Unity 2d 中的自定义形状生成对象

Question

我是 Unity 新手。我正在尝试从 Unity http://www.boxcar2d.com/index.html 的网站重写游戏

所以我发现我应该使用 Sprites。现在我正在尝试动态生成一个任意形状的“汽车”。我需要它与物理和重力发生碰撞和相互作用。 我尝试使用Mesh，但似乎没有办法将Mesh 变成Sprite 并像处理物理对象一样使用它。

我应该使用什么样的结构或方法来动态创建这些“汽车”？

这是我到目前为止的代码，如果它有用的话。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GenerateCar : MonoBehaviour {

    public Material mat;



    // Use this for initialization
    void Start()
    {
        Mesh mesh = new Mesh();

        Vector3[] vertices = new Vector3[6];

        vertices[0] = new Vector3(0, 0);
        vertices[1] = new Vector3(4, 1);
        vertices[2] = new Vector3(3, -1);
        vertices[3] = new Vector3(-1, -3);
        vertices[4] = new Vector3(3, -6);
        vertices[5] = new Vector3(0, 1);
        //vertices[6] = new Vector3(width, height);
        //vertices[7] = new Vector3(width, -height);

        mesh.vertices = vertices;

        mesh.triangles = new int[] { 0, 1, 2, 0, 2, 3, 0, 3, 4, 0, 4, 5, 0, 5, 1};

        GetComponent<MeshRenderer>().material = mat;

        GetComponent<MeshFilter>().mesh = mesh;
    }

}

Answer 1

如果您需要制作仅使用提前制作的水平和垂直拉伸精灵无法制作的任意形状，那么精灵不适合。 Mesh 会更实用。

如果您可以将要制作的形状描述为具有已知有序点列表的多边形，则可以使用社区Triangulator 类来创建Mesh。还有其他方法，但这是社区备用。

无论您使用什么来制作Mesh，您都需要确保在与Mesh 相同的对象上还有一个PolygonCollider2D。您可以使用SetPath 使用与输入Triangulator 相同的点创建其轮廓。您还需要Rigidbody2D 来处理车身的物理和碰撞。我从未使用过轮子，但 WheelJoint2D 可能是你可以用于轮子的东西。

Triangulator 使用示例

using UnityEngine;
 
public class PolygonTester : MonoBehaviour {
    void Start () {
        // Create Vector2 vertices
        Vector2[] vertices2D = new Vector2[] {
            new Vector2(0,0),
            new Vector2(0,50),
            new Vector2(50,50),
            new Vector2(50,100),
            new Vector2(0,100),
            new Vector2(0,150),
            new Vector2(150,150),
            new Vector2(150,100),
            new Vector2(100,100),
            new Vector2(100,50),
            new Vector2(150,50),
            new Vector2(150,0),
        };
 
        // Use the triangulator to get indices for creating triangles
        Triangulator tr = new Triangulator(vertices2D);
        int[] indices = tr.Triangulate();
 
        // Create the Vector3 vertices
        Vector3[] vertices = new Vector3[vertices2D.Length];
        for (int i=0; i<vertices.Length; i++) {
            vertices[i] = new Vector3(vertices2D[i].x, vertices2D[i].y, 0);
        }
 
        // Create the mesh
        Mesh msh = new Mesh();
        msh.vertices = vertices;
        msh.triangles = indices;
        msh.RecalculateNormals();
        msh.RecalculateBounds();
 
        // Set up game object with mesh;
        gameObject.AddComponent(typeof(MeshRenderer));
        MeshFilter filter = gameObject.AddComponent(typeof(MeshFilter)) as MeshFilter;
        filter.mesh = msh;
    }
}

Triangulator源

using UnityEngine;
using System.Collections.Generic;
 
public class Triangulator
{
    private List<Vector2> m_points = new List<Vector2>();
 
    public Triangulator (Vector2[] points) {
        m_points = new List<Vector2>(points);
    }
 
    public int[] Triangulate() {
        List<int> indices = new List<int>();
 
        int n = m_points.Count;
        if (n < 3)
            return indices.ToArray();
 
        int[] V = new int[n];
        if (Area() > 0) {
            for (int v = 0; v < n; v++)
                V[v] = v;
        }
        else {
            for (int v = 0; v < n; v++)
                V[v] = (n - 1) - v;
        }
 
        int nv = n;
        int count = 2 * nv;
        for (int m = 0, v = nv - 1; nv > 2; ) {
            if ((count--) <= 0)
                return indices.ToArray();
 
            int u = v;
            if (nv <= u)
                u = 0;
            v = u + 1;
            if (nv <= v)
                v = 0;
            int w = v + 1;
            if (nv <= w)
                w = 0;
 
            if (Snip(u, v, w, nv, V)) {
                int a, b, c, s, t;
                a = V[u];
                b = V[v];
                c = V[w];
                indices.Add(a);
                indices.Add(b);
                indices.Add(c);
                m++;
                for (s = v, t = v + 1; t < nv; s++, t++)
                    V[s] = V[t];
                nv--;
                count = 2 * nv;
            }
        }
 
        indices.Reverse();
        return indices.ToArray();
    }
 
    private float Area () {
        int n = m_points.Count;
        float A = 0.0f;
        for (int p = n - 1, q = 0; q < n; p = q++) {
            Vector2 pval = m_points[p];
            Vector2 qval = m_points[q];
            A += pval.x * qval.y - qval.x * pval.y;
        }
        return (A * 0.5f);
    }
 
    private bool Snip (int u, int v, int w, int n, int[] V) {
        int p;
        Vector2 A = m_points[V[u]];
        Vector2 B = m_points[V[v]];
        Vector2 C = m_points[V[w]];
        if (Mathf.Epsilon > (((B.x - A.x) * (C.y - A.y)) - ((B.y - A.y) * (C.x - A.x))))
            return false;
        for (p = 0; p < n; p++) {
            if ((p == u) || (p == v) || (p == w))
                continue;
            Vector2 P = m_points[V[p]];
            if (InsideTriangle(A, B, C, P))
                return false;
        }
        return true;
    }
 
    private bool InsideTriangle (Vector2 A, Vector2 B, Vector2 C, Vector2 P) {
        float ax, ay, bx, by, cx, cy, apx, apy, bpx, bpy, cpx, cpy;
        float cCROSSap, bCROSScp, aCROSSbp;
 
        ax = C.x - B.x; ay = C.y - B.y;
        bx = A.x - C.x; by = A.y - C.y;
        cx = B.x - A.x; cy = B.y - A.y;
        apx = P.x - A.x; apy = P.y - A.y;
        bpx = P.x - B.x; bpy = P.y - B.y;
        cpx = P.x - C.x; cpy = P.y - C.y;
 
        aCROSSbp = ax * bpy - ay * bpx;
        cCROSSap = cx * apy - cy * apx;
        bCROSScp = bx * cpy - by * cpx;
 
        return ((aCROSSbp >= 0.0f) && (bCROSScp >= 0.0f) && (cCROSSap >= 0.0f));
    }
}