You will have to write your own DX9 functions for all images,texture,entities,camera Blitz3D functions which is not a simple job ... or you will have to "hack" pointer/memory structure of Blitz images/textures/models/cameras so you can access it. It is terrible/serious job and would involve some "hacking" for sure!
It's possible ... but so unpractical compared to have Blitz research updating Blitz3D to DX9 (which will never happen I guess)
It's possible ... but so unpractical compared to have Blitz research updating Blitz3D to DX9 (which will never happen I guess)