DirectX

You are currently browsing articles tagged DirectX.

7 Things for February 8

February 8, 2010 in Resources by Eric | No comments

I use a LIFO stack for these link collections, so we’re starting to get into older news. Olds? Still good stuff, though.

  • I hadn’t noticed this set of notes before from Valve, “Post Processing in the Orange Box.” It’s about sRGB (think, gamma correction), tone mapping (think, rescaling using the histogram), and motion blur (think, types of blur). Interesting that a variable frame rate combined with blur made people sick. They’d also turn blur off if a single frame was taking too long. (from Morgan)
  • Wolfgang Engel has posted DirectX 11 and DirectX 10 pipeline overview charts. In a similar vein, Mark Kilgard has a talk about the changes from OpenGL 1.0 to 3.2 with some worthwhile data flow diagrams and other material.
  • openSourceVFX.org is a catalog of open source projects that are particularly suited for film visual effects and animation work. It is maintained by professionals in the field, so the resources listed are those known to actually be used and production-worthy. (thanks, Larry)
  • Here’s another PhysX demo, of water—a little jelly-like (good spray is hard, since it’s so fine-grained), but pretty amazing to see happen at interactive rates.
  • One resource I didn’t recall for my blog entry about tools for teaching about graphics and game creation: Kodu, from Microsoft. For grade schoolers, it uses a visual language. Surprisingly, it’s in 3D, with a funky chiclet terrain system. For still more tools, check the comments on the original blog entry—some great additions there. (pointed out by Mark DeLoura)
  • Another interesting graphics programming tool is NodeBox 2, now in beta. It uses a node graph-based approached, see some examples here.
  • The story of Duke Nukem in Wired is just fascinating. We all like to tell and listen to stories, so it’s hard to know how true any narrative is, but this one seems reasonably on the mark. A little balance is provided by Raphael van Lierop.

Tags: , , , , , , , , , ,

7 Things for February 7

February 7, 2010 in Resources by Eric | 1 comment

Comin’ at ya, lots of one-liners, vs. yesterday’s verbose posting.

Tags: , , , , , , , ,

7 Things for February 6

February 6, 2010 in Resources by Eric | 1 comment

With the excitement of Ground Hog’s Day and James Joyce’s birthday over, it’s time to take off the silly paper hats and get back to writing “7 things” columns. Here goes:

  • Jeremy Shopf gives a nice summary of recent ambient occlusion papers. AO is becoming the new Shadows—every conference must have a paper on the topic. Honestly, it’s amazing that some of these ideas haven’t popped up earlier, like the line integral method. If you accept the basic approximation of AO from the start, then it’s a matter of how to best integrate the hemisphere around the point. I’m not downplaying the contribution of this research. Just the opposite, it’s more along the lines of “d’oh, brilliant, and why didn’t anyone think of that earlier?” The answer is both, “because those guys are smart” and, “they actually tried it out, vs. thinking of an idea and not pursuing it.”
  • Thinking about C++ and looking at my old utilities post, I realized I forgot an add-on I use just about every day: Visual Assist X. This product makes Visual Studio much more usable for C++. Over the years it’s become indispensable to me, as more and more features get integrated into how I work. I started off small: there’s a great button that simply switches you between the .cpp and .h version of the file. Then I noticed that other button which takes a set of lines I’ve selected and comments them out in a single mouse press, and the other button that uncomments them back. Then I found I could add a control that lets me type in a few characters to find a code file, or find a class. On and on it goes… Anyway, there’s a free trial, and for individuals it’s an entirely reasonable (for what you get) $99 license. By the way, you really don’t need to get the maintenance renewal every year.
  • As you may know, MIT has had a mandate for a number of years to put all of its courses online in some form—there are now 1900 of them. The EE & CS department, naturally enough, has quite a selection. The third most visited course on the whole site is Introduction to Computer Science and Programming, from Fall 2008 (and I approve: they use Python!). There’s only one computer graphics course, from 2003, but it covers unchanging principles and concepts so the “ancient” date is a minor problem.
  • Naty pointed out this article about deferred rendering. He notes, “A nice description of a deferred rendering system used in a demo—of particular interest is the use of raytraced distance fields for rendering fluids, and the integration of this into the overall deferred system.”
  • A month and a half ago I listed some articles about reconstructing the position or linear z-depth in a shader. Here’s another.
  • It’s the ongoing debate, back again. No, not dark vs. milk chocolate, nor Ferrari vs. Porsche, but DirectX vs. OpenGL. My own feeling is “whatever, we support both”. By the way, the upcoming book GPU PRO (which also has a blog, and has just been listed on Amazon) includes an in-depth article on porting from DX9 to OpenGL 2.0. Mark Kilgard’s presentation also discusses the differences, including the coordinate space and window space conventions.
  • I love human pixels. The Arirang Festival in North Korea is a famous example, check out Google Images. But that’s just a card stunt, impressive as it is. This video shows a technique I hadn’t seen before (note that some of it is sped up—check the speed of the people on the field—but still fantastic). There are other videos, such as this and this.

Tags: , , , , , ,

Clearing the Queue

September 17, 2009 in Resources by Eric | 5 comments

I’ve have a goal this week (it should be clear by now) of clearing my queue of stored-up RTR links by my birthday, today! (Hint: I want a pony.) So excuse the excessively-long list o’ links. Next task on my list, update the main RTR page itself.

  • StructureSynth. This looks pretty cool, and I love procedural models (my ancient SPD package was all about this, back in the days when downloading models was oppressively slow). I do wish they just provided an executable – building looks like a pain.
  • That previous link was on Meshula.net, which also blogs about Pixel Bender Fractals. Great stuff, sort of steampunk computer graphics: you must click this link, if no other on this page, and look on in awe.
  • Shapeways has a blog, and it’s not just dull company announcements. I’m glad they find people as pixels as interesting as I do. They also cover exporting Spore characters to Collada files (which is a great addition to Spore) and creating physical models from these.
  • In related news, The Economist has a reasonable summary of some trends in 3D printing. Their Technology Quarterly also has articles on Augmented Reality, 3D displays, and CAPTCHAs, among other topics.
  • This is one more reason the Internet is great: an in-depth article on normal compression techniques, weighing the pros and cons of each. This sort of article would probably not see the light of day in traditional publications, even Game Developer - too long for them, but all the info presented here is worthwhile for a developer making this decision. Aras’ blog has other nice bits such as packing a float into RGBA and SSAO blurring.
  • I need to add a link to the article itself to the object intersection page, but Morgan McGuire recently verified that he found this ray/box algorithm super-fast in SIMD. Code’s downloadable from that page, free version of article is downloadable here. Morgan uses this test in the ray tracer for his cool photon mapping paper at HPG 2009; if nothing else, you should at least see the video.
  • In related news, I am happy to see that AK Peters is beginning to put past journal of graphics tools articles online. At $15 each, the price of an article is quite high for individuals (or at least this individual), but current journal of graphics (gpu, & game) tools subscribers have full access to this archive for free. The mechanism to get access is a little clunky right now: if you’re a subscriber, you need to register with Metapress, then tell AK Peters your userid and they’ll provide you access.
  • Related to this, I hope Google Books conquers the world (or anyone else doing similar work, as long as it isn’t Apple or Amazon or other overcharging closed-box “we’re just protecting the authors, who get 10% or less for a purely digital sale with nil physical cost to us per unit” retailers – rant over, and I do understand there are fixed start-up costs for the retailer/publisher/etc., but really…). Google Books is so darn handy to look for short articles in books at Google’s repository, such as this one giving a clean way to build an orthonormal basis given a vector, from Graphics Tools: The JGT Editors’ Choice.
  • Humus provides a whole slew of new cubemaps he captured, if you’re getting tired of Grace Cathedral.
  • CUDA itself (vs. others) may or may not be a critical technology, but what it shows about the underlying GPU architecture is fascinating.
  • It should be mentioned: August 2009 DirectX SDK is available. Includes the first official release of DirectX 11.
  • This is hilarious, and possibly even useful!
  • I love seeing things like this: build your own multitouch display. Not that I’ll ever do it, but I hope others will.
  • You might be sick of Larrabee news (ship one, already!), but I found Phil Taylor’s article pleasantly hype-free and informative.
  • ATI’s Eyefinity (cute marketing name, I must admit – now I want to use the word everywhere) seems to me to solve a problem that rarely occurs: too much GPU for too few screens. Still, it’s nice to have the option. Eyefinity allows up to six monitors to be driven by a single GPU. I guess Eyefinity is useful when running older flight simulator programs on newer GPUs; otherwise, Eyefinity is pretty irrelevant. Eyefinity, eyefinity, eyefinity. At work I find two displays is plenty, one to run, one to debug. Anyway, the sweet spot for the monitor:GPU ratio is 13:1, as can be seen here:
    Flight Simulator - living the dream
  • There’s an article on instancing animated grass using DX10 on Gamasutra.
  • Humus’ summary of z interpolation is a good summary of the topic. He gives some of the key tricks, e.g., if you’re using floating point, use a near=1.0 and far=0.0 to help preserve precision.
  • Here’s a basic tutorial on different projection methods used in videogames, with lots of visual examples (add “Zaxxon” and it’s complete, for me). The one new tidbit I learnt from it was about reverse perspective, an effect I’ve made myself once every now and then when I screw up a projection matrix.
  • While I’ve been on break (one of the reasons I’ve been posting so much – Autodesk gives wonderful 6 week “sabbaticals”, aka “long vacations”, to U.S. employees every four years you’re there; it’s like being French or Swedish every fourth year), the rest of the company’s been busy: this new sketch application for the iPhone looks pretty cool, at the usual $2.99 “cup of coffee” type price.
  • Caustics can be dangerous. I can attest to this myself; a goofy award Andrew Glassner gave me long ago sat on my windowsill for years (I moved once, as you should discern from the picture), until I noticed what was happening to the base:
    caustics
  • I usually don’t have time to keep up with Slashdot, but SeenOnSlash, the funny bits of SlashDot, is sometimes entertaining. Graphics-related example: AMD’s latest chip.

Tags: , , , , , , , , , , , , , , ,

7 Things for July 18th

July 18, 2009 in Resources by Eric | 1 comment

Well, I have 69 links stored up, wade through them here if you want unedited content. I’ve decided that getting 7 links out per post is a good round number, so here’s the first.

  • This is my screen-saver du jour: Pixel City (put the .scr file in your Windows directory). It’s fully described (along with source) in this great set of articles; if you’re too busy to read it all (though you should: it’s an fun read and he has some interesting insights), watch the video summary on that page. If you feel like researching the area of procedural modeling of cities more thoroughly, start here.
  • The book Real-Time Cameras, which is about camera control for games, now has a sample excerpt on Gamasutra.
  • NPR: Forrester Cole has two worthwhile GPU methods for deriving visible line segments for a set of edges (e.g., computing partial visibility of geometric lines). He’s put source code for his methods up at his site, the program “dpix“. Note: you’ll need Qt to compile & link.
  • The author of the Legalize Adulthood blog has recently had a number of posts on using DirectX10.
  • DirectX9 is still with us. Richard Thomson has a free draft of his book about DirectX 9 online. He knows what he’s about; witness his detailed pipeline posters. The bad news is that the book’s coverage of shaders is mostly about 1.X shaders (a walk down memory lane, if by “lane” you mean “horrifically complex assembly language”). The good news is that there’s some solid coverage of the theory and practice of vertex blending, for example. Anyway, grist for the mill – you might find something of use.
  • Around September I have 6 weeks off, so like every other programmer on the planet I’ve contemplated playing around with making a program for the iPhone. The economics are terrible for most developers, but I’d do it just for fun. It’s also interesting to see people thinking about what this new platform means for games. Naturally, Wolfenstein 3D, the “Hello World” of 3D games, has been ported. Andrew Glassner recommended this book for iPhone development, he said it’s the best one he found for beginners.
  • Speaking of Andrew, he pointed me at an interesting little language he’s been messing with, Processing. It’s essentially Java with a lot of built-in 2D (and to a lesser extent, 3D) graphics support: color, primitives, transforms, mouse control, lerps, window, etc., all right there and trivial to use. You can make fun little programs in just a page or two of code. That said, there are some very minor inconsistencies, like transparency not working against the background fill color. Pretty elaborate programs can be made, and it’s also handy for just drawing stuff easily via a program. Here’s a simple image I did in just a few lines, based on mouse moves:
    Processing output
That’s seven – ship it.

Tags: , , , , ,

This and That

November 20, 2008 in Resources by Eric | No comments

I’ll someday run out of titles for these occasional summaries of new(ish) resources, but in the meantime, this one’s “This and That”.

Christer Ericson’s article on dealing with grouping and sorting objects for rendering is excellent. It mostly depends on input latency, but has concepts that can be applied in immediate mode.

An element that continues to renew the field of computer graphics is that the rules change. This article is about taking Quake 2 (from 1997) and moving it to a modern GPU.

If you haven’t seen it yet, Farbrausch’s demo “debris” is truly impressive. It’s only 183,462 bytes, and is absolutely packed with procedural content. Download here (last link works). Or be lazy and watch on YouTube.

NVIDIA’s pulled together its resources for shadow generation and ambient occlusion all onto one handy page (plus ray tracing – just one entry so far, but it’s a good one).

How to deal with various rendering paradigms on multiple platforms? GRAMPS looks intriguing.

Gamasutra put a useful Game Developer article online, all about commercial middleware game engines currently available.

OpenGL will always exist, since Macs and Linux need it. It’s easier to use in college courses because of its clarity and readability. But otherwise the pendulum’s swung far towards DirectX. Phil Taylor comments on and gives some historical context to the controversy around the latest release, OpenGL 3.0.

A nice trend for OpenGL is that people continue to write useful bits, such as GLee, which manages extensions.

New info on older effects: blur and glow, volumetric clouds, and particle systems.

The glorious teapot. I like “a wireframe view”. Yes, the real thing is taller than the synthetic model, as the model makers were compensating for non-square pixels.

“What’s the future hold?” is always a fun topic, one we’ve used each edition to end our book. I liked this presentation on SlideShare for its sheer “here are a hundred things that hurtle us towards the Singularity” feel, though I don’t buy it for a minute. SlideShare, where it is hosted, is a pleasant medium-attention-span kind of place, with all sorts of random and fun slidesets.

Finally, I am pleased to find that LittleBIGPlanet is just as gorgeous as it looked like it would be. I’ve played myself for only a bit, but walking by when my kids are playing I find I have to stop and stare.

Tags: , , , , , , , , , , ,

Direct3D 11 Technical Preview

November 11, 2008 in Resources by Naty | No comments

The newly-released November 2008 DirectX SDK (available here) contains a technical preview of Direct3D 11. Details can be found in the release notes.

Tags: , ,

Direct 3D Details Part V: Other Features

August 10, 2008 in Reports by Naty | No comments

This grab-bag of a post summarizes the various other features of Direct3D 11 which Microsoft described at Gamefest.

Dynamic shader linkage is supported (similar to the interfaces feature of Cg). This allows for separate light and material shaders to be written and compiled. These are later linked when the shader is set. This offers a solution to the combinatorial explosion resulting from a variety of lights and materials (this explosion, and some other solutions to it, are discussed in section 7.9 of our book).

Two new compressed texture formats have been added. BC6 supports high dynamic range RGB textures, using 1 byte per texel (instead of 6 bytes for an RGB 16-bit float texture). BC7 supports low dynamic range RGB or RGBA textures. It also uses one byte per texel (like DXT5/BC3), but offers significantly higher quality than texture formats available in D3D10. Both formats offer multiple block types (the compression tool selects the appropriate block type based on its content).

The block compression formats in D3D9 and D3D10 are based on the idea that each 4×4 texel block has all its values arranged along a single line, and the bits for each texel encode where on the line it is placed. For example, in DXT1/BC1, a line in RGB space is represented by two RGB endpoints, and each texel gets two bits to select one of four points along the line.

The new D3D11 formats support block types with one, two or even three (in the case of BC7) color lines. There is a tradeoff between the number of lines and the number of points along each line, since each block takes up the same amount of memory.

In principle, a 4×4 block with two color lines would need 16 additional bits per block to determine which line each texel was associated with (even more bits are needed for three color lines). To reduce storage requirements, only a subset of possible line association patterns are supported. The compression tool selects the best association out of this subset for each block.

Direct3D11 also tightens up the texture specifications. Decompression results must be bit-accurate, and subtexel/submip filtering precision is required to be at least 8 bits.

Direct3D11 increases the texture size limits from 8K texels to 16K texels. Note that a 16K x 16K DXT1/BC1 texture takes up 128MB – not many games will have textures this large! In general, D3D11 allows for resources as large as 2GB.

Hardware can optionally support double-precision floats. This was the only optional feature of D3D11 mentioned at Gamefest.

There was a slide listing a bunch of other features without further explanation. Most are a bit mysterious, but I list them here in case someone else is able to puzzle out what they mean:

  • Addressable Stream Out
  • Draw Indirect
  • Pull-model attribute eval
  • Improved Gather4
  • Min-LOD texture clamps
  • Conservative oDepth
  • Geometry shader instance programming model
  • Read-only depth or stencil views

This completes my report on Direct3D11 from Gamefest. Check the XNA Presentations Page for the slides and audio – they are not up there yet, but hopefully will be there soon.

Tags: , , ,

Direct3D 11 Details Part IV: Multithreaded Rendering

August 10, 2008 in Reports by Naty | No comments

Direct3D 10 only allows graphics commands to be issued from a single thread (there is a multithreaded mode, but Microsoft explicitly warns against using it due to its poor performance). In an API such as Direct3D, issuing graphics commands involves a fair amount of CPU overhead. Given the trend towards increasing the number of cores on a processor rather than the performance of a single core, it is desirable to efficiently spread this work among multiple threads.

Direct3D 11 adds the ability to create display lists from multiple threads and execute them from the main rendering thread. In addition, the Device (which creates resources) has been separated from the Context (which issues graphics commands). This enables creating resources asynchronously. Deferred Contexts are used to create display lists and the Immediate Context issues graphics commands to the GPU, including the execution of display lists created on Deferred Contexts.

Unlike the other features in Direct3D 11, multithreaded rendering is not a hardware feature at all. With the appropriate drivers, D3D10 (perhaps even D3D9) hardware will be able to perform multithreaded rendering efficiently (some level of multithreaded performance will be available even without new drivers, but it was unclear what the limitations would be in this case).

Tags: , , ,

Direct 3D 11 Details Part III: Compute Shaders & Unordered Memory

August 10, 2008 in Reports by Naty | 4 comments

GPGPU (General-Purpose computation on GPU) approaches such as NVIDIA’s CUDA have become increasingly popular the last few years, recently coming full-circle with various non-traditional rendering algorithms (perhaps this should be called GPGPUG?). However, the existing solutions are vendor-specific, often requiring reprogramming even for different GPUs from the same vendor. They also tend not to “play well” with the traditional graphics pipeline. For example, on GeForce 8000-series GPUs using CUDA there is a large delay when switching between CUDA and traditional graphics rendering.

Direct3D 11 introduces a new kind of shader called a Compute Shader. A compute shader is invoked as a regular array of threads. The threads are divided into groups. Each group has 32KB of memory shared among the threads in the group. Thus the threads can use partial results computed by other threads in the same group, improving performance. Threads can also perform random-access reads and writes to graphics resources such as textures, vertex arrays or render targets. These memory accesses are unordered, although various synchronization instructions exist to impose ordering when needed.

Pixel shaders can also perform random-access (unordered) writes. This allows them to write data structures such as linked lists that can then be processed by a compute shader, or vice-versa (pixel shaders have always had the ability to perform random access reads via texture lookups).

Several examples of compute shaders were shown at Gamefest, performing post-process operations such as finding the average luminance of a render target, or computing a luminance histogram (both used in tone mapping). For these operations, a 2X speedup was quoted over the best performance possible using pixel shaders.

Compute shaders can also perform operations such as computing summed-area tables and fast-Fourier transforms significantly faster than traditional GPU methods. Microsoft is looking into providing library functions to perform such operations.

Microsoft speculated that algorithms such as A-buffer rendering and ray tracing could also be performed efficiently, but they don’t have any hard performance numbers for those.

Tags: , , , ,

« Older entries