什么是glMultiDrawElementsIndirect中使用的间接cmd的含义

Question

我对使用glMultiDrawElementsIndirect（）感到困惑，是否有人可以向我解释该绘图命令使用的cmd结构的含义？

struct cmd：

count = ..
primCount = ..
firstIndex = ..
baseVertex = ..
baseInstance = ..

如果我有三个不同的三角形条画，那会是这样的吗？

for (int n = 0; n < 3; n++)
{
    count = indexCount;
    primCount = 1;
    firstIndex = n * count;
    baseVertex = 0;
    baseInstance = n;
    ...
}

设置缓冲区：

protected void setupBuffers()
{
    gl.glGenVertexArrays(1, vaoBuff);
    gl.glBindVertexArray(vaoBuff.get(0));

    gl.glGenBuffers(5, vboBuff);

    //bind indirect buffer object
    gl.glBindBuffer(GL4.GL_DRAW_INDIRECT_BUFFER, vboBuff.get(0));
    gl.glBufferData(GL4.GL_DRAW_INDIRECT_BUFFER, instanceCount * 5 * Integer.SIZE / 8, null, GL4.GL_STATIC_DRAW);
    gl.glBufferSubData(...);

    //bind draw instance ID in the shader with a buffer object
    gl.glBindBuffer(GL4.GL_ARRAY_BUFFER, vboBuff.get(1));
    gl.glBufferData(GL4.GL_ARRAY_BUFFER, instanceCount * Integer.SIZE / 8, drawIndexBuff, GL4.GL_STATIC_DRAW);
    gl.glVertexAttribIPointer(d_idLoc, 1, GL4.GL_UNSIGNED_INT, 0, 0);
    gl.glVertexAttribDivisor(d_idLoc, 1);
    gl.glEnableVertexAttribArray(d_idLoc);

    //bind vertex data buffer object
    gl.glBindBuffer(GL4.GL_ARRAY_BUFFER, vboBuff.get(2));
    gl.glBufferData(GL4.GL_ARRAY_BUFFER, instanceCount / column_subdivision * vertBuffSize * Float.SIZE / 8, null, GL4.GL_STATIC_DRAW);
    gl.glBufferSubData(...);
    gl.glVertexAttribPointer(verPosLoc, 3, GL4.GL_FLOAT, false, 0, 0);
    gl.glEnableVertexAttribArray(verPosLoc);

    //bind vertex index data buffer object
    gl.glBindBuffer(GL4.GL_ELEMENT_ARRAY_BUFFER, vboBuff.get(3));
    gl.glBufferData(GL4.GL_ELEMENT_ARRAY_BUFFER, instanceCount / column_subdivision * indexBuffSize * Integer.SIZE / 8, null, GL4.GL_STATIC_DRAW);
    gl.glBufferSubData(...);

    //bind texture coordinate data buffer object
    gl.glBindBuffer(GL4.GL_ARRAY_BUFFER, vboBuff.get(4));
    gl.glBufferData(GL4.GL_ARRAY_BUFFER, instanceCount / column_subdivision * texBuffSize * Float.SIZE / 8, null, GL4.GL_STATIC_DRAW);
    gl.glBufferSubData(...);
    gl.glVertexAttribPointer(tc_inLoc, 2, GL4.GL_FLOAT, false, 0, 0);
    gl.glEnableVertexAttribArray(tc_inLoc);
}

绘图命令：

gl.glBindVertexArray(vaoBuff.get(0));
glBindBuffer(GL4.GL_DRAW_INDIRECT_BUFFER, vboBuff.get(0));
gl.glMultiDrawElementsIndirect(GL4.GL_TRIANGLE_STRIP, GL4.GL_UNSIGNED_INT, null, 3, 0);

修正了它，顶点数据中出现了一些问题。另一个是正确的。