The precision problem of depth texture in unity shader - stepping pit - BRP pipeline (there is no solution, it is recommended to replace URP)

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Environmental Science

Unity: 2018.2.11f1
Pipeline: BRP
Platform : Android
Graphics API : OpenGL ES 3/+
Color Space : Linear

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problem

Some mobile devices GPU The accuracy is relatively low , Abnormal display that will lead to poor accuracy performance
（ Originally wanted to use RenderDoc, Snapdragon Profiler To check the real machine FB The format of , But these two tools are becoming less and less awesome , There are fewer and fewer real machine frame grabbing tools available in the market , Basically, what can be used now is only RenderDoc Catch PC,Intel GPA Catch PC,Snapdragon Profiler Only some applications of Qualcomm models can be grasped ： Must be turned on debuggable, read/write permission You have to open it to catch it , however Snapdragon Profiler very many BUG, often collapse 、 Flash back , or Unable to display Pixel History data , Now these big factories , Or are mainstream tools so awesome ？-_-!!!）

such as ：

• Soft particles and opaque Content fade Excessive abnormality
• Water body and opaque Content depth fade Excessive abnormality

（ After some testing , It can't be solved in the end , Fortunately, new projects in the future will use URP）

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test Shader Part of the code

// depth gradient control foam
float sceneZ = LinearEyeDepth(SAMPLE_DEPTH_TEXTURE_PROJ(_CameraDepthTexture, UNITY_PROJ_COORD(i.projPos)));
float fragZ = i.projPos.z;
// return sceneZ;
// return fragZ;
float detalZ = sceneZ-fragZ;
return saturate(detalZ); //  Here again ：oppo, vivo  Of low-end mobile phones , There will be a serious problem of precision loss , Lead to ,PC On   and   On low-end devices   The effect varies greatly 

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test C#

// jave.lin : 2022/06/29
//  test   The color of water depth is too abnormal 
//  Later, it was located as yes ： Depth accuracy problem 

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.UI;

public class Test_WaterReflectionError_Script : MonoBehaviour {
    

    public Text graphicsAPI_Text;
    // jave.lin :  Before my ： Unity -  Picture quality settings  https://blog.csdn.net/linjf520/article/details/123546253
    //  The print listed in the article 
    public static string DumpSystemInfoByManualyPrint()
    {
    
        var list = new List<string>(
            new string[]{
    
                "SystemInfo:\n",
                "\tbatteryLevel:" + SystemInfo.batteryLevel,
                "\tbatteryStatus:" + SystemInfo.batteryStatus,
                "\toperatingSystem:" + SystemInfo.operatingSystem,
                "\toperatingSystemFamily:" + SystemInfo.operatingSystemFamily,
                "\tprocessorType:" + SystemInfo.processorType,
                "\tprocessorFrequency:" + SystemInfo.processorFrequency,
                "\tprocessorCount:" + SystemInfo.processorCount,
                "\tsystemMemorySize:" + SystemInfo.systemMemorySize,
                "\tdeviceUniqueIdentifier:" + SystemInfo.deviceUniqueIdentifier,
                "\tdeviceName:" + SystemInfo.deviceName,
                "\tdeviceModel:" + SystemInfo.deviceModel,
                "\tsupportsAccelerometer:" + SystemInfo.supportsAccelerometer,
                "\tsupportsGyroscope:" + SystemInfo.supportsGyroscope,
                "\tsupportsLocationService:" + SystemInfo.supportsLocationService,
                "\tsupportsVibration:" + SystemInfo.supportsVibration,
                "\tsupportsAudio:" + SystemInfo.supportsAudio,
                "\tdeviceType:" + SystemInfo.deviceType,
                "\tgraphicsMemorySize:" + SystemInfo.graphicsMemorySize,
                "\tgraphicsDeviceName:" + SystemInfo.graphicsDeviceName,
                "\tgraphicsDeviceVendor:" + SystemInfo.graphicsDeviceVendor,
                "\tgraphicsDeviceID:" + SystemInfo.graphicsDeviceID,
                "\tgraphicsDeviceVendorID:" + SystemInfo.graphicsDeviceVendorID,
                "\tgraphicsDeviceType:" + SystemInfo.graphicsDeviceType,
                "\tgraphicsUVStartsAtTop:" + SystemInfo.graphicsUVStartsAtTop,
                "\tgraphicsDeviceVersion:" + SystemInfo.graphicsDeviceVersion,
                "\tgraphicsShaderLevel:" + SystemInfo.graphicsShaderLevel,
                "\tgraphicsMultiThreaded:" + SystemInfo.graphicsMultiThreaded,
                "\tsupportsShadows:" + SystemInfo.supportsShadows,
                "\tsupportsRawShadowDepthSampling:" + SystemInfo.supportsRawShadowDepthSampling,
                "\tsupportsMotionVectors:" + SystemInfo.supportsMotionVectors,
                "\tsupports3DTextures:" + SystemInfo.supports3DTextures,
                "\tsupports2DArrayTextures:" + SystemInfo.supports2DArrayTextures,
                "\tsupports3DRenderTextures:" + SystemInfo.supports3DRenderTextures,
                "\tsupportsCubemapArrayTextures:" + SystemInfo.supportsCubemapArrayTextures,
                "\tcopyTextureSupport:" + SystemInfo.copyTextureSupport,
                "\tsupportsComputeShaders:" + SystemInfo.supportsComputeShaders,
                "\tsupportsInstancing:" + SystemInfo.supportsInstancing,
                "\tsupportsHardwareQuadTopology:" + SystemInfo.supportsHardwareQuadTopology,
                "\tsupports32bitsIndexBuffer:" + SystemInfo.supports32bitsIndexBuffer,
                "\tsupportsSparseTextures:" + SystemInfo.supportsSparseTextures,
                "\tsupportedRenderTargetCount:" + SystemInfo.supportedRenderTargetCount,
                "\tsupportsMultisampledTextures:" + SystemInfo.supportsMultisampledTextures,
                "\tsupportsMultisampleAutoResolve:" + SystemInfo.supportsMultisampleAutoResolve,
                "\tsupportsTextureWrapMirrorOnce:" + SystemInfo.supportsTextureWrapMirrorOnce,
                "\tusesReversedZBuffer:" + SystemInfo.usesReversedZBuffer,
                "\tnpotSupport:" + SystemInfo.npotSupport,
                "\tmaxTextureSize:" + SystemInfo.maxTextureSize,
                "\tmaxCubemapSize:" + SystemInfo.maxCubemapSize,
                "\tsupportsAsyncCompute:" + SystemInfo.supportsAsyncCompute,
                "\tsupportsAsyncGPUReadback:" + SystemInfo.supportsAsyncGPUReadback,
                "\tsupportsMipStreaming:" + SystemInfo.supportsMipStreaming,
            });
        return string.Join("\n", list.ToArray());
    }

    // jave.lin :  Now let's debug , Only part of it is needed 
    public static string MyDump()
    {
    
        var list = new List<string>(
            new string[]{
    
                "SystemInfo:\n",
                "\toperatingSystem:" + SystemInfo.operatingSystem,
                "\toperatingSystemFamily:" + SystemInfo.operatingSystemFamily,
                "\tdeviceName:" + SystemInfo.deviceName,
                "\tdeviceType:" + SystemInfo.deviceType,
                "\tgraphicsMemorySize:" + SystemInfo.graphicsMemorySize,
                "\tgraphicsDeviceName:" + SystemInfo.graphicsDeviceName,
                "\tgraphicsDeviceVendor:" + SystemInfo.graphicsDeviceVendor,
                "\tgraphicsDeviceType:" + SystemInfo.graphicsDeviceType,
                "\tgraphicsDeviceVersion:" + SystemInfo.graphicsDeviceVersion,
                "\tgraphicsShaderLevel:" + SystemInfo.graphicsShaderLevel,
                "\tsupportsComputeShaders:" + SystemInfo.supportsComputeShaders,
                "\tsupportsInstancing:" + SystemInfo.supportsInstancing,
                "\tusesReversedZBuffer:" + SystemInfo.usesReversedZBuffer,
            });
        return string.Join("\n", list.ToArray());
    }

    // Use this for initialization
    void Start () {
    
        graphicsAPI_Text.text = MyDump();
    }
}

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Performance in each device

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Unity Editing

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In the night God Simulator

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millet 10

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OPPO A5

You can see OPPO A5 It shows an exception

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BRP There is no relevant solution in

After all BRP It is not recommended in the future
So this problem , Recommended or used URP

I wanted to see it project setting Medium graphics, quality Whether there is relevant depth precision setting , After some searching and project configuration searching , No relevant content was found

• goolgle : how to improve precision in unity shaderlab

And then in In official documents Cameras and depth textures Find some precision related instructions

Found configuration ：

• ProjectSetting->Player->OtherSetting->Rendering - There's no correlation
• ProjectSetting->Player->OtherSetting->Resolution and Presentation - There's no correlation
• ProjectSetting->Graphics Next try to put all Tier Settings All set to the highest , Not good either.
• Shader Add ：#pragma fragmentoption ARB_precision_hint_nicest Not good either.
• Shader Revision in China _CameraDepthTexture by float The texture sampler settings are also not good , such as ：uniform sampler2D_float _CameraDepthTexture;

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URP There are solutions in

The question is In the early URP There are also , For example, this post ：Android depth texture precision issue. - The Lord is to ：Unity 2019.3.6f1 URP 7.2.1, stay URP：7.4.1 Repair the

Is probably ：application layer , Yes _CameraDepthTexture Texture object format settings （ Precision setting ）

also shader Precision declaration in

stay BRP There is no corresponding controllability in , This is in URP Can be controlled , therefore URP Can solve this problem

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in addition , The high version of the unity I also saw ：shader precision mode Set up

Here is ：2022.1.4f1 The screenshots

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Cause these accuracy problems , Generally, it is also related to Camera Of Near section , Far section The difference between , The greater the difference , Then the more likely it is to have this problem

And this project before I came , The scale of their models and other related productions are abnormal , such as ：500 scale,x,y,z

then Camera Of near plane, far plane Can only be set very large , such as ：near : 0.1, far : 10000, Then the value of precision must be greatly limited

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References

• Android depth texture precision issue. - The Lord is to ：Unity 2019.3.6f1 URP 7.2.1, stay URP：7.4.1 Repair the