Tag Archives: iPhone

SIGGRAPH schedule for your device

Dan Wexler pointed out this great page by skitten, which lets you quickly load up your Google Calendar with all SIGGRAPH events. Dan notes, “I’ve used these the past three years and they are fantastic”. Non-West-Coasters: don’t try to use these events for planning before SIGGRAPH, unless you go lock the time zone to West Coast times (or if you like to be three hours late for everything).

So if you want to thank Dan in person, see their talk, Intelligent Brush Strokes, around 4:20 pm Thursday, room 408A. Or virtually thank him by checking out the one-page abstract or the related, and brand-new, Glaze iPhad/iPone app.

The Graphics Codex app is now available

The Graphics Codex is a little $3.99 Apple app developed by Morgan McGuire, a noted researcher and practitioner in graphics, especially interactive graphics. He’s written numerous research papers and a number of books on videogame development, consults for NVIDIA, teaches at Williams College, and has worked on games such as Titan Quest (recently named #65 in PC Gamer’s top 100 games of all time). From talking with him, the Graphics Codex is basically his reference notebook. It holds the compact nuggets of knowledge he wants to have instantly available at his fingertips (literally, since it’s an iPad/iPhone app; it also runs on iPods running iOS 5.x).

This Graphics Codex been available for a few weeks, but this new version, 1.2, has faster scrolling and display, among other features. Morgan felt this was an important improvement so I’ve been holding off blogging about the app. Upgrades are free and simple, as with most apps. Morgan says he’s working on version 1.3, which will focus on iOS 5.1 support, color theory, and diagrams useful for explaining computer graphics topics.

So, what is it? Well, let’s start with pictures:

We all have our own favorite pieces of information we like to see included. This codex fits me pretty well: I see the reflection and refraction formulas, and various matrix types described (perspective, rotation, scale, translation, skew, determinants, etc.). I see handy things like the formatting for printf, and the latex and HTML codes for Greek letters and for math symbols. I see pseudocode for object/object intersection and distance formulas, as well as various common sorting algorithms. I see raster and 3D file formats (nicely linking to original documents on the web, when available). That’s just for starters.

There are a lot of topics included, and you can see the whole list before purchasing. In the app topics are listed alphabetically, index-style, but that’s fine, as the normal way to access this work is to search the index. Some topics I don’t know a thing about, which is great – knowing what you don’t know is important. Seeing some of these concepts inspires me to learn about them (elsewhere – like I say, this app is a reference, not a textbook). Some topics I may rarely or never look at, such as the examples shown in the images above, but I like knowing they’re there. Given that the author is a professor and consultant, I understand why they exist: these are teaching aids, information you can easily pull up and show a student, client, or other developer to help explain a concept or algorithm.

That said, there are some minor gaps. Things that came to mind for me to test but that I didn’t find: compositing (“over”, etc.), sampling and filtering (e.g. sinc and Gaussian curves), dithering (but when did I last use that?), and regular expressions (which admittedly sometimes have variations between computer languages). There’s other stuff I wouldn’t mind having: all HTML letter codes, a decimal/hexadecimal table, etc., but these are trivial to find & bookmark from sites on the web. Some domain-specific things like the various architectural projections (e.g., the various axonometric projections) would be nice, but that’s very specific to me and Wikipedia mostly fills the gap. Someday I imagine there could be a framework for such codex apps to allow you to add your own index entries, similar to how you can make your own reference work on Wikipedia (update: Morgan notes that this feature exists for his app, it’s called “email him and ask for a topic to be added”). The difference is that this app gives you the core, relevant ideas and algorithms of computer graphics in a usable form, with a consistent style, and cross-referenced to only directly relevant articles. A single author and editor, focused on a single area, adds considerable value.

This is not the first time someone has collected such reference entries. The most direct “competitor” that comes to mind is Phil Dutre’s great Global Illumination Compendium. This is a free PDF, go get it. Its focus is indeed global illumination, and it’s quite an extensive reference in this area. I would say there’s about a 25% overlap with the Graphics Codex. Another resource that comes to mind is Steve Hollasch’s collection of USENET articles, free on the web. This collection is a bit ancient, but math and physical formulas don’t change quickly. It’s a pretty shotgun-scattered set of articles, more like Graphics Gemlets, but an interesting place to wander through and try for information.

Back to the Graphics Codex. Each index entry is nicely formatted and readable, and every page (except the Bibliography, which I have reported as a bug) can be made larger or smaller. This larger/smaller functionality works well, reformatting the entry to be fully visible side-to-side, vs. typical PDF zoom, where the page can become wider than the display.

All the entries are aimed to be for reference, such as hard information that you basically understand but want to get the precise formula or code. This is information you could eventually find on your bookshelf or on the web, but instead is quickly available for you by simply searching the index. You can’t actually search the entries themselves, and the bibliography doesn’t have back links, i.e., “which Codex entries reference this article?” These are minor niggles: entries use cross-references to other entries, and most entries have a reference to related books or papers, sometimes links directly to the reference, if online. Reference back-links are more useful in a textbook; for this reference, they’d probably mostly be clutter.

Summary

Negatives:

Can’t copy and paste, unlike a computer-viewable version. (There might be an app for that…?)
Doesn’t have everything I personally might need.
Entries themselves are not searchable.

Positives:

Searchable index makes finding things a snap.
Nicely formatted, color illustrations and pseudocode snippets.
Cross-referencing and original source references, with links.
Weighs much less than the related pile of books.
Has many to most things I like to have handy.

All in all, worth $3.99 to me.

The above are my own impressions, before reading the email Morgan sent me about the app. Here’s what Morgan said:

What I’m doing with the app is converting all of my course notes and the professional notes that I take with me consulting into easily searchable topics. This way I always have the reference material with me, without having to carry all of my graphics books between my home, office, lab, and remote sites. I usually cite not only the paper and book that material comes from, but the exact page, so that I can quickly find more information when I am in the same place as my books. DirectX, OpenGL, Unity, Mitsuba, G3D, and JOGL entry points link to their official documentation on the web. Unlike a PDF or Apple IBook, The Graphics Codex does all typesetting live so it reflows for the orientation and size of your mobile device, and zooming in recomputes the text rather than scrolling it off the side of the page.

I’m prioritizing topics that people e-mail me about and vote for on the website…and anything that I look up in my regular work immediately goes into the next version. Version 1.2 not only adds a bunch of new topics from convolution to quaternions but an all-new UI and the ability to show the types and units of subexpressions.

So, if you get the app and see something missing, email him and go vote!

Two and a Half Books

I’ve learnt of two new books in the past few weeks, worth mentioning as books to check out at SIGGRAPH (or using Amazon’s “Look Inside”, of course):

iPhone 3D Programming: Developing Graphical Applications with OpenGL ES, by Philip Rideout, O’Reilly Press. A better title might have been “Programming OpenGL ES on the iPhone”, as it focuses on OpenGL ES more than on the iPhone per se. Which is fine; there are already lots of iPhone programming books, and almost none that are focused more on OpenGL ES itself (the only other OpenGL ES 2.0 book I know of is this one). The book is C++ oriented, with some Objective C as needed for glue. From my brief skim, this looks like a well-illustrated, readable guide that hits many different effects: reflection maps, skinning, antialiasing, etc. That said, I haven’t yet had the opportunity to program on any mobile devices, so can’t give an expert review. When I do give it a try, this looks like the book I’ll read first.

Update: A draft of this book is free on the web, see it here. It looks to be essentially the same as the published work (but with some hand-drawn figures), and is nicer in some ways, as the pages allow color images (always good for a graphics book).

Light & Skin Interactions: Simulations for Computer Graphics Applications, by Gladimir V. G. Baranoski and Aravind Krishnaswamy, Morgan-Kaufmann Press. This one’s out of my league as a casual skim. Paging through and seeing “the eumelanin absorption coefficient is given by…” and “Scattering in either the stratum corneum or epidermis…” shows me how little I know of the world in general. Anyway, interesting to see a whole book about this critical type of material. Searching through it, there’s minimal coverage of, for example, d’Eon and Luebke’s work, so I can’t say it has much direct application to interactive computer graphics at this point.

That’s all for the real books…

The half a book (at best): Game GPU Graphics Gems: Real-Time Rendering The Redux (aka GGGG:RTRTR), by anyone who wants to edit it. When I “edited” the quasi-book Another Introduction to Ray Tracing a few months ago, I thought back then that I’d start another book for SIGGRAPH. Like the first stunning collection, this was an hour of work gathering Wikipedia articles (hardest part was choosing a cover). There are plenty more articles to gather about interactive rendering, and you’re most welcome to add any good ones you find to this book, make your own, etc. – it’s a wiki page, after all. More seriously, I like having a single, tight page of links to Wikipedia articles about interactive rendering, vs. wandering around and haphazardly seeing what’s there.

7 Things for July 18th

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:

That’s seven – ship it.

More Statistics

One followup to Naty’s article (below): Ke-Sen Huang’s page has submission and acceptance stats for many recent conferences.

If you have five minutes to kill, it’s fun to search on various phrases at the Google Trends site. Buzzwords like “cloud computing” have trackable data, but most graphics terms don’t have enough traffic to be worth recording. Here are some examples of graphics-related terms that have sufficient hit-counts:

Ray Tracing – I like how Google Trends points out relevant articles for various spikes.
SSAO – some definite spikes there, and what’s with all the traffic from Brazil? Is this the end of some word in Portugese? But there aren’t really hits before 2007, so I guess it’s real…
Collision detection, SIGGRAPH, and computer graphics – is interest in these areas waning, or are they simply established and not newsworthy? But then, GPU is going up.
Companies and products are fun to try: Larrabee, NVIDIA, Crytek.
You can also compare various terms. Here’s “DirectX programming, OpenGL programming, iPhone programming“. Pretty easy to guess which one is going up. Surprisingly un-spikey for DirectX and OpenGL.
And of course, Real-Time Rendering – Various random spikes; South Korea loves us.

Happy hunting, and please do comment if you find any interesting results.

More With the Links

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.

TrueSpace Free, iPhone/iPod engines, Cache misses

So you want to play with a 3D modeler, or want to teach a class using one, but have zero budget. TrueSpace is now free. This is pretty darn wonderful; TrueSpace has been around approximately forever – I once wrote an exporter from the Trispectives modeler to its file format back in 1994 – and has grown in capabilities over the years.

The Torque game engine is now available for making games on the iPhone. The licensing terms are of the “email us and we’ll tell you” type, but the standard Torque engine is ridiculously affordable for indie game developers at $150, including all source, etc. If you spent all your spare money on an iPhone, oolong is a free engine for games on the iPhone/iPod, originated by Wolfgang Engel and Erwin Coumans, along with assets from PowerVR – it even has a physics engine.

There’s an interesting performance post on cache misses from Dave Moore. Dave Eberly told me a related tale recently: “I am the PS3 programmer. I spent a lot of time trying to write code to avoid branching, to remove load-hit-stores, and to avoid cache misses. For example, our physics programmer decided that if one function in a class is virtual, then make them all virtual. He did not realize that a look-up in the virtual function table invariably causes a cache miss. Make a lot of function calls (like physics systems tend to do), and now you have a serious performance problem. I removed all the unnecessary virtual modifiers and reduced frame time by 5 milliseconds. When your goal is 30 fps (33 millisecond frame time), 5 ms is significant.”