass * buoyancyScale;
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// 限制单点最大向上加速度，防止小物体落水被“顶飞”
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// a = F/m -> Fmax = amax * m
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float Fmax = maxBuoyantAccelPerPoint * rb.mass;
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if (buoyancy.sqrMagnitude > Fmax * Fmax)
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buoyancy = buoyancy.normalized * Fmax;
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// 水中阻尼（相对水流速度）
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Vector3 waterVel = waterProvider?.GetWaterVelocity(worldPos) ?? Vector3.zero;
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Vector3 pointVel = rb.GetPointVelocity(worldPos);
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Vector3 relVel = pointVel - waterVel;
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// 阻尼随入水程度增强：越深越“粘”
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Vector3 dampingForce = -relVel * (linearDamping * displacedMass);
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// 把力施加在采样点上 -> 自然产生扭矩（形状/重心不同效果不同）
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rb.AddForceAtPosition(buoyancy + dampingForce, worldPos, ForceMode.Force);
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// 额外角阻尼（整体），只在“确实有一部分在水里”时施加更合理，
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// 这里用 submergence01 做比例：越入水越强
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rb.AddTorque(-rb.angularVelocity * (angularDamping * displacedMass), ForceMode.Force);
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}
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}
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#if UNITY_EDITOR
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void OnDrawGizmosSelected()
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{
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if (!drawGizmos) return;
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Gizmos.matrix = Matrix4x4.identity;
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// 水面
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Gizmos.color = new Color(0f, 0.6f, 1f, 0.25f);
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Vector3 p = transform.position;
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float y = (waterProvider != null) ? waterProvider.GetWaterHeight(p) : waterLevel;
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Gizmos.DrawCube(new Vector3(p.x, y, p.z), new Vector3(0.5f, 0.001f, 0.5f));
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// 采样点
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if (samplePoints == null) return;
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Gizmos.color = Color.yellow;
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foreach (var sp in samplePoints)
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{
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if (!sp.col) continue;
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Vector3 w = sp.col.transform.TransformPoint(sp.localPos);
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Gizmos.DrawSphere(w, 0.005f);
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}
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// COM
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if (TryGetComponent<Rigidbody>(out var r))
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{
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Gizmos.color = Color.red;
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Gizmos.DrawSphere(transform.TransformPoint(r.centerOfMass), 0.01f);
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}
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}
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#endif
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} |