Enhancing Game Visuals with Zibra Liquid and Zibra Smoke & Fire - A creator's journey

A further challenge was to include liquid simulation. In the first episode of Echoes of Somewhere, the story is focused on water. 

The developer wanted to use realistic water effects to create custom game mechanics based on liquid control, where water reacts to player actions and interacts with its surroundings in real-time. 

Having used Zibra AI’s smoke and fire effects before, the creators turned to Zibra Liquid to create custom game mechanics based on realistic liquid physics. 

Zibra Liquid employs Signed Distance Fields (SDFs) to enable precise interactions between the liquid and scene geometries, ensuring realistic collisions and behaviors.

“Zibra AI tools contain scripts that allow you to generate an SDF from either rigid, or skinned geometry. This allows their fluids or smokes to collide with complex, even animated geometry. You do not need to worry about colliders or anything, really. Just make sure the mesh is watertight (it does not have holes)”. 

The solution also uses AI acceleration to optimize both performance and memory footprint, making it possible for simulation to interact with various objects using their precise shapes, without need to manually setup approximated collisions, sacrifice collision precision or performance.

The creator modeled a detailed, watertight scene mesh in Blender. 

High level of detail made it possible to ensure that the water could go in all the nooks and crannies, providing realistic collision of liquid simulation against scene geometry. 

Afterwards, the scene was integrated into Unity. A Neural SDF was generated from the geometry to serve as the base against which the water collides. 

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“I was lucky with my scene and the SDFs just worked out of the box! The water has pretty nice collisions with the scene mesh. Everything in the scene is stored in the same mesh, there are no colliders, just polygonal geometry.”

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To achieve natural-looking water, the developer tweaked several liquid parameters, such as the index of refraction, scattering, and absorption. 

A dark color was chosen for the water, and the simulation volume resolution was increased to make the water behave more naturally.

“When I was tweaking the options, I found out that the most natural look comes when the index of refraction was set unrealistically low and the scattering to 0 and the absorption to some low value. With a dark color, this made the water look pretty natural to me. You can also render the water as a normal mesh with any custom material you like, but I found out that this made the performance dramatically worse“.

Shadows were added to the scene to give depth and realism to the water simulations. A reflection probe was also incorporated to enhance the visual fidelity of the water by reflecting the environment.

“I duplicated my special shader version of the scene mesh (that has the custom shadow renderer and placed a simple default lit shader on it and changed the render to shadows only. This is to make the environment cast shadows on the player character when it is moving in the scene. It now also casts shadows on itself as well, but it seemed to work ok as long as I lined up the light with the shadows that were in the AI image. The fluid rendering also requires a reflection probe, so I placed on in the scene and created an otherwise invisible mesh contraption that fills the probe with something for it to reflect.”

To adjust the behavior of the simulation, the creator also set up the volume resolution parameter. 

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“Getting the water to act naturally requires the simulation volume resolution to be quite high. In this scene there also is quite a lot of water, so the volume had to be rather large. I was pretty surprised to see this scene run in Unity editor at 100fps even on my M1 Max. on my PC with 2080 it easily surpasses 250fps. This is pretty bonkers!”

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