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?

You probably already realized this, but glCopyBufferSubData is available in GLES 3.0 if you would rather migrate from 1.0 to 3.0 in one step.