WaterRW

WaterRW is 2D interactive water system for Unity.

📜 Table of Contents

• WaterRW
  • 📜 Table of Contents
  • 🔥 Installation
    • Requirements
    • Install via UPM git dependency
  • 👉 Quick Start
    • 1. Import Prefabs and Materials
    • 2. Place a prefab
    • 3. Enable reflection and refraction (optional)
  • ☑️ Material Settings Guide
  • 🏄 Enable Interactions
    • WaterRWCompute Settings
    • Avoid Divergence
    • Buffer Scrolling

🔥 Installation

Requirements

• Unity 2022.3 or later
• Compute shader compatible platform
• Universal Render Pipeline enabled
  • 2D Renderer is also required to enable reflection and refraction.

Install via UPM git dependency

Add git URL from Package Manager:

https://github.com/ruccho/WaterRW.git?path=/Packages/com.ruccho.water-rw

👉 Quick Start

1. Import Prefabs and Materials

• Import Prefabs & Samples from Samples page in Package Manager.

2. Place a prefab

• Place Prefab/Water-RW (Compute).prefab to the scene.

3. Enable reflection and refraction (optional)

• To enable reflection and refraction, you have to use 2D Renderer.

  • https://docs.unity3d.com/Packages/com.unity.render-pipelines.universal@16.0/manual/2DRendererData-overview.html

• Enable Camera Sorting Layer Texture at the layer you want to reflect and refract.

  • 

• Water-RW has to be rendered after Camera Sorting Layer Texture. Use Mesh Renderer Sorting component to configure the sorting layer of a Water-RW instance.

  • 

☑️ Material Settings Guide

WaterRW uses the shader Water-RW/With Compute.

• 

Property	Type
Tint	Color	Tint color.
Pixel Snap	Float	Same as one in Sprites-Default shader.
Normal A	Texture2D	Normal map A. Use tiling properties to scale a map.
Normal A Intensity	Float	Amount of distortion of normal map A.
Normal A Speed	Vector	Scroll speed of normal map A. Only X and Y works.
Normal B	Texture2D	Same as normal A.
Normal B Intensity	Float	Same as normal A.
Normal B Speed	Vector	Same as normal A.
Background Blend	Float	Rate of reflection blend.
Transparency	Float	Dark reflection areas goes transparent.
Multiplier	Color	Color multiplier.
Addend	Color	Color addend.
Wave Size in Viewport Space	Float	Horizontal size of near-surface distortion.
Wave Distance in Viewport Space	Float	Vertical size of near-surface distortion.
Wave Frequency by Position	Float	Frequency of sin curve used for near-surface distortion by vertical position.
Wave Frequency by Time	Float	Frequency of sin curve used for near-surface distortion by vertical time.
Surface Color	Color	Color of surface line.
Surface Width in Pixel	Color	Width of surface line in pixels.
Fade Distance in Viewport Space	Float	Vertical size of fade to avoid display reflection areas out of Camera Sorting Layer Texture.
Smooth Buffer Edge in World Space	Float	Size of smoothing area in world space at the edge of wave buffer.
Reflection Intensity	Float	Intensity of reflection.
Enable Lighting	bool	Enables Light2D integration (experimental).

🏄 Enable Interactions

WaterRW supports rough interation with rigidbodies. (Colliders with complex shapes may not be handled correctly!)

In inspector of WaterRWCompute script, select layers to interact with in Layers To Interact With property.

WaterRWCompute Settings

Property	Type
Mesh segments Per Unit	float	Numbers of mesh divisions per unit.
Update Mode	FixedUpdate / Update	Timing to calculate wave. Use FixedUpdate to work interactions correctly.
Override Fixed Time Step	bool	Determine whether to use custom timestep.
Fixed Time Step	float	Custom time step.
C	float	The constant used in wave calculation. Increasing this will increase the speed of the waves.
Decay	float	Coefficient for damping waves.
Enable Interaction	float	Determine whether to use interaction.
Layers To Interact With	LayerMask	Layers to interact with.
Spatial Scale	float	Horizontal scale used in wave calculation.
Max Interaction Items	float	Max number of rigidbodies to interact with.
Wave Buffer Pixels Per Unit	float	Resolution of buffers used to wave calculation.
Scroll To Main Camera	bool	Track the range of the wave calculation to the position of the main camera.
Flow Velocity	float	Velocity of the flow.
Max Surface width	float	Max width of the wave in world scale.

Avoid Divergence

Values of Fixed Time Step, C, Spatial Scale and Wave Buffer Pixels Per Unit may cause divergence.

To avoid divergence, keep: 0 ≤ (C * dt / dx) ≤ 1.

dt = time step (Fixed Time Step when Override Fixed Time Step is true, otherwise Time.deltaTime or Time.fixedDeltaTime is used)

dx = Spatial Scale / Wave Buffer Pixels Per Unit

Buffer Scrolling

Although the size of the buffer used for wave calculation is finite, interaction with the seemingly infinite surface of the water can be achieved by making the wave calculation range follow the camera position. If Scroll To Main Camera is true, it will automatically follow Camera.main. To set it manually, set the X coordinate to float WaterRWCompute.WavePosition.