Post-Processing Analysis pt.4 - Creating the Toon Shader

Research Summary

This research explores post-processing in stylized 3D horror video games and how these post-processing methods are used to create the emotion of unease. The previous blog posts shows the process taken to create the pixel shader.

This post covers the development of the second post-process style: the toon shader. This is not a step-by-step guide, but instead an explanation and justification of the decisions made throughout the creation of the post-process style to achieve an 'eerie' look.

Creating the Toon Shader

A toon shader, also known as a cel shader, is characterized by minimal gradients, sharp edges, and often the addition of outlines to the 3D models. Jet Set Radio (Smilebit, 2000) and The Legend of Zelda: Wind Waker (Nintendo, 2002) are examples of games that use a toon shader.

(Smilebit. 2000)

(Nintendo. 2002)

There are not many horror games that have a toon-shaded visual style, which is one of the reasons I am including it in this research. I want to explore if and how it can achieve an 'eerie' experience successfully, despite its association with cartoons. Making the toon shader involved utilizing my personal knowledge combined with referencing a variety of tutorials explaining different methods for accomplishing a toon shader.

There are a range of different methods to achieve cel shaded lighting through post-process materials. The methods I experimented with came from the Unreal Engine 5 Shaders Effects Cookbook - Second Edition (Ramos B, 2023), as well as tutorials by Michael Little, Pitchfork Academy, and Reality Adrift Studios.

Image of the post-process material, based on the Unreal Engine 5 Shaders and Effects Cookbook - Second Edition (Ramos B, 2023).

Image of the post-process material, based on a mix of tutorials (Michael Little, Pitchfork Academy, and Reality Adrift Studios).

I ended up choosing the second technique (shown in above right image), as I felt the harsher shadows made the scene appear more eerie.

Material graph used to convert scene textures into sharp banding.

The lighting information was added back into the scene by masking in the max values of each channel (RGB), which was then added to the toon shader using the multiply node.

Material graph used to add lighting back into the scene.

The shader also removes the sky information - making it appear a solid black colour. To fix this, the scene depth input is used to remove the toon shader from areas over 100,000 meters away.

The result is shown in the following image:

To add to the 'toon' appearance, I also created an outline shader within a separate post-process material. The outline colour can be adjusted for further stylization. I used Ben Cloward's cartoon outline tutorial as a reference, although I intentionally set the material up so it only added outlines to the outer edges and not the inner edges of the models as a stylistic choice.

Simply put, the outline shader works but offsetting the screen position four times (once for left, right, up, and down), applying that to the scene depth UVs, and then using that as a alpha to lerp between the 'PostProcessInput0' scene texture and a vector 3 parameter which controls the outline colour.

Screenshot of the outline post-process material.

Achieving eeriness

The resulting scene was very brightly lit, which is typically associated with positivity and safety - not what I want when aiming for an eerie mood.

"For the brightness of images, the greater the color Saturation is, the more positive the valence of these feelings is" (Geslin E, et. al., 2016).

To improve the scene, I increased the intensity of the shadows, lowered the saturation, and adjusted the gain and gamma for the mid-tones and highlights. Although, to test whether it would have an effect on the eeriness, I chose to give this shader a warm tone. If we go back to the first blog post, a reviewer of Birds Watching (Studio Ortica, 2026) - one of the games I reviewed - actually mentioned the dusty orange hues contributed to the eeriness of the game visuals.

Image of post-process material with no adjustments

Image of post-process material with with adjustments

I felt the end result looked visually pleasing, although unsure if it would be perceived as eerie. The next blog post will show the development of the third and final post-process style - the painterly shader.

Scene with the final toon shader applied.

References

Anterill. (2025). [UE5 Material Tutorial] Toon Shader. YouTube. https://www.youtube.com/watch?v=YrNSfUOdGKw&t=498s

Ben Cloward. (2022). Post Process Cartoon Outlines - Shader Graph Basics - Episode 57. YouTube. https://www.youtube.com/watch?v=Wpsqfpxb55Y&t=1472s

Geslin E, Jégou Laurent, Beaudoin D. (2016). How Color Properties Can Be Used to Elicit Emotions in Video Games. Pg. 7. International Journal of Computer Games Technology.

Michael Little. (2025). Building a Toon Shader in Unreal Engine 5 (Globally, not per-mesh); Part 1. Medium. https://medium.com/@little_michael101/building-a-toon-shader-in-unreal-engine-5-globally-not-per-mesh-part-1-6ef9aade3380

Michael Little. (2025). Building a Toon Shader in Unreal Engine 5, Part 2; The Outlines. Medium. https://medium.com/@little_michael101/building-a-toon-shader-in-unreal-engine-5-part-2-the-outlines-6e86c8886ca3

Nintendo. (2002). The Legend of Zelda: Wind Waker. [Video Game].

Pitchfork Academy. (2025). How Create A Simple Cel Shader - Unreal Engine 5 Materials Tutorial. YouTube. https://www.youtube.com/watch?v=lOOs74MLxec

Pitchfork Academy. (2025). How Create An Advanced Cel Shader - Unreal Engine 5 Materials Tutorial. YouTube. https://www.youtube.com/watch?v=HDyswSWIdY0&t=717s

Ramos B. (2023). Unreal Engine 5 Shaders and Effects Cookbook - Second Edition. Chap. 9. Packt Publishing.

Reality Adrift Studio. (2023). UE5 | UE4 Tutorial: Cel - Toon Shader. YouTube. https://www.youtube.com/watch?v=ry-E3QmpIBU

Smilebit. (2000). Jet Set Radio. Sega. [Video Game].

Studio Ortica. (2026). Birds Watching. [Video Game].