Converting DirectX 9 code to DirectX 10

Question

Preface:

I purchased Programming an RTS in DirectX recently, and I know the code uses DirectX 9, but it has fantastic reviews and is apparently one of the best books you can get on beginning DirectX.

Question:

To my understanding, DirectX is just a means of displaying graphics to the scene. I will still have to code any games in C++ using game logic code, input, etc. Was I naive in thinking I could read the book with the MSDN tutorial site open for DirectX 10, and convert all of the samples to DirectX 10, or is that gonna be extremely difficult for me to do? Also, is DirectX 9 still relevant, or would it really behoove me to go about converting to DX 10?

Thanks!

Answer 1

It is important to note that the DirectX API is independent of the DirectX Hardware. That is to say that a DirectX 11 video card can still be accessed through the DirectX 9 API.

Much legacy code still uses the DirectX 9 API, and as I recall, Direct X is a backwards compatible API, so your code targeting DirectX 9 should run on a machine with DirectX 11 installed.

To asnwer your specific questions, DirectX is an API to facilitate running high performance graphics and sound on the computer. You will still write your game logic in C/C++, as I recall DirectX has some classes for dealing with user input as well. With respect to API changes between 9, 10, and 11 I do not really know, but I cannot imagine that a good programmer would have difficulty figuring it out, given a well written book and MSDN. I should also mention here, that I don't do much native DirectX programming, so take my words about API changes with a grain of salt.

Answer 2

While I haven't read the book in question, you're absolutely right (IMHO) that one graphics API can be fairly easily substituted for another without seriously impacting all the other stuff you need to do.

As to whether DX9 is relevant - there are a lot of XP users around still... really depends on your audience. If it's mostly just for personal consumption, I'd say go with DX10/11.

Answer 3

To the best of my knowledge, there is no fixed function pipeline in DirectX 10/11. That means the way you interact with the API has changed very dramatically on some levels. If your book delves into the the ins and outs of vertex and pixel shaders and programmable hardware, then it might not be that big a difference. But if your book is mainly based on utilization of that fixed function pipeline, you're in for a general shift of paradigms when/if you make a transition.

If you really want to stick to this book, it won't do any harm to just pull all the stuff off using DX9 because learning is never a bad thing. But if you really want to make a transition towards DX10/11 further down the road, be ready to invest quite some time.