u3d mesh构造

u3d  mesh的组织方法  ,u3d 默认的mesh构造方法是三角形，即index指向三个点，那么这三个点就会被连接成三角形，

那么之前必须先申请很多点，uv，法线，然后设置点，index即可，有一点需要注意就是 ，u3d里面必须逆时针绘制才会显示面，否则不显示，以下代码先记录

using UnityEngine;
using System.Collections;

public class LiDiBoxOne : MonoBehaviour
{
    private GameObject TObj;

    public Material Tmeterial;
    public float THeight;
    private Mesh teMesh;

    private int MNUMPOINT = 12100;
    private Vector3[] vertex;
    private Vector2[] uvs;
    private int[] trangles;
    private Vector4[] tangents;

    private Vector3 m_OldPos;
    private Vector3 m_OldLeftPos;
    private Vector3 m_OldRightPos;

    private int m_Step;
    // Use this for initialization
    void Start()
    {
        m_Step = 0;
        m_OldPos = new Vector3(0, 0, 0);

        TObj = new GameObject();
        TObj.name = "abc";
        TObj.transform.position = new Vector3(0, 0, 0);

        vertex = new Vector3[MNUMPOINT];
        uvs = new Vector2[MNUMPOINT];
        tangents = new Vector4[MNUMPOINT];

        trangles = new int[MNUMPOINT *12];

        TObj.gameObject.AddComponent<MeshFilter>();
        TObj.gameObject.AddComponent("MeshRenderer");
        if (Tmeterial)
            TObj.renderer.material = Tmeterial;
        else
            TObj.renderer.material.color = Color.white;

        teMesh = new Mesh();

    }

    // Update is called once per frame
    void Update()
    {
        LidiNewAction();

    }

    void LidiOldAction()
    {
        Vector3 mTempPositionCar = this.transform.position;
        Vector3 mTempPosition = new Vector3(mTempPositionCar.x, THeight, mTempPositionCar.z);

        if (Vector3.Distance(m_OldPos, mTempPosition) > 4.0f)
        {
            Vector3 m_leftstep = this.transform.right * 4.50f;

            Vector3 m_left = mTempPosition - m_leftstep;
            Vector3 m_right = mTempPosition + m_leftstep;
            float PointDis;
            for (int j = 0; j < 2; ++j)
            {
                if (j == 0)
                {
                    vertex[m_Step * 2 + j] = new Vector3(m_left.x, THeight, m_left.z);

                    PointDis = 0;

                    uvs[m_Step * 2 + j] = new Vector2(0.0f, m_Step);
                    m_OldLeftPos = new Vector3(m_left.x, THeight, m_left.z);
                }
                else
                {
                    vertex[m_Step * 2 + j] = new Vector3(m_right.x, THeight, m_right.z);
                    uvs[m_Step * 2 + j] = new Vector2(1.0f, m_Step);

                    m_OldRightPos = new Vector3(m_right.x, THeight, m_right.z);
                }

                tangents[m_Step * 2 + j] = new Vector4(0, 1, 0, 1);

            }

            if (m_Step > 0)
            {
                int ggtemp = m_Step - 1;

                trangles[ggtemp * 6 + 0] = ggtemp * 2;
                trangles[ggtemp * 6 + 1] = ggtemp * 2 + 2;
                trangles[ggtemp * 6 + 2] = ggtemp * 2 + 1;

                trangles[ggtemp * 6 + 3] = ggtemp * 2 + 2;
                trangles[ggtemp * 6 + 4] = ggtemp * 2 + 3;
                trangles[ggtemp * 6 + 5] = ggtemp * 2 + 1;
            }

            teMesh.vertices = vertex;
            teMesh.uv = uvs;

            teMesh.triangles = trangles;
            teMesh.RecalculateNormals();
            teMesh.RecalculateBounds();
            teMesh.tangents = tangents;
            TObj.GetComponent<MeshFilter>().mesh = teMesh;

            m_Step++;

            m_OldPos = mTempPosition;
        }

    }

    void LidiNewAction()
    {
        Vector3 mTempPosition = this.transform.position;
        Vector3 m_leftstep = this.transform.right * 6.50f;
        Vector3 m_leftPos = mTempPosition - m_leftstep;
        Vector3 m_rightPos = mTempPosition + m_leftstep;

        float disleft = Vector3.Distance(m_leftPos, m_OldLeftPos);
        float disright = Vector3.Distance(m_rightPos, m_OldRightPos);

        if (disleft > 1.5250f || disright > 1.525f)
        {
            for (int j = 0; j < 3; ++j)
            {
                if (j == 0)
                {
                    vertex[m_Step * 3 + j] = new Vector3(m_leftPos.x, THeight, m_leftPos.z);
                    uvs[m_Step * 3 + j] = new Vector2(0.0f, m_Step *0.25f);
                }

                if (j == 1)
                {
                    vertex[m_Step * 3 + j] = new Vector3(mTempPosition.x, THeight, mTempPosition.z);
                    uvs[m_Step * 3 + j] = new Vector2(0.5f, m_Step *0.25f);
                }

                if (j == 2)
                {
                    vertex[m_Step * 3 + j] = new Vector3(m_rightPos.x, THeight, m_rightPos.z);
                    uvs[m_Step * 3 + j] = new Vector2(1.0f, m_Step *0.25f);

                }

                // tangents[m_Step * 2 + j] = new Vector4(0, 1, 0, 1);

            }

            if (m_Step > 0)
            {
                int ggtemp = m_Step - 1;

                trangles[ggtemp * 12 + 0] = ggtemp * 3;
                trangles[ggtemp * 12 + 1] = ggtemp * 3 + 3;
                trangles[ggtemp * 12 + 2] = ggtemp * 3 + 4;

                trangles[ggtemp * 12 + 3] = ggtemp * 3 + 0;
                trangles[ggtemp * 12 + 4] = ggtemp * 3 + 4;
                trangles[ggtemp * 12 + 5] = ggtemp * 3 + 1;

                trangles[ggtemp * 12 + 6] = ggtemp * 3 + 1;
                trangles[ggtemp * 12 + 7] = ggtemp * 3 + 4;
                trangles[ggtemp * 12 + 8] = ggtemp * 3 + 2;

                trangles[ggtemp * 12 + 9] = ggtemp * 3 + 2;
                trangles[ggtemp * 12 + 10] = ggtemp * 3 + 4;
                trangles[ggtemp * 12 + 11] = ggtemp * 3 + 5;

            }

            teMesh.vertices = vertex;
            teMesh.uv = uvs;

            teMesh.triangles = trangles;
            teMesh.RecalculateNormals();
            teMesh.RecalculateBounds();
            teMesh.tangents = tangents;

            TObj.GetComponent<MeshFilter>().mesh = teMesh;

            m_Step++;

            m_OldLeftPos = m_leftPos;
            m_OldRightPos = m_rightPos;
            m_OldPos = mTempPosition;
        }

    }
}

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