When Tencent's most successful MMO began to study the open world

Text/Thomas's skull

Too many people underestimate Tianya Yueming Dao OL's annual new information piece: City on the Cloud.

Don't close the article yet-maybe you will think that this end-game MMO, which has been online for 5 years, can't play any new tricks. But if you have experienced the "city on the cloud", you will find that it has quietly taken a small step towards the open world.

The map of this expansion will reach the size of 8X8, and the real-life scanning technology with the same production process as that of film and television is adopted. Such a production pipeline is the basis for producing a large number of resources needed by the open world.

At the same time, they also upgraded the effect of ray tracing and realized the simulation of full real physical collision. With these functions, players will have more interaction with the world, which is the premise of exploring gameplay in the open world.

Last year, Yang Feng, the producer of Jack Nifei, said that they dismantled many single-player open-world games, analyzed whether they could find a cycle to support the long-term experience of online games after stripping off the one-time experience, and planned to make an open-world Demo on the new map. There are indications that "City on the Cloud" meets this definition: it opens the curtain of a big drama.

A few days ago, Mr. Grape interviewed the R&D team of "Jack Nifei" and learned about the technological breakthrough and realization process behind this expansion, as well as their views on the open world.

0 1 How to restore a realistic scene?

At the end of last year, the Northern Lights reserved a lot of technology through the development of several new and old projects. Considering the social value, the Jack nife team set a goal: to engage in a cultural tourism linkage and move the whole Zhangjiajie into the game.

Then the problem comes: Zhangjiajie has a strange mountain shape, dense vegetation and huge terrain ups and downs. In order to restore the local lighting and natural geographical conditions and make an 8×8 map, it is necessary to be able to mass-produce high-quality resources. So the team decided to follow the example of the film and television industry and introduce the process of real-life scanning-to shoot everything on the spot and then restore the parameters one by one.

It sounds easy to understand, but this process needs too many details.

First, it seems simple to take pictures, but it is difficult to record everything. What kind of camera should I use? What are the standard apertures, shutters, lenses and shading sheets? How to record materials, lighting and environmental data? How to ensure the accuracy, illumination unit and time continuity of the HDR map? Even after doing a lot of homework, the art group ran twice to get enough original materials.

Second, how to ensure the degree of reduction? After getting the original source file, the team needs to use algorithms to restore the imaging laws of the real world-in traditional crafts, art can be directly adjusted to make finished products; But if we want to pursue realistic effects, the team must pursue the final "physically correct" production line, and all links must follow the process. You can't let the master play at will and omit the steps in order to pursue good-looking effects.

Third, after making the material, the team will also use Look Dev for acceptance-that is, viewing and adjusting various parameters in a variety of lighting environments. This requires the technical team to truly understand the theory and ensure that the algorithm completely conforms to all formulas. "In the brightest and darkest environments, the illumination range of HDR may be poor. You have to ensure that the cutting part is reasonable through the high-light pipeline, and completely restore every step detail from physical illumination to exposure imaging. "

In this process, even people's eyes are not reliable. Liu, who is in charge of the engine, gave an example: A TA in charge of Look Dev made a video, and he felt that the light was inconsistent, but after careful investigation, he found that the parameters were ok. "Nature's lighting conditions are ever-changing. Only by doing Look Dev seriously can players feel the real-world effect. However, we are used to the artificial light in our life. If it is only adjusted according to cognition, the game will become featureless and too mediocre. "

Now you should understand the difficulty of "mass production of high-quality resources by live scanning", but this is only the first step. If you want to shoot a truly realistic scene, you must have a huge investment from the art team.

For example, in order to photograph the rocks and vegetation in Zhangjiajie, the scene group first fabricated geographical knowledge to find out how the erosion structure would shape the sandstone landform; According to the latitude and altitude of Zhangjiajie, hundreds of plants are listed, and more than 20 common plants such as Wuling pine, yew and wild banana are selected to think about how to restore them.

In conventional maps, as long as you make more than a dozen stones, you can use them repeatedly. However, the sandstone landform is too strange. At least forty or fifty kinds of stone pillars, stones and cliffs are needed to restore the atmosphere. Moreover, the timely sandstone is a little soft, so it is difficult for the outsourcing team responsible for carving high molds to take into account the details. In the end, each stone has to go through about 10 times of communication to complete.

However, putting these rocks into the landscape, the art team found a new problem: the number of rocks in Zhangjiajie is much higher than that in the conventional scene, and the interval between them is very small. If placed as it is, the performance burden is too great. So after 3-4 months of production, the artist spent an extra 1 month, readjusted the model and details, and then cooperated with the mixed materials to ensure the performance finally.

Fortunately, however, the art team's work on vegetation is progressing smoothly. Teacher Sun said that in addition to the upgrading of production tools, the improvement of engine performance and bottom support, there has also been a qualitative leap in artistic effect: the trees have been upgraded from 2000-3000 to 5000- 10000, and the baking of AO maps makes their outline modeling more three-dimensional and the texture of leaves under light irradiation more natural.

This also leads to the next topic: in addition to the new development process and the efforts of the art team, Jack Nifei has also made a lot of efforts in the lower part. As Amber Berlin, the technical director of the Northern Lights, said before, "The previous techniques are all moves, but they are all internal skills."

02 endless optimization,

And a stronger bottom support.

Liu said that there is a very common law in game development: when the complexity of details increases, the team has to solve the multiplication relationship between multiple systems, which has a great impact on the design of the underlying system and will also put forward higher requirements.

An intuitive example is ray tracing. Different light irradiation on different materials will produce different effects. Therefore, it is not enough to make more physical materials with film and television technology. If we want to simulate the real world, we must achieve better ray tracing effect.

Because Jack nife adopted the self-developed engine QuicksilverX, the team did not adopt the software light-tracing scheme of other engines, but studied the light-tracing algorithm of NVIDIA, AMD and other hardware. "This is the most thorough understanding, the cleanest code and less restrictions." In order to achieve this, they should understand all the principles behind hardware optical tracking, and always keep in touch and research with engineers of hardware companies to ensure that every detail index is understood in place.

We can do this because QuicksilverX focuses on performance optimization. Jack nife team has a system to monitor the number of lines of code to strictly control the amount of code, so as to ensure that the engine is light and simple enough and it is easier to upgrade the pipeline. They have also developed many automated tools, which allow robots to do AI verification as soon as the artist submits the map, divide the map into 64X64 areas, show the performance of different areas, record problems, play back scenes, and output a "physical examination report" with one click, so that QA and programs can be adjusted in a targeted manner.

Liu said that more than 50% of Jack Nife's programs are responsible for optimization, and they are all experienced. "Are resources and algorithms reasonable? Is there a better solution? If everything is reasonable, is its design reasonable enough? For example, can you do it according to the district, or do some artistic shielding effects? These all require experience. "

Even so, performance optimization still faces many challenges. After the mapping and model specifications are constantly upgraded and the film-level process is introduced, the team should grasp the new variables. "It's a bit like solving equations. There are many variables here, there must be a fixed result there, and then calculate how to allocate it. " To this end, they will not only study the changes at the assembly language level (below the algorithm), but also communicate with artists from the product perspective. For example, the wild monster will be killed far away, so the details can be appropriately reduced to ensure the accuracy of the main characters.

In terms of process, this also requires full trust between technical and art teams. In the preliminary work, technology will try to reduce the restrictions on art and fill in the effect first; However, art will also understand that in order to ensure performance, everyone has to adjust resources repeatedly and try their best to optimize. "I didn't hear about the performance explosion, I wanted to cut resources, but I wanted to kill a programmer to sacrifice to heaven."

However, if it is only to achieve better artistic effects, City on the Cloud can not be regarded as the prelude to the study of the open world. More importantly, the construction of some underlying abilities has laid the foundation for future gameplay innovation.

As mentioned above, Zhangjiajie has a complex landform and huge ups and downs. If the player keeps standing on the ground and watching, it is obviously not so interesting. So in order to realize the movement and observation between 3D spaces, the team began to study better physical simulation technology.

The basis of physics is collision. Previously, Jack nife used a voxel-based collision method, which would split resources into a large number of voxels in the background and then calculate them. This method can save performance, but it is not accurate enough. "For example, it will set the upper surface of a voxel as a walkable area, and it is only legal if it falls within this range."

In "City on the Cloud", the team realized a completely real physical collision, so that the side can also be detected. At the back end, it also supported many people to change the overall environment, which increased the player's operating area, "like climbing a mountain." Terrain and physical characteristics will also play a greater role in the single-player exploration scene of the new expansion and the PvP game "War of Wealth". The team said that with the improvement of technical strength, they will try more innovative gameplay based on real physical engines. In the future, this 8x8 area will become a testing ground for Jack Niffe to study the open world.

To tell the truth, many of the update functions of City on the Cloud may not be particularly top-notch in a single-player masterpiece-after all, Jack Niffe is a multiplayer online game that has been online for six years, and they have to shoulder the historical burden and find technical solutions according to local conditions. But in Amblin's view, "standardization" is a major factor of industrialization. Through the "city on the cloud", they took a key step towards their ideal goals.

Conclusion: A chess piece in Sun's arch.

We often feel that there is still a huge gap between the technology of domestic game companies and 3A manufacturers. However, Amblin said that the latest achievements published on GDC or SIGGRAPH every year will definitely be realized by his own team within 2-4 months; Even if you want to pursue the technical characteristics beyond your predecessors, as long as you are willing to pay higher costs, "for example, Jack Neferi's sea of clouds and clothes made of transparent cloth."

However, these partial breakthroughs can only be said to be the beginning. Liu told a short story: once Yang Feng, the producer of Jack Niffe, asked him if he could make a 64km X 64km map similar to Ghost Action. He evaluated it and thought it was no problem: "We have a streaming mechanism, and we only need to load the map resources around the players, and the performance is no problem; And now Houdini-based process generation technology has been very skilled in the team, and it can be done in the production line, or even more. "

However, after the technical factors are ok, we should make a more comprehensive consideration: on such a large map, can players play enough rich and diverse content? The design and production of these contents will put forward higher difficulty and greater workload requirements for tool chain, art and planning-playing games is never a single breakthrough task, but a systematic challenge.

Faced with such a challenge, Jack nife's choice is to evolve in each version in a slow and stable way. "From the Jiuhua map of the novice village, to the dragon in the back, and now to Zhangjiajie, the picture has changed a lot, which is hardly a game ... Every time we make a map, we will take a step forward."

The team told me that this rhythm will continue in the future. The opening area of the current version of Zhangjiajie is only one sixteenth of the planned area, and the battlefield drama is just a test of water; In April next year, Jack Nifei will open the next version of "solo exploration", which will present a gameplay and strength closer to the team's imagination of the open world; The whole new map will be completed in 2022-2023-it sounds like a long time, but in Liu's words, "the sun rises and sets, which is a process that must be experienced."