code: func (rce RenderCommandEncoder) SetVertexBuffer(buf Buffer, offset, index int) {
  	C.RenderCommandEncoder_SetVertexBuffer(rce.commandEncoder, buf.buffer, C.uint_t(offset), C.uint_t(index))
  }
docs: // SetVertexBuffer sets a buffer for the vertex shader function at an index
  // in the buffer argument table with an offset that specifies the start of the data.
  //
  // Reference: https://developer.apple.com/documentation/metal/mtlrendercommandencoder/1515829-setvertexbuffer.