Pointers on learning OpenGL ES 2.0?

Are you writing a game to learn OpenGL, or are you writing a game to write a game?

If the former, I guess you'll have to dig deep into OpenGL (and I can't help ya). If the latter, I suppose you should consider using unity or some other engine that takes care of a lot of the gritty stuff for you.

 

http://nehe.gamedev.net/

 

Hmmm, well best of luck! OpenGL makes my head hurt.

 

Take what I say with a grain of salt because every time I get back into OpenGL some other project rips me right back out.

As for learning, I would highly suggest not making a game with it from the bat. There is lots to worry about in a game (not sure if you ever wrote one or not so if you did disregard) and it'll just get in the way of learning OpenGL.

Also for learning it, there is the old way with a fixed function pipeline and the newer way using shaders. The new way (OpenGL 3 and higher) is what you'll want to probably work on learning, although many people suggest learning the old way first to grab the concepts, then switch to the new way.

As for your vec3 and vec4 those *should* be vector types which is more of a struct than an array. Take for instance a point in 3D space:

vec3 myCoords = (25, 25, 0);

For a vec4, something like a color would fit in there (a color with an alpha channel)

vec4 myColor = (0.25f, 0.25f, 1.0f, 1.0f);

The first three arguments in the red, green, and blue channel respectively, and the fourth argument is the alpha so if its less than one, and your blend modes are enabled the color will blend with what is behind it.

I'm not sure what varying is, I've never run in to that but the

"GLKMatrix4" is most likely a 4 x 4 matrix used for something like custom transformations. I'm not sure if OpenGL supports built in transformations or not anymore, if not this would be one use for these.

I hope this made more sense than confusion. Its been awhile since I got to play in OpenGL and I'm not quite sure how to translate it to Objective-C since I've always used it in C++.

EDIT: Also remember, take the above with a grain of salt! Its been awhile since I used OpenGL, and when I did use it it was an older version so some of my info may be incorrect.