Qt/3D - vertex and index buffers thrash the bound buffer state

QGLPainter::setVertexBuffer() does this over and over:

buffer->bind();
setVertexAttribute(...);
buffer->unbind();

If the same buffer is used for the next paint, then this will constantly flip from the id to 0 to the id to 0, etc. Same with index buffers.

QGLPainter should keep track of this internally and only glBindBuffer() when a real buffer switch occurs, or raw client-side arrays are used for a drawing request.