Preface: I'm on android using C++ with the NDK.

I'm upgrading some old GL ES 1.0 code to GL ES 2.0 and have two internal array buffers already. In my code I simply want to copy from one buffer to the other.

Originally I bound the buffers with `GL_READ_ONLY` and `GL_WRITE_ONLY` and used

glCopyBufferSubData(GLEXT_GL_COPY_READ_BUFFER, GLEXT_GL_COPY_WRITE_BUFFER, 0, 0, sizeof(Vertex) * vertexBuffer.m_size));

To copy over. This function is not available on mobile and (correct me if I'm wrong) it seems my only options are `glBufferData` and `glBufferSubData` which take pointers to arrays on the CPU to be used for drawing.

How can I copy an already existing, internal buffer array to another internal destination buffer?