Unity Shader学习：SSAO屏幕环境光遮蔽

主要思路：1.随机采样像素法线半球周围的像素，平均对比与该像素深度是否处在暗处。2.双边滤波去噪点。3.后期AO图与原图混合。

原文链接:https://blog.csdn.net/puppet_master/article/details/82929708

无AO

有AO

AO图

c#部分:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class SSAO : MonoBehaviour {public Material SSAOMaterial;private List<Vector4> sampleKernelList = new List<Vector4>();[Range(0f, 0.002f)]public float depthBiasValue = 0f;[Range(0.01f, 1f)]public float sampleKernelRadius = 1.0f;[Range(4,32)]public int sampleKernelCount = 16;[Range(0.0f, 5.0f)]public float AOStrength = 1.0f;[Range(0, 2)]public int downSample = 0;[Range(1, 4)]public int blurRadius = 1;[Range(0f, 0.2f)]public float bilateralFilterStrength = 0.2f;public bool onlyShowAO = false;public enum SSAOPassName{GenerateAO=0,BilateralFilter=1,Composite=2}private Camera currentCamera;void Start () {currentCamera = Camera.main;currentCamera.depthTextureMode = DepthTextureMode.DepthNormals;}private void OnRenderImage(RenderTexture source, RenderTexture destination){//采样点生成GenerateAOSampleKernel();RenderTexture aoRT = RenderTexture.GetTemporary(source.width >> downSample, source.height >> downSample, 0);SSAOMaterial.SetMatrix("_InverseProjectionMatrix", currentCamera.projectionMatrix.inverse);SSAOMaterial.SetFloat("_DepthBiasValue", depthBiasValue);SSAOMaterial.SetVectorArray("_SampleKernelArray", sampleKernelList.ToArray());SSAOMaterial.SetFloat("_SampleKernelCount", sampleKernelList.Count);SSAOMaterial.SetFloat("_AOStrength", AOStrength);SSAOMaterial.SetFloat("_SampleKernelRadius", sampleKernelRadius);Graphics.Blit(source, aoRT, SSAOMaterial, (int)SSAOPassName.GenerateAO);RenderTexture blurRT = RenderTexture.GetTemporary(source.width >> downSample, source.height >> downSample, 0);SSAOMaterial.SetFloat("_BilaterFilterFactor", 1.0f - bilateralFilterStrength);SSAOMaterial.SetVector("_BlurRadius", new Vector4(blurRadius, 0, 0, 0));Graphics.Blit(aoRT, blurRT, SSAOMaterial, (int)SSAOPassName.BilateralFilter);SSAOMaterial.SetVector("_BlurRadius", new Vector4(0, blurRadius, 0, 0));if (onlyShowAO){Graphics.Blit(blurRT, destination, SSAOMaterial, (int)SSAOPassName.BilateralFilter);}else{Graphics.Blit(blurRT, aoRT, SSAOMaterial, (int)SSAOPassName.BilateralFilter);SSAOMaterial.SetTexture("_AOTex", aoRT);Graphics.Blit(source, destination, SSAOMaterial, (int)SSAOPassName.Composite);}RenderTexture.ReleaseTemporary(aoRT);RenderTexture.ReleaseTemporary(blurRT);}private void GenerateAOSampleKernel(){if (sampleKernelCount==sampleKernelList.Count){return;}sampleKernelList.Clear();for (int i = 0; i < sampleKernelCount; i++){Vector4 vec = new Vector4(Random.Range(-1f, 1f), Random.Range(-1f, 1f), Random.Range(-1f, 1f), 1f);vec.Normalize();float scale = ((float)i) / sampleKernelCount;//调整分布的曲线scale = Mathf.Lerp(0.01f, 1.0f, scale * scale);vec *= scale;sampleKernelList.Add(vec);}}
}

shader部分:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class SSAO : MonoBehaviour {public Material SSAOMaterial;private List<Vector4> sampleKernelList = new List<Vector4>();[Range(0f, 0.002f)]public float depthBiasValue = 0f;[Range(0.01f, 1f)]public float sampleKernelRadius = 1.0f;[Range(4,32)]public int sampleKernelCount = 16;[Range(0.0f, 5.0f)]public float AOStrength = 1.0f;[Range(0, 2)]public int downSample = 0;[Range(1, 4)]public int blurRadius = 1;[Range(0f, 0.2f)]public float bilateralFilterStrength = 0.2f;public bool onlyShowAO = false;public enum SSAOPassName{GenerateAO=0,BilateralFilter=1,Composite=2}private Camera currentCamera;void Start () {currentCamera = Camera.main;currentCamera.depthTextureMode = DepthTextureMode.DepthNormals;}private void OnRenderImage(RenderTexture source, RenderTexture destination){//采样点生成GenerateAOSampleKernel();RenderTexture aoRT = RenderTexture.GetTemporary(source.width >> downSample, source.height >> downSample, 0);SSAOMaterial.SetMatrix("_InverseProjectionMatrix", currentCamera.projectionMatrix.inverse);SSAOMaterial.SetFloat("_DepthBiasValue", depthBiasValue);SSAOMaterial.SetVectorArray("_SampleKernelArray", sampleKernelList.ToArray());SSAOMaterial.SetFloat("_SampleKernelCount", sampleKernelList.Count);SSAOMaterial.SetFloat("_AOStrength", AOStrength);SSAOMaterial.SetFloat("_SampleKernelRadius", sampleKernelRadius);Graphics.Blit(source, aoRT, SSAOMaterial, (int)SSAOPassName.GenerateAO);RenderTexture blurRT = RenderTexture.GetTemporary(source.width >> downSample, source.height >> downSample, 0);SSAOMaterial.SetFloat("_BilaterFilterFactor", 1.0f - bilateralFilterStrength);SSAOMaterial.SetVector("_BlurRadius", new Vector4(blurRadius, 0, 0, 0));Graphics.Blit(aoRT, blurRT, SSAOMaterial, (int)SSAOPassName.BilateralFilter);SSAOMaterial.SetVector("_BlurRadius", new Vector4(0, blurRadius, 0, 0));if (onlyShowAO){Graphics.Blit(blurRT, destination, SSAOMaterial, (int)SSAOPassName.BilateralFilter);}else{Graphics.Blit(blurRT, aoRT, SSAOMaterial, (int)SSAOPassName.BilateralFilter);SSAOMaterial.SetTexture("_AOTex", aoRT);Graphics.Blit(source, destination, SSAOMaterial, (int)SSAOPassName.Composite);}RenderTexture.ReleaseTemporary(aoRT);RenderTexture.ReleaseTemporary(blurRT);}private void GenerateAOSampleKernel(){if (sampleKernelCount==sampleKernelList.Count){return;}sampleKernelList.Clear();for (int i = 0; i < sampleKernelCount; i++){Vector4 vec = new Vector4(Random.Range(-1f, 1f), Random.Range(-1f, 1f), Random.Range(-1f, 1f), 1f);vec.Normalize();float scale = ((float)i) / sampleKernelCount;//调整分布的曲线scale = Mathf.Lerp(0.01f, 1.0f, scale * scale);vec *= scale;sampleKernelList.Add(vec);}}
}

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