Simple Fog Effects For URP

This project will provide some URP-based fog effects, and implement it in a relatively quick way.

Requirements

• URP v17

Unity 6 Compatibility Note

Unity 6000.4 removed the URP Compatibility Mode option. This package keeps the old non-RenderGraph path only for Unity versions below 6000.4, and uses the RenderGraph path on 6000.4+.

• Unity 6000.0 to 6000.3: RenderGraph and Compatibility Mode are both supported.
• Unity 6000.4+: only the RenderGraph path is used.

For URP v14~16, check urp14 branch

Installation

• Install via UPM git URL

  https://github.com/meryuhi/URPFog.git?path=Packages/Fog

• Install via Packages/manifest.json

  "moe.meryuhi.effects.fog": "https://github.com/meryuhi/URPFog.git?path=Packages/Fog"

Full Screen Fog

It based on Volume framework and URP Renderer Feature. Also the FullScreenFog shader itself is also a Fullscreen Shader Graph, so it can be used in Full Screen Pass Renderer Feature.

Because it is based on Volume framework, you can smoothly switch different effects between different areas without coding.

Screen Shoots

Depth Mode

Distance Mode

Height Mode

With Transparent Objects (Experimental)

This requires setting up a Camera Stack. Please refer to the instructions.

With Noise

https://user-images.githubusercontent.com/23119289/233851479-d5f80709-403a-4a09-9b70-240634c55bcb.mp4

Instructions

1. Add a Full Screen Fog Renderer Feature into your URP renderer.

   Name	Description
   Injection Point	Selection for when the effect is rendered. Before Rendering Skybox: Using this if you do not want to override skybox.
   Render Camera	Selection for which camera type want to render.
   Shader	Automatically set FullScreenFog shader provided by the package, or you can create your own (you need to check parameter design).

2. Add a Meryuhi/Full Screen Fog override into any local or global Volume, just like with other post-processing effects. Turn Fog -> Color settings on and adjust the alpha, and then you can see the effect.

   By default it set to be similar to Unity built-in fog, but you can configure it.

   Name	Mode	Description
   Mode	Depth	Directly use the depth value calculation, which is consistent with Unity.
   	Distance	Using distance for calculation, the calculation will be more complex, but it looks better.
   	Height	Use the height in Y asix for calculation.
   Color	-	Fog color.
   Density Mode	Linear
   	Exponential
   	ExponentialSquared
   Start Line	-	Start depth or distance.
   End Line	-	End depth or distance.
   Start Height	-	Start height.
   End Height	-	End height.
   Noise
   Noise Mode	Off	Disable.
   	Procedural	Procedurally generated noise effects, possibly expensive.
   	Texture	Use a custom noise texture.
   Noise Texture	-	Texture used by the noise.
   Noise Intensity	-	Mixing strength of the noise.
   Noise Scale	-	Scaling of the noise.
   Noise Speed	-	Scrolling speed of the noise.

3. (Optional step for transparent objects)

   Experimental support. The approximate effect is produced by rendering fog and transparent objects twice, which is not completely correct.

   1. Add a StandardFullScreenFogOverlayRenderer or your own renderer into your URP pipeline asset.
   2. Set up a Overlay camera on your Main Camera.
   3. Switch Renderer property to StandardFullScreenFogOverlayRenderer on the Overlay camera.

Performance

Use Rendering Debugger to evaluate time. Use the development build to run the SampleScene in the project at 2560*1440 resolution with Radeon RX 580.

Mode	Density Mode	Noise	Time(ms)
Depth	Linear	Off	~0.6
Depth	Exponential	Off	~0.6
Distance	Linear	Off	~0.6
Height	ExponentialSquared	Off	~0.6
Height	ExponentialSquared	Procedural	~0.8

This is a rough and not very accurate test, but you can know something about the approximate performance consumption.

Known issues

• In the case of using noise, if the Noise Scale is too large, the result may not be very good.

Todo

• Volume Fog

References

• URP Document
• Unity Shaders Book

License

This project is under the MIT License.