DirectX 11

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Well, let’s see how far I get tonight in clearing the backlog of 219 potential resources I’ve stored up. Here goes:

  • NShader – If you use MSVC and you write shaders, this one’s for you. It highlights shader text as you’d expect, highlighting function names correctly and generally making code more readable. Worthwhile, I’ve installed it, it’s fine. That said, you can get 90% of the way there (and for sure 100% virus free) by simply using “Options | Text Editor | File Extension” and setting extension .fx (.fxh, etc.), choosing Microsoft Visual C++, then clicking Add. Do it now.
  • Speaking of shaders, I lost much of a day tracking down a bug in Cg: writing code like this, “max(0,someVar);” gave different results than HLSL when someVar was a float. My advice: always use the floating point version of numbers in shaders. So “max(0.0f,someVar);” fixed the problem. Reported to NVIDIA.
  • Morgan McGuire pointed out that John Carmack now has a Twitter account. It’s pretty interesting, in that he’s writing a ray tracer in OpenCL and relearning or rederiving various bits of knowledge that are not really written down anywhere. The guy’s unnervingly productive: “Goal for today: implement photon maps and contrast with my current megatexture radiosity gathering.” But what will he do after lunch?
  • Speaking of Carmack, you must see the Epic Citadel demo for the iPad. Demo video here. Stunning.
  • Speaking of Morgan, his Twitter feed mentioned a number of new resources: a new demo (with complete source) of ambient occlusion volumes at NVIDIA, a demo of sample distribution shadow maps (optimized z partitions for cascading maps) at Intel, and an introduction to DX 11 at Gamasutra. He also points out some entertaining visual bits, like the fascinating style of Devil’s Tuning Fork and a game map scale comparison chart (wow, WoW is small!). Morgan and others’ free multi-platform G3D Innovation Engine is now in release 8.0, and is supposed to be good for students, researchers, and indie game developers.
  • Speaking of Intel, they actually have three new DirectX 11 demos with source, as noted in this Geeks3D article.
  • Implementing some form of an A-buffer (multiple fragments stored in a pixel) is becoming more common. It’s an algorithm that can perform antialiasing and, more importantly, order-independent transparency. We already mentioned AMD’s efforts using DirectX 11; Cyril Crassin has taken their idea and improved cache coherency a bit, creating an OpenGL 4.0+ version of the linked-list approach, with source.
  • I love the idea of driving rendering computations by drawing some simple quad or whatever on the screen and having the pixel shader figure out where, at what depth, and what normal the surface is actually located. The quad is like a bounding volume, the pixel shader essentially a ray caster. Naty sent on this link: the game Hustle Kings uses this technique to great effect for rendering its billiard balls – gorgeous. Video here. Perfect spheres here look lovely. I have to wonder how many triangles in a mesh would be visually identical at closest approach; it seems like the eye is quite good at picking up slight irregularities in tessellated spheres when they are rotating.
  • There’s also a pretty displacement mapping demo in OpenGL 4.0 showing GPU tessellation at work.
  • I like seeing that 3D printers are becoming still cheaper yet, $1500, and this one looks like a fairly clean system (vs. cornstarch dust everywhere, etc.).
  • There’s a basic object/object intersection library now available for XNA, GeometricIntersection.
  • Blending Terrain Textures is a nice little article on just that. Lerping bad, thresholding good.
  • Valve discusses how it worked with vendors to optimize graphics performance on the Mac.
  • NASA provides a fair number of 3D models free to download – 87 models and counting.
  • HWiNFO32 is a free utility which provides tons of information about your system. The thing that appeals to me is that it appears to show GPU memory load over time (and I verified the load indeed increased when I ran a game). I hadn’t seen this before, and thought it was essentially impossible for Vista, so this makes me pretty happy. I did just notice that my desktop icons all turned to generic white document icons and are unusable, and this happened some time around when I tried this utility. Hmmm.
  • Colors in Cultures infographic – I like the concept, it could have been interesting, but it’s mostly just hard to read in this form. Lots of world maps with the countries colored would have perhaps revealed more. Anyway, there’s their data, for remixing.

Now I’m down to 196 potential resources – good! More later.

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A demo of the game Just Cause 2 is available on Steam today. What’s interesting is that this is the third DirectX 10-only game to be released. There have been any number of DirectX 10 enhanced games, but until a few months ago there was just one DirectX 10-only game release, Stormrise, a mediocre game released in March 2009. Shattered Horizon then came out in November from Futuremark, who are known more for their graphics benchmarks. Just Cause 2 is a sequel, and distributed by a well-known publisher. Humus describes the logic in going DirectX 10-only.

I’m looking forward to see how DirectX 11′s DirectCompute gets used in commercial applications. Perhaps the day there’s a DirectX 11-only game of any significance is the day we need to start writing a fourth edition. Let’s see: DirectX 10 was released November 2006 with Vista, so it took about three and a quarter years for an anticipated game to be released that was DirectX 10-only (and even now it’s considered dangerous by many to do so). DirectX 11 was released in October 2009, so if the same rule holds, then we’ll need to start writing in February 2013. Pre-order today!

Even now, 13% of Steam gamers have only SM 2.0. Games like World of Warcraft and Left 4 Dead 2 don’t require more, for example. So what’s the magic percentage where the AAA games decide to set the minimum level to the next shader model? I don’t recall it being much of a deal between shader model 2.0 and 3.0 games; there was a little hype, but I think this was because going from SM 2.0 to 3.0 involved just a card upgrade, vs. an OS upgrade. Which is funny, in that an OS upgrade is usually cheaper than a new GPU, but I think it’s also because it’s more critical, like a heart transplant vs. a cornea transplant.

Poking around, I found the interesting graphs below. I’m sure games have been left off, and some are miscategorized, e.g. Cryostatis is the only one under SM 4.0, and it doesn’t require DirectX 10. But, let’s assume this data is semi-reasonable; I’m guessing the games are categorized more by a “recommended configuration” than a minimum. So Shader Model 1.x game releases (and remember, 1.x was pretty darn limited) peaked in 2006, 2.0 peaked in 2007 but outnumbered 3.0 until 2009. SM 3.0 hasn’t peaked yet, I’d say (ignore 2010 and 2011 graph values at this point, of course). Remember that SM 2.0 hardware came out around 2002, so it peaked 5-6 years later and still was strong 7 years later (and perhaps longer, we’ll see). SM 3.0 came out in 2004, and seems likely to continue to be strong through 2010 and into 2011. 4.0 came out in 2006, so I’d go with it peaking in 2011-2012 from just staring at these charts. Which entirely ignores the swirl of other data—Vista and Windows 7, Xbox trends, GPU trends, blah-di-blah—but it’ll be interesting to see if this prediction is about right. (Click on a graph for the lists of games for that shader model.)

Shader Model 1.x

Shader Model 2.0

Shader Model 3.0

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Here are 7 for the day:

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Today, AMD shipped the Radeon HD 5870, the first GPU to support the DirectX11 feature set.  Most of the resources have been doubled in comparison to AMD’s previous top GPU, including two triangle rasterization units. The Tech Report has a nice writeup – to help make sense of the various counts of ALUs / “wavefronts” / cores / etc.  I recommend reading the slides from Kayvon Fatahalian’s excellent presentation at SIGGRAPH this year.

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I love the movie sequel title “2 Fast 2 Furious”. How clever, and a great way to guarantee there will never be a third movie. Well, there was, but they had to go the colon route, “… : Tokyo Drift”.

Which is indicative of nothing, as I don’t think I’ve ever actually seen any of these movies. I was reminded of the title as my goal today is to whip through the backlog of 72 potential blog resource links I’ve been gathering on del.icio.us. [Well, as it turns out, I got through 39 of them (the fresher ones), 33 to go...]

ShaderX^7 has been published. We hope to give it an overview sometime soon (mine’s on backorder from Amazon.com).

From various source I heard that OnLive got a bit of notice at GDC. Think: pure server-side computation of all graphics for a game, i.e., a cloud computing model. Now even your grandma’s computer or even a rigged-out TV can play Crysis, assuming the net bandwidth is there. Which of course makes me think: what about latency? Lag for how other players see your action is always there, and causes mismatches (“how did I instantly die?”). But increasing lag for you seeing the consequences of your own actions seems like a non-starter for shooters, at least.

Mark DeLoura has a great two-part article on what game engines are licensed for titles. First part is a general survey, second is about the technology involved. I found it interesting to see what people cared about, e.g. multicore is on people’s minds. Nothing too shocking here, but it’s fantastic to see what is getting used, and why, in this marketplace.

Related to this, I happened across a list of game engines on wikipedia. Not massively useful (e.g. no sense of what’s popular), but a starting place.

John Ratcliff has a graphics math library available for download with an unrestrictive reuse license. He recently added best fit methods for AABB’s and OBB’s.

I was interested to look at the open source, cross-platform (!) model viewer GLC. I’ve wanted something like this for doing some experiments with mesh manipulation. Not a bad viewer, but that’s all it is at this point, unfortunately: you can’t even export to a different 3D format. The search continues… If you know a reasonable open source 3D file viewer/converter out there, please tell me. I should probably bite the bullet and just use Blender, but this application is way overkill.

CUDA voxel rendering – pretty impressive!

I liked this post on optimization mainly because of the line “I went in and found out that some title bar was getting rendered 140 times every time you refreshed the screen”. I can entirely relate (though 140 must be some kind of record): too many times I’ve put output debugging statements showing updates, only to see 2,3,6 updates happening. I once started on a project and in the first few weeks increased performance by 100%, simply by noting the main draw path was being executed twice each frame.

Speaking of performance, there’s an article on volume rendering optimizations when using a ray-casting approach on the GPU.

Wolfenstein source code for the free iPhone version, along with Carmack’s documentation on the project, is available.

Software patents are only slightly dumber than business method patents, which are patently absurd. I hadn’t noticed until now, but there was recently a ruling on a business method patent, In re Bilski, which has been used to strike down software patents.

A detailed data and execution flow diagram for the new DirectX 11 pipeline front-end is available from Jolly Jeffers.

People are still making ray-tracing specific hardware; witness Caustic Graphics. They have a rather amazing claim: “The CausticOne, however, thrives in incoherent raytracing situations: encouraging the use of multiple secondary rays per pixel. Its level of performance is not affected by the degree of incoherence.” Good trick. That said, I can’t say I see any large customer base for such a product. This seems like a company designed for acquisition, similar to Ageia. Fine by me, best of luck to them.

I’m happy to learn that the Humus site now has a news blog. This is a great site for demos of advanced techniques, and for honest comments about strengths and limitations of various approaches.

Another blog: The Geeks of 3D. Tracks demos, APIs, SDKs, and graphics card releases. Handy – some of the links here I found there.

There was a nice little article on data alignment on Gamasutra. Proper alignment is a key element in getting high performance.

I was trying to find the name of the projection of equidistant latitude and longitude lines for a surrounding spherical environment. From this interesting page (click on the “Wall Maps of the World” text) I found it: Plate Carrée.

Predicting the future is so much more interesting than predicting the past. I love this: MIPS per $1000. It’s entertaining to equate raw computing power with structured processing. By the same equivalence, I should be able to hook up 1700 mice in parallel to get a human brain.

A great line from a GPU review: “Nvidia’s new line of unbelievably expensive cards will block out the sun, and ray-trace its own shadow in real time.”

Faber College’s motto is “Knowledge is Good”. Learning about the idea of metamers would have saved this article from confusion. Coming back to this article now, I see all the comments have been removed, and an apologia trying to convert confusion into enlightenment added, but I think this still misses the point. Sure, there is a color associated with a single wavelength of light. But, my guess is that 99.99% of the colors we perceive arrive at any location on the eye as light with a spectral mix of wavelengths, not a single wavelength (Naty will correct me if I’m wrong). Unless you’re Dr. Evil and deal with sharks with frickin’ laser beams on their heads on a daily basis. Hmmm, I’m probably forgetting some other single-wavelength phenomena, like fluorescence. Anyway, the article did lead me to look up more information on metamers on Wikipedia, where I learnt about metameric failure, a term I hadn’t heard before. One more reason a simple RGB representation of color isn’t sufficient.

Cute thing: Snapily lets you turn some set of images or video into lenticular prints.

I don’t have a lot to say about what I do at Autodesk. Here’s a tidbit.

Art for the day, crayons as pixels.

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I’ve been collecting links via del.icio.us of things for the blog. Let’s go:

Antialiasing thick lines by using textures is an old technique. Areakkusu’s site is nice in that it has good examples and code.

The Level of Detail blog has a great pointer to Slisesix’s amazing demo. “Demo” as in “Demoscene,” where his program is a mere 4k bytes in size. It’s not animated, not real-time, but shows how distance fields could be used for ambient occlusion approximation. Definitely check out all the links: Alex Evan (of LittleBIGPlanet) has a worthwhile talk, and Iñigo’s presentation is even better: good technical content and real-time programs running inside the slides.

I’d rather avoid logrolling in this blog, but did want to mention enjoying Christer Ericson’s post on graphical shader systems. I have to agree that such systems are bad for creating efficient shaders, but these tools do at least allow a wider range of people to experiment and explore. There are a lot of worthwhile followup comments on this thread.

Oogst has a clever trick he calls interior mapping, for rendering walls, floors, and ceilings for buildings seen from the outside. Define a texture to be used for each interior element, and have the pixel shader compute from the eye direction what would be seen inside. There’s no actual geometry, it’s all just computing the ray intersection using (wait for it) a floor function. Humus has demo code available for this technique, using DirectX 10. Admittedly, the various tiles repeat and there are other limits, but actual interiors are vastly superior to the usual dirty or reflective windows currently used in games, with no extra geometry added.

Bavoil and Sainz have a new approach for Screen-Space Ambient Occlusion, using a more elaborate form of horizon mapping: http://developer.nvidia.com/object/siggraph-2008-HBAO.html. Code’s available in NVIDIA’s DX 10 SDK.

If you missed Jon Olick’s talk at SIGGRAPH about voxel octree representation, Timothy Farrar has a summary. Personally, I think Jon’s research is very much that-research, not something that is immediately practical-but I love seeing how changing capabilities and increased flexibility can lead to different approaches.

On Amazon: 4 graphics books for the price of 2, minus the papery bits. Pharr and Humphrey’s “Physically Based Rendering” (PBR) and Luebke’s “Level of Detail for 3D Graphics” are certainly worthwhile, the other two I don’t know about (though look worthwhile and are well-rated). I don’t know a thing about the electronic media used; I’m guessing the books are DRM’ed, not naked PDFs. Searchable is certainly nice. While it’s too bad you can’t just buy the ones you want (I smell a marketing department having some “what can we get them to pay for what bundle?” meetings, given the negligible physical cost), I did notice an interesting thing on Amazon I hadn’t seen before for each book except PBR: “Upgrade this book for $18.39 more, and you can read, search, and annotate every page online.” You can also upgrade books you’ve previously purchased on Amazon.

On Gamasutra, an article summarizing DirectX 11. I liked it: to the point, and with some useful figures.

Every once in awhile someone will say he has a new graphics rendering method that’s awesome, but won’t explain it because of some reason (usually involving money or fame). Here’s one, from Sunfish Studio: no micropolygons, no point sampling. OK, so that leaves-what?-voxels? If anyone knows what this is about, please comment; I’m curious.

GameDeveloperTools.com is a new site that tracks news and has users rate books. To be honest, a lot more voting needs to happen to make the ratings useful-I’d stick with Amazon for now. The main use is that you can look at specific categories, which are a bit better than Amazon’s somewhat random sorting of graphics books (e.g., our book is in three categories on Amazon, competing against artists’ books on using mental ray and RenderMan).

Finally, this, well, this is not interactive graphics, but is just so cool: parking signs understandable from only certain locations.

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