实现mesh的原理可参考我写的Unity中的自定义mesh的原理，

碰撞检测算法——分离轴算法在Unity中实现（一）_unity　自定义高性能碰撞检测方案-CSDN博客

实现可传入shader两张贴图的顶点声明如下：

	var vertexDeclaration=Laya.VertexPositionNormalTexture0Texture1.vertexDeclaration;

默认的顶点声明如下：

	var vertexDeclaration=VertexPositionNormalTexture.vertexDeclaration;

实现代码：

var CustomMesh=(function(_super){function CustomMesh(long,width){/**@private */this._long=NaN;/**@private */this._width=NaN;(long===void 0)&& (long=1);(width===void 0)&& (width=1);RoadMesh.__super.call(this);this._long=long;this._width=width;this.activeResource();this._positions=this._getPositions();this._generateBoundingObject();}Laya.class(CustomMesh,'laya.d3.resource.models.CustomMesh',_super);var __proto=RoadMesh.prototype;__proto.recreateResource=function(){this._numberVertices=4;this._numberIndices=6;var vertexDeclaration=Laya.VertexPositionNormalTexture0Texture1.vertexDeclaration;var vertexFloatStride=vertexDeclaration.vertexStride / 4;var vertices=new Float32Array([0,0,0,0,0,1,0,0,0,0,this._width,0,0,0,0,1,1,0,1,0,0,0,this._long,0,0,1,0,1,0,1,this._width,0,this._long,0,0,1,1,1,1,1]);var indices=new Uint16Array([0,1,2,3,2,1,]);this._vertexBuffer=new Laya.VertexBuffer3D(vertexDeclaration,this._numberVertices,/*laya.webgl.WebGLContext.STATIC_DRAW*/0x88E4,true);this._indexBuffer=new Laya.IndexBuffer3D(/*laya.d3.graphics.IndexBuffer3D.INDEXTYPE_USHORT*/"ushort",this._numberIndices,/*laya.webgl.WebGLContext.STATIC_DRAW*/0x88E4,true);this._vertexBuffer.setData(vertices);this._indexBuffer.setData(indices);this.memorySize=(this._vertexBuffer._byteLength+this._indexBuffer._byteLength)*2;this.completeCreate();}return CustomMesh;
})(Laya.PrimitiveMesh)