【Unity】RenderFeature应用（简单场景扫描效果）
RenderFeature 是一个用于渲染图形的概念，通常在图形引擎或游戏引擎中使用。它是一个模块化的组件，负责处理特定的渲染功能，例如阴影、光照、粒子效果等。
点击地面生成一个不断扩展的圆光效果，用于实现一些画面的特效
实现效果
一、实现方法
1.要求和原理
案例是基于unity urp渲染管线制作，使用了RenderFeature后处理效果。
基本原理一句话，通过相机深度图重建像素的世界空间位置，空间坐标和点击点的坐标进行距离运算画出圆。
2.实现步骤
1）创建UniversalRenderPipelineAsset
在编写RenderFeature前需要创建UniversalRenderPipelineAsset
Create→Randering→URPAsset（with Universal Render）
创建后会同时生成UniversalRenderPipelineAsset和UniversalRenderData
动态设置当前UniversalRenderPipelineAsset的方法（也可以手动设置）
c#
//使用的UniversalRenderPipelineAsset
public UniversalRenderPipelineAsset UniversalRenderPipelineAsset;
void Start()
{
//分别在Graphics和 Quality里设置成使用的UniversalRenderPipelineAsset
GraphicsSettings.renderPipelineAsset = UniversalRenderPipelineAsset;
QualitySettings.renderPipeline = UniversalRenderPipelineAsset;
}2）编写RenderFeature
创建RenderFeature，具体介绍可以参见【Unity】RenderFeature笔记
Create→Randering→RenderFeature
下面是通用的shader后处理方法，不同的是参数内容和方法
c#
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;
public class ScanRenderPassFeature : ScriptableRendererFeature
{
class CustomRenderPass : ScriptableRenderPass
{
public Material _Material;
public Vector4 _Pos;//点击点
public Color _Color;//线颜色
public float _Interval;//线间距
public float _Strength;//强度范围
public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
{
// Matrix4x4 frustumCorners = GetFrustumCornersRay();
CommandBuffer cmd = CommandBufferPool.Get("ScanRender");
_Material.SetVector("_CentorPoint", _Pos);
_Material.SetColor("_Color", _Color);
_Material.SetFloat("_Interval", _Interval);
_Material.SetFloat("_Strength", _Strength);
cmd.Blit(colorAttachment, RenderTargetHandle.CameraTarget.Identifier(), _Material);
//执行CommandBuffer
context.ExecuteCommandBuffer(cmd);
//回收CommandBuffer
CommandBufferPool.Release(cmd);
}
}
CustomRenderPass m_ScriptablePass;
public Shader ScanShader;
public Vector4 Pos;
public Color Color;
public float Interval;//间距
public float Strength;//强度
/// <inheritdoc/>
public override void Create()
{
m_ScriptablePass = new CustomRenderPass();
m_ScriptablePass._Material = new Material(ScanShader);
m_ScriptablePass._Pos = Pos;
m_ScriptablePass._Color = Color;
m_ScriptablePass._Interval = Interval;
m_ScriptablePass._Strength = Strength;
// Configures where the render pass should be injected.
m_ScriptablePass.renderPassEvent = RenderPassEvent.AfterRendering;
}
public void SetParam()
{
m_ScriptablePass._Pos = Pos;
m_ScriptablePass._Strength = Strength;
}
public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
{
renderer.EnqueuePass(m_ScriptablePass);
}
}3）编写shader
shader要实现的是两个功能，一是深度图重建像素的世界空间位置，再是根据空间位置画出扩展圆
重建像素的世界空间位置可以参照官方的案例
从深度纹理重建像素的世界空间位置 |URP |7.7.1 (unity3d.com)
核心方法：
ComputeWorldSpacePosition：是一个用于计算物体在世界空间中位置的函数。它通常用于计算游戏中的物体 在世界坐标系中的位置。
SampleSceneDepth：用于获取深度图像。它主要用于实现一些基本的深度相关功能，比如观察场景中物体深 度信息、计算物体之间的距离等。
下面结合官方的方法进行修改
c
Shader "Unlit/ScanShaderURP"
{
Properties
{
_CentorPoint("CentrePoint",Vector) = (0, 0, 0, 0)
_Color("color",Color) = (1,1,1,1) //颜色
}
SubShader
{
Tags { "RenderType"="Opaque" }
LOD 100
Pass
{
HLSLPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DeclareDepthTexture.hlsl"
struct Attributes
{
float4 positionOS : POSITION;
};
struct Varyings
{
float4 positionHCS : SV_POSITION;
};
float4x4 _FrustumCornersRay;
float _Interval;//间距
float _Strength;//强度
sampler2D _CameraColorTexture;
float4 _CentorPoint;
float4 _Color;
Varyings vert(Attributes IN)
{
Varyings OUT;
OUT.positionHCS = TransformObjectToHClip(IN.positionOS.xyz);
return OUT;
}
half4 frag(Varyings IN) : SV_Target
{
//uv变换
float2x2 muls = float2x2(-1, 0, 0, 1);
float2 centerUV = float2(1, 0);
float2 UV =1-( mul(( IN.positionHCS.xy / _ScaledScreenParams.xy), muls)+centerUV);
//获取深度图
#if UNITY_REVERSED_Z
real depth = SampleSceneDepth(UV);
#else
real depth = lerp(UNITY_NEAR_CLIP_VALUE, 1, SampleSceneDepth(UV));
#endif
//获取世界坐标位置
float3 worldPos = ComputeWorldSpacePosition(UV, depth, UNITY_MATRIX_I_VP);
half4 col2 = tex2D(_CameraColorTexture, UV);
float lerpValue = 0;
//对截面外的空间进行屏蔽
if (depth < _ProjectionParams.z - 1) {
float Mul = distance(_CentorPoint.xyz, worldPos.xyz);
//change控制圈的距离
float change = _Strength;
//Mul的值是一定大于0的
//第一个smoothstep小于change的值裁剪为0，大于_Interval + change的为1
//第二个smoothstep大于_Interval + change的为1，小于的为0
//两smoothstep相减得到0 + change和 _Interval + change距离间0到1的变化，其余为0
float lerp1 = smoothstep(0 + change, _Interval + change, Mul);
float lerp2 = smoothstep(_Interval + change, _Interval + change, Mul);
float dis = lerp1 - lerp2;
lerpValue = dis;
}
half4 myCol = lerp(col2, _Color, lerpValue);
return myCol;
}
ENDHLSL
}
}
}4）控制方法
c#
using System.Linq;
using UnityEngine;
using UnityEngine.Rendering.Universal;
public class ScanControl : MonoBehaviour
{
public UniversalRendererData renderData;
ScanRenderPassFeature custom;
private void Start()
{
custom = renderData.rendererFeatures.OfType<ScanRenderPassFeature>().FirstOrDefault();
}
private void Update()
{
if (Input.GetMouseButtonDown(1))
{
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
RaycastHit hit;
if (Physics.Raycast(ray, out hit))
{
Vector3 vector = hit.point;
Vector4 vector4 = new Vector4(vector.x, vector.y, vector.z, 1);
custom.Pos = vector4;
custom.Strength = 0;
}
}
}
private void LateUpdate()
{
custom.Strength += Time.deltaTime*10;
custom.SetParam();
}
}3.在built-in里的实现方法
shader
c
Shader "Unlit/ScanShaderBuiltIn"
{
Properties
{
_MainTex("Base (RGB)", 2D) = "white" {} // 主纹理
_CentorPoint("CentrePoint",Vector) = (0, 0, 0, 0)
_Color("color",Color) = (1,1,1,1) //颜色，一般用fixed4
_InverseZ("InverseZ", Float) = -1
}
SubShader
{
Tags { "RenderType"="Opaque" }
LOD 100
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
};
struct v2f
{
float2 uv : TEXCOORD0;
float4 pos : SV_POSITION;
float3 viewVec :TEXCOORD1;
};
sampler2D _MainTex; // 主纹理
float _Interval;//间距
float _Strength;//强度
float _InverseZ;
sampler2D _CameraColorTexture;
sampler2D _CameraDepthTexture;
float4 _CentorPoint;
fixed4 _Color;
v2f vert (appdata v)
{
v2f o;
o.uv = v.uv;
o.pos = UnityObjectToClipPos(v.vertex); //MVP变换
float4 screenPos = ComputeScreenPos(o.pos); // 计算"齐次空间"下的屏幕坐标
// float4 ndcPos = (screenPos / screenPos.w) * 2 - 1; //屏幕坐标--->ndc坐标变换公式
// float4 ndcPos = o.pos / o.pos.w; //手动进行透视除法
float3 ndcPos = float3(o.uv.xy * 2.0 - 1.0, 1); //直接把uv映射到ndc坐标
float far = _ProjectionParams.z; //获取投影信息的z值，代表远平面距离
float3 clipVec = float3(ndcPos.x, ndcPos.y, ndcPos.z * _InverseZ) * far; //裁切空间下的视锥顶点坐标
o.viewVec = mul(unity_CameraInvProjection, clipVec.xyzz).xyz; //观察空间下的视锥向量
return o;
}
fixed4 frag (v2f i) : SV_Target
{
fixed4 col2 = tex2D(_MainTex, i.uv);
// fixed4 col2 = tex2D(_CameraColorTexture, i.uv);
float depth = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture,i.uv);//采样深度图
depth = Linear01Depth(depth); //转换为线性深度
float3 viewPos = i.viewVec * depth; //获取实际的观察空间坐标（插值后）
float3 worldPos = mul(unity_CameraToWorld, float4(viewPos,1)).xyz; //观察空间-->世界空间坐标
float factor = 0;
if (depth < _ProjectionParams.z - 1) {
float Mul = distance(_CentorPoint.xyz, worldPos.xyz);
float change = _Strength;
//Mul的值是一定大于0的
//第一个smoothstep小于change的值裁剪为0，大于_Interval + change的为1
//第二个smoothstep大于_Interval + change的为1，小于的为0
//两smoothstep相减得到0 + change和 _Interval + change距离间0到1的变化，其余为0
float lerp1 = smoothstep(0 + change, _Interval + change, Mul);
float lerp2 = smoothstep(_Interval + change, _Interval + change, Mul);
float dis = lerp1 - lerp2;
float lerpDis = smoothstep(0.99, 1, dis);
factor = dis;
}
fixed4 myCol = lerp(col2, _Color, factor);
return myCol;
}
ENDCG
}
}
}控制脚本
c#
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class ScanManager : MonoBehaviour
{
[SerializeField]
private bool enableWave = false; // 是否开启扫描特效
[SerializeField]
private Shader scanShader;
private Material material = null; // 材质
Vector4 _Pos=Vector4.zero;
public Color _Color;
float _Interval=1;//间距
float _Strength=0;//强度
// Start is called before the first frame update
void Start()
{
material = new Material(scanShader);
}
// Update is called once per frame
void Update()
{
if (Input.GetMouseButtonDown(1))
{
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
RaycastHit hit;
if (Physics.Raycast(ray, out hit))
{
Vector3 vector = hit.point;
Vector4 vector4 = new Vector4(vector.x, vector.y, vector.z, 1);
Debug.Log(vector4);
_Pos = vector4;
_Strength = 0;
enableWave = true;
}
}
}
private void OnRenderImage(RenderTexture src, RenderTexture dest)
{
if (enableWave)
{
_Strength += Time.deltaTime * 10;
material.SetVector("_CentorPoint", _Pos);
material.SetColor("_Color", _Color);
material.SetFloat("_Interval", _Interval);
material.SetFloat("_Strength", _Strength);
Graphics.Blit(src, dest, material);
}
else
{
Graphics.Blit(src, dest);
}
}
}