Making Graphics More Realistic in World of Tanks Blitz

Intro

About a year ago, a 7.0 update was released in World of Tanks Blitz, in which several noticeable graphical improvements appeared at once: gun barrel rollback, vehicle hit marks, tracks from tracks, dynamic shadows, soft particles, and soft water boundaries. Some of them are useful from a gameplay point of view (hit marks), others made the game environment more beautiful.

Even before the release of the 7.0 update last year, the studio began work on the next package of graphics and technologies upgrades, and in version 8.0 these improvements were presented.

When introducing the update, the developers stick to the main principle: graphical innovations should not worsen the user experience of weak/old device owners. Therefore, the minimum system requirements of the game itself do not change, a huge range of devices is supported. At the same time, devices with certain characteristics are required to enable and use new graphical features.

Dynamic Suspension

World of Tanks Blitz's tanks have acquired all the external attributes and effects inherent in real military equipment, including tracks from tracks, rolling back when fired by guns, and hit marks. But there was one important point that made the tanks look a little inaccurate: an immobile, static suspension.

In fact, the vast majority of prototypes of equipment in the game had some kind of independent suspension, in which each of the rollers is mounted using a spring system of different designs (springs, torsion bars, etc.) and can move individually.

The new suspension does not affect gameplay, like gun barrel rollback or traces on the ground, but adds visual realism to each vehicle and to battles in general.

Alexey Cherepanov: “Players have been asking for this feature for a long time. After all, many people who play the game are fans of tanks as a vehicle. Therefore, it is important for them to see the real tank. For example, there are toy cars that have neither opening doors nor turning wheels. And there are better quality cars that have it all. It is the same for the players - it is important that the wheels of the tank spin, the tracks move, the barrel rolls back. Yes, this is not so important for the gameplay, but users are just pleased when the tank looks like a real one."

Alexander Babey: “The main difficulty in implementing this feature was that we did not create a suspension from scratch. Because in that case, it would not be difficult for us to initially prepare all the models for suspension operation and simulate each moving track. We had a lot of tanks that needed to be adapted for this feature. They had monolithic fixed tracks and rollers. To implement dynamic suspension, we had to programmatically cut the track into many separate segments and simulate their movement. And all this in code, no artists."

Key Features

• The suspension uses a realistic physical model. The movement of the track rollers, track tension, and sagging depends on the design of the undercarriage - the relative position of the drive and guide wheels, the presence/absence of support rollers, the size and position of the track rollers, the location of the balancers, etc. The dynamic and total stroke of the rollers (their visual mobility) will be greater in the case of Christie's spring suspension and less in the case of torsion suspension with staggered rollers, as in reality. Finally, the suspension dynamics depend on gravity and differs in Random modes and in Gravity mode.
• Dynamic suspension is available on all tanks in the game, and each tank is configured individually – according to the peculiarities of the design.
• Dynamic suspension is enabled by choosing an option on the graphics settings screen (if supported by the device). The functionality has certain system requirements, but many players will be able to enable and use it.

A New Visual Quality of Vehicles

The overall appearance of the tank is formed not only by effects and dynamic design elements, a big role is played by the 3D model itself and its detailing. Early researchable branches and premium vehicles were created under very tight restrictions on model detailing, texture quality, and the technology used. Gradually, the power of devices grew, and new vehicles gradually became more detailed and beautiful: developers began to use more complex models and, for some time, higher resolution textures. However, you always want more - both game creators and users who have been waiting for something like "HD models" from World of Tanks on PC for a long time.

Today, developers are still limited in the detail of the models themselves, as they are used on a wide range of devices, but there are other ways to make the tanks in the game more realistic. Even last year has released a set of graphical improvements in version 7.0, the studio began extensive engine tweaks, which eventually made it possible to radically improve the appearance of vehicles without sacrificing performance on weak and outdated devices.

Alexei Cherepanov: "Naturally we are always in favor of updating the graphics, introducing new features. But at the same time, we realize that we cannot exclude the players who have older devices, and there are a lot of them. That's why we always compromise and do less than we would like, so as not to harm such users."

What Has Changed?

As of version 8.0, the tank quality graphics settings work differently. "High" setting activates ultra settings for vehicles that have already been reworked for the new visual quality, "Medium" setting is the former high quality, and the former "Medium" quality has become "Low". "Low" settings for the weak devices have become "Ultra Low" – so the number of quality levels has increased from three to four.

What Does the New Visual Quality Include?

• A new physically based rendering (PBR) of materials and lights that uses the principles of light propagation in the real world. Metal, fabric covers, rubber rims, and other materials look more realistic, and a global lighting scheme is applied to the tanks themselves, unique to each map.
• Effects of sticking mud or snow. Tanks moving on the battlefield gradually become dirty (or covered with snow on appropriate maps).
• Wetting effects. Getting into the water, the tank gets wet, and the clogged mud - washed away. Once out of the water, the tank gradually dries out.
• More detailed models and textures for early/old tanks, which will gradually be updated. The newer vehicles already have all the details of the 3D models themselves, but each of them will also need to be reworked to include all the features described above.

Alexei Cherepanov: "The PBR concept has long been used on World of Tanks PC. However, for mobile platforms, it has started to appear recently because for a long time mobile devices lagged behind PCs in terms of power. Render methods used in the past were developed with great emphasis on computational simplicity, as the performance of devices did not allow for complex lighting models. Now, as GPU power has increased dramatically, engineers are thinking about physically correct rendering which respects most of the laws of physics in terms of light interacting with the surface. And PBR allows to make the picture realistic for users, and for developers, it allows to simplify the content management". 

Alexander Babey: "The features we've introduced help the tank fit better into the environment. When you see snow on the tank, you're more likely to believe that it's actually driving through a winter location, and it improves your perception of that particular battle."

Important to Know

• In update 8.0 all American heavy tanks from the new Yoh branch and the German Kunze Panzer light tank are available in a new visual quality.
• Every tank in the game will need a rework to "enable" the new quality. For recently released vehicles it is easier, for "veteran" vehicles from the early years of the project it is much more difficult because in addition to adjusting the new rendering capabilities and dirt/wetting the old tanks will also need to improve (or even replace) the 3D models themselves to the current standards of detail. So the whole process won't be quick, but in each version, the developers plan to redesign several existing tanks to the new visual quality. All new vehicles will come out with new quality support.
• The new quality is quite demanding on the performance of mobile devices, it's best demonstrated on the flagships of recent years. If your device can't "pull" the new high settings of the tanks, it's worth switching to medium - in this case, the visual quality will match the high in versions up to 8.0.
• In version 8.0 when using high-quality vehicles it will be impossible to use epic composite camouflages (with separate colouring for hull and gun/tower). This is a temporary limitation that will be removed in upcoming updates after 8.0.

What Determines the Appearance of a Tank in the Game?

The principles of physically accurate rendering (PBR) are not unique to World of Tanks Blitz and are used in many major projects. At the same time, Tanks has implemented this functionality and incorporated it into its own engine in-house and with adaptations for its own production process and needs.

Without going into technical details, let's consider a very simplified scheme of how and from what components to build the visual appearance of the tank in the old (non-PBR) and new (PBR) quality. Terminology is simplified, third-party software is used (in the game itself everything happens somewhat differently), but the basic principles and differences are conveyed. 

Old quality (Non-PBR)

Images go in this order: Map; Before applying the map; After applying the map.

Basic geometry (original 3D model):

Albedo texture: defines color, also baked in approximate static lighting:

Normal mapping: (defines surface topography, increases details without complicating the model itself):

Final result:

New quality (PBR)

Basic geometry (original 3D model):

Base Color texture: defines color:

Normal mapping: (defines surface topography, increases detail without increasing the complexity of the model itself):

Roughness texture: determines which areas appear smooth/polished and which appear rough (merged with Metalness in Blitz, has its own channel):

Metalness texture: determines which areas reflect light as metal and which areas reflect light as a dielectric (not a conductor), e.g. cloth or plastic  (merged with Roughness in Blitz, has its own channel):

Ambient Occlusion texture: forms natural shading in recesses, underparts, etc. (in Blitz it is part of the texture that also includes the tank's pollution mask, etc.):

Final result:

Conclusion

Thus, the new renderer allows for a more realistic display of materials and uses a global lighting scheme on every game map. 

In the end, we would like to summarize: no matter how global the plans of World of Tanks Blitz developers in an effort to make the game more realistic, their main principle is to allow users to enjoy the product on as wide a range of devices as possible. But at the same time, developers want to show that they are keeping up with the technologies and constantly improving the game.

Alexey Cherepanov and Alexander Babey, Render Developers at Wargaming MS-1