三、Unity 生成几种常用模型mesh-----BoxShape

生成方块盒子的mesh，由底面的四个顶点和顶面的四个顶点组成，底面的Mesh是朝下的，所以底面的四个顶点以逆时针的方式排列，顶面的四个顶点还是以顺时针顺序排列。

1、获得顶点的数据集合

  protected override Vector3[] GetVertices()
        {
            var p0 = new Vector3(-_xSize * 0.5f, -_ySize * 0.5f, -_zSize * 0.5f) - _verticeOffset;//左下
            var p1 = new Vector3(_xSize * 0.5f, -_ySize * 0.5f, -_zSize * 0.5f) - _verticeOffset;//右下
            var p2 = new Vector3(_xSize * 0.5f, -_ySize * 0.5f, _zSize * 0.5f) - _verticeOffset;//右上
            var p3 = new Vector3(-_xSize * 0.5f, -_ySize * 0.5f, _zSize * 0.5f) - _verticeOffset;//左上

            var p4 = new Vector3(-_xSize * 0.5f, _ySize * 0.5f, -_zSize * 0.5f) - _verticeOffset;//左下
            var p5 = new Vector3(-_xSize * 0.5f, _ySize * 0.5f, _zSize * 0.5f) - _verticeOffset;//左上
            var p6 = new Vector3(_xSize * 0.5f, _ySize * 0.5f, _zSize * 0.5f) - _verticeOffset;//右上
            var p7 = new Vector3(_xSize * 0.5f, _ySize * 0.5f, -_zSize * 0.5f) - _verticeOffset;//右下

            return new Vector3[]
             {
                //下
                p1,p2,p3,p0,
                //上
                p4,p5,p6,p7,
                //左
                p3,p5,p4,p0,
                //右
                p1,p7,p6,p2,
                //前
                p2,p6,p5,p3,
                //后
                p0,p4,p7,p1
             };
        }

2、获得三角面顶点的索引

protected override int[] GetTriangles()
        {
            return new int[]
            {
                //下
                0, 1, 2,
                2, 3, 0,
                //上
                0 + 4 * 1, 1 + 4 * 1, 2 + 4 * 1,
                2 + 4 * 1, 3 + 4 * 1, 0 + 4 * 1,
                //左
                0 + 4 * 2, 1 + 4 * 2, 2 + 4 * 2,
                2 + 4 * 2, 3 + 4 * 2, 0 + 4 * 2,
                //右
                0 + 4 * 3, 1 + 4 * 3, 2 + 4 * 3,
                2 + 4 * 3, 3 + 4 * 3, 0 + 4 * 3,
                //前
                0 + 4 * 4, 1 + 4 * 4, 2 + 4 * 4,
                2 + 4 * 4, 3 + 4 * 4, 0 + 4 * 4,
                //后
                0 + 4 * 5, 1 + 4 * 5, 2 + 4 * 5,
                2 + 4 * 5, 3 + 4 * 5, 0 + 4 * 5,
            };
        }

BoxShape整体代码如下

public class BoxShape : Shape
    {
        private static readonly string _boxMeshName = "Box Mesh";//mesh的名称

        #region private members
        private float _xSize, _ySize, _zSize;
        #endregion

        #region ctor
        public BoxShape(float xSize, float ySize, float zSize, MeshPivot meshPivot) : base(meshPivot, _boxMeshName)
        {
            _xSize = xSize;
            _ySize = ySize;
            _zSize = zSize;

            _verticeOffset = GetVertexOffset();
        }

        #endregion

        #region override functions
        /// <summary>
        /// 根据mesh中心点的位置，获得顶点位置的偏移量
        /// </summary>
        /// <returns></returns>
        protected override Vector3 GetVertexOffset()
        {
            Vector3 offset;
            switch (_meshPivot)
            {
                case MeshPivot.CENTER:
                    offset = Vector3.zero;
                    break;
                case MeshPivot.TOP:
                    offset = new Vector3(0, _ySize, 0) * 0.5f;
                    break;
                case MeshPivot.BOTTOM:
                    offset = new Vector3(0, -_ySize, 0) * 0.5f;
                    break;
                case MeshPivot.LEFT:
                    offset = new Vector3(-_xSize, 0, 0) * 0.5f;
                    break;
                case MeshPivot.RIGHT:
                    offset = new Vector3(_xSize, 0, 0) * 0.5f;
                    break;
                case MeshPivot.FRONT:
                    offset = new Vector3(0, 0, _zSize) * 0.5f;
                    break;
                case MeshPivot.BACK:
                    offset = new Vector3(0, 0, -_zSize) * 0.5f;
                    break;
                default:
                    offset = Vector3.zero;
                    break;
            }
            return offset;
        }

        /// <summary>
        /// 获得顶点的数据集合
        /// </summary>
        /// <returns></returns>
        protected override Vector3[] GetVertices()
        {
            var p0 = new Vector3(-_xSize * 0.5f, -_ySize * 0.5f, -_zSize * 0.5f) - _verticeOffset;//左下
            var p1 = new Vector3(_xSize * 0.5f, -_ySize * 0.5f, -_zSize * 0.5f) - _verticeOffset;//右下
            var p2 = new Vector3(_xSize * 0.5f, -_ySize * 0.5f, _zSize * 0.5f) - _verticeOffset;//右上
            var p3 = new Vector3(-_xSize * 0.5f, -_ySize * 0.5f, _zSize * 0.5f) - _verticeOffset;//左上

            var p4 = new Vector3(-_xSize * 0.5f, _ySize * 0.5f, -_zSize * 0.5f) - _verticeOffset;//左下
            var p5 = new Vector3(-_xSize * 0.5f, _ySize * 0.5f, _zSize * 0.5f) - _verticeOffset;//左上
            var p6 = new Vector3(_xSize * 0.5f, _ySize * 0.5f, _zSize * 0.5f) - _verticeOffset;//右上
            var p7 = new Vector3(_xSize * 0.5f, _ySize * 0.5f, -_zSize * 0.5f) - _verticeOffset;//右下

            return new Vector3[]
             {
                //下
                p1,p2,p3,p0,
                //上
                p4,p5,p6,p7,
                //左
                p3,p5,p4,p0,
                //右
                p1,p7,p6,p2,
                //前
                p2,p6,p5,p3,
                //后
                p0,p4,p7,p1
             };
        }

        /// <summary>
        /// 获得法线方向的数据集合
        /// </summary>
        /// <returns></returns>
        protected override Vector3[] GetNormals()
        {
           return new Vector3[]
           {
                //下
                Vector3.down,Vector3.down,Vector3.down,Vector3.down,
                //上
                Vector3.up, Vector3.up, Vector3.up, Vector3.up,
                //左
                Vector3.left,Vector3.left,Vector3.left,Vector3.left,
                //右
                Vector3.right,Vector3.right,Vector3.right,Vector3.right,
                //前
                Vector3.forward, Vector3.forward, Vector3.forward, Vector3.forward,
                //后
                Vector3.back,Vector3.back,Vector3.back,Vector3.back,
           };
        }

        /// <summary>
        /// 获得三角面顶点的索引
        /// </summary>
        /// <returns></returns>
        protected override int[] GetTriangles()
        {
            return new int[]
            {
                //下
                0, 1, 2,
                2, 3, 0,
                //上
                0 + 4 * 1, 1 + 4 * 1, 2 + 4 * 1,
                2 + 4 * 1, 3 + 4 * 1, 0 + 4 * 1,
                //左
                0 + 4 * 2, 1 + 4 * 2, 2 + 4 * 2,
                2 + 4 * 2, 3 + 4 * 2, 0 + 4 * 2,
                //右
                0 + 4 * 3, 1 + 4 * 3, 2 + 4 * 3,
                2 + 4 * 3, 3 + 4 * 3, 0 + 4 * 3,
                //前
                0 + 4 * 4, 1 + 4 * 4, 2 + 4 * 4,
                2 + 4 * 4, 3 + 4 * 4, 0 + 4 * 4,
                //后
                0 + 4 * 5, 1 + 4 * 5, 2 + 4 * 5,
                2 + 4 * 5, 3 + 4 * 5, 0 + 4 * 5,
            };
        }

        /// <summary>
        ///  获得UV坐标的数据集合
        /// </summary>
        /// <returns></returns>
        protected override Vector2[] GetUVs()
        {
            return new Vector2[]
             {
                new Vector2(0,0),new Vector2(0,1),new Vector2(1,1),new Vector2(1,0),
                new Vector2(0,0),new Vector2(0,1),new Vector2(1,1),new Vector2(1,0),
                new Vector2(0,0),new Vector2(0,1),new Vector2(1,1),new Vector2(1,0),
                new Vector2(0,0),new Vector2(0,1),new Vector2(1,1),new Vector2(1,0),
                new Vector2(0,0),new Vector2(0,1),new Vector2(1,1),new Vector2(1,0),
                new Vector2(0,0),new Vector2(0,1),new Vector2(1,1),new Vector2(1,0),
             };
        }

        #endregion
    }

最终下过如下：