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UnshavenBastard

OpenGL Turning to Computer Graphics again, after years of abstinence - Where to go, what to read?

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Howdy.

I have done some 3D graphics programming many years ago, some simple software rendering stuff and then Fixed Function OpenGL. I have not written one shader program.
I'm interested to get into that subject again, learning how things are done today.
It's not fixed that it has to be OpenGL (or Vulkan?) - I heard D3D has become a nice API, OO and all. OTOH, I guess it's still true that OpenGL/Vulkan opens doors to more platforms, which is a could-be-nice thing, but the main thing will remain desktop, and if D3D is so much nicer of an API, also debugging wise (?) ...
But *if* I were to go the "open software" route - is OpenGL a dead end now, because of Vulkan? I'm not sure I'd like to "do everything myself" as is said about vulkan, with pages of boilerplate for everything. Let's face it, I won't create the next Cry engine, I probably won't need extreme control of everything. As it's spare time stuff, one of the most important aspects here is not spending too much time for not very good reason (cost / benefit). But investing time into a dead end would be bad.
 

Sorry for seeming / being a bit confused here, I have not yet made up my mind about some things, apparently ;-)

So, what kind of resources do you suggest I consume on those subjects?
Is there some "best book", or really good online resources - something allowing me to start from zero again, and get some results?
 

As an aside: Are there concepts, functions in old OpenGL which are still valid today? Next to my job of quite some years as a degree-less developer, I am also working on actually getting a BSc degree*.
They offer a computer graphics course which uses really old OpenGL (< 2.0), ok it gets credit points, but otherwise probably a waste of time?
 

* (it does matter, at least here in Germany. For those wondering: Their program allows me to do only some cources in a semester, spreading the whole thing over more years... but less work load next do day job)

Regards,
- unshaven

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t's not fixed that it has to be OpenGL (or Vulkan?) - I heard D3D has become a nice API, OO and all. OTOH, I guess it's still true that OpenGL/Vulkan opens doors to more platforms, which is a could-be-nice thing, but the main thing will remain desktop, and if D3D is so much nicer of an API, also debugging wise (?) ...

IMO the available tools in D3D/Windows are preferable to what's available for OpenGL or Vulkan right now. But stuff like RenderDoc means you're certainly not out in the cold with GL.

But *if* I were to go the "open software" route - is OpenGL a dead end now, because of Vulkan? I'm not sure I'd like to "do everything myself" as is said about vulkan, with pages of boilerplate for everything. Let's face it, I won't create the next Cry engine, I probably won't need extreme control of everything. As it's spare time stuff, one of the most important aspects here is not spending too much time for not very good reason (cost / benefit). But investing time into a dead end would be bad.

GL is definitely not a dead end, and I would not recommend Vulkan or D3D 12 as the way to get back into things from effectively zero current knowledge. That would be a pretty long road to take and there's a lot of code out there right now built on the "old" stuff.

So, what kind of resources do you suggest I consume on those subjects? Is there some "best book", or really good online resources - something allowing me to start from zero again, and get some results?

Hopefully someone else has some good info here, as I'm a bit disconnected from that. Choosing an API will help narrow down resources.

As an aside: Are there concepts, functions in old OpenGL which are still valid today? Next to my job of quite some years as a degree-less developer, I am also working on actually getting a BSc degree*. They offer a computer graphics course which uses really old OpenGL (< 2.0), ok it gets credit points, but otherwise probably a waste of time?

Probably a waste of time. I mean... there are a couple relevant functions. Textures still upload pretty much the same, and handful of render states that are still relevant (blend modes, depth, stencil) work mostly the same. That's about it. You can use some of the other old stuff, but you shouldn't.

Edited by Promit

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Vulkan isn't as crossplatform as you'd think since apple isn't supporting it.  As far as opengl being a deadend, I don't think so.  First of all the modern low level api's (d3d12 and vulkan) weren't meant to replace the older api's they were meant to exist side by side with them.  Second, extensions are still being released for opengl making its performance on par with vulkan.  For example bindless extensions and command lists ( http://on-demand.gputechconf.com/siggraph/2015/presentation/SIG1512-Tristan-Lorach.pdf ).  I am not sure about debug tools.  If you choose the DX route I'd suggest you start with D3D11.  I don't know much about opengl so I can't give any opinion other than ver 4.4.and 4.5 seem on par with D3D11.

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Ah, I see. Thanks for the pointers so far. RenderDoc looks like something I'd really would have loved to have when I was using OpenGL 13 years ago or so :-D

As for "not as cross platform as I think". Well, to be frank, although it's a big market, I'm kind of "meh" about the whole Apple thing. You know, those people, with their, what I call "developer harassment program", thinking they can make you jump through all sorts of hoops all the time to be granted the privilege to (continue to) take part in their oh so magnificent platform, well I feel like I kinda rather take a pass on that. I've been through a good taste of it at work. Luckily, there is no economic pressure for me to succumb to their BS, nor buy their ivory coated products (they got to be, right?) /rant

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If you already did OpenGL, then why not continue with OpenGL. Just create an 'oldy' context and use extensions, and remove deprecated calls progressively.

The easiest thing to my opinion: start with an old OpenGL 1.x program (even with glut, or quickly learn glfw), then start to learn shaders (you just need a couple of extensions for that).

Once you're good with it, then move forward. To avoid harmful things, don't do any glBegin, glColor... things at all. Start with vertex pointers and glDrawArrays.

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I would not recommend Vulkan or D3D 12 as the way to get back into things from effectively zero current knowledge.

I would. I've just started digging into Graphics Programming since new year, and I'm doing pretty good so far. I've implemented a fully working ray tracer & am now working on implementing a realtime path tracer.

The tutorials out there are still very few, but mostly, the ones there are, are quite good. Apart from that, Vulkan is basically really simple. (can't tell you something about dx12 unfortunately) it's just very explicit. That is, you will have to specify alot, the specification however describes most of the stuff pretty good.
I can also recommend the Vulkan Programming Guide, it's not a good book, but rather another reference with some more explanation.
Sascha Willems also has a huge, open git repository with all kind of Vulkan Samples.

 

Vulkan isn't as crossplatform as you'd think since apple isn't supporting it.

That's only partly true. You can not develope with Vulkan on OS X, but you can ship Vulkan builds to OS X.

Edited by Life Is Good

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That's only partly true. You can not develope with Vulkan on OS X, but you can ship Vulkan builds to OS X.
wat

Vulkan isnt there in OSX. Neither for developing nor for running. 

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D3D11 is a brilliant API. It's been slimmed down and had all the cruft removed from it (unlike GL where there's multiple ways to accomplish a task, and endless deprecated functions), driver stability is rock solid, and the dev tools are good. Part of the momentum behind it is that the vast majority of Windows games use it, which keeps the focus on D3D drivers over GL... When google wanted to support OpenGL|ES on PC (which doesn't exist), they chose to implement it on top of D3D11 rather than on top of OpenGL, which is really saying something...
D3D11's approach to varying hardware via "feature levels" is also a hell of a lot easier to use than GL's fragmented extension mechanism. It also has a great validation layer that you can enable, which tells you about invalid API usage during development and lets you catch any problems in your code (D3D12/Vulkan also have this feature, but OpenGL doesn't quite). I would definitely recommend it as a starting point for anyone wanting to get into graphics programming.

I would not recommend Vulkan or D3D 12 as the way to get back into things from effectively zero current knowledge.

I would. I've just started digging into Graphics Programming since new year, and I'm doing pretty good so far. I've implemented a fully working ray tracer & am now working on implementing a realtime path tracer.
The tutorials out there are still very few, but mostly, the ones there are, are quite good. Apart from that, Vulkan is basically really simple. (can't tell you something about dx12 unfortunately) it's just very explicit. That is, you will have to specify alot, the specification however describes most of the stuff pretty good.

The main reason why D3D12/Vulkan aren't great for non-experts (and D3D11/OpenGL are better) is that Vulkan/D12 don't at all abstract away the fact that the GPU and CPU are running asynchronously. In other words, the user is given the burden of writing "thread safe" code that manually synchronizes ownership and access of memory buffers between those two co-processors.
D3D11/GL do abstract away this detail, so it's really hard to create any kind of "thread safety" bugs.
Parallel programming across multiple processors, without the use of any kind of high level framework or language (just raw, low level, manual, shared memory programming) is one of the most error prone tasks for any programmer, and worse, errors often aren't noticable as incorrect synchronisation code often just happens to work by chance, most of the time :(

One of the main areas where this matters is in sending dynamic shader parameters to your draw calls. In D3D11 you just update a constant buffer, draw something, update the constant buffer and draw something else -- the API makes it look like the draw calls are occurring on the CPU timeline and there's no problem updating a resource like this. OpenGL can be even simpler of setting a particular uniform variable, drawing something, setting that variable again, and drawing something else.
On the other hand in D3D12/Vulkan, once you issue a draw-call that will use a particular resource (e.g. a constant buffer), you cannot modify that resource at all until the draw-call has completed (otherwise you have a race condition)... so you have to implement your own ring-buffers, etc, to manage the memory allocations for these dynamic data blocks. Worse still, the validation layers for D3D12/Vulkan will not catch these kinds race condition bugs and tell you that your code is wrong, so you're on your own in proving the correctness.

Besides that, Vulkan/D12 expose many other areas of "undefined behaviour" where slightly incorrect code may seem to work, yet in the future could have disastrous consequences :(
If you want to get up to speed on GPU programming, D3D11/OpenGL let you focus on how GPU programming APIs work, without having to face these extra burdens :) That said, sure, there's something to be said for diving straight into D3D12/Vulkan and dealing with the harsh reality of CPU<->GPU communication right from the start!

Edited by Hodgman

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