pbrtools/bindatastruct.js

laya pbr tools

/**
 * 根据描述创建一个buffer或者描述一个buffer
 * 通过描述中的属性来访问或者修改buffer的内容。
 */
class binDataStruct {
    constructor(desc) {
        this.desc = desc;
        var sz = this.calcBufSz(desc);
        this.buff = new ArrayBuffer(sz);
        this.cook(desc, this.buff, 0);
    }
    /**
     * 返回[type，num]
     */
    _gettype(str) {
        var st = str.indexOf('[');
        var ed = str.indexOf(']');
        if (st < 0) {
            return [str, 1];
        }
        if (ed < 0)
            throw 'error no ]' + str;
        return [str.substr(0, st), parseInt(str.substr(st + 1, ed - st - 1))];
    }
    cook(desc, buff, off) {
        var off = off;
        desc.forEach((v) => {
            var av = v.split(',');
            if (av.length < 2)
                throw 'error ' + v;
            var ti = this._gettype(av[1]);
            var cls = binDataStruct.typeinfo[ti[0]][1];
            var num = ti[1];
            var isarr = num > 1;
            //问题：如果某个uint32或者f32没有按照4对齐会报错。
            if (!isarr) {
                var dt = new cls(buff, off, 1);
                Object.defineProperty(this, av[0], {
                    set: function (v) { dt[0] = v; },
                    get: function () { return dt[0]; },
                    enumerable: true,
                    configurable: true
                });
            }
            else {
                this[av[0]] = new cls(buff, off, num);
            }
            off += binDataStruct.typeinfo[ti[0]][0] * num;
            ;
        });
    }
    calcBufSz(desc) {
        var sz = 0;
        desc.forEach((v) => {
            var av = v.split(',');
            if (av.length < 2)
                throw 'error ' + v;
            var ti = this._gettype(av[1]);
            var tp = ti[0];
            var num = ti[1];
            sz += binDataStruct.typeinfo[tp][0] * num;
        });
        return sz;
    }
    attachBuff(buff, off) {
        this.cook(this.desc, buff, off);
    }
}
binDataStruct.typeinfo = {
    u8: [1, Uint8Array],
    u16: [2, Uint16Array],
    u32: [4, Uint32Array],
    f32: [4, Float32Array]
};
/**
 * 根据描述字符串读写数据
 */
class strDataStruct {
    constructor() {
    }
    desc(str) {
    }
    size() {
        return 0;
    }
    fromBuff(buff, off) {
    }
    toBuff(buff, off) {
    }
}
/*
//var，type，defvalue
var bf = new binDataStruct(['id,u16','padd,u16','dataoff,u32','datasize,u32']) as any;
bf.datasize=22;

//test
bf = new binDataStruct(['id,u32','dt,u32[4]']) as any;
bf.dt[0]=10;
bf.dt[1]=11;

var bb = new Uint8Array([1,2,3]);
var c=new binDataStruct(['a,u8','b,u8','c,u8'])
c.attachBuff(bb.buffer,0)
*/