Simple Liquid Simulation in Unity!

Summary

In this tutorial, the Code Monkey demonstrates how to create a simple fluid simulation in Unity using basic physics. By simulating individual water particles as physics objects, the tutorial walks through creating a basic liquid particle, applying physics properties, and refining the simulation for more realistic fluid behavior. The tutorial covers rendering particles with visual effects, creating custom shaders, and optimizing for performance. By the end, the system can simulate both liquid and gas, with different visual styles and colors for various fluids. This simple yet effective fluid simulation can be used in various game scenarios.

Takeaways

• 😀 Fluid simulation in Unity is complex, but this tutorial covers the simplest possible implementation.
• 😀 The core idea behind fluid simulation is to use physics-based particles to represent the liquid, mimicking real-world fluid properties.
• 😀 A simple liquid particle is created using an empty GameObject with a sprite renderer, a circle collider, and a rigid body 2D.
• 😀 To adjust the fall speed of the liquid particles, you can modify properties like mass and gravity scale in the rigid body.
• 😀 A physics material with zero friction can be used to make particles slide smoothly, simulating water-like behavior.
• 😀 The scene initially contains separate particles, but visual trickery is used to merge them and create a cohesive liquid appearance.
• 😀 A secondary camera renders the liquid particles to a separate texture, which is then blurred to visually merge the particles.
• 😀 The render texture is displayed on a quad in the scene, making the fluid appear smooth and blurry, resembling a liquid.
• 😀 Transparency settings are crucial to ensuring the render texture appears without a background or unwanted post-processing effects.
• 😀 A custom shader is created to improve the visual quality, allowing for smooth transitions and solid shapes for the liquid particles.
• 😀 The system can be adapted to simulate gases by adjusting the gravity scale to a negative value, making particles float upwards.

Q & A

What is the primary goal of the fluid simulation in this video?

The primary goal of the fluid simulation in the video is to create a simple and straightforward implementation of a fluid system in Unity, using basic physics and visual tricks to simulate water or liquid behavior.

How does the video define a fluid, and why is this important for the simulation?

A fluid is defined as formless and shapeless, like water. This is important for the simulation because it emphasizes that the fluid's behavior should adapt to the container's shape, and that it consists of millions of tiny particles, which will be simulated using physics to create realistic movement.

Why does the author use a circle sprite for the water particle?

The circle sprite is used to represent the individual water particles because it visually simulates the basic shape of a liquid particle, making it easier to understand how the fluid behaves. The circle serves as a simple placeholder for more complex visual representations of water.

What role does the Circle Collider play in the fluid simulation?

The Circle Collider defines the shape of each water particle and enables the physics engine to detect collisions with other objects or particles. It allows the fluid particles to interact physically with their environment, such as not passing through walls.

How does the gravity scale affect the particle's movement in the simulation?

The gravity scale affects how fast the particles fall. By increasing the gravity scale, the particles fall faster, which is important for making the fluid behave more realistically according to the scene's desired scale.

What is the purpose of the physics material with zero friction?

The purpose of the physics material with zero friction is to make the water particles slippery, allowing them to slide easily along surfaces, much like how water behaves in real life. This material simulates the lack of friction in liquid interactions.

How does the author use layers and cameras to render the particles separately from the rest of the scene?

The author uses layers to categorize the water particles, then sets up two cameras: one main camera to render everything except the fluids, and a second 'fluid camera' to render only the fluid particles. This helps isolate the water simulation visually from the rest of the scene.

What is the significance of the render texture in this simulation?

The render texture is used to capture the image of the water particles as seen by the fluid camera and apply a blur effect. This helps merge the particles visually, making them appear as a continuous fluid rather than individual discrete particles.

What is the purpose of creating a custom shader for the water simulation?

The custom shader is used to enhance the visual appearance of the water, making the gaps between particles disappear and providing a more solid, continuous appearance. It also allows for effects like transparency, color changes, and the addition of foam to make the water look more realistic.

How does the simulation handle performance issues with a large number of particles?

The simulation handles performance issues by using a limited number of particles. The more particles used, the more accurate the simulation becomes, but this comes at the cost of performance. The video emphasizes the importance of balancing particle count for optimal performance.