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HedgehogEngine

The Hedgehog Engine logo, as seen in Sonic Unleashed.

The Hedgehog Engine (ヘッジホッグエンジン Hejjihogguenjin?) is a proprietary game engine developed by Sonic Team that is primarily used in games in the Sonic the Hedgehog series. The engine was first used in the Xbox 360/PlayStation 3 version of Sonic Unleashed.[1]

History[]

Sonic Unleashed[]

Development of the Hedgehog Engine began in 2005, approximately a year before Sonic Unleashed entered production.[2][3] Yoshihisa Hashimoto, the director of Sonic Unleashed, wanted to achieve in-game graphical fidelity on par with pre-rendered computer-generated imagery, particularly the work of Pixar.[4][2] From the observation of several computer-generated images and films, Hashimoto and artists at Sonic Team concluded that high-end game graphics at the time were missing a key element, global illumination, where light bounces off every object in the scene. The team would then work for two months to develop an experimental global illumination rendering algorithm.[2]

Inexperienced with traditional rendering techniques such as ray tracing, radiosity, and photon mapping, Sonic Team devised other methods of calculating global illumination for terrain. The first of these was a "light model", where light sources emit "particles" that travel instantaneously in straight lines from every direction. Upon hitting an object's surface, a light particle is temporarily absorbed by it. Some of the particle's energy is absorbed by the material of the object, while the rest is split into more particles and re-emitted, and the process repeats. Anticipating that this method would generate an infinite number of lighting calculations impossible for the hardware to process, the team dropped the idea.[2]

The second global illumination calculation method devised by the team was the "light network." With this method, each object in the game world is given a texture embedded with global illumination data and subdivided into microfacets based on textels. A set number of rays are then radially cast from each microfacet, and data is stored for the first microfacet intersected by each ray. Ray calculations are done on all microfacets, creating a network. Diffuse texture textels that overlap the centers of microfacets have their material colors sampled to determine their reflectivity. Three different light source models, "directional," "point," and "sky," are used to determine the behavior of the rays cast from the microfacets, with the rays that do not intersect objects being considered "direct light." Finally, the strength of the direct light is precomputed, linking the ray network with each light source type and completing the light network.[2]

To handle the considerable amount of computing time and data required by global illumination, Sonic Team created a system of over a hundred computers to evenly distribute the rendering workload.[2]

Sonic Forces[]

Sonic Frontiers[]

Sonic games using the Hedgehog Engine[]

Other games using the Hedgehog Engine[]

References[]

  1. Sarkar, Samit (April 3, 2008). Sega confirms Sonic Unleashed: I'm trying really hard not to use a pun here. Destructoid. Retrieved on November 24, 2022. "Sega: Along with seamless 3D to classic 2D camera transitions, the game is built on a powerful, new proprietary "Hedgehog Engine," which introduces impressive lighting abilities and new technology tailor made for Sonic's new speed capabilities."
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Hashimoto, Yoshihisa (March 27, 2009). Global Illumination in Sonic Unleashed. GDC Vault. Informa. Retrieved on December 8, 2020.
  3. Riley, Patrick (October 16, 2008). A New Direction. IGN. Archived from the original on October 19, 2008. Retrieved on November 24, 2022.
  4. Yoshihisa, Hashimoto (October 23, 2008). Progress. IGN. Archived from the original on December 23, 2010. Retrieved on November 24, 2022.
  5. Yashiro, Atsushi (May 3, 2019). 『新サクラ大戦』開発者に徹底的に訊く! 「シリーズのキャラは?」「主人公の神山はどんな男?」 など疑問に答えまくるロングインタビュー!(2/2) (Japanese). Famitsu. Retrieved on July 27, 2023. "Tetsu Katano: 技術的には『ソニック』シリーズの“ヘッジホッグエンジン”を使っていたり、イベントシーンでは『龍が如く』シリーズのノウハウを使わせてもらうなど、社内の総力を結集しました。"
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