Customer story: LOD Authoring in Forza Horizon 5
Forza Horizon 5 is the latest award-winning open world racing game from Playground Games. The Horizon festival explores the vibrant and ever-evolving landscapes of Mexico, with a limitless, exhilarating driving experience in hundreds of the world’s greatest cars.
In Forza Horizon 5, you discover the beauty and striking contrast of Mexico, driving through living deserts, lush jungles, historic cities, hidden ruins, pristine beaches, vast canyons, and a towering snow-capped volcano. Each area of the map brings diversity, variety, and adventure on an expansive scale, utilising the power of the Xbox Series X|S to showcase unparalleled load times, detailed visuals, and pivotal responsiveness.
Each biome posed unique technical challenges and the team at Playground Games relied on Simplygon to optimise many areas of development. This was especially apparent where dramatic elevations, giving breath-taking vistas across the large open world, required advanced LOD workflows and optimal mesh reduction, making Simplygon integral to the game’s visual quality. Playground Games worked closely with the team at Simplygon to integrate cutting-edge optimisation solutions into their environment workflow. From the very start of asset creation, Simplygon’s reduction features allowed the team to take highly detailed photogrammetry models and optimise them for in-game use.
Forza Horizon 5 was built for Xbox Series X|S and this allowed the highest complexity LOD to be more detailed than ever before. Once the high-poly assets were ready for use close-up in game, Simplygon’s reduction tools were relied on again to create optimised, accurate LODs for all platforms and reduce the cost of the asset into the distance.
The traditional, individual LOD assets were used up to a middle distance, at which point mesh grouping was required to reduce the number of individual assets being drawn on screen. The first of these grouped LODs was named a “ClusterLOD”. This LOD took meshes of a similar type, in the same vicinity, and merged them into a single asset, reducing the GPU strain. Additionally, meshes with the same material would be merged, allowing them to be rendered in a single draw call. Assets in Forza Horizon 5 are given individual variations for properties like damage or colour, but the ClusterLOD is a combination of individual assets into one, so this variation value is moved to a vertex value.
As the ClusterLODs moved into the distance, Simplygon was used to combine and re-mesh these into more optimised assets, creating new geometry and baking the material information into a unique texture. At Playground Games they call these “UberLODs”, and in some areas can take groups of UberLODs and LOD them again.
During development, assets are updated and repositioned numerous times. The speed and usability of Simplygon allows the artist to re-run the LOD workflow whenever the mesh changes. The ability to automate LOD workflows means that ClusterLODs and UberLODs can be daily re-baked with no additional work. Playground Games’ use of Simplygon provides the complexity and detail to create the beauty and vibrancy of Forza Horizon 5, while the optimal meshes and materials utilised for the vast vistas showcase the breathtaking and diverse landscape of Mexico.