我正在尝试运行一个用于 4x4 矩阵乘法的 C++ 函数。两天后，它终于成功了，但不如预期。

通常，参数会反馈给函数，然后出现以下行：

dataHeap2.set( new Uint8Array(data2.buffer) );

产生错误“Uncaught RangeError: Source is too large”

乍一看，它似乎只是一个包含 16 个元素的普通 Float32Array，但查看其缓冲区大小后，似乎有所不同

console.log(data2.buffer.bufferLength);

结果不是预期的 64 字节，而是像 3342345 这样的大数字。这是问题吗？我找到了一种解决方法，即手动复制值（如下所示），返回该值，然后问题就消失了。不幸的是，它使我的代码比直接在缓冲区上操作慢得多。

// bad solution - which works
    for(var i = 0; i < 16; i++) {
        dataTarget[i] = result[i];
    }

希望今晚我能找到更好的解决方案，我想继续使用这个函数，因为它使用编译的 C++ 代码，使用 ASM.JS + SIMD 来动画多个字符。在纯 JavaScript 中它仍然太慢了。这是整个函数。我很确定 data2 正在使用 Emscripten 的 HEAP，我想避免它。

matrix4multiply = function(data, data2) {
    // Import function from Emscripten generated file
    var mmul_vec4 = Module.cwrap(
      'mmul_vec4', 'number', ['number', 'number', 'number']
    );

    var dataTarget = new Float32Array(16);

    // Get data byte size, allocate memory on Emscripten heap, and get pointer
    var nDataBytes = dataTarget.length * dataTarget.BYTES_PER_ELEMENT;

    // First matrix copy data to Emscripten heap
    var dataPtr = Module._malloc(nDataBytes);
    var dataPtr2 = Module._malloc(nDataBytes);
    var dataPtr3 = Module._malloc(nDataBytes);

    var dataHeap = new Uint8Array(Module.HEAPU8.buffer, dataPtr, nDataBytes);
    dataHeap.set( new Uint8Array(data.buffer) );

    // second matrix allocate and copy to emscripten's heap
    var dataHeap2 = new Uint8Array(Module.HEAPU8.buffer, dataPtr2, nDataBytes);
    dataHeap2.set( new Uint8Array(data2.buffer) );

    // target heap
    var targetHeap = new Uint8Array(Module.HEAPU8.buffer, dataPtr3, nDataBytes);
    targetHeap.set( new Uint8Array(dataTarget.buffer) );

    // Call the function by passing a number pointing to the byte location of 
    // the array of pointers on the Emscripten heap.  Emscripten knows what to do!
    mmul_vec4(dataHeap.byteOffset, dataHeap2.byteOffset, targetHeap.byteOffset);

    // get result
    var result = new Float32Array(targetHeap.buffer, targetHeap.byteOffset, 16);

    // bad solution - which works
    //for(var i = 0; i < 16; i++) {
    //    dataTarget[i] = result[i];
    //}

    // Free memory
    Module._free(dataHeap.byteOffset);
    Module._free(dataHeap2.byteOffset);
    Module._free(targetHeap.byteOffset);

    return result;
}

编辑：简化版本不用担心 malloc 等

    new Uint8Array(Module.HEAPU8.buffer, this.dataPtr, 64).set( new Uint8Array(data.buffer, data.byteOffset, 64) );

    // second matrix allocate and copy to emscripten's heap
    new Uint8Array(Module.HEAPU8.buffer, this.dataPtr + 72, 64).set( new Uint8Array(data2.buffer, data2.byteOffset, 64) );

    // multiply first two parameters and return in the last one 
    this.mmul_vec4(this.dataPtr, this.dataPtr + 72, this.dataPtr + 144);

    // like that it works, unfotunately copying is being made here
    return new Float32Array(Module.HEAPU8.buffer.slice(this.dataPtr + 144, this.dataPtr + 208));
    // with this version (if uncommented) there's just white screen(but it looks like the game is working.
    //return new Float32Array(Module.HEAPU8.buffer, this.dataPtr + 144, 16);