Unreal Engine 5.6 Tech Demo: The Witcher 4 on PlayStation 5 Showcases Raytracing, Nanite Foliage, and Performance Enhancements

IGN

Introduction to The Witcher 4 Tech Demo [0:00]

• The presentation showcases a technological demo set in the world of The Witcher 4.
  • This demo runs on a standard PlayStation 5.
  • It achieves 60 frames per second (fps) with raytracing enabled.
• Players will embody Ciri, a professional monster slayer (Witcher).
  • Ciri explores the world and hunts monsters for coin.
  • The region featured in the demo is called Kovier.

Character and Mount Fidelity [0:44]

• Ciri is accompanied by her loyal horse, Kelpy, akin to Geralt and Roach.
  • The goal is to make these two characters feel like one during exploration.
  • Riding on horseback is designed to be seamless, natural, and enjoyable.
• Multi-Character Motion Matching [1:10]:
  • Unreal Engine introduces multi-character motion matching, ensuring Ciri and Kelpy are perfectly synchronized when mounting from any angle and speed.
  • Root motion movement is supported on Kelpy, making control realistic and grounded.
  • This feature is part of the new Unreal Animation Framework released experimentally in UE 5.6.
• Advanced Physics for Characters [1:31]:
  • Improvements to Unreal Chaos Flesh Solver and machine-learned deformations allow for realistic muscles moving and stretching under Kelpy's skin without compromising performance.

    

Dynamic Open World Environments [1:50]

• The Witcher world is characterized by its natural and organic environments, particularly Kovier with its dense forests and wild nature.
• Nanite Foliage [2:02]:
  • Building on Nanite Geometry, Nanite Foliage aims to extend this freedom to dense vegetation.
  • The goal is to achieve gorgeous foliage density everywhere while being memory-efficient and fast to render.
  • A new approach replaces the traditional card-based method, allowing artists to model every single leaf and pine needle.
  • Old Level of Detail (LOD) tricks are replaced by a new adaptive voxel representation in Nanite.
    • This representation is volumetric, fully 3D, and super fast to render.
    • Dense clusters of triangles turn into cubes that are no larger than a pixel at a distance.

      

      

    • They react dynamically to changing light and shadows.
  • Nanite Foliage enables artists to render any amount of foliage without compromise.

    

  • It's slated for release in Unreal Engine 5.7.
• Nanite Assemblies [11:31]:
  • To create trees for Nanite Foliage, Nanite Assemblies were developed.
  • These are small, reusable parts (e.g., 28 parts for spruces) that are instanced thousands of times.
  • They act like building blocks to assemble diverse trees.

    

  • Assemblies support skeletal animation (e.g., wind effects) running on the GPU.

    

  • This significantly reduces storage, runtime memory, and rendering costs.
• Fast Geometry Streaming Plugin [3:24]:
  • Developed with Epic, this plugin provides a faster way to load the world.
  • It allows for bringing in more content more quickly for a smoother experience.

Lively Townscapes and NPC Interactions [3:48]

• The demo features Vest, a bustling port town, a hub for fishing, trade, and mining.
  • It's a place where players can meet characters, overhear gossip, and take on contracts.
• Responsive World and Characters [4:46]:
  • The world is highly responsive, with character actions directly affecting the environment and sometimes setting off chain reactions.
  • The marketplace is powered by various technologies to create a vibrant scene.
  • Character Technology [6:38]:
    • MetaHuman tools are used for high-fidelity character models.
    • Improved Unreal Smart Objects enable dynamic interactions.
    • Chaos Cloth provides realistic clothing physics.
    • The aim is to minimize the quality gap between main characters like Ciri and non-player characters (NPCs).
    • NPCs react authentically to changes in the world around them.
  • Crowd Simulation [7:32]:
    • To simulate large crowds (over 300 animated skeletal mesh agents), significant optimizations were made.
    • An entirely new Unreal animation framework was introduced to maintain a 60fps budget, even with hundreds of animated agents.
    • This framework allows developers to create dense, lively scenes without performance compromise.

      

Unreal Engine 5.6 Rendering Advancements [10:57]

• The main goal for Unreal Engine 5.6 is performance, enabling the engine to scale to large, rich worlds while preserving graphics quality and delivering high frame rates.
• Nanite Evolution:
  • Initially supporting static geometry, Nanite now includes skinning (from last year) and is introducing Nanite Foliage.
• Ray Tracing and Lumen Performance [12:54]:
  • Ray tracing and Lumen now run more than twice as fast compared to the initial UE5 release, with no visual trade-off.
  • This allows for achieving 60fps on consoles.
• Asynchronous Rendering Pipeline [13:09]:
  • The rendering pipeline has been rewritten to run asynchronously, enabling increased scene richness.

Enhanced Physics Simulations [13:19]

• Chaos Cloth [13:22]:
  • Improvements in cloth-to-cloth constraint solutions reduce collision evaluation when garments pile up and interact.
  • Even complex setups like Ciri's cloak maintain a sub-millisecond budget on PS5.

    

• Chaos Flesh [13:40]:
  • Introduces procedural muscle activations for more natural deformation and motion.
  • Artists retain control over tetrahedral simulations and can train machine learning models that run fast in real-time.

    

• Fluid Surface Baking [13:56]:
  • Supports baking fluid surface data into lightweight assets for low-cost playback.
  • This enables high-fidelity water without the performance cost of real-time fluid simulation.

    

Next-Generation Animation Framework [14:10]

• Focus on both performance and fidelity in animation.
• Multi-Character Motion Matching [14:16]:
  • Ensures seamless interaction and matching between characters like Ciri and Kelpy, regardless of approach angle.

    

• Motion Matching in Sequencer [14:29]:
  • Added to Sequencer for building "stitch tracks," allowing seamless transitions from gameplay to cinematics.

    

• Physics-Driven Secondary Animation [14:42]:
  • A secondary layer of animation is now driven by physics in the control rig.
  • Used in Kelpy's rig to drive the mane, tail, and saddlebags for added realism.

    

• New Unreal Animation Framework [14:53]:
  • All these features are integrated into this new framework, released as experimental in UE 5.6.
  • Built with performance first, animation evaluations now run in parallel off the game thread.
  • Other costly character systems (movement avoidance, state tree behaviors) are also moved to worker threads, aiding in creating crowded and lively scenes.

Optimized World Streaming and Performance [15:32]

• Streaming is a critical aspect of performance in open worlds.
• Three Major Streaming Improvements:
  1. Physics State Creation: Now runs asynchronously.
  2. Improved Runtime PCG: For ground scatter on the GPU.
  3. New Fast Geometry Streaming Plugin: To stream static geometry efficiently.
• These improvements drastically cut down streaming times, exemplified by a 90% reduction in city sample streaming time at high speeds.
  • This allows for incredible visual fidelity in open worlds.

    

• Mobile Optimizations [16:05]:
  • Unreal Engine 5.6 also includes better defaults and scalability settings for mobile platforms.
  • Minimizes default package size.
  • Workflow improvements include a UI refactor of the viewport toolbar and content browser, on-device iteration workflows, and a mobile preview solution.