Unity-ScreenSpaceReflections-URP

SSR solution for Unity URP. Supports Linear Tracing and Hi Z tracing. The package includes SSR render feature and Hierarchical Min-Z Depth Buffer render feature.

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Images Requirements:

• Unity URP 12 or newer

• Unity 2021 LTS or newer

!Does not support VR!

Installation Instructions:

1. Copy: "https://github.com/JoshuaLim007/Unity-ScreenSpaceReflections-URP.git"
2. Go into the package manager in unity
3. Select "add package from git url"
4. Paste the link into the text entry
5. Press "add"

In your URP Asset

Tracing Modes

• Linear Tracing
• Hi-Z Tracing

Hi Z tracing requires "Depth Pyramid" render feature to be added in the pipeline asset. The Depth Pyramid is included in this package.

API:

Changing settings during runtime

void LimSSR.SetSettings(ScreenSpaceReflectionsSettings o)

• o.StepStrideLength = The length of each ray march stride. Increasing this will reduce image quality but allow for further objects to be visible in the reflections.
• o.MaxSteps = The number of steps the shader does before ending the ray march. Increasing this will allow further objects to be visible in the reflections but reduce performance.
• o.Downsample = The number of times the working resolution is downscaled. Increasing this will reduce image quality but increase performance.
• o.MinSmoothness = The minimum smoothness of a material has to be in order to have reflections.

For the best quality, try to minimize StepStrideLength and maximize MaxSteps

bool LimSSR.Enabled

• True: Enables effect
• False: Disables effect

Enables or disables the SSR shader

static RaytraceModes TracingMode

Sets the tracing mode: Linear tracing, or Hi Z tracing

Known Limitations and bugs

• Wider apart the near and far clip plane, more banding artifact appears.
• Far reflections are inaccurate and have banding artifact.
• Making the hi-z trace more accurate causes triangle like artifacts to appear.
• Non-power of 2 resolution are the core cause of the artifacts to appear. Current implementation does not handle non-power of 2 resolutions correctly.
• Transparent objects cannot have reflections.
• Transparent objects are not correctly reflected onto objects.
• Downsampling ssr on hi-trace mode causes it to break.
• Current fix for non-power of 2 resolutions causes warping around edges of objects with a reflection behind it.
• Hi-z trace cannot have camera facing reflections.

Resources and References

Screen Space Reflection | 3D Game Shaders For Beginners (lettier.github.io)

Screen Space Reflections : Implementation and optimization – Part 1 : Linear Tracing Method – Sugu Lee (wordpress.com)

Screen Space Reflections : Implementation and optimization – Part 2 : HI-Z Tracing Method – Sugu Lee (wordpress.com)

bitsquid: development blog: Notes On Screen Space HIZ Tracing

Screen Space Reflections in Killing Floor 2 (sakibsaikia.github.io)

Hierarchical Depth Buffers - Mike Turitzin