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OpenGL OpenGL 4.3 - compute shaders and much more

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OpenGL compute shaders... or 'opps, we got it wrong and MS got it right... quick back track!'

I skimmed a few other things; basically bringing the features up to D3D11 level and continuing the OpenGL tradition of 'here are 101 ways to do things... good luck with that!'

In fact could someone give me an update on the state of Direct State Access in OGL? 4.3 doesn't seem to have it as a feature and last I checked it was a case of some things and not all things...

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[quote name='larspensjo' timestamp='1344280003' post='4966758']
For us lazy programmers, please give a short summary of the benefits or disadvantages, as you see it!
[/quote]
I think people that are more involved with all this can give more competent insights. g-truc has a nice review: http://www.g-truc.net/post-0494.html#menu

I literally just saw this hours ago and have still to go through all of it. I am mostly excited for compute shaders. The other additions I looked into seemed to be some obvious fixes ("layout(location =...)" for uniforms, imageSize etc.) as well as improvements to memory related aspects that play nice with compute shaders (ARB_shader_storage_buffer_object).

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Not much to be excited about it seems, i think most of it has been available as extensions for ages as usual, only thing i find interesting is the texture parameter queries and shader storage buffers allthough i guess its just the old ext_texture_buffer in a new package, ES3 compatibility might be nice if we get some ES3 capable devices to play with.

It would be nice if moderators didn't try to start an API flamewar though, i think we get enough of those.

Edit: To phantom, i never said you weren't correct. i've replied in a PM to you instead to avoid derailing this thread. Edited by SimonForsman

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[quote name='SimonForsman' timestamp='1344283395' post='4966787']
It would be nice if moderators didn't try to start an API flamewar though, i think we get enough of those.
[/quote]

Really?

Tell me what was wrong with my statements?

Computer Shaders - admission that OpenCL/GL interop has failed to work.
Features - brings it up to D3D11 standard but, with at least one extension, introduces yet another way to do things
DSA - genuine question about the state of it...

Note: no where did I say 'D3D11 is better!' - all I did was call them out on areas they are still lacking - which is the API interface in general and MAYBE the state of DSA, which I asked about..

So, yeah, if not fawning over a new release of an incremental update to an outdated API is 'starting a flame' war then fine, I started a flame war...

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phantom is actually correct, although the wording chosen can certainly come across as "let's start a flame war" - but look beyond that at what the update actually does have to offer.

All the same, I'm feeling moderately stoked about this update, despite there being a high percentage of "things that should have been done ages ago" in it. There are some genuine API usability improvements in there, and the push for standardised and patent-free texture compression formats seems well-intentioned at least. Let's have the ability to use FBOs with the default depth/stencil buffer in the next one (if they didn't sneak in somewhere in this one), some DSA, and some solid drivers, and things will be really looking good.

Overall though I suspect that ES3 is going to turn out to be the more significant recent release.

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CL/GL interop didn't fail to work. It did work quite well. Despite this I have to admit that it is way more complicated than the DX11 compute shaders, BUT it DID work. In fact I could port DX11 compute shaders to OpenCL and make it work together with OpenGL. see:
[url="http://www.gamedev.net/page/community/iotd/index.html/_/tile-based-deferred-shading-via-opencl-r233"]http://www.gamedev.n...via-opencl-r233[/url]
I'm looking forward to trying out OGL compute shaders though, as it seems more reasonable to use it for processing textures / lighting.
The debugging feature is quite an improvement as such functionality was missing. Edited by Yours3!f

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[quote name='phantom' timestamp='1344284153' post='4966790']Computer Shaders - admission that OpenCL/GL interop has failed to work.
Features - brings it up to D3D11 standard but, with at least one extension, introduces yet another way to do things
DSA - genuine question about the state of it...
Note: no where did I say 'D3D11 is better!'
[/quote]
[quote name='mhagain' timestamp='1344286880' post='4966809']
phantom is actually correct, although the wording chosen can certainly come across as "let's start a flame war" - but look beyond that at what the update actually does have to offer.[/quote]None of that is surprising, though. And indeed D3D11 is "better", except for the little detail that it's proprietary and Windows-only (which, as it happens, is [i]the one [/i]important detail for me personally).

OpenGL is necessarily worse because it is designed by committee (ARB, Khronos, name it as you like). In addition to design by committee being always kind of troublesome, this particular committee has contained and contains members that have strong antipodal interests.

I won't say that Microsoft certainly has no interest in making OpenGL as good or better than their own product, because Microsoft is no longer involved (...at least [i]officially[/i]). However, there's still Intel as a good example of an entity that is still officially involved.
Intel who already struggles supporting OpenGL 3.x on their Sandy/Ivy Bridge CPUs has a strong motivation not to add too many features too quickly. Promoting CPUs with integrated graphics is much harder if people have the impression that they don't support most modern features. Thus, advertising OpenGL and pushing its development forward lessens revenue.

Companies like AMD and nVidia on the other hand do have a (rather obvious) strong interest in pushing new features onto the market, because this allows them to sell new cards. But then again supporting [i]both [/i]D3D and OpenGL means having twice as much driver development cost than actually necessary. If 90-95% of the software in their target market already uses D3D anyway, that's a bad deal. So again, even though there is some motivation, it is not necessarily overwhelming for OpenGL as such. If people buy the new nVidia 780 GTX Ultra because it supports D3D 12.1, which is needed to play Warcraft Ultimate, then that's just as good.

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[quote name='samoth' timestamp='1344334319' post='4966961']
And indeed D3D11 is "better", except for the little detail that it's proprietary and Windows-only (which, as it happens, is [i]the one [/i]important detail for me personally).
[/quote]

While I don't doubt the importance of this, once you get outside of Windows things get a bit ropey support wise - OSX, the largest of the non-Windows home computer platforms, lags OpenGL versions by some way with OSX10.7 supporting GL3.2, a standard released in 2009 on an OS only a year old.

I'm not sure about Linux support tbh; I tend to hear it swinging betweeen 'good' and 'bad' with a healthy dose of 'no closed source code in my linux!' kicking around.

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[quote name='Yours3!f' timestamp='1344330295' post='4966948']
CL/GL interop didn't fail to work. It did work quite well. Despite this I have to admit that it is way more complicated than the DX11 compute shaders, BUT it DID work. In fact I could port DX11 compute shaders to OpenCL and make it work together with OpenGL. see:
[url="http://www.gamedev.net/page/community/iotd/index.html/_/tile-based-deferred-shading-via-opencl-r233"]http://www.gamedev.n...via-opencl-r233[/url]
I'm looking forward to trying out OGL compute shaders though, as it seems more reasonable to use it for processing textures / lighting.
The debugging feature is quite an improvement as such functionality was missing.
[/quote]

I'd consider OpenCL to be more of an alternative to nvidias CUDA than to DirectCompute aswell, OpenCL works without a OpenGL render context and can also be used with Direct3D (atleast on nvidia hardware, which is quite an advantage if you want to use different renderers but still use the same GPGPU solution), OpenGL definitly needed built in compute shaders aswell but OpenCL still has its place). One can debate if the OpenCL interop should be in core rather than as an extension though. (it might have made more sense to keep the interop functions as an extension and pushed in compute shaders earlier)

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[quote name='phantom' timestamp='1344336318' post='4966969']I'm not sure about Linux support tbh; I tend to hear it swinging betweeen 'good' and 'bad' with a healthy dose of 'no closed source code in my linux!' kicking around.[/quote]For me, it has always "kind of" worked, but never really well as compared to how well it works under Windows.

This will (hopefully) drastically change in the near future, if Mr. Stallman doesn't prevent it. Linux becoming a Windows8-competing Steam platform would mean that some modern, advanced graphics API would [i]have to[/i] be available and well-supported. What else could it mean but serious OpenGL support from IHVs?

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[quote name='samoth' timestamp='1344337679' post='4966978']
What else could it mean but serious OpenGL support from IHVs?
[/quote]

Maybe, or it could take the same route that OpenGL on Windows takes to some extent; make it work for Game X.

For some time if you wanted performance you had to hit the same path as iD games, maybe the same will happen when it comes to following Valve's lead onto Linux? Do it their way or fall off the 'fast' path.

We'll see how it works out - I remember when Linux games appeared in the shops for a short while around 1999 with the iD games going on sale; at the time that failed to set the world alight as it seemed no one wanted to buy them. Maybe, 10+ years on Linux users (note: users. I maintain Stallman is a crazy person) as a little more pragmatic about things and Steam will work out and enough of a market share will be carved out for a good feedback loop to be generated with regards to market share, driver development and tool development going forward.

My only 'worry' about that is the continued involvement of the ARB who, historically, simply don't make good choices.
OpenGL2.0 and 3.0 are proof of this and nothing they have done since then has convinced me otherwise - if gaming on Linux makes it then it'll be down to Valve, NV and AMD working together and not the ARB.

I'm watching with intrest to see how this pans out, not least of all because it might well affect my day job [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img] Edited by phantom

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I think it's fair to say that both APIs have a healthy (or unhealthy, delete as appropriate) dollop of "worse is better" in them, so it really does come down to target platforms and personal preferences.

Regarding Intel, have you been following the Valve blog about porting Steam and L4D to Linux? Intel are definitely playing quite an active role, working with Valve, and taking feedback on board. Currently it's only the Linux driver, of course, but it seems reasonable to guess that some of the quality improvements coming out of this can also be fed into their drivers for other platforms.

The overall feeling here is definitely one of OpenGL coming into the ascendant again, while D3D appears to be languishing with a somewhat unknown/uncertain future. Can it be sustained? No idea, but the next few years sure won't be boring.

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[quote name='phantom' timestamp='1344338536' post='4966979']
[quote name='samoth' timestamp='1344337679' post='4966978']
What else could it mean but serious OpenGL support from IHVs?
[/quote]

Maybe, or it could take the same route that OpenGL on Windows takes to some extent; make it work for Game X.

For some time if you wanted performance you had to hit the same path as iD games, maybe the same will happen when it comes to following Valve's lead onto Linux? Do it their way or fall off the 'fast' path.

We'll see how it works out - I remember when Linux games appeared in the shops for a short while around 1999 with the iD games going on sale; at the time that failed to set the world alight as it seemed no one wanted to buy them. Maybe, 10+ years on Linux users (note: users. I maintain Stallman is a crazy person) as a little more pragmatic about things and Steam will work out and enough of a market share will be carved out for a good feedback loop to be generated with regards to market share, driver development and tool development going forward.

My only 'worry' about that is the continued involvement of the ARB who, historically, simply don't make good choices.
OpenGL2.0 and 3.0 are proof of this and nothing they have done since then has convinced me otherwise - if gaming on Linux makes it then it'll be down to Valve, NV and AMD working together and not the ARB.

I'm watching with intrest to see how this pans out, not least of all because it might well affect my day job [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img]
[/quote]

The big problem with IDs Linux push was that there was essentially only one game you could find in stores (Quake3) and the number of stores carrying the Linux version was extremely limited, most Linux users ended up buying the Windows version and downloading the Linux binary anyway since that was the easiest option (The pragmatic users went with the path of least resistance)

With steam the big change is that everything is available for everyone at any time and buying a game for PlatformX usually lets you install and play the same game on PlatformsY and Z aswell (So even users of dualboot systems don't have to choose between buying for Windows and buying for Linux, they just buy it and play on whatever OS they happen to be logged into at the moment) (Personally i primarily buy Windows versions even though i use Linux aswell since it is far easier to get Windows games running in Linux than vice versa and having to reboot or switch machine to play a different game is far too annoying (With work there isn't much choice, Linux is simply the better OS for what i'm doing (apart from some legacy ASP.Net systems i have to maintain that just won't work properly with mono)).

As for what Valves Linux move will do for OpenGL i'd expect pretty much the same as AAA OpenGL use on Windows and Mac have done, IHVs will optimize the paths used by big AAA titles, it doesn't really matter that much though, indie titles will not push the limits far enough for that to matter and end users don't care if random indie title X runs at 3000 fps or 6000 fps (They will however care if expensive AAA title Y runs at 25fps or 60fps but as long as the IHVs optimize for the AAA titles its all good), The API is fine, you can complain about the ARB making bad or slow decisions but the API itself is fine(it might not be perfect but it doesn't have to be), it gives developers access to the features they need on the platforms they're targeting and according to Valve OpenGL also still performs better on both Windows and Linux than D3D9 does and they did manage to get better performance in Linux than on Windows so overall things are looking decent.

The main problems i see with gaming on Linux, (apart from the low number of available titles) is hardware support, There still isn't a really good solution for more advanced controllers, the soundsystem(s) are a bit of a mess and the desktop enviroments take far too much tweaking to get really good(Which really scares users away, Unity might be easy to use but its a real pain if you want to do anything even remotely advanced while Gnome/KDE have become quite a mess in the latest versions.

When it comes to OpenGL the biggest problem is Apple, they add support for newer versions at an extremely slow pace, 4.3 will not be relevant for another 2-3 years (The main reason to use OpenGL is to support OS X, and that means using OpenGL 2.1+extensions today or possibly 3.2)

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[quote name='SimonForsman' timestamp='1344343410' post='4966992']
The API is fine, you can complain about the ARB making bad or slow decisions but the API itself is fine(it might not be perfect but it doesn't have to be), it gives developers access to the features they need on the platforms they're targeting and according to Valve OpenGL also still performs better on both Windows and Linux than D3D9 does and they did manage to get better performance in Linux than on Windows so overall things are looking decent.
[/quote]

I disagree on the API - the bind to edit model is broken. The D3D model of 'operations on objects' is saner. The ARB put two years of work into a better API with these semantics (still C style, not C++ I might add) and then dumped it. Until DSA is the norm the API will remain broken.

The OpenGL vs D3D9 thing is a non-event.
I've commented on this else where; D3D9 is known to be slower on small batches than OpenGL, it's been public knowledge for some time.
The 'zomg fps difference!' reaction is also a non-event once you look closer at it;
Linux + OpenGL : 3.17ms/frame
Win7 + D3D9 (270fps): 3.7ms/frame
Win7 + D3D9 (304fps): 3.29ms/frame

Once you factor in differences in code due to being able to clean write the OpenGL backend to take more advantage of 'lessons learnt' on the D3D9 and probabl with a more modern slant on things (they uses a DX11 class device; how many D3D11 class feature extensions or NV extensions did they use?) and the D3D9 overhead 0.12ms/frame is... well, nothing. (The 0.6ms was worrying but they basically said in their post 'opps, we got the batching wrong' although apprently no one noticed this 'performance loss').

I suspect that if they gave the same treatment, a clean rewrite, using D3D11 and properly structured for it then on Windows the performance would be equal at worst, if not slightly better as a well structured D3D11 app will have less CPU overhead than a D3D9 application (or indeed a D3D11 application written in the D3D9 style).

In short; well done to Valve but nothing we didn't already know about D3D9 has been found.

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You guys are no fun [img]http://public.gamedev.net//public/style_emoticons/default/sad.png[/img]. I was having so much fun with compute shaders (actually, still have [img]http://public.gamedev.net//public/style_emoticons/default/tongue.png[/img]).
gravitational n-body: https://github.com/progschj/OpenGL-Examples/blob/master/experimental/XXcompute_shader_nbody.cpp Edited by japro

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[quote name='phantom' timestamp='1344344804' post='4966997']
Linux + OpenGL : 3.17ms/frame
Win7 + D3D9 (270fps): 3.7ms/frame
Win7 + D3D9 (304fps): 3.29ms/frame
[/quote]

The 303.4fps was Win7 + OpenGL, not D3D9. But yes, D3D9's high per batch overhead is old news, what isn't old news is that (nvidias) OpenGL drivers are still good enough to take advantage of this. (Most "recent" games with both OpenGL and D3D9 renderers have gotten far worse performance with OpenGL and it does show that OpenGL performance is "good enough"). As for what OpenGL version they're using it is quite likely that it is 2.x since they didn't make a clean rewrite, (its based on the Mac version afterall).

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I think people are over-excited about Valve's contribution to all of this. Desura has already been providing a viable portal for Linux games for some time now. I don't see Valve's entry as groundbreaking; rather, they do not want to be left behind. The endorsement of Valve however is good for OpenGL because Desura doesn't have the brand name recognition or pull that Valve has.

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[quote name='japro' timestamp='1344350667' post='4967024']
You guys are no fun [img]http://public.gamedev.net//public/style_emoticons/default/sad.png[/img]. I was having so much fun with compute shaders (actually, still have [img]http://public.gamedev.net//public/style_emoticons/default/tongue.png[/img]).
gravitational n-body: [url="https://github.com/progschj/OpenGL-Examples/blob/master/experimental/XXcompute_shader_nbody.cpp"]https://github.com/p...hader_nbody.cpp[/url]
[/quote]
well, good for you. I'm still waiting for the AMD drivers as from nvidia I only have a gf8600gt, which doesn't support this. I can't wait to port my tile based deferred renderer to OGL CS. Actually thanks for the sample code :) I'll have to think less on my own :D Edited by Yours3!f

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[quote name='SimonForsman' timestamp='1344351532' post='4967031']
The 303.4fps was Win7 + OpenGL, not D3D9. But yes, D3D9's high per batch overhead is old news, what isn't old news is that (nvidias) OpenGL drivers are still good enough to take advantage of this. (Most "recent" games with both OpenGL and D3D9 renderers have gotten far worse performance with OpenGL and it does show that OpenGL performance is "good enough"). As for what OpenGL version they're using it is quite likely that it is 2.x since they didn't make a clean rewrite, (its based on the Mac version afterall).
[/quote]

Ah, my bad - I was short of time when I originally skimmed the article and just recycled my numbers from my original comment on another forum :)

I suspect the GL vs DX9 speed was simply people not finding the GL 'fast path' either due to the API not making it easy or effort not being placed in that area. I don't think there has ever been a question of OpenGL's performance vs D3D9 being anything but 'good enough' - the problem was that for ages D3D9 had features GL did not which were pretty fundimental (hello FBO extension!) and driver quality wasn't that good (ATI, back in the day, I'm looking at you).

They don't mention what they basis it on, reading it seems to imply it was based off the core D3D path just with abstraction layers built in; so it doesn't really answer how they did it.

If anything this result seems to imply that despite 'batch batch batch' being shoved down everyones throats for the past X years Valve are Doing It Wrong ;)

The "problem" faced by OpenGL right now is that;
a) "Everyone" already has a D3D11 path in place and are phasing out D3D9 engines and features
b) D3D11-a-like is the expected API for the XBox
c) The biggest OpenGL market, outside of Windows, is OSX
d) OSX is massively lagging cutting edge GL development (OSX10.7 supporting 3.2; 3 year old spec on a 1 year old machine)
e) Not including Compute or requiring OpenCL interop in the core was also a mistake imo

Between feature lag in the API, an established API and tools path in existance and OSX's lag most AAA studios have no intrest in it right now; however I suspect they will be watching Valve's experiance closely and when the first numbers come out with regards to market share this might change.

(On a personally note, while I once prefered GLSL's way of doing things to HLSL's when it came to declaring inputs and varyings all that 'layout' stuff is just horrible - I'd love to know what they were smoking when they decided on that. HLSL really nails that. Same with providing things like batch ids etc via semantic tagged inputs into the main function vs globals. Really not a fan of 'magic' globals in my shaders these days; prefer to be able to name and require them myself - its the gl<Matrix name> all over again.)

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[quote name='bvanevery' timestamp='1344372756' post='4967137']
I think people are over-excited about Valve's contribution to all of this. Desura has already been providing a viable portal for Linux games for some time now. I don't see Valve's entry as groundbreaking; rather, they do not want to be left behind. The endorsement of Valve however is good for OpenGL because Desura doesn't have the brand name recognition or pull that Valve has.
[/quote]

It's maybe not groundbreaking, but it's certainly [i]important[/i], as Valve are a major studio with no small measure of influence and Steam is utterly gigantic for content delivery; being something of a de-facto standard in the Windows world.

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There's not much point over-analysing Valve's L4D profiling results, I wouldn't be distracted by them.
Win7+D9 = 270.6Hz = 3.7ms
Win7+GL = 303.4Hz = 3.3ms
Difference = 0.4ms.

Firstly, if a game is running at >60Hz, then performance has already been achieved. Secondly, 0.4ms is a trivial difference in your renderer's CPU usage. Thirdly D9 is known to have a lot of overhead, so these numbers should be expected.
if two radically different approaches only differ by half a milli, then I'd go with the one that's simpler to write/maintain. If it's critical for you to shave half a milli off your frame times, then you've got bigger problems to deal with![hr]So, uh, Steam for Linux driving GL adoption and GL4.3 catching up to the D11 feature set, cool! Edited by Hodgman

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[quote name='phantom' timestamp='1344417475' post='4967311']
Between feature lag in the API, an established API and tools path in existance and OSX's lag most AAA studios have no intrest in it right now; however I suspect they will be watching Valve's experiance closely and when the first numbers come out with regards to market share this might change.
[/quote]

I don't think valves results will matter for other studios (Linux marketshare is small so reaching out to 1-2% extra customers isn't all that important), Valves move has far more to do with indie game distribution(Linux is a rather big platform for indie sales) than pushing their own games, AAA titles can get noticed by 100% of the Windows gamer market quite easily, Indie games can't (but can quite easily get noticed by 100% of the Linux gamers) Edited by SimonForsman

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      I'm looking to render multiple objects (rectangles) with different shaders. So far I've managed to render one rectangle made out of 2 triangles and apply shader to it, but when it comes to render another I get stucked. Searched for documentations or stuffs that could help me, but everything shows how to render only 1 object. Any tips or help is highly appreciated, thanks!
      Here's my code for rendering one object with shader!
       
      #define GLEW_STATIC #include <stdio.h> #include <GL/glew.h> #include <GLFW/glfw3.h> #include "window.h" #define GLSL(src) "#version 330 core\n" #src // #define ASSERT(expression, msg) if(expression) {fprintf(stderr, "Error on line %d: %s\n", __LINE__, msg);return -1;} int main() { // Init GLFW if (glfwInit() != GL_TRUE) { std::cerr << "Failed to initialize GLFW\n" << std::endl; exit(EXIT_FAILURE); } // Create a rendering window with OpenGL 3.2 context glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); glfwWindowHint(GLFW_RESIZABLE, GL_FALSE); // assing window pointer GLFWwindow *window = glfwCreateWindow(800, 600, "OpenGL", NULL, NULL); glfwMakeContextCurrent(window); // Init GLEW glewExperimental = GL_TRUE; if (glewInit() != GLEW_OK) { std::cerr << "Failed to initialize GLEW\n" << std::endl; exit(EXIT_FAILURE); } // ----------------------------- RESOURCES ----------------------------- // // create gl data const GLfloat positions[8] = { -0.5f, -0.5f, 0.5f, -0.5f, 0.5f, 0.5f, -0.5f, 0.5f, }; const GLuint elements[6] = { 0, 1, 2, 2, 3, 0 }; // Create Vertex Array Object GLuint vao; glGenVertexArrays(1, &vao); glBindVertexArray(vao); // Create a Vertex Buffer Object and copy the vertex data to it GLuint vbo; glGenBuffers(1, &vbo); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW); // Specify the layout of the vertex data glEnableVertexAttribArray(0); // layout(location = 0) glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, 0); // Create a Elements Buffer Object and copy the elements data to it GLuint ebo; glGenBuffers(1, &ebo); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elements), elements, GL_STATIC_DRAW); // Create and compile the vertex shader const GLchar *vertexSource = GLSL( layout(location = 0) in vec2 position; void main() { gl_Position = vec4(position, 0.0, 1.0); } ); GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER); glShaderSource(vertexShader, 1, &vertexSource, NULL); glCompileShader(vertexShader); // Create and compile the fragment shader const char* fragmentSource = GLSL( out vec4 gl_FragColor; uniform vec2 u_resolution; void main() { vec2 pos = gl_FragCoord.xy / u_resolution; gl_FragColor = vec4(1.0); } ); GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER); glShaderSource(fragmentShader, 1, &fragmentSource, NULL); glCompileShader(fragmentShader); // Link the vertex and fragment shader into a shader program GLuint shaderProgram = glCreateProgram(); glAttachShader(shaderProgram, vertexShader); glAttachShader(shaderProgram, fragmentShader); glLinkProgram(shaderProgram); glUseProgram(shaderProgram); // get uniform's id by name and set value GLint uRes = glGetUniformLocation(shaderProgram, "u_Resolution"); glUniform2f(uRes, 800.0f, 600.0f); // ---------------------------- RENDERING ------------------------------ // while(!glfwWindowShouldClose(window)) { // Clear the screen to black glClear(GL_COLOR_BUFFER_BIT); glClearColor(0.0f, 0.5f, 1.0f, 1.0f); // Draw a rectangle made of 2 triangles -> 6 vertices glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, NULL); // Swap buffers and poll window events glfwSwapBuffers(window); glfwPollEvents(); } // ---------------------------- CLEARING ------------------------------ // // Delete allocated resources glDeleteProgram(shaderProgram); glDeleteShader(fragmentShader); glDeleteShader(vertexShader); glDeleteBuffers(1, &vbo); glDeleteVertexArrays(1, &vao); return 0; }  
    • By Vortez
      Hi guys, im having a little problem fixing a bug in my program since i multi-threaded it. The app is a little video converter i wrote for fun. To help you understand the problem, ill first explain how the program is made. Im using Delphi to do the GUI/Windows part of the code, then im loading a c++ dll for the video conversion. The problem is not related to the video conversion, but with OpenGL only. The code work like this:

       
      DWORD WINAPI JobThread(void *params) { for each files { ... _ConvertVideo(input_name, output_name); } } void EXP_FUNC _ConvertVideo(char *input_fname, char *output_fname) { // Note that im re-initializing and cleaning up OpenGL each time this function is called... CGLEngine GLEngine; ... // Initialize OpenGL GLEngine.Initialize(render_wnd); GLEngine.CreateTexture(dst_width, dst_height, 4); // decode the video and render the frames... for each frames { ... GLEngine.UpdateTexture(pY, pU, pV); GLEngine.Render(); } cleanup: GLEngine.DeleteTexture(); GLEngine.Shutdown(); // video cleanup code... }  
      With a single thread, everything work fine. The problem arise when im starting the thread for a second time, nothing get rendered, but the encoding work fine. For example, if i start the thread with 3 files to process, all of them render fine, but if i start the thread again (with the same batch of files or not...), OpenGL fail to render anything.
      Im pretty sure it has something to do with the rendering context (or maybe the window DC?). Here a snippet of my OpenGL class:
      bool CGLEngine::Initialize(HWND hWnd) { hDC = GetDC(hWnd); if(!SetupPixelFormatDescriptor(hDC)){ ReleaseDC(hWnd, hDC); return false; } hRC = wglCreateContext(hDC); wglMakeCurrent(hDC, hRC); // more code ... return true; } void CGLEngine::Shutdown() { // some code... if(hRC){wglDeleteContext(hRC);} if(hDC){ReleaseDC(hWnd, hDC);} hDC = hRC = NULL; }  
      The full source code is available here. The most relevant files are:
      -OpenGL class (header / source)
      -Main code (header / source)
       
      Thx in advance if anyone can help me.
    • By DiligentDev
      This article uses material originally posted on Diligent Graphics web site.
      Introduction
      Graphics APIs have come a long way from small set of basic commands allowing limited control of configurable stages of early 3D accelerators to very low-level programming interfaces exposing almost every aspect of the underlying graphics hardware. Next-generation APIs, Direct3D12 by Microsoft and Vulkan by Khronos are relatively new and have only started getting widespread adoption and support from hardware vendors, while Direct3D11 and OpenGL are still considered industry standard. New APIs can provide substantial performance and functional improvements, but may not be supported by older hardware. An application targeting wide range of platforms needs to support Direct3D11 and OpenGL. New APIs will not give any advantage when used with old paradigms. It is totally possible to add Direct3D12 support to an existing renderer by implementing Direct3D11 interface through Direct3D12, but this will give zero benefits. Instead, new approaches and rendering architectures that leverage flexibility provided by the next-generation APIs are expected to be developed.
      There are at least four APIs (Direct3D11, Direct3D12, OpenGL/GLES, Vulkan, plus Apple's Metal for iOS and osX platforms) that a cross-platform 3D application may need to support. Writing separate code paths for all APIs is clearly not an option for any real-world application and the need for a cross-platform graphics abstraction layer is evident. The following is the list of requirements that I believe such layer needs to satisfy:
      Lightweight abstractions: the API should be as close to the underlying native APIs as possible to allow an application leverage all available low-level functionality. In many cases this requirement is difficult to achieve because specific features exposed by different APIs may vary considerably. Low performance overhead: the abstraction layer needs to be efficient from performance point of view. If it introduces considerable amount of overhead, there is no point in using it. Convenience: the API needs to be convenient to use. It needs to assist developers in achieving their goals not limiting their control of the graphics hardware. Multithreading: ability to efficiently parallelize work is in the core of Direct3D12 and Vulkan and one of the main selling points of the new APIs. Support for multithreading in a cross-platform layer is a must. Extensibility: no matter how well the API is designed, it still introduces some level of abstraction. In some cases the most efficient way to implement certain functionality is to directly use native API. The abstraction layer needs to provide seamless interoperability with the underlying native APIs to provide a way for the app to add features that may be missing. Diligent Engine is designed to solve these problems. Its main goal is to take advantages of the next-generation APIs such as Direct3D12 and Vulkan, but at the same time provide support for older platforms via Direct3D11, OpenGL and OpenGLES. Diligent Engine exposes common C++ front-end for all supported platforms and provides interoperability with underlying native APIs. It also supports integration with Unity and is designed to be used as graphics subsystem in a standalone game engine, Unity native plugin or any other 3D application. Full source code is available for download at GitHub and is free to use.
      Overview
      Diligent Engine API takes some features from Direct3D11 and Direct3D12 as well as introduces new concepts to hide certain platform-specific details and make the system easy to use. It contains the following main components:
      Render device (IRenderDevice  interface) is responsible for creating all other objects (textures, buffers, shaders, pipeline states, etc.).
      Device context (IDeviceContext interface) is the main interface for recording rendering commands. Similar to Direct3D11, there are immediate context and deferred contexts (which in Direct3D11 implementation map directly to the corresponding context types). Immediate context combines command queue and command list recording functionality. It records commands and submits the command list for execution when it contains sufficient number of commands. Deferred contexts are designed to only record command lists that can be submitted for execution through the immediate context.
      An alternative way to design the API would be to expose command queue and command lists directly. This approach however does not map well to Direct3D11 and OpenGL. Besides, some functionality (such as dynamic descriptor allocation) can be much more efficiently implemented when it is known that a command list is recorded by a certain deferred context from some thread.
      The approach taken in the engine does not limit scalability as the application is expected to create one deferred context per thread, and internally every deferred context records a command list in lock-free fashion. At the same time this approach maps well to older APIs.
      In current implementation, only one immediate context that uses default graphics command queue is created. To support multiple GPUs or multiple command queue types (compute, copy, etc.), it is natural to have one immediate contexts per queue. Cross-context synchronization utilities will be necessary.
      Swap Chain (ISwapChain interface). Swap chain interface represents a chain of back buffers and is responsible for showing the final rendered image on the screen.
      Render device, device contexts and swap chain are created during the engine initialization.
      Resources (ITexture and IBuffer interfaces). There are two types of resources - textures and buffers. There are many different texture types (2D textures, 3D textures, texture array, cubmepas, etc.) that can all be represented by ITexture interface.
      Resources Views (ITextureView and IBufferView interfaces). While textures and buffers are mere data containers, texture views and buffer views describe how the data should be interpreted. For instance, a 2D texture can be used as a render target for rendering commands or as a shader resource.
      Pipeline State (IPipelineState interface). GPU pipeline contains many configurable stages (depth-stencil, rasterizer and blend states, different shader stage, etc.). Direct3D11 uses coarse-grain objects to set all stage parameters at once (for instance, a rasterizer object encompasses all rasterizer attributes), while OpenGL contains myriad functions to fine-grain control every individual attribute of every stage. Both methods do not map very well to modern graphics hardware that combines all states into one monolithic state under the hood. Direct3D12 directly exposes pipeline state object in the API, and Diligent Engine uses the same approach.
      Shader Resource Binding (IShaderResourceBinding interface). Shaders are programs that run on the GPU. Shaders may access various resources (textures and buffers), and setting correspondence between shader variables and actual resources is called resource binding. Resource binding implementation varies considerably between different API. Diligent Engine introduces a new object called shader resource binding that encompasses all resources needed by all shaders in a certain pipeline state.
      API Basics
      Creating Resources
      Device resources are created by the render device. The two main resource types are buffers, which represent linear memory, and textures, which use memory layouts optimized for fast filtering. Graphics APIs usually have a native object that represents linear buffer. Diligent Engine uses IBuffer interface as an abstraction for a native buffer. To create a buffer, one needs to populate BufferDesc structure and call IRenderDevice::CreateBuffer() method as in the following example:
      BufferDesc BuffDesc; BufferDesc.Name = "Uniform buffer"; BuffDesc.BindFlags = BIND_UNIFORM_BUFFER; BuffDesc.Usage = USAGE_DYNAMIC; BuffDesc.uiSizeInBytes = sizeof(ShaderConstants); BuffDesc.CPUAccessFlags = CPU_ACCESS_WRITE; m_pDevice->CreateBuffer( BuffDesc, BufferData(), &m_pConstantBuffer ); While there is usually just one buffer object, different APIs use very different approaches to represent textures. For instance, in Direct3D11, there are ID3D11Texture1D, ID3D11Texture2D, and ID3D11Texture3D objects. In OpenGL, there is individual object for every texture dimension (1D, 2D, 3D, Cube), which may be a texture array, which may also be multisampled (i.e. GL_TEXTURE_2D_MULTISAMPLE_ARRAY). As a result there are nine different GL texture types that Diligent Engine may create under the hood. In Direct3D12, there is only one resource interface. Diligent Engine hides all these details in ITexture interface. There is only one  IRenderDevice::CreateTexture() method that is capable of creating all texture types. Dimension, format, array size and all other parameters are specified by the members of the TextureDesc structure:
      TextureDesc TexDesc; TexDesc.Name = "My texture 2D"; TexDesc.Type = TEXTURE_TYPE_2D; TexDesc.Width = 1024; TexDesc.Height = 1024; TexDesc.Format = TEX_FORMAT_RGBA8_UNORM; TexDesc.Usage = USAGE_DEFAULT; TexDesc.BindFlags = BIND_SHADER_RESOURCE | BIND_RENDER_TARGET | BIND_UNORDERED_ACCESS; TexDesc.Name = "Sample 2D Texture"; m_pRenderDevice->CreateTexture( TexDesc, TextureData(), &m_pTestTex ); If native API supports multithreaded resource creation, textures and buffers can be created by multiple threads simultaneously.
      Interoperability with native API provides access to the native buffer/texture objects and also allows creating Diligent Engine objects from native handles. It allows applications seamlessly integrate native API-specific code with Diligent Engine.
      Next-generation APIs allow fine level-control over how resources are allocated. Diligent Engine does not currently expose this functionality, but it can be added by implementing IResourceAllocator interface that encapsulates specifics of resource allocation and providing this interface to CreateBuffer() or CreateTexture() methods. If null is provided, default allocator should be used.
      Initializing the Pipeline State
      As it was mentioned earlier, Diligent Engine follows next-gen APIs to configure the graphics/compute pipeline. One big Pipelines State Object (PSO) encompasses all required states (all shader stages, input layout description, depth stencil, rasterizer and blend state descriptions etc.). This approach maps directly to Direct3D12/Vulkan, but is also beneficial for older APIs as it eliminates pipeline misconfiguration errors. With many individual calls tweaking various GPU pipeline settings it is very easy to forget to set one of the states or assume the stage is already properly configured when in fact it is not. Using pipeline state object helps avoid these problems as all stages are configured at once.
      Creating Shaders
      While in earlier APIs shaders were bound separately, in the next-generation APIs as well as in Diligent Engine shaders are part of the pipeline state object. The biggest challenge when authoring shaders is that Direct3D and OpenGL/Vulkan use different shader languages (while Apple uses yet another language in their Metal API). Maintaining two versions of every shader is not an option for real applications and Diligent Engine implements shader source code converter that allows shaders authored in HLSL to be translated to GLSL. To create a shader, one needs to populate ShaderCreationAttribs structure. SourceLanguage member of this structure tells the system which language the shader is authored in:
      SHADER_SOURCE_LANGUAGE_DEFAULT - The shader source language matches the underlying graphics API: HLSL for Direct3D11/Direct3D12 mode, and GLSL for OpenGL and OpenGLES modes. SHADER_SOURCE_LANGUAGE_HLSL - The shader source is in HLSL. For OpenGL and OpenGLES modes, the source code will be converted to GLSL. SHADER_SOURCE_LANGUAGE_GLSL - The shader source is in GLSL. There is currently no GLSL to HLSL converter, so this value should only be used for OpenGL and OpenGLES modes. There are two ways to provide the shader source code. The first way is to use Source member. The second way is to provide a file path in FilePath member. Since the engine is entirely decoupled from the platform and the host file system is platform-dependent, the structure exposes pShaderSourceStreamFactory member that is intended to provide the engine access to the file system. If FilePath is provided, shader source factory must also be provided. If the shader source contains any #include directives, the source stream factory will also be used to load these files. The engine provides default implementation for every supported platform that should be sufficient in most cases. Custom implementation can be provided when needed.
      When sampling a texture in a shader, the texture sampler was traditionally specified as separate object that was bound to the pipeline at run time or set as part of the texture object itself. However, in most cases it is known beforehand what kind of sampler will be used in the shader. Next-generation APIs expose new type of sampler called static sampler that can be initialized directly in the pipeline state. Diligent Engine exposes this functionality: when creating a shader, textures can be assigned static samplers. If static sampler is assigned, it will always be used instead of the one initialized in the texture shader resource view. To initialize static samplers, prepare an array of StaticSamplerDesc structures and initialize StaticSamplers and NumStaticSamplers members. Static samplers are more efficient and it is highly recommended to use them whenever possible. On older APIs, static samplers are emulated via generic sampler objects.
      The following is an example of shader initialization:
      ShaderCreationAttribs Attrs; Attrs.Desc.Name = "MyPixelShader"; Attrs.FilePath = "MyShaderFile.fx"; Attrs.SearchDirectories = "shaders;shaders\\inc;"; Attrs.EntryPoint = "MyPixelShader"; Attrs.Desc.ShaderType = SHADER_TYPE_PIXEL; Attrs.SourceLanguage = SHADER_SOURCE_LANGUAGE_HLSL; BasicShaderSourceStreamFactory BasicSSSFactory(Attrs.SearchDirectories); Attrs.pShaderSourceStreamFactory = &BasicSSSFactory; ShaderVariableDesc ShaderVars[] = {     {"g_StaticTexture", SHADER_VARIABLE_TYPE_STATIC},     {"g_MutableTexture", SHADER_VARIABLE_TYPE_MUTABLE},     {"g_DynamicTexture", SHADER_VARIABLE_TYPE_DYNAMIC} }; Attrs.Desc.VariableDesc = ShaderVars; Attrs.Desc.NumVariables = _countof(ShaderVars); Attrs.Desc.DefaultVariableType = SHADER_VARIABLE_TYPE_STATIC; StaticSamplerDesc StaticSampler; StaticSampler.Desc.MinFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MagFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MipFilter = FILTER_TYPE_LINEAR; StaticSampler.TextureName = "g_MutableTexture"; Attrs.Desc.NumStaticSamplers = 1; Attrs.Desc.StaticSamplers = &StaticSampler; ShaderMacroHelper Macros; Macros.AddShaderMacro("USE_SHADOWS", 1); Macros.AddShaderMacro("NUM_SHADOW_SAMPLES", 4); Macros.Finalize(); Attrs.Macros = Macros; RefCntAutoPtr<IShader> pShader; m_pDevice->CreateShader( Attrs, &pShader );
      Creating the Pipeline State Object
      After all required shaders are created, the rest of the fields of the PipelineStateDesc structure provide depth-stencil, rasterizer, and blend state descriptions, the number and format of render targets, input layout format, etc. For instance, rasterizer state can be described as follows:
      PipelineStateDesc PSODesc; RasterizerStateDesc &RasterizerDesc = PSODesc.GraphicsPipeline.RasterizerDesc; RasterizerDesc.FillMode = FILL_MODE_SOLID; RasterizerDesc.CullMode = CULL_MODE_NONE; RasterizerDesc.FrontCounterClockwise = True; RasterizerDesc.ScissorEnable = True; RasterizerDesc.AntialiasedLineEnable = False; Depth-stencil and blend states are defined in a similar fashion.
      Another important thing that pipeline state object encompasses is the input layout description that defines how inputs to the vertex shader, which is the very first shader stage, should be read from the memory. Input layout may define several vertex streams that contain values of different formats and sizes:
      // Define input layout InputLayoutDesc &Layout = PSODesc.GraphicsPipeline.InputLayout; LayoutElement TextLayoutElems[] = {     LayoutElement( 0, 0, 3, VT_FLOAT32, False ),     LayoutElement( 1, 0, 4, VT_UINT8, True ),     LayoutElement( 2, 0, 2, VT_FLOAT32, False ), }; Layout.LayoutElements = TextLayoutElems; Layout.NumElements = _countof( TextLayoutElems ); Finally, pipeline state defines primitive topology type. When all required members are initialized, a pipeline state object can be created by IRenderDevice::CreatePipelineState() method:
      // Define shader and primitive topology PSODesc.GraphicsPipeline.PrimitiveTopologyType = PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE; PSODesc.GraphicsPipeline.pVS = pVertexShader; PSODesc.GraphicsPipeline.pPS = pPixelShader; PSODesc.Name = "My pipeline state"; m_pDev->CreatePipelineState(PSODesc, &m_pPSO); When PSO object is bound to the pipeline, the engine invokes all API-specific commands to set all states specified by the object. In case of Direct3D12 this maps directly to setting the D3D12 PSO object. In case of Direct3D11, this involves setting individual state objects (such as rasterizer and blend states), shaders, input layout etc. In case of OpenGL, this requires a number of fine-grain state tweaking calls. Diligent Engine keeps track of currently bound states and only calls functions to update these states that have actually changed.
      Binding Shader Resources
      Direct3D11 and OpenGL utilize fine-grain resource binding models, where an application binds individual buffers and textures to certain shader or program resource binding slots. Direct3D12 uses a very different approach, where resource descriptors are grouped into tables, and an application can bind all resources in the table at once by setting the table in the command list. Resource binding model in Diligent Engine is designed to leverage this new method. It introduces a new object called shader resource binding that encapsulates all resource bindings required for all shaders in a certain pipeline state. It also introduces the classification of shader variables based on the frequency of expected change that helps the engine group them into tables under the hood:
      Static variables (SHADER_VARIABLE_TYPE_STATIC) are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. Mutable variables (SHADER_VARIABLE_TYPE_MUTABLE) define resources that are expected to change on a per-material frequency. Examples may include diffuse textures, normal maps etc. Dynamic variables (SHADER_VARIABLE_TYPE_DYNAMIC) are expected to change frequently and randomly. Shader variable type must be specified during shader creation by populating an array of ShaderVariableDesc structures and initializing ShaderCreationAttribs::Desc::VariableDesc and ShaderCreationAttribs::Desc::NumVariables members (see example of shader creation above).
      Static variables cannot be changed once a resource is bound to the variable. They are bound directly to the shader object. For instance, a shadow map texture is not expected to change after it is created, so it can be bound directly to the shader:
      PixelShader->GetShaderVariable( "g_tex2DShadowMap" )->Set( pShadowMapSRV ); Mutable and dynamic variables are bound via a new Shader Resource Binding object (SRB) that is created by the pipeline state (IPipelineState::CreateShaderResourceBinding()):
      m_pPSO->CreateShaderResourceBinding(&m_pSRB); Note that an SRB is only compatible with the pipeline state it was created from. SRB object inherits all static bindings from shaders in the pipeline, but is not allowed to change them.
      Mutable resources can only be set once for every instance of a shader resource binding. Such resources are intended to define specific material properties. For instance, a diffuse texture for a specific material is not expected to change once the material is defined and can be set right after the SRB object has been created:
      m_pSRB->GetVariable(SHADER_TYPE_PIXEL, "tex2DDiffuse")->Set(pDiffuseTexSRV); In some cases it is necessary to bind a new resource to a variable every time a draw command is invoked. Such variables should be labeled as dynamic, which will allow setting them multiple times through the same SRB object:
      m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "cbRandomAttribs")->Set(pRandomAttrsCB); Under the hood, the engine pre-allocates descriptor tables for static and mutable resources when an SRB objcet is created. Space for dynamic resources is dynamically allocated at run time. Static and mutable resources are thus more efficient and should be used whenever possible.
      As you can see, Diligent Engine does not expose low-level details of how resources are bound to shader variables. One reason for this is that these details are very different for various APIs. The other reason is that using low-level binding methods is extremely error-prone: it is very easy to forget to bind some resource, or bind incorrect resource such as bind a buffer to the variable that is in fact a texture, especially during shader development when everything changes fast. Diligent Engine instead relies on shader reflection system to automatically query the list of all shader variables. Grouping variables based on three types mentioned above allows the engine to create optimized layout and take heavy lifting of matching resources to API-specific resource location, register or descriptor in the table.
      This post gives more details about the resource binding model in Diligent Engine.
      Setting the Pipeline State and Committing Shader Resources
      Before any draw or compute command can be invoked, the pipeline state needs to be bound to the context:
      m_pContext->SetPipelineState(m_pPSO); Under the hood, the engine sets the internal PSO object in the command list or calls all the required native API functions to properly configure all pipeline stages.
      The next step is to bind all required shader resources to the GPU pipeline, which is accomplished by IDeviceContext::CommitShaderResources() method:
      m_pContext->CommitShaderResources(m_pSRB, COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES); The method takes a pointer to the shader resource binding object and makes all resources the object holds available for the shaders. In the case of D3D12, this only requires setting appropriate descriptor tables in the command list. For older APIs, this typically requires setting all resources individually.
      Next-generation APIs require the application to track the state of every resource and explicitly inform the system about all state transitions. For instance, if a texture was used as render target before, while the next draw command is going to use it as shader resource, a transition barrier needs to be executed. Diligent Engine does the heavy lifting of state tracking.  When CommitShaderResources() method is called with COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES flag, the engine commits and transitions resources to correct states at the same time. Note that transitioning resources does introduce some overhead. The engine tracks state of every resource and it will not issue the barrier if the state is already correct. But checking resource state is an overhead that can sometimes be avoided. The engine provides IDeviceContext::TransitionShaderResources() method that only transitions resources:
      m_pContext->TransitionShaderResources(m_pPSO, m_pSRB); In some scenarios it is more efficient to transition resources once and then only commit them.
      Invoking Draw Command
      The final step is to set states that are not part of the PSO, such as render targets, vertex and index buffers. Diligent Engine uses Direct3D11-syle API that is translated to other native API calls under the hood:
      ITextureView *pRTVs[] = {m_pRTV}; m_pContext->SetRenderTargets(_countof( pRTVs ), pRTVs, m_pDSV); // Clear render target and depth buffer const float zero[4] = {0, 0, 0, 0}; m_pContext->ClearRenderTarget(nullptr, zero); m_pContext->ClearDepthStencil(nullptr, CLEAR_DEPTH_FLAG, 1.f); // Set vertex and index buffers IBuffer *buffer[] = {m_pVertexBuffer}; Uint32 offsets[] = {0}; Uint32 strides[] = {sizeof(MyVertex)}; m_pContext->SetVertexBuffers(0, 1, buffer, strides, offsets, SET_VERTEX_BUFFERS_FLAG_RESET); m_pContext->SetIndexBuffer(m_pIndexBuffer, 0); Different native APIs use various set of function to execute draw commands depending on command details (if the command is indexed, instanced or both, what offsets in the source buffers are used etc.). For instance, there are 5 draw commands in Direct3D11 and more than 9 commands in OpenGL with something like glDrawElementsInstancedBaseVertexBaseInstance not uncommon. Diligent Engine hides all details with single IDeviceContext::Draw() method that takes takes DrawAttribs structure as an argument. The structure members define all attributes required to perform the command (primitive topology, number of vertices or indices, if draw call is indexed or not, if draw call is instanced or not, if draw call is indirect or not, etc.). For example:
      DrawAttribs attrs; attrs.IsIndexed = true; attrs.IndexType = VT_UINT16; attrs.NumIndices = 36; attrs.Topology = PRIMITIVE_TOPOLOGY_TRIANGLE_LIST; pContext->Draw(attrs); For compute commands, there is IDeviceContext::DispatchCompute() method that takes DispatchComputeAttribs structure that defines compute grid dimension.
      Source Code
      Full engine source code is available on GitHub and is free to use. The repository contains two samples, asteroids performance benchmark and example Unity project that uses Diligent Engine in native plugin.
      AntTweakBar sample is Diligent Engine’s “Hello World” example.

       
      Atmospheric scattering sample is a more advanced example. It demonstrates how Diligent Engine can be used to implement various rendering tasks: loading textures from files, using complex shaders, rendering to multiple render targets, using compute shaders and unordered access views, etc.

      Asteroids performance benchmark is based on this demo developed by Intel. It renders 50,000 unique textured asteroids and allows comparing performance of Direct3D11 and Direct3D12 implementations. Every asteroid is a combination of one of 1000 unique meshes and one of 10 unique textures.

      Finally, there is an example project that shows how Diligent Engine can be integrated with Unity.

      Future Work
      The engine is under active development. It currently supports Windows desktop, Universal Windows and Android platforms. Direct3D11, Direct3D12, OpenGL/GLES backends are now feature complete. Vulkan backend is coming next, and support for more platforms is planned.
    • By michaeldodis
      I've started building a small library, that can render pie menu GUI in legacy opengl, planning to add some traditional elements of course.
      It's interface is similar to something you'd see in IMGUI. It's written in C.
      Early version of the library
      I'd really love to hear anyone's thoughts on this, any suggestions on what features you'd want to see in a library like this? 
      Thanks in advance!
    • By Michael Aganier
      I have this 2D game which currently eats up to 200k draw calls per frame. The performance is acceptable, but I want a lot more than that. I need to batch my sprite drawing, but I'm not sure what's the best way in OpenGL 3.3 (to keep compatibility with older machines).
      Each individual sprite move independently almost every frame and their is a variety of textures and animations. What's the fastest way to render a lot of dynamic sprites? Should I map all my data to the GPU and update it all the time? Should I setup my data in the RAM and send it to the GPU all at once? Should I use one draw call per sprite and let the matrices apply the transformations or should I compute the transformations in a world vbo on the CPU so that they can be rendered by a single draw call?
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