2d中的Unity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

中的网站重新编写游戏

因此，我发现我应该使用Sprites。现在，我尝试动态生成任意形状的“汽车”。我需要它与物理和重力碰撞并相互作用。  我尝试使用Mesh，但似乎无法将Mesh变成Sprite并像处理物理对象一样使用它。

我应该使用哪种结构或方法动态创建那些“汽车”？

到目前为止，这是我的代码，如果可以使用该代码。

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

如果您需要提前制作水平和垂直拉伸的精灵无法创建的任意形状，则精灵不适合。 Mesh会更实用。

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

无论用什么来制作Mesh，都需要确保在与PolygonCollider2D相同的对象上也有一个Mesh。您可以使用SetPath使用与输入Triangulator相同的点来创建轮廓。您还需要一个Rigidbody2D来处理汽车车身的物理问题和碰撞问题。我从未使用过轮子，但是WheelJoint2D可能是您可以使用的轮子。

Triangulator用法示例

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来源

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));
    }
}