C ++-缓冲区组合，添加额外的空值 [英] C++ - Buffer combining adding extra empty values

问题描述

我正在尝试填充两个缓冲区，即C ++中的索引缓冲区对象和顶点缓冲区对象.

I am trying to fill two buffers, an index buffer object and a vertex buffer object in C++.

// Create the IBO and VBO data
GLushort* iboData = new GLushort[polyProcessed * 3];
Vertex* vboData = new Vertex[vertProcessed];

int iboPos = 0;
int vboPos = 0;

// Create the VBO and IBO
for(int i = 0; i < fragMap[0x36]; i++)
{
    // Copy the data to the IBO
    memcpy(iboData + iboPos, zmeshes[i].indices, zmeshes[i].numPoly * 3 * sizeof(GLushort));//sizeof(*zmeshes[i].indices));

    // Advance the position
    iboPos += zmeshes[i].numPoly * 3 * sizeof(GLshort);

    // Copy the data to the VBO
    memcpy(vboData + vboPos, zmeshes[i].vertices, zmeshes[i].numVert * sizeof(Vertex));//sizeof(*zmeshes[i].vertices));

    // Advance the position
    vboPos += zmeshes[i].numVert * sizeof(Vertex);

    errorLog.writeSuccess("Build log: VBO size %i VBO pos %i IBO size %i IBO pos %i", zmeshes[i].numVert * sizeof(Vertex), 
                          vboPos, zmeshes[i].numPoly * 3 * sizeof(GLshort), iboPos);
}

它只是获取要复制的数据的大小，将其复制，然后前进位置(将下一个数据放入缓冲区的位置).

It's simply getting the size of the data to be copied, copying it, and then advancing the position (where to put the next data in the buffer).

我得到这样的输出:

<---> Index dump: 0
<---> Index dump: 1
<---> Index dump: 2
<---> Index dump: 2
<---> Index dump: 3
<---> Index dump: 0
<---> Index dump: 4
<---> Index dump: 5
<---> Index dump: 23
<---> Index dump: 23
<---> Index dump: 22
<---> Index dump: 4
<---> Index dump: 26
<---> Index dump: 6
<---> Index dump: 7
<---> Index dump: 7
<---> Index dump: 8
<---> Index dump: 26
<---> Index dump: 9
<---> Index dump: 34
<---> Index dump: 10
<---> Index dump: 10
<---> Index dump: 11
<---> Index dump: 9
<---> Index dump: 12
<---> Index dump: 25
<---> Index dump: 13
<---> Index dump: 13
<---> Index dump: 14
<---> Index dump: 12
<---> Index dump: 13
<---> Index dump: 25
<---> Index dump: 31
<---> Index dump: 31
<---> Index dump: 15
<---> Index dump: 13
<---> Index dump: 28
<---> Index dump: 33
<---> Index dump: 16
<---> Index dump: 36
<---> Index dump: 33
<---> Index dump: 35
<---> Index dump: 31
<---> Index dump: 24
<---> Index dump: 15
<---> Index dump: 17
<---> Index dump: 25
<---> Index dump: 18
<---> Index dump: 18
<---> Index dump: 25
<---> Index dump: 12
<---> Index dump: 27
<---> Index dump: 34
<---> Index dump: 9
<---> Index dump: 2
<---> Index dump: 1
<---> Index dump: 19
<---> Index dump: 30
<---> Index dump: 32
<---> Index dump: 20
<---> Index dump: 29
<---> Index dump: 25
<---> Index dump: 17
<---> Index dump: 17
<---> Index dump: 21
<---> Index dump: 29
<---> Index dump: 32
<---> Index dump: 26
<---> Index dump: 8
<---> Index dump: 8
<---> Index dump: 20
<---> Index dump: 32
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0
<---> Index dump: 0

这可以看作是复制了正确的72个值，并在其后面复制了72 0.我在复制缓冲区时是否做错了什么，或者这表明其他地方有问题?

This can be seen as the correct 72 values being copied in and 72 0's being copied in behind it. Did I do something wrong in the copying of my buffer or does this indicate a problem elsewhere?

进一步的解释:

网格1-72索引 网格2-300索引 网格3-45个索引.

Mesh 1 - 72 indices Mesh 2 - 300 indices Mesh 3 - 45 indices.

使用上面的函数，它会产生一个执行此操作的缓冲区:

Using the function above, it produces a buffer that does this:

[0]-[71]-网格1顶点全部正确 [72]-[142]-空 [142]-[EndofBuffer]-网格2

[0]-[71] - Mesh 1 vertices all correct [72]-[142] - Empty [142]-[EndofBuffer] - Mesh 2

它会创建重复的大小，并用0填充.

It creates duplicate sizes filled with 0's.

推荐答案

由于iboData是GLushort*，因此iboData+iboPos实际上指向内存位置(int)iboData + iboPos * sizeof(GLushort).您将字节偏移量与数组偏移量混淆了.在您的两个+=语句中，请勿乘以memcpy中使用的sizeof，因为iboPos记录的是GLushort偏移量，而不是字节偏移量.

Since iboData is a GLushort*, then iboData+iboPos actually points to the memory location (int)iboData + iboPos * sizeof(GLushort). You're confusing byte offsets with array offsets. In your two += statements, don't multiply by the sizeof you used in memcpy, as iboPos records the GLushort offset, not the byte offset.

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