OpenGL vs OpenGL ES and OpenGL 1.x vs OpenGL 2.0 What to learn?

Question

I am going to buy a book on OpenGL, but I have a few questions as to what I should be learning.

I am torn between dedicating myself to learn OpenGL 1.x or OpenGL 2.0, because OpenGL ES 2.0 only exists on 3G and beyond, and if I were to develop an app and place it on the app store, I would want everyone with an iphone capable of utilizing the app.

Also, I want to experiment with desktop OpenGL.

So, my question is as follows:

simply put, what should I be learning? If I learn Desktop OpenGL, would this be easily transferable to OpenGL ES? Like if I knew OpenGL in c/c++, would I also know OpenGL ES, what major differences are there?

Also, would you recommend I learn both 1.x and 2.0, for the specific reason I stated previously, that I would want all iphone owners capable of utilizing my app, not just 3G and beyond?

Lastly, are there any books you would recommend? I really enjoy the style of this tutorial. It's very easy to follow, shows a lot of code, and explains every line of code carefully.

Answer 1

I faced the same question myself, and my decision was to go with OpenGL ES 2.0. Firstly because the great majority of iOS devices in use today can run it (iPhone 3GS or better). Secondly because the future of OpenGL is shaders because they offer so much more flexibility than the fixed pipeline of ES 1.

That said, I will add that using shaders is NOT easy. It takes a lot more effort to set everything up in ES 2 than it does in ES 1. Many more things can go wrong, with many more times that you'll be looking at your program creating nothing but a blank screen leaving you scratching your head and wondering why.

Once you get the basics, though, ES 2 isn't really all that bad. It's just a pretty steep learning curve.

As for the desktop vs ES question, I would recommend learning ES. It's a very nice & functional subset of OpenGL, and will allow you to write programs that run on many more platforms. Using full OpenGL might get you into trouble if you want to port your code to ES, since there are aspects of it that don't translate.

To get you started with OpenGL ES 2, I highly recommend this tutorial and this book.

Answer 2

OpenGL ES 1.1 uses much of the old deprecated functionality, whereas OpenGL ES 2.0 uses the modern shader-only vertex array/buffer approach, being more future ready. If you learn desktop GL, you won't have too much difficulties using OpenGL ES, as they are quite similar.

If you really want to use the old-style OpenGL ES 1.1, then I suggest you to learn desktop OpenGL 2.0 (best done with the "OpenGL Programming Guide"/"Red Book") which will teach you the old immediate API along with the modern vertex array/buffer functionality and (in conjunction with the book "OpenGL Shading Language"/"Orange Book") also the use of programmable shaders. So this way you will be ready to use old-style (1/(2)) and modern ((2)/3/4) desktop GL along with OpenGL ES 1.1 and 2.0.

But if you want to start directly with the new and modern way of programming OpenGL (which might be advisable, although the old-style is a valuable experience), then I would rather suggest to use the newest edition of the "OpenGL SuperBible", which will teach you modern-style ((2)/3/4) desktop OpenGL without the old deprecated functionality. But then much OpenGL ES 1.1 code won't be of much use to you (although you will surely understand its principles). Although I really appreciate my knowledge of the fixed-function old-style OpenGL, I would rather suggest beginners to start with modern OpenGL right-away, even if it might be a bit harder to learn for a beginner, as this is the way to do hardware-accelerated real-time graphics today (and tomorrow).

But what really matters is, that in contrast to learning the API by mind you should understand the underlying principles and the principles of 3d graphics in general. Then you won't have much difficulty switching to other APIs, like Direct3D, anyway.