glBindTexture(GL_TEXTURE_2D, texture);
glBindBuffer(GL_PIXEL_UNPACK_BUFFER, PBO);
glBufferData(GL_PIXEL_UNPACK_BUFFER, 4 * fbw * fbh, nullptr, GL_STREAM_DRAW);
core::types::u8* ptr = reinterpret_cast<core::types::u8*>(glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY));
if(ptr)
{
    background_sprite.blit_on_opengl_buffer(ptr, fbw, fbh);
    glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);  // release pointer to mapping buffer
}
glTexImage2D(
    GL_TEXTURE_2D,
    0,
    GL_RGB,
    fbw, fbh,
    0,
    GL_RGBA,
    GL_UNSIGNED_BYTE,
    nullptr
);
glFinish();