ImmediatePhysics.GenerateContacts

参数

返回

int 返回生成的接触点总数。

说明

生成所有给定形状对的接触点。将生成的接触点存储在 ImmediateContact 数组中，并将每个配对的接触点数存储在 `outContactCounts` 数组中。

此代码示例定义了 PhysX 在此场景中需要多少对对象。您可以为小型联系人检查设置一个特定数字，或者，如果您打算运行更复杂的仿真，则可能需要实现广相位筛选，找出多少对对象将交互。最简单且性能最差的选择是将所有可能的身体对放入场景中存在的 GenerateContacts 函数中。此示例展示了手动添加两对物体并检查它们之间接触的基本设置。

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

public class ImmediatePhysics_GenerateContacts_Example : MonoBehaviour
{
    private int m_NumberOfPairs = 2;

    // Pull in a reference from the Editor to the Mesh Collider.
    [SerializeField]
    private MeshCollider m_Mesh;

    List<Vector3> contactPoints = new List<Vector3>();

    // There is no way to know how many contacts the shapes will generate,
    // so set a maximum value that should confidently fit all of them.
    int s_MaxContactCount = 100;

    void Start()
    {
        // Create and set up geometry and transform arrays.
        NativeArray<GeometryHolder> geom1 = new NativeArray<GeometryHolder>(m_NumberOfPairs, Allocator.Temp);
        NativeArray<GeometryHolder> geom2 = new NativeArray<GeometryHolder>(m_NumberOfPairs, Allocator.Temp);

        // Create a box shape that is 1 meter wide on each axis, and use that to construct a GeometryHolder object.
        BoxGeometry boxShape = new BoxGeometry(new Vector3(0.5f, 0.5f, 0.5f));
        GeometryHolder box = GeometryHolder.Create(boxShape);

        // Get the geometry of an existing collider.
        GeometryHolder convexMesh = m_Mesh.GeometryHolder;

        NativeArray<ImmediateTransform> xForms1 = new NativeArray<ImmediateTransform>(m_NumberOfPairs, Allocator.Temp);
        NativeArray<ImmediateTransform> xForms2 = new NativeArray<ImmediateTransform>(m_NumberOfPairs, Allocator.Temp);

        ImmediateTransform body1Transform = new ImmediateTransform
        {
            Position = new Vector3(0, 0, 0),
            Rotation = Quaternion.identity
        };

        ImmediateTransform body2Transform = new ImmediateTransform
        {
            Position = new Vector3(0, 0.75f, 0),
            Rotation = Quaternion.Euler(new Vector3(45f, 0, 0))
        };


        // First pair is two boxes interacting.
        geom1[0] = box;
        geom2[0] = box;

        xForms1[0] = body1Transform;
        xForms2[0] = body2Transform;

        // Second pair is a box and a convex Mesh Collider.
        geom1[1] = convexMesh;
        geom1[2] = box;

        xForms1[1] = body1Transform;
        xForms2[1] = body2Transform;

        // This code re-uses the same transforms, which means that if all the bodies
        // were part of the same simulation, they would all overlap with each other. However,
        // because we are only generating contacts per pair, one pair of bodies does not affect
        // the other pairs.

        // Create a place to hold the output contacts and their counts per pair.
        // There is no way to know how many contacts the shapes will generate,
        // so set a maximum value that should confidently fit all of them.
        NativeArray<ImmediateContact> contacts = new NativeArray<ImmediateContact>(s_MaxContactCount, Allocator.Temp);
        // The number of contactCounts is the same as the number of pairs.
        NativeArray<int> contactCounts = new NativeArray<int>(m_NumberOfPairs, Allocator.Temp);

        // Finally, call the GenerateContacts function and put all the arrays in. 
        // Keep note of the ReadOnly status of the input arrays.

        var totalContacts = ImmediatePhysics.GenerateContacts(geom1.AsReadOnly(), geom2.AsReadOnly(), xForms1.AsReadOnly(), xForms2.AsReadOnly(), m_NumberOfPairs, contacts, contactCounts);

        // It is now possible to check whether there were any contacts for the pairs.
        // First, iterate over the number of input pairs defined in m_NumberOfPairs.
        int idx = 0;
        for (int i = 0; i < m_NumberOfPairs; i++)
        {
            // Iterate over the number of contacts that were generated per each pair.
            for (int j = 0; j < contactCounts[i]; j++)
            {
                // Add the contact points to a list for visualization later.
                contactPoints.Add(contacts[idx].Point);

                // The number of contact points per each pair can be variable, so
                // use a separate index to keep track of which contact to retrieve.
                idx++;
            }
        }
    }
}