Which UE version is Wuthering Waves developed with, and why was this particular version chosen?
Li: We chose UE4.26 for its stability and maturity when we started development. Throughout the development process, we integrated essential functions by incorporating new features from UE5 into UE4.26. This approach allowed us to meet our specific needs and maintain a steady flow of content production.
What are the main considerations when integrating 2D cartoon characters into a 3D environment?
Li: Two critical factors are the time of day (TOD) and post-processing lighting.
The implementation of the underlying lighting system, especially TOD, is crucial in ASG projects. We utilized Unreal Engine's curve tools to simulate the natural daily changes in character brightness, ensuring they align with the 3D environment's lighting. This helps maintain accuracy in character portrayal within the open world and ensures visual consistency across the performance pipeline.
Additionally, we took a measured approach to the engine's physical features to achieve the "hand-drawn" feel. For example, we used limited sampling for certain elements.
Regarding post-processing lighting, we set up an independent character lighting pipeline. This allows for quick environmental lighting adjustments using presets and automated tools, now an integral part of our character and skill design workflows.
Why was deferred shading chosen for Wuthering Waves when so many mobile games opt for forward shading?
Li: Our goal is to deliver top-notch visual quality on mobile devices. To achieve this, we utilized techniques like Screen Space Reflections (SSR) and Ground Truth Ambient Occlusion (GTAO). These advanced techniques rely on deferred rendering to boost rendering efficiency and streamline the pipeline.
For an open-world game like Wuthering Waves, where new content is continuously added, rendering technology faces significant challenges. Traditional Forward Rendering can lead to a rapid increase in shader variants, which raises maintenance costs. Deferred Rendering, however, offers advantages in managing materials, weather, day/light changes, and atmospheric transitions. It simplifies the pipeline's complexity and reduces maintenance costs.
Moreover, aiming for consistency in multi-platform development helps lower development costs. Deferred Rendering standardizes the development process, improving the efficiency of feature implementation and problem-solving. This uniformity enhances overall development productivity and reduces the workload for the art team when adapting to the mobile version.
Furthermore, advancements in mobile hardware have enabled the use of one-pass deferred technology. This method significantly cuts down the read/write bandwidth to 1.5G per second while maintaining a steady 60 frames per second rate, mitigating the issues of overheating and high power consumption associated with high bandwidth. This creates a strong technical foundation for optimizing performance in mobile applications.
After adopting the deferred shading pipeline, what technical challenges were encountered, and how were they resolved?
Li: Implementing the one-pass deferred approach revealed limitations on specific platforms. For example, on the Mali platform, using PLS for one pass deferred is restricted to a 128-bit on-chip cache without alpha blend, only allows resolving one render target, and incurs extra performance overhead due to depth fetch. To address these challenges, we adjusted our effects implementation.
Moreover, we had to integrate rendering effects like SSR and GTAO without disrupting the one-pass deferred workflow. This required leveraging depth and scene color data from the previous frame to generate SSR, using re-projection for reflection mapping in the current frame, and improving SSR quality with denoising techniques.
Our testing showed that most mobile devices could support SSR at medium quality and GTAO at high settings without substantial performance loss.
How did you approach the design of the characters' features and personalities to ensure strong recognition and appeal? (For instance, Lingyang's integration of Lingnan lion dance culture in China.)
Li: In the initial stage of art design, we focused on identifying a unique characteristic that could be highlighted throughout the production process. For Lingyang, our goal was to integrate the unique charm of lion dance culture into the Wuthering Waves world. We combined lion dance gestures with Hongquan martial arts to design his movements, creating a character with a dynamic and vivid presence.