cocos creator渲染流程（render-data）

    // 初始化頂點索引
    //矩形要轉換為兩個三角形進行渲染，所以是6個頂點
    //使用頂點索引是為了減少發送給GPU的數據，6個頂點中有兩個是重復的
    //indices = [0,1,2,1,3,2]
    initQuadIndices(indices) {
        let count = indices.length / 6;
        for (let i = 0, idx = 0; i < count; i++) {
            let vertextID = i * 4;
            indices[idx++] = vertextID;
            indices[idx++] = vertextID+1;
            indices[idx++] = vertextID+2;
            indices[idx++] = vertextID+1;
            indices[idx++] = vertextID+3;
            indices[idx++] = vertextID+2;
        }
    }

    //設置vDatas、uintVDatas，iDatas
    //vDatas和uintVDatas指向同一片存儲區域，vDatas是按照Float32讀取，uintVDatas按照Uint32讀取
    //使用vDatas來更新pos和uv
    //使用uintVDatas來更新color
    updateMesh (index, vertices, indices) {
        this.vDatas[index] = vertices;
        this.uintVDatas[index] = new Uint32Array(vertices.buffer, 0, vertices.length);
        this.iDatas[index] = indices;
        this.meshCount = this.vDatas.length;
    }

    createData (index, verticesFloats, indicesCount) {
        let vertices = new Float32Array(verticesFloats);
        let indices = new Uint16Array(indicesCount);
        this.updateMesh(index, vertices, indices);
    }

    //創建四個頂點的數據
    //verticesFloats:20, 單個頂點包含5個float,四個頂點就是20個
    //indicesCount: 6, 切分為兩個三角形，6個頂點索引
    createQuadData (index, verticesFloats, indicesCount) {
        this.createData(index, verticesFloats, indicesCount);
        this.initQuadIndices(this.iDatas[index]);
    }