Archive notice: This article was originally published on February 25, 2015. Links and embedded videos are preserved as part of the historical record.
The “Tomb Raider” project was nominated in the “Best Game Design” category in 2013.
Prequels to classics are all the rage at the moment – we now know what Mr Spock was like when he was young or how the Wizard got to Oz in the first place. Of course, the youth story of one of the few female game protagonists could not be missing. Lara Croft is back and her hair is particularly noteworthy in this part, which is simulated using the newly developed TressFX technology.
In addition to AMD, the company Confetti Inc. from Encinitas in Southern California was involved in the development of the new hair simulation for Lara’s hair. The CEO and co-founder of the company is Wolfgang Engel from Baden-Württemberg. At the beginning of the 1990s, the game developer had just completed his second state examination in law. While working as an assistant at the law faculty, however, he realised that he was much more interested in games and wanted to know more about their development. Like other people with chess, he began to occupy himself with C programming in his spare time and wrote articles about it – the start of a stellar career as a developer.
Since then, Wolfgang Engel has published the ShaderX and GPU Pro series of books on real-time rendering – his book ShaderX4 even won the Game Developer Front Line Award in 2006. After more than four years at Rockstar’s core technology group RAGE and many programming techniques that he integrated into Xbox 360 and PS3 games, he founded his own studio, Confetti Inc(www.confettispecialfx. com), in 2009. “Red Dead Redemption” and “Medal of Honor” are two of the titles he has worked on.
“Tomb Raider” was released in March 2013 and the new hair simulation technology TressFX gave the game heroine a more realistic look, which was well received by fans and increased graphics card sales for AMD.
Digital Production met Wolfgang Engel at FMX 2013 for a hairy interview. You can also find Wolfgang Engel’s FMX PowerPoint presentation in the DP 06_13 folder on the DP website at www.digitalproduction.com/de/downloads.
DP: How did the name TressFX come about?
Wolfgang Engel: TressFX is an AMD marketing name. The technology was to be advertised like a hair care product, which is why the advert for TressFX looks like a print campaign for shampoo. The term Tress (curl) is directly associated with hair.
DP: What’s in Lara’s new hair package?
Wolfgang Engel: What’s new in the latest “Tomb Raider” is that every single strand of hair is simulated and illuminated for the first time in a game. Until now, hair in games has tended to be static, looking and moving like a block. Both the simulation and the lighting and shading of Lara’s hair run on the GPU. This means that the CPU does almost no work at all, it just passes the data on to the GPU. What’s more, the simulation of the hair is physically correct. Artists can adapt the behaviour of the hair to external influences by setting parameters for wet or dry hair, for example. Another new feature is the transparency simulation of each individual hair. We used LinkedList for this, which has never been used in a game before. From the side, the hair looks like building blocks stacked on top of each other. Each building block is a pixel and each pixel represents a hair. Sometimes there are more or less, depending on how many hairs are to be there. These are then blended together to form the final value. This LinkedList per pixel means that each pixel has a different colour value and becomes more or less transparent. This makes the hair look softer.
DP: How was the lighting of the hair solved?
Wolfgang Engel: Each individual pixel contains a mixture of lighting and shadow values. The lighting is based on an old research paper by Kajiya & Kay from 1989, which developed an anisotropic lighting model for hair. By using anisotropic lighting or filtering, the contours of individual objects are displayed more sharply and the general depth of field is increased. Just as it is the case with a record when you see the fine grooves reflecting the light from the side. It is almost twenty years old and was also used in the Ruby demo, an ATI demo clip with a red-haired woman from 2004. This woman also had hair, but it wasn’t lit and simulated in such a complex way for a long time. But we used the same lighting model
DP: And what role does the texture of the hair play?
Wolfgang Engel: Each hair has its own texture, with which you can give each individual hair its own colour. Because real hair also has different colours, some are darker, some are lighter. This creates a natural look. The colour can also change over the length of the hair, for example. This hasn’t been used much with Lara’s hair because it is very dark and doesn’t have many variations in colour. It would certainly be very interesting to see how the hair works with this technique without a plait and with different hair strands and colours.
DP: Are there any new projects or characters with this lighting technique yet?
Wolfgang Engel: We are currently working on AMD’s Ruby demo. The main actress has red hair. This is interesting because of the different shades of brown and red.
DP: What tools did you use?
Wolfgang Engel: All our development programmes were standard. We used Visual Studios from Microsoft, a C development environment, and DirectX.
DP: What problems did you encounter when integrating the hair technology into the game?
Wolfgang Engel: The hair was only in a fortnight before the game was released. So it was only then that we saw what it actually looked like in the game and, at two weeks, the error correction phase was very short.
DP: How many characters in a scene can the TressFX technology be used for at the same time?
Wolfgang Engel: Due to this short processing time towards the end, this is currently only possible for one character in “Tomb Raider”. If you were to mix the old hair with the new hair, for example, it would be much easier to render several characters at the same time. We are currently thinking a lot about optimisation solutions to apply the realistic hair to several characters at the same time in the future.
DP: Were there any references for Lara’s hair?
Wolfgang Engel: The look of Lara’s hair comes from the cinematic trailer that was made before the actual game development by an internal Square-Enix film team called Visual Works. The game developers used the hair created for the cinematic, but at 4,700 hairs, the resolution was far too low. The total amount was then increased by 20,000 hairs, which is only 20 per cent of the actual amount of hair on a real person.
DP: Which PC setup offers an optimal hair experience?
Wolfgang Engel: The best result is of course achieved with the largest AMD graphics card. However, if the existing graphics card is not fast enough, there is also an option in “Tomb Raider” to switch off the hair simulation.
DP: Is it not yet possible to play with the new hair on the console?
Wolfgang Engel: No, that’s not possible and wasn’t planned for the Xbox 360 and PS3 either. The graphics cards of the old consoles are not fast enough for the technology. But many game developers are planning to implement the hair for the PS4 and Xbox One.
DP: How was the new hair received by gamers?
Wolfgang Engel: We have been working on visual effects at Confetti for four years and have done hair and the like very often. The amazing thing in this case, however, was that there was such a huge response to Lara’s hair. People created an incredible number of YouTube videos with before and after shots and I understand that AMD sold a lot of graphics cards as a result because people really wanted to play the game with the new hair simulation. This made us realise that this was probably an important and big step forward in terms of game development. None of us in the team had expected such a strong reaction from people beforehand.
DP: Do you believe that hair is a decisive factor in the realistic effect of a game character?
Wolfgang Engel: Apart from Lara Croft, there are very few female main characters in games. And hair is not so important for male actors. But technology is now opening the door for more female main characters. The aim of a developer is to draw the player completely into the game’s storyline. I think the realism of the game is very important for people to achieve this. I can’t explain why people buy AMD graphics cards otherwise. We are also already involved in implementing the technology in other games, and many other game manufacturers now want to have it in their games too.
DP: So there will soon be a lot of hair in games?
Wolfgang Engel: The fact is that the design decisions in games depend on the technologies. Many games have soldiers with helmets as characters. That’s because they all look similar and the developers can reuse the same resources. The helmet means they don’t have hair – because that would be really hairy to have to animate them all. It’s still difficult to render hair as well as other differentiated surfaces, this way the problem is solved. Once you’ve done it for one soldier, you can replicate it on the others. With our new technology, more long-haired characters can now be rendered.
DP: How did the collaboration with AMD come about?
Wolfgang Engel: AMD called in September and asked if we would be interested in working on Lara’s hair. However, the condition was that we had to be on site, which meant that one of our employees had to be at AMD. Something we don’t do that often. I think AMD brought us on board because we have the dual qualification of experience with game engines and visual effects.
DP: How was the workflow organised?
Wolfgang Engel: Crystal Dynamics is the game developer and Square Enix is the publisher. AMD created the graphics cards and the basic technology for the game, which was developed over the last two years on the basis of various research papers. We received a sample program from AMD from a 2002 paper and then took care of the optimisation and integration of the program into the game. The workflow with AMD was organised in such a way that we had a telephone conference every Friday morning at half past nine. Our colleague worked in the Crystal Dynamics offices. From time to time, he travelled over to the AMD building and coordinated directly with the colleague who was doing the simulation. We used an SVN repository to keep all colleagues worldwide on the same level. This repository contained the current status of the sample programme. AMD now also offers the source code and the final version of the hair demo example as a free download for game developers: http://bit.ly/1a7mkKo
DP: So no further business is planned with the TressFX technology, as the source code is already available free of charge?
Wolfgang Engel: The aim of the hair technology was to show that their graphics cards are the better ones. Graphics card manufacturers often work closely with game developers, who then incorporate certain elements that run particularly well on the company’s specific graphics card. In return, the company offers marketing and helps with optimisation. So what we did was a service from AMD for Crystal Dynamics. The game is now also offered in a bundle with AMD cards.
DP: How long did you work on Lara’s Hair and how big was the team?
Wolfgang Engel: We at Confetti worked on it for a total of six months. That’s an unusually long time for the development of just one element. We had a very long start-up time and it took us from October to January before we were even able to integrate the technology into the game. Normally we work on several things in the same time and the hair only takes us two weeks. But I think AMD’s marketing department had the right instinct to think that the hair would be well received by people and was therefore prepared to invest this time. The team that worked solely on Lara’s hair was very large, with around a dozen people. The people were based in the Netherlands, England, Germany and California.
DP: How did Confetti come about?
Wolfgang Engel: Eight years ago, I was hired by Rockstar in San Diego. I worked there for four years until I thought to myself: what I do here for Rockstar internally, I can also do with my own company for a larger group of customers. At Rockstar, we also produced and processed parts of the engine for various game studios and I then took over the support for them. Another idea was that there are a lot of VFX houses for films, but hardly any for games. I always assumed that the games industry would develop along similar lines to the film industry, and at the moment it looks like it will. For films, there are many very specialised, small companies for specific tasks. That’s exactly what we’re doing for games now – our very small company can be integrated into the production to do visual effects and extend the engine. We also offer middleware for certain tasks, such as a global illumination or sky system. We also have a post-processing pipeline that can be licensed and that we also incorporate.
DP: Are you planning to expand?
Wolfgang Engel: We would like to have someone in Europe. I can imagine if we had an employee in the same time zone who could fly to a company in London quickly, that would be very advantageous. What’s more, we’ve achieved almost everything we wanted to this year. The only problem is that we have too much work and too few people to do it.
DP: Is it so difficult for you to find qualified employees?
Wolfgang Engel: In our field, it really is. We need a certain level of experience in graphics programming and someone with a stable personality who can fly somewhere and has some experience in project management. This combination is hard to find. But since I’ve been working in the games industry, I’ve never known it any other way. It has always been difficult to find qualified people.
DP: Are the next generation of game developers not well trained?
Wolfgang Engel: I think it’s relatively difficult for young people to get in properly. Almost everyone wants senior people with huge amounts of experience. I also teach at the University of California (USCD) and my classes have about 20 to 30 people. One of my current colleagues was in my first class, we hired him right out of college. A lot of people have a very broad skill set after graduation, but in graphics programming you need specialised experience to find bugs in the pipeline, for example. A lot is also down to the will to actually do it. In our field, you have to love what you do because your head has to be engaged a lot to get into it. However, many students are not interested in joining a small company and would rather join the big ones. It depends a lot on a mixture of character and interest. And this combination doesn’t seem to be so common.
DP: You entered the games industry as a career changer in your early 30s. Is a degree still not absolutely necessary for the games industry, does it depend on other things?
Wolfgang Engel: Like so many in this industry, I’m a classic career changer. But the great thing is that these training centres today offer the possibility of preliminary training that didn’t exist in the 80s and 90s. The problem today is also that technology has become more complicated and development has become much more complex. If you compare the last ten years alone. This means that you have to learn a lot more today to even get to a level where you can enter the industry. The risks have also become greater than 10 or 15 years ago. Back then, the development of a game cost less than a million. Today, 100 to 200 million is no longer a rarity for a title with production spread across the entire world. Because everything has become so complex, lateral entrants have also become much rarer.
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