Physics.ContactEvent

参数

描述

订阅此事件以读取物理模拟步骤期间发生的所有碰撞。

此事件的每个订阅者都会使用物理场景和 ContactPairHeader 的原生数组进行调用。每个 ContactPairHeader 包含一个 ContactPair 数组，每个 ContactPair 包含一个 ContactPairPoint 数组。

您可以使用此事件来加速碰撞处理，因为它比 MonoBehaviour.OnCollisionEnter 和其他消息快得多。您还可以使用此事件来调度使用提供的原生数组的作业。从此事件调度的作业必须在下一个 Physics.Simulate、PhysicsScene.Simulate 或 PhysicsScene.RunSimulationStages 与 RunSimulation 阶段调用之前完成。默认情况下，完成这些作业的理想位置是 MonoBehaviour.FixedUpdate。

备注

• 此事件中仅报告碰撞体碰撞，提供的缓冲区中不会出现任何触发事件。
• 提供的缓冲区中的所有数据都是只读的。不允许写入。
• 此事件在变换同步后调用。
• 要接收来自碰撞体的碰撞，请将 Collider.providesContacts 属性设置为 true 或附加具有 OnCollisionStay 方法的 MonoBehaviour 脚本。

using System.Collections.Generic;
using Unity.Collections;
using Unity.Jobs;
using UnityEngine;

public class BounceScipt : MonoBehaviour
{
    [SerializeField]
    private float m_ImpulseMultiplier = 5f;

    private struct JobResultStruct
    {
        public int thisInstanceID;
        public int otherInstanceID;
        public Vector3 averageNormal;
    }

    private NativeArray<JobResultStruct> m_ResultsArray;
    private int m_Count;
    private JobHandle m_JobHandle;

    private readonly Dictionary<int, Rigidbody> m_RigidbodyMapping = new Dictionary<int, Rigidbody>();

    private void OnEnable()
    {
        m_ResultsArray = new NativeArray<JobResultStruct>(16, Allocator.Persistent);

        Physics.ContactEvent += Physics_ContactEvent;

        var allRBs = GameObject.FindObjectsOfType<Rigidbody>();
        foreach (var rb in allRBs)
            m_RigidbodyMapping.Add(rb.GetInstanceID(), rb);
    }

    private void OnDisable()
    {
        m_JobHandle.Complete();
        m_ResultsArray.Dispose();

        Physics.ContactEvent -= Physics_ContactEvent;

        m_RigidbodyMapping.Clear();
    }

    private void FixedUpdate()
    {
        m_JobHandle.Complete(); // The buffer is valid until the next Physics.Simulate() call. Be it internal or manual

        // Do something with the contact data.
        // E.g. Add force based on the average contact normal for that body
        for (int i = 0; i < m_Count; i++)
        {
            var thisInstanceID = m_ResultsArray[i].thisInstanceID;
            var otherInstanceID = m_ResultsArray[i].otherInstanceID;

            var rb0 = thisInstanceID != 0 ? m_RigidbodyMapping[thisInstanceID] : null;
            var rb1 = otherInstanceID != 0 ? m_RigidbodyMapping[otherInstanceID] : null;

            if (rb0)
                rb0.AddForce(m_ResultsArray[i].averageNormal * m_ImpulseMultiplier, ForceMode.Impulse);
            if (rb1)
                rb1.AddForce(m_ResultsArray[i].averageNormal * -m_ImpulseMultiplier, ForceMode.Impulse);
        }
    }

    private void Physics_ContactEvent(PhysicsScene scene, NativeArray<ContactPairHeader>.ReadOnly pairHeaders)
    {
        int n = pairHeaders.Length;

        if (m_ResultsArray.Length < n)
        {
            m_ResultsArray.Dispose();
            m_ResultsArray = new NativeArray<JobResultStruct>(Mathf.NextPowerOfTwo(n), Allocator.Persistent);
        }

        m_Count = n;

        AddForceJob job = new AddForceJob()
        {
            pairHeaders = pairHeaders,
            resultsArray = m_ResultsArray
        };

        m_JobHandle = job.Schedule(n, 256);
    }

    private struct AddForceJob : IJobParallelFor
    {
        [ReadOnly]
        public NativeArray<ContactPairHeader>.ReadOnly pairHeaders;

        public NativeArray<JobResultStruct> resultsArray;

        public void Execute(int index)
        {
            Vector3 averageNormal = Vector3.zero;
            int count = 0;

            for (int j = 0; j < pairHeaders[index].pairCount; j++)
            {
                ref readonly var pair = ref pairHeaders[index].GetContactPair(j);

                if (pair.IsCollisionExit)
                    continue;

                for (int k = 0; k < pair.ContactCount; k++)
                {
                    ref readonly var contact = ref pair.GetContactPoint(k);
                    averageNormal += contact.Normal;
                }

                count += pair.ContactCount;
            }

            if (count != 0)
                averageNormal /= (float)count;

            JobResultStruct result = new JobResultStruct()
            {
                thisInstanceID = pairHeaders[index].bodyInstanceID,
                otherInstanceID = pairHeaders[index].otherBodyInstanceID,
                averageNormal = averageNormal
            };

            resultsArray[index] = result;
        }
    }
}

此脚本读取缓冲区中的所有碰撞，并计算每个 ContactPairHeader 的平均法线。然后根据结果应用力。