The Hedgehog Engine is a graphics engine, and has no bearing on gameplay. It is not compatible with PlayStation 2, Wii, or Nintendo 3DS hardware because they are not powerful enough to handle its next-gen lighting and visual effects. The engine was in development for three years, beginning in 2005.
The Hedgehog Engine features seamless camera transitions between 3D and 2D perspectives. It also uses a piece of technology called the light field, which can generate CGI-quality graphics in the in-game graphics system. The basic concept of the light field is that light bounces off every single object on screen, creating an ultra realistic look on the area. Light is reflected off of Sonic as well, to make sure that he didn't look "out of place" as reviewers would claim from past Sonic games.
Features of the Hedgehog Engine include:
- Pre-baked global illumination (GI)
- GI-generated textures
- Post-processed high-dynamic-range (HDR) bloom
- Eye adaptation & HDR lighting
- Color grading and tone mapping
- Light field character illumination
- Dynamic shadows
- Motion blur & depth of field
- Multi-core support
Sonic games using the Hedgehog Engine
- Sonic Unleashed (Xbox 360/PlayStation 3 version only)
- Sonic Generations (HD version only)
- Sonic Lost World (HD version only)
- Mario & Sonic at the Sochi 2014 Olympic Winter Games
- Sonic Colors: Ultimate
Hedgehog Engine 2
The Hedgehog Engine 2 is the successor to the original Hedgehog Engine. It was developed around the same time as Sonic Forces, with Sonic Forces being the first game to use it. The main features of Hedgehog Engine 2 are improved global illumination, the addition of physically based rendering (PBR), and improved shadows. The engine was developed by Sonic Team to improve lighting and shadows and other problems that occurred with the original Hedgehog Engine.
In 2018, Japanese computer graphics magazine CGWORLD published an article about the Hedgehog Engine 2. In it, Sonic Forces art director Yoshitaka Miura stated, "We wanted to achieve not only realism, but also the atmosphere of the design culture that existed in 80s graphics in 3D." The article highlights features such as:
- Spherical gaussian global illumination (SGGI), which prevents artifacts of conventional light mapping methods.
- Image-based lighting (IBL) with parallax correction to provide natural looking reflections.
- Capsule shadows to imitate ambient occlusion on the characters.
- Curvature-dependent reflectance function (CDRF) to render subsurface scattering of the characters' skin.
- Color grading and consistent pseudo-bloom post processing effects.
The goal of Hedgehog Engine 2 was to provide cutting-edge rendering visuals that seamlessly react to changes in gameplay and the environment in real time. With the help of multiple in-house tools, it also allows the developers to edit the stages in Autodesk Maya and quickly see the results in-game.
Sonic games using the Hedgehog Engine 2
- The Hedgehog Engine has been used in several Sega games outside the Sonic the Hedgehog series:
- Phantasy Star Online 2 uses the Hedgehog Engine.
- Sakura Wars, Olympic Games Tokyo 2020 - The Official Video Game and Puyo Puyo Tetris 2 use the Hedgehog Engine 2.
- Takahashi (3 April 2008). Hedgehog Engine In Development For 3 Years, Sonic Unleashed Official. Gemaga. Archived from the original on 6 April 2008. Retrieved on 19 November 2017.
- GDC Vault - Global Illumination in SONIC UNLEASHED. Retrieved on 8 December 2020.
- Sonic the Hedgehog (16 March 2017). Sonic Official - Ep. 8 - SXSW Recap. Youtube. Retrieved on 12 December 2020.