Ray Tracing Explained

World of Tanks will soon support real-time ray-traced shadows. Thanks to this cutting-edge technology, the smallest details on players’ tanks will be able to cast softer, more natural and realistic shadows — check it out!

We're Still Moving Forward!

After the release of Update 1.0 in March 2018 and the large visual upgrade of World of Tanks, our consistent work on the new Core engine never stopped. We’ve implemented concurrent rendering support, while discontinuing support for Windows XP and DirectX 9. 

Thanks to these steps, we were able to move forward and introduce new technologies to the Core engine. One of these technologies is Ray Tracing, a rendering method which has long been the “Holy Grail” of computer graphics. Just take a look at these amazing ray-traced pictures!

The Challenge

One of the biggest challenges in game development is the correct implementation of shadows. It’s a truly challenging task to create realistic shadows using modern graphics cards. Dynamic tank shadows in our game are currently made using the common Cascaded Shadow Mapping technology, which is based on the use of regular textures. Their resolution is limited, which leads to the following issues: 

• Shadows are not detailed, and when approaching a shadow, you can see its jagged and uneven edges (known as “aliased” shadows).
• So-called “Peter Panning”. This term derives its name from a children’s book character whose shadow became detached and who could fly. This effect makes objects with missing shadows appear to be detached from and to float above the surface.
• At a distance of more than a hundred meters, tank shadows disappear.

The level of detail of our tanks at some point overtook the level of detail of their shadows, and we wanted to fix that disparity. Theoretically, it would be possible to increase the resolution of shadows, but this would lead to a greater load on the graphics card and a drop in FPS. Instead, we turned our attention to the latest technology of creating shadows using Ray Tracing, allowing for dramatically more lifelike shadows.

Invaluable Assistance From Intel 

While we were looking for a solution to the problem of creating soft and realistic shadows on tanks, our long-standing partner, Intel, offered to share their expertise and to assist us. Intel Advanced Rendering engineers helped with high performance kernels and optimizations. Thanks to concurrent rendering support and the ability to parallelize the rendering we implemented in Update 1.4, the Intel Embree technology was perfect for our game.

As a result, we can now recreate tank shadows in higher quality, their smallest details giving super-realistic soft shadows when sunlight hits them. Visually, we are now one step closer to physically-accurate shadows that exist in the real world. Real-time ray-traced shadows further immerse you in an atmosphere of furious tank combat and provide an even more enjoyable gameplay experience.

Frequently Asked Questions

Do I need a special graphics card with Ray Tracing support to see the new shadows? 

No, you don’t. Our implementation of Ray Tracing technology will work with all graphics cards that support DirectX 11 API and higher, but only for intact vehicles (not destroyed). You can enable/disable this function manually in the game settings. 

How will Ray Tracing affect my PC’s FPS? 

When this option is disabled, the FPS of your computer will not change. But when Ray Tracing is on, you may need to sacrifice some FPS depending on your graphics card.

Will Ray Traced shadows be used for all objects in the game? 

As the first step we chose to include Ray Tracing shadows for the "main actors" of our game – the tanks (intact, not destroyed). Their smallest details will give super-realistic shadows when the sun hits them.

What are the ray-traced shadows’ quality settings? 

There are four settings options:

1. Turned off. Tanks cast normal shadows, as in the current version of the game.
2. High. Vehicles have high-quality hard shadows which remain clear at any distance. However, these shadows are not physically correct.
3. Maximum. It is at this stage that the physically-correct “soft shadows” appear. They become more blurred as they move away from an object that casts a shadow.
4. Ultra. The quality and appearance of shadows remain the same as at the Maximum setting, but are created using the denoiser algorithm.

What’s Next? 

Recreating incredibly soft and natural shadows is just the beginning of the Ray Tracing era in gaming graphics. Thanks to this technology, we’ll be able to recreate realistic reflections, ambient occlusion, and global illumination in real time. But this is something for the more distant future.

Real-time ray-traced shadows will soon become a reality in World of Tanks in one of the upcoming updates. Stay tuned and good luck on the battlefield, Commanders!