各位大佬。3.3 MeshRenderer 怎么用啊，一直没有效果，不显示

[serytw]

代码如下
import { Component, gfx, macro, Material, MeshRenderer, SpriteFrame, Texture2D, utils, Vec3, _decorator } from ‘cc’;

const { ccclass, property } = _decorator;

@ccclass(‘DrawSectorMesh’)

/**

• 绘制扇形网格

*/

export class DrawSectorMesh extends Component {

@property({ type: Material })

public mat: Material | null = null;

@property({

    tooltip: "外圈半径"

})

public radius: number = 5;

@property({

    tooltip: "内圈半径"

})

public innerRadius: number = 1;

@property({

    tooltip: "扇形角度"

})

public angledegree: number = 60;

@property(Texture2D)

spriteFrame: Texture2D = null;

start() {

    this.createMesh()

}

createMesh() {

    const model = this.addComponent(MeshRenderer)!;

    const segments: number = Math.floor(this.angledegree / 4) + 1;                

    var positions: number[] = [];                                                    

    // 组装顶点数据

    var vertices_count: number = segments * 2 + 2;                                    

    var vertices: Array<Vec3> = new Array<Vec3>(vertices_count);

    var angleRad: number = this.angledegree * macro.RAD;                          

    var angleCur: number = angleRad;

    var angledelta: number = angleRad / segments;                                  

    for (var i = 0; i < vertices_count; i += 2) {                                    

        var cosA: number = Math.cos(angleCur);

        var sinA: number = Math.sin(angleCur);

        vertices[i] = new Vec3(this.radius * cosA, 0, this.radius * sinA);              

        vertices[i + 1] = new Vec3(this.innerRadius * cosA, 0, this.innerRadius * sinA);

        angleCur -= angledelta;

        positions.push(vertices[i].x);

        positions.push(vertices[i].y);

        positions.push(vertices[i].z);

        positions.push(vertices[i + 1].x);

        positions.push(vertices[i + 1].y);

        positions.push(vertices[i + 1].z);

    }

    // 组装三角形数据

    var indice_count: number = segments * 6;                                              

    var indices: Array<number> = new Array<number>(indice_count);

    for (var i = 0, vi = 0; i < indice_count; i += 6, vi += 2) {                          

        indices[i] = vi;

        indices[i + 1] = vi + 3;

        indices[i + 2] = vi + 1;

        indices[i + 3] = vi + 2;

        indices[i + 4] = vi + 3;

        indices[i + 5] = vi;

    }

    // 组装UV数据

    var uvs: number[] = [];

    for (var i = 0; i < vertices_count; i++) {

        var u = vertices[i].x / this.radius / 2 + 0.5

        var v = vertices[i].z / this.radius / 2 + 0.5

        uvs.push(u, v);

    }

    const primitiveMode = gfx.PrimitiveMode.TRIANGLE_FAN;

    const attributes: any[] = [{

        name: gfx.AttributeName.ATTR_NORMAL,

        format: gfx.Format.RGB32F,

    }];

    var IGeometry = {

        positions: positions,

        indices: indices,

        uvs: uvs,

        primitiveMode: primitiveMode,

        attributes: attributes

    }

    const mesh = utils.createMesh(IGeometry);

    model.mesh = mesh;

    model.material = this.mat;

}

}