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shader - OpenGL 4.x learning resources


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I cordially dislike negative answers, but I'm afraid I have to give one to this question.

You are ultimately asking for beginner material that uses features unique to OpenGL version 4.0 and above. Well, let's look at some of the unique features of 4.x.

Perhaps the biggest feature is tessellation. What does that mean? It means tessellating primitives to generate more primitives. Before one can even begin to understand what that means, one must first understand how primitives get rendered at all. That uses pre-4.x level features.

But even with a firm understanding of how rendering works, there is still a problem. In order to have any meaningful discussion of tessellation shaders, one must first have a strong understanding of tessellation algorithms. And that is not a simple subject. For a tutorial to teach a user to use tessellation shaders, the tutorial will first have to introduce spline curves and patches or subdivision surfaces. Both of these are lengthy topics that have numerous white papers devoted to them. Only after detailing the algorithms would a user be ready to see how those algorithms are implemented in the tessellation shader.

Or, to put it another way, tessellation shaders are not beginner material. I wouldn't even qualify them as intermediate-level material.

Another big feature of 4.x level hardware is shader image load store (and its companion, atomic counters), core in 4.2. It allows for some very nifty things, including order-independent transparency. However, in order for a user to even begin to understand all of the quirks around it, the user needs to be intimately familiar with the deep workings of modern shader hardware. So any tutorial would first have to explain how modern VLIW/SIMD-based hardware works, as well as how shaders are used with such hardware. Again, this is not trivial material.

Another big feature of 4.x hardware is indirect rendering. That is, putting the parameters to a glDraw call in the buffer object itself. The problem is that there is really only one reason to use this functionality: because the GPU generated data directly into one or more buffers for later rendering. And doing that usually involves some form of GPGPU operation, which is very much not a beginner-level topic.

All of these features are useful and have a real purpose. But none of them should be used by beginners; in some cases, not even intermediate-level programmers should touch them.

Now to be completely fair, there are some 4.2 features that are both non-hardware-based (so they are often implemented on 3.3 and lower versions) and quite useful. Separate program objects, for example. These features hit while I was writing my 3.3-based tutorials, and I considered going back over them and incorporating this functionality. The only reason I didn't is because implementations (drivers) are still not entirely stable with regard to this functionality. But it would be useful to do.

The main point I'm getting across is this: if you are at the stage in your graphics knowledge where you are ready to take advantage of the unique features of GL 4.x hardware, then you also have enough graphics experience that you don't need an explicit step-by-step instructional material to implement features of graphics hardware. You would be the kind of person who could read the GL_ARB_tessellation_shader extension specification and understand how to make them do what you need to.

That being said, if you are interested in material that teaches OpenGL core 3.0 or better, the OpenGL Wiki has a nice collection of such links. In the interest of full disclosure, I did write one of them.


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