How does tracing work?

Ray tracing simulates how light behaves in the real world by tracing the path of light rays as they interact with objects in a scene. In simple terms, ray tracing starts with a virtual camera that “shoots” rays of light into a 3D scene. Each ray travels from the camera’s origin through a pixel and then into the virtual scene until it hits a diffuse surface. As the ray travels through the scene, it interacts with objects it encounters.

Technical details

Each ray will hit or miss geometry within the scene, based on the idea that two points in space are said to be visible to each other if the line segment that joins them does not intersect any obstacles.

When a ray hits an object, three things can happen:

1. Reflect. Reflected light bounces off the object’s surface like a mirror.

2. Refract. Refracted light passes through transparent objects, like glass for example.

3. Be absorbed. Absorbed light doesn’t continue further in the scene.

When rays interact with objects, they collect information about the visual appearance of the object, including color, texture, and lighting of those objects. This intersection point returns a color based on:

1. How much light touches the object’s surface.

2. The direction of light touching the object.

3. The object’s surface properties.

4. The position of the observer (camera).

By performing this process simultaneously for every pixel making up the raster image of the scene, highly realistic graphics are possible. That said, ray tracing can be computationally intensive, especially in a world where games can be played in 4k resolution—that’s over eight million visible pixels in a scene.

Comparison to traditional rendering techniques.

In traditional rendering (rasterization), algorithms focus on determining the color of each pixel on the screen individually. 3D objects in the scene are projected onto a 2D plane, then it’s determined which pixels are covered by each object. Once the pixels are identified, the color of each pixel is calculated based on lighting, shading, and textures.

Because ray tracing takes a more physically accurate approach, it can produce farm more realistic results. Typical rasterization algorithms may rely on simplifications and approximations, thus limiting the overall quality of an image or scene.

As mentioned before, ray tracing is more hardware intensive than traditional methods and often requires specialized hardware like GPUs specifically optimized for ray tracing.

Real-time vs pre-rendering techniques.

In video games, a hybrid approach between ray tracing and rasterization is often used, known as real-time ray tracing. This method looks to use the efficiency of rasterization with the power of ray tracing techniques. It’s important in gaming to find a balance between performance and visual fidelity when developers need a game to not only look good, but also run smoothly.
Real-time ray tracing image of a large Egyptian cat sitting next to a pyramid at sunset
Image by Pierre Gable and Guillaume Duflos.

Advantages of ray tracing in video games.

Despite increased hardware requirements, ray tracing is a useful tool for improving graphics in video games and improving immersion.

Improved lighting and shadows.

Ray tracing can simulate complex interactions more accurately, improving the overall lighting and shadows in a scene, creating more believable and immersive environments in games.

More realistic reflections and refractions.

Because ray tracing calculates the path of reflected light, it allows for objects in scenes to be realistically reflected in reflective surfaces, adding more depth and realism to a game’s visuals.

Increased detail and visual quality.

Real-time ray tracing vastly improves the overall visual fidelity of game environments. When combining all elements like improved, shadows, reflections, refractions, and effects like global illumination, ambient occlusion, and soft shadows, stunning graphics, and immersive gaming experiences reign.

Challenges and limitations of implementing ray tracing in video games.

We’ve mentioned the major downside to ray tracing being its computationally intense nature. Here are some of the challenges and limitations of ray tracing in video games and how developers deal with these concerns.

Hardware requirements.

Ray tracing is demanding on hardware to achieve high results. Here are some hardware components that play major roles in supporting ray tracing:

1. A powerful GPU (graphics processing unit) is essential for real-time ray tracing. Modern GPUs with dedicated ray tracing hardware, such as NVIDIA’s RTX series or AMD’s RDNA2-based GPUs provide specialized cores to accelerate ray tracing calculations, which significantly speeds up ray-tracing computations.

2. Although ray tracing is primarily GPU-intensive, having a capable CPU is still important to promote overall system performance. The CPU handles many tasks like scene management, processing geometry, AI computations, and other game-related calculations.

3. Having sufficient system memory (RAM) is needed to store data related to the scene, including geometry, textures, and intermediate calculations. Games utilizing ray tracing will benefit greatly when played on systems with sufficient RAM.

4. Utilizing a fast storage system, such as SSDs (solid-state drives) is beneficial for loading large game assets and reducing general loading times. This helps maintain smooth gameplay and minimize frame drops when rendering complex scenes with ray tracing.

5. To fully appreciate the benefits of ray tracing, consider using a display that supports high dynamic range (HDR) and has a high refresh rate, such as 144 Hz or higher. Higher resolution displays also allow for the improved visuals created via ray tracing to be seen and appreciated by the player.

Performance and optimization.

Remember that the hardware requirements for ray tracing and the end results will vary from game to game, its settings, and the player’s desired frame rate. Check a game developer’s recommended system specs for games that use ray tracing to ensure your hardware can perform optimally while you play.

Ray tracing’s effect on video game performance.

The number one question here on any competitive gamer’s mind is probably: does ray tracing lowers FPS? In general, yes, activating ray tracing is going to impact performance and will cause a drop in frames.

Using the right hardware and having proper GPUs are useful for counteracting this performance loss. Many gamers already lower graphic settings to ensure stable frames and performance, so whether you choose to enable ray tracing is completely up to you and the experience you want to have with your games.

With ray tracing enabled, gamers can typically expect to get 30fps, with the benefits of realistic lighting, shadows, and reflections.

Do I really need ray tracing?

Whenever potential impacts to performance are mentioned in gaming, asking why that feature should be used is only natural. When it comes to visual fidelity in graphics, improvement is going to be steady and incremental. As hardware also accelerates, tools like ray tracing will become easier to use with less hits on performance.

When graphics are bad it tends to stick out in our minds. While good graphics may get praise, many gamers might be coming to expect the level of visual fidelity top studios are creating. As this benchmark raises, ray tracing makes developers’ jobs even easier. With ray tracing, they don’t have to spend as much time on small details like shadows.

In the end, there’s no pressure to use ray tracing or not, however, when 60fps isn’t required, and if you have the right hardware, there is no question that enabling it can vastly improve your immersion and enjoyment of a game’s graphics.

Create stunning graphics with powerful tools like Substance 3D Painter.

Ray tracing is an amazing advancement in computer graphics, but if you’re a developer or artist, you’re going to need the right tools to ensure you have high quality scenes to light up in the first place. Level up your 3D design work with Substance 3D Painter, the industry-leader in 3D texture painter.

Frequently Asked Questions


Yes, enabling ray tracing will reduce FPS. How much frame loss occurs is affected by the hardware capabilities of the console or PC you are playing on. You can improve this by using a GPU that supports ray tracing, as well as using the best hardware within your budget in your gaming PC. As technology continues to advance, hardware will improve to better be able to accommodate computationally heavy processes like ray tracing.


In terms of visual fidelity and immersion, there is no question that ray tracing produces better visuals. Ray tracing mimics real-world light behavior to enhance reflections, shadows, and the overall appearance of a 3D scene, creating more vibrant and realistic environments.


No. It is possible to use ray tracing without an RTX graphics card. Ray tracing can be implemented using hardware with any GPU above the NVIDIA 20-series, but also with any older hardware, too. However, ray tracing’s performance is completely dependent on the hardware capabilities of the system, so it isn’t practical to use ray tracing on a system that wasn’t specifically made to do so. Both NVIDIA and AMD offer competitive ray tracing performance in any ray tracing enabled game, so it is easier than ever to find a good graphics card that is ready for the challenge.