physics: joint constraints (fixed/hinge/ball)

- JointComponent: type, target UUID, per-body local anchors, hinge axis
  + angle limits (data only, zero Jolt deps)
- PhysicsWorld::SyncConstraints: create/remove/rebuild on snapshot
  change; body rebuild contagion via invalidated-bits list; target
  resolved lazily by UUID each sync (no two-pass load needed)
- Jolt FixedConstraint/HingeConstraint/PointConstraint in
  LocalToBodyCOM space (anchors minus shape COM); fixed frames lock
  creation-time relative pose; hinge axis aligned across bodies
- Inspector: Joint section with target entity name dropdown
- Serialization: Joint map with UUID target, as<T> fallbacks

Engine/include/Engine/ECS/Components.h

@@ -236,6 +236,29 @@ namespace Engine::ECS {
         glm::vec3 velocity{0.0f}; // 只读调试视图：线速度（m/s）
     };
 
+    // 约束/关节（Jolt TwoBodyConstraint 家族）。纯数据 POD 零 Jolt 依赖；
+    // 创建/对账在 PhysicsWorld::SyncConstraints（kPhyDbgConstraints 出图元）。
+    // target 存 UUID（跨存档稳定），惰性解析——SyncScene 每帧按 UUID 反查
+    // 实体：序列化无需两遍解析，UUID 再生后自然失联，加载顺序无关
+    struct JointComponent {
+        enum class Type : u8 { Fixed = 0, Hinge = 1, Ball = 2 };
+        Type type = Type::Fixed;
+        UUID target{};   // 目标实体（0 = 未设置，不建约束）
+
+        // 锚点：各体 Transform 局部系（Unity connectedAnchor 语义，
+        // × 本体缩放烘焙）。Fixed/Hinge/Ball 都连这两点
+        glm::vec3 anchorA{0.0f};   // 本体（挂组件的实体）
+        glm::vec3 anchorB{0.0f};   // 目标体
+
+        // Hinge 专用：转轴（本体局部系，方向量不吃缩放）+ 角度限位（度）
+        glm::vec3 hingeAxis{1.0f, 0.0f, 0.0f};
+        bool enableLimit = false;
+        f32 limitMin = -90.0f;   // Jolt 语义 min∈[-180,0] max∈[0,180]
+        f32 limitMax = 90.0f;
+
+        bool operator==(const JointComponent&) const = default;
+    };
+
 } // namespace Engine::ECS
 
 #endif //HELLOVULKAN_COMPONENTS_H

Engine/include/Engine/Physics/PhysicsWorld.h

@@ -30,6 +30,7 @@
 #include <Jolt/Jolt.h>
 #include <Jolt/Physics/PhysicsSystem.h>
 #include <Jolt/Physics/Body/BodyID.h>
+#include <Jolt/Physics/Constraints/Constraint.h>   // JPH::Ref<Constraint>
 #include <Jolt/Core/JobSystemThreadPool.h>
 #include <Jolt/Core/TempAllocator.h>
 
@@ -114,6 +115,12 @@ namespace Engine {
         void CollectDebugData();   // 按 m_DebugBits 收集调试图元（渲染帧率）
         void CreateBody(u32 entityBits, ECS::RigidBodyComponent& rb,
                         ECS::TransformComponent& tr);
+        // 约束对账：owner 孤儿清理 / body 重建传染失效 / 建缺失与变更重建
+        // invalidated = 本帧 SyncScene 中被销毁或重建 body 的实体位模式
+        void SyncConstraints(const std::vector<u32>& invalidated);
+        void CreateConstraint(u32 ownerBits, u32 targetBits,
+                              const ECS::JointComponent& jc);
+        void RemoveConstraint(u32 ownerBits);
         // Mesh 碰撞体：实体视觉网格 → Jolt 形状（Static=MeshShape /
         // Dynamic=ConvexHull）。无 MeshRenderer 或构建失败返回 null（回退 Box）
         JPH::RefConst<JPH::Shape> BuildMeshShape(u32 entityBits,
@@ -128,6 +135,15 @@ namespace Engine {
         void QueueEvent(CollisionEvent&& ev);   // 回调线程 append（多线程并发，加锁）
         bool TryBitsByBodyId(const JPH::BodyID& id, u32& outBits) const;
 
+        // ---- 约束（JointComponent → Jolt TwoBodyConstraint；owner 实体寻址）----
+        // target 惰性解析 UUID；body 重建/销毁 → 引用它的约束失效重建
+        struct ConstraintRecord {
+            JPH::Ref<JPH::Constraint> constraint;
+            ECS::JointComponent snapshot;   // 变更检测 → 移除重建
+            u32 targetBits = 0;
+        };
+        std::unordered_map<u32, ConstraintRecord> m_Constraints;
+
         ECS::Scene& m_Scene;
         Assets::AssetManager* m_Assets = nullptr;  // Mesh 碰撞体解析 modelRef
         bool m_Enabled = true;

Engine/src/Physics/PhysicsWorld.cpp

@@ -19,6 +19,9 @@
 #include <Jolt/Physics/Collision/Shape/CapsuleShape.h>
 #include <Jolt/Physics/Collision/Shape/CylinderShape.h>
 #include <Jolt/Physics/Collision/Shape/StaticCompoundShape.h>
+#include <Jolt/Physics/Constraints/FixedConstraint.h>
+#include <Jolt/Physics/Constraints/HingeConstraint.h>
+#include <Jolt/Physics/Constraints/PointConstraint.h>
 
 #include <Engine/Assets/AssetManager.h>
 #include <Engine/Renderer/Model.h>
@@ -331,6 +334,7 @@ namespace Engine {
     void PhysicsWorld::SyncScene() {
         auto &reg = m_Scene.GetRegistry();
         auto &bi = m_System->GetBodyInterface();
+        std::vector<u32> invalidated; // 本帧销毁/重建 body → 约束失效传染
 
         // 1. 孤儿清理：实体销毁 / 组件被移除 → 移除 body
         for (auto it = m_Bodies.begin(); it != m_Bodies.end();) {
@@ -339,6 +343,7 @@ namespace Engine {
                 !reg.all_of<ECS::RigidBodyComponent, ECS::TransformComponent>(e)) {
                 bi.RemoveBody(it->second.id);
                 bi.DestroyBody(it->second.id);
+                invalidated.push_back(it->first);
                 it = m_Bodies.erase(it);
             } else {
                 ++it;
@@ -355,6 +360,7 @@ namespace Engine {
                     bi.RemoveBody(found->second.id);
                     bi.DestroyBody(found->second.id);
                     m_Bodies.erase(found);
+                    invalidated.push_back(bits);
                 }
                 CreateBody(bits, rb, tr);
                 continue;
@@ -375,6 +381,7 @@ namespace Engine {
                 bi.RemoveBody(rec.id);
                 bi.DestroyBody(rec.id);
                 m_Bodies.erase(found);
+                invalidated.push_back(bits);
                 rb.bodyValid = false;
                 CreateBody(bits, rb, tr);
                 continue;
@@ -396,6 +403,160 @@ namespace Engine {
                 rec.lastRot = tr.GetRotationQuat();
             }
         }
+
+        // 3. 约束对账（body 循环之后：依赖新建 body 的最终 ID）
+        SyncConstraints(invalidated);
+    }
+
+    // ---- 约束对账 ----
+
+    void PhysicsWorld::SyncConstraints(const std::vector<u32> &invalidated) {
+        auto &reg = m_Scene.GetRegistry();
+        const auto tainted = [&invalidated](u32 bits) {
+            return std::find(invalidated.begin(), invalidated.end(), bits)
+                   != invalidated.end();
+        };
+
+        // 1. owner 实体/组件没了，或任一端 body 本帧被销毁/重建 → 移除
+        for (auto it = m_Constraints.begin(); it != m_Constraints.end();) {
+            const u32 owner = it->first;
+            const auto ownerEnt = static_cast<entt::entity>(owner);
+            const bool ownerGone = !reg.valid(ownerEnt) ||
+                                   !reg.all_of<ECS::JointComponent>(ownerEnt);
+            if (ownerGone || tainted(owner) || tainted(it->second.targetBits)) {
+                m_System->RemoveConstraint(it->second.constraint.GetPtr());
+                it = m_Constraints.erase(it);
+            } else {
+                ++it;
+            }
+        }
+
+        // 2. 遍历组件：快照变更 → 重建；缺失 → 创建。
+        //    target 惰性按 UUID 反查（UUID 失联/body 未就绪 → 下帧再试）
+        auto view = reg.view<ECS::JointComponent>();
+        for (auto [e, jc]: view.each()) {
+            const u32 bits = static_cast<u32>(entt::to_integral(e));
+            const auto found = m_Constraints.find(bits);
+            if (found != m_Constraints.end()) {
+                if (found->second.snapshot == jc) {
+                    continue;
+                }
+                m_System->RemoveConstraint(found->second.constraint.GetPtr());
+                m_Constraints.erase(found);
+            }
+            const ECS::Entity target = m_Scene.FindEntityByUUID(jc.target);
+            if (target == entt::null) {
+                continue;
+            }
+            const u32 targetBits = static_cast<u32>(entt::to_integral(target));
+            if (bits == targetBits || !m_Bodies.contains(bits) ||
+                !m_Bodies.contains(targetBits)) {
+                continue;
+            }
+            CreateConstraint(bits, targetBits, jc);
+        }
+    }
+
+    void PhysicsWorld::CreateConstraint(u32 ownerBits, u32 targetBits,
+                                        const ECS::JointComponent &jc) {
+        auto &reg = m_Scene.GetRegistry();
+        const auto &b1 = m_Bodies.find(ownerBits)->second;
+        const auto &b2 = m_Bodies.find(targetBits)->second;
+
+        // 锚点（Transform 局部系）× 本体缩放 → COM 局部系
+        //（EConstraintSpace::LocalToBodyCOM 要求减 Shape::GetCenterOfMass，
+        // Compound 等形状 COM 会偏离原点；Box/Sphere/Capsule 为零）
+        const auto *tr1 = reg.try_get<ECS::TransformComponent>(
+            static_cast<entt::entity>(ownerBits));
+        const auto *tr2 = reg.try_get<ECS::TransformComponent>(
+            static_cast<entt::entity>(targetBits));
+        if (tr1 == nullptr || tr2 == nullptr) {
+            return;
+        }
+        const glm::vec3 s1 = tr1->GetScale();
+        const glm::vec3 s2 = tr2->GetScale();
+
+        // 双写锁读位姿/COM + 创建（SyncScene 在主线程，与 Update 不并发）
+        JPH::BodyLockWrite lock1(m_System->GetBodyLockInterface(), b1.id);
+        JPH::BodyLockWrite lock2(m_System->GetBodyLockInterface(), b2.id);
+        if (!lock1.Succeeded() || !lock2.Succeeded()) {
+            return;
+        }
+        JPH::Body &body1 = lock1.GetBody();
+        JPH::Body &body2 = lock2.GetBody();
+        const JPH::Quat r1 = body1.GetRotation();
+        const JPH::Quat r2 = body2.GetRotation();
+        const JPH::Vec3 com1 = body1.GetShape()->GetCenterOfMass();
+        const JPH::Vec3 com2 = body2.GetShape()->GetCenterOfMass();
+        const JPH::RVec3 p1(jc.anchorA.x * s1.x - com1.GetX(),
+                            jc.anchorA.y * s1.y - com1.GetY(),
+                            jc.anchorA.z * s1.z - com1.GetZ());
+        const JPH::RVec3 p2(jc.anchorB.x * s2.x - com2.GetX(),
+                            jc.anchorB.y * s2.y - com2.GetY(),
+                            jc.anchorB.z * s2.z - com2.GetZ());
+
+        JPH::Ref<JPH::Constraint> constraint;
+        if (jc.type == ECS::JointComponent::Type::Fixed) {
+            // 轴框架 = 同一世界姿态在各体局部系的表达 → 锁定创建时相对姿态
+            JPH::FixedConstraintSettings s;
+            s.mSpace = JPH::EConstraintSpace::LocalToBodyCOM;
+            s.mPoint1 = p1;
+            s.mPoint2 = p2;
+            s.mAxisX1 = r1.Conjugated() * JPH::Vec3::sAxisX();
+            s.mAxisY1 = r1.Conjugated() * JPH::Vec3::sAxisY();
+            s.mAxisX2 = r2.Conjugated() * JPH::Vec3::sAxisX();
+            s.mAxisY2 = r2.Conjugated() * JPH::Vec3::sAxisY();
+            constraint = s.Create(body1, body2);
+        } else if (jc.type == ECS::JointComponent::Type::Hinge) {
+            // 转轴：本体局部轴 → 世界（不吃缩放，归一化），再投到两体局部系；
+            // 法线任取与轴垂直的世界方向，保证两体框架共轴共面
+            JPH::HingeConstraintSettings s;
+            s.mSpace = JPH::EConstraintSpace::LocalToBodyCOM;
+            s.mPoint1 = p1;
+            s.mPoint2 = p2;
+            const JPH::Vec3 localAxis = JPH::Vec3(
+                jc.hingeAxis.x, jc.hingeAxis.y, jc.hingeAxis.z).Normalized();
+            const JPH::Vec3 worldAxis = r1 * localAxis;
+            JPH::Vec3 helper = std::abs(worldAxis.GetY()) < 0.99f
+                                   ? JPH::Vec3::sAxisY()
+                                   : JPH::Vec3::sAxisX();
+            const JPH::Vec3 worldNormal = worldAxis.Cross(helper).Normalized();
+            s.mHingeAxis1 = r1.Conjugated() * worldAxis;
+            s.mNormalAxis1 = r1.Conjugated() * worldNormal;
+            s.mHingeAxis2 = r2.Conjugated() * worldAxis;
+            s.mNormalAxis2 = r2.Conjugated() * worldNormal;
+            if (jc.enableLimit) {
+                s.mLimitsMin = std::clamp(glm::radians(jc.limitMin),
+                                          -JPH::JPH_PI, 0.0f);
+                s.mLimitsMax = std::clamp(glm::radians(jc.limitMax),
+                                          0.0f, JPH::JPH_PI);
+            }
+            constraint = s.Create(body1, body2);
+        } else {
+            // Ball = PointConstraint（球窝：三旋转自由度全放开）
+            JPH::PointConstraintSettings s;
+            s.mSpace = JPH::EConstraintSpace::LocalToBodyCOM;
+            s.mPoint1 = p1;
+            s.mPoint2 = p2;
+            constraint = s.Create(body1, body2);
+        }
+
+        m_System->AddConstraint(constraint.GetPtr());
+
+        ConstraintRecord rec;
+        rec.constraint = std::move(constraint);
+        rec.snapshot = jc;
+        rec.targetBits = targetBits;
+        m_Constraints[ownerBits] = rec;
+    }
+
+    void PhysicsWorld::RemoveConstraint(const u32 ownerBits) {
+        const auto found = m_Constraints.find(ownerBits);
+        if (found == m_Constraints.end()) {
+            return;
+        }
+        m_System->RemoveConstraint(found->second.constraint.GetPtr());
+        m_Constraints.erase(found);   // Ref 析构 → 引用计数释放
     }
 
     // ---- Mesh 碰撞体：视觉网格 → Jolt 形状 ----

Engine/src/Serialization/SceneSerializer.cpp

@@ -307,6 +307,27 @@ namespace Engine::Serialization {
                 out << YAML::EndMap;
             }
 
+            if (const auto* jc = reg.try_get<ECS::JointComponent>(e)) {
+                out << YAML::Key << "Joint" << YAML::Value
+                    << YAML::BeginMap;
+                out << YAML::Key << "Type" << YAML::Value
+                    << static_cast<int>(jc->type);
+                // 实体引用存 UUID（跨存档稳定；target=0 未设置）
+                out << YAML::Key << "Target" << YAML::Value
+                    << jc->target.Value();
+                out << YAML::Key << "AnchorA" << YAML::Value;
+                EmitVec3(out, jc->anchorA);
+                out << YAML::Key << "AnchorB" << YAML::Value;
+                EmitVec3(out, jc->anchorB);
+                out << YAML::Key << "HingeAxis" << YAML::Value;
+                EmitVec3(out, jc->hingeAxis);
+                out << YAML::Key << "EnableLimit" << YAML::Value
+                    << jc->enableLimit;
+                out << YAML::Key << "LimitMin" << YAML::Value << jc->limitMin;
+                out << YAML::Key << "LimitMax" << YAML::Value << jc->limitMax;
+                out << YAML::EndMap;
+            }
+
             out << YAML::EndMap;   // Components
             out << YAML::EndMap;   // Entity
         }
@@ -562,6 +583,24 @@ namespace Engine::Serialization {
                 rb.isSensor = n["IsSensor"].as<bool>(rb.isSensor);
                 // bodyId/bodyValid/velocity 保持默认（对账重建）
             }
+
+            // Joint：target 只存 UUID，加载后由 PhysicsWorld 惰性反查
+            //（两遍解析不需要——UUID 再生/加载顺序均由逐帧解析消化）
+            if (const YAML::Node n = comps["Joint"]) {
+                auto& jc = handle.AddComponent<ECS::JointComponent>();
+                if (const int type = n["Type"].as<int>(0);
+                    type >= 0 && type <= 2) {
+                    jc.type =
+                        static_cast<ECS::JointComponent::Type>(type);
+                }
+                jc.target = UUID{n["Target"].as<u64>(0)};
+                jc.anchorA = ReadVec3(n["AnchorA"], jc.anchorA);
+                jc.anchorB = ReadVec3(n["AnchorB"], jc.anchorB);
+                jc.hingeAxis = ReadVec3(n["HingeAxis"], jc.hingeAxis);
+                jc.enableLimit = n["EnableLimit"].as<bool>(jc.enableLimit);
+                jc.limitMin = n["LimitMin"].as<f32>(jc.limitMin);
+                jc.limitMax = n["LimitMax"].as<f32>(jc.limitMax);
+            }
         }
 
         // 加载在 OnImGuiRender 段，错过本帧 UpdateTransforms：