Shader教程：基于高度的雾效实现
发表于2018-03-28
学习Unity的都知道，Unity可以进行基本的雾效模拟，其中Unity里设置雾效有两种方式，一种最简单的就是直接开启全局雾效，也就是在Edit->Render Settings里配置。本篇文章就和大家介绍下基于高度的雾效实现。
代码如下：
using UnityEngine;
using System.Collections;
[ExecuteInEditMode]
[RequireComponent (typeof(Camera))]
public class PostEffectsBase : MonoBehaviour ｛
protected void Start() ｛
CheckResources();
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// Called when start
protected void CheckResources() ｛
bool isSupported = CheckSupport();
if (isSupported == false) ｛
NotSupported();
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// Called in CheckResources to check support on this platform
protected bool CheckSupport() ｛
if (SystemInfo.supportsImageEffects == false || SystemInfo.supportsRenderTextures == false) ｛
Debug.LogWarning("This platform does not support image effects or render textures.");
return false;
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return true;
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// Called when the platform doesn't support this effect
protected void NotSupported() ｛
enabled = false;
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// Called when need to create the material used by this effect
protected Material CheckShaderAndCreateMaterial(Shader shader, Material material) ｛
if (shader == null) ｛
return null;
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if (shader.isSupported && material && material.shader == shader)
return material;
if (!shader.isSupported) ｛
return null;
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else ｛
material = new Material(shader);
material.hideFlags = HideFlags.DontSave;
if (material)
return material;
else
return null;
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using UnityEngine;
using System.Collections;
public class FogWithDepthTexture : PostEffectsBase ｛
public Shader fogShader;
private Material fogMaterial = null;
public Material material ｛
get ｛
fogMaterial = CheckShaderAndCreateMaterial(fogShader, fogMaterial);
return fogMaterial;
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private Camera myCamera;
public Camera camera ｛
get ｛
if (myCamera == null) ｛
myCamera = GetComponent<Camera>();
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return myCamera;
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private Transform myCameraTransform;
public Transform cameraTransform ｛
get ｛
if (myCameraTransform == null) ｛
myCameraTransform = camera.transform;
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return myCameraTransform;
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[Range(0.0f, 3.0f)]
public float fogDensity = 1.0f;
public Color fogColor = Color.white;
public float fogStart = 0.0f;
public float fogEnd = 2.0f;
void OnEnable() ｛
camera.depthTextureMode |= DepthTextureMode.Depth;
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void OnRenderImage (RenderTexture src, RenderTexture dest) ｛
if (material != null) ｛
Matrix4x4 frustumCorners = Matrix4x4.identity;
float fov = camera.fieldOfView;
float near = camera.nearClipPlane;
float aspect = camera.aspect;
float halfHeight = near * Mathf.Tan(fov * 0.5f * Mathf.Deg2Rad);
Vector3 toRight = cameraTransform.right * halfHeight * aspect;
Vector3 toTop = cameraTransform.up * halfHeight;
Vector3 topLeft = cameraTransform.forward * near + toTop - toRight;
float scale = topLeft.magnitude / near;
topLeft.Normalize();
topLeft *= scale;
Vector3 topRight = cameraTransform.forward * near + toRight + toTop;
topRight.Normalize();
topRight *= scale;
Vector3 bottomLeft = cameraTransform.forward * near - toTop - toRight;
bottomLeft.Normalize();
bottomLeft *= scale;
Vector3 bottomRight = cameraTransform.forward * near + toRight - toTop;
bottomRight.Normalize();
bottomRight *= scale;
frustumCorners.SetRow(0, bottomLeft);
frustumCorners.SetRow(1, bottomRight);
frustumCorners.SetRow(2, topRight);
frustumCorners.SetRow(3, topLeft);
material.SetMatrix("_FrustumCornersRay", frustumCorners);
material.SetFloat("_FogDensity", fogDensity);
material.SetColor("_FogColor", fogColor);
material.SetFloat("_FogStart", fogStart);
material.SetFloat("_FogEnd", fogEnd);
Graphics.Blit (src, dest, material);
｝ else ｛
Graphics.Blit(src, dest);
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Shader "Fog With Depth Texture" ｛
Properties ｛
_MainTex ("Base (RGB)", 2D) = "white" ｛｝
_FogDensity ("Fog Density", Float) = 1.0
_FogColor ("Fog Color", Color) = (1, 1, 1, 1)
_FogStart ("Fog Start", Float) = 0.0
_FogEnd ("Fog End", Float) = 1.0
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SubShader ｛
CGINCLUDE
#include "UnityCG.cginc"
// 脚本传递过来这个参数
// (0, bottomLeft);
// (1, bottomRight);
// (2, topRight);
// (3, topLeft);
float4x4 _FrustumCornersRay;
sampler2D _MainTex;
half4 _MainTex_TexelSize;
sampler2D _CameraDepthTexture;
half _FogDensity;
fixed4 _FogColor;
float _FogStart;
float _FogEnd;
struct v2f ｛
float4 pos : SV_POSITION;
half2 uv : TEXCOORD0;
half2 uv_depth : TEXCOORD1;
// 保存了插值后的像素向量
float4 interpolatedRay : TEXCOORD2;
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v2f vert(appdata_img v) ｛
v2f o;
o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
o.uv = v.texcoord;
o.uv_depth = v.texcoord;
// unity左下角0,0 右上角1,1
//判断是否是directx平台，如果开启了抗锯齿，如果此时使用了渲染到纹理技术
//那么此时纹理不会翻转，在顶点着色器中加入这样的处理
#if UNITY_UV_STARTS_AT_TOP
if (_MainTex_TexelSize.y < 0)
o.uv_depth.y = 1 - o.uv_depth.y;
#endif
int index = 0;
if (v.texcoord.x < 0.5 && v.texcoord.y < 0.5) ｛
index = 0;
｝ else if (v.texcoord.x > 0.5 && v.texcoord.y < 0.5) ｛
index = 1;
｝ else if (v.texcoord.x > 0.5 && v.texcoord.y > 0.5) ｛
index = 2;
｝ else ｛
index = 3;
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#if UNITY_UV_STARTS_AT_TOP
if (_MainTex_TexelSize.y < 0)
index = 3 - index;
#endif
// 插值后的像素向量
o.interpolatedRay = _FrustumCornersRay[index];
return o;
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fixed4 frag(v2f i) : SV_Target ｛
// LinearEyeDepth：视角空间下的线性深度值，
// SAMPLE_DEPTH_TEXTURE：深度纹理采样
float linearDepth = LinearEyeDepth(SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, i.uv_depth));
// 1.摄像机的世界空间中的位置
// 2.空间世界下该像素相对于摄像机的偏移量，把他们相加，得到的就是该像素的世界坐标
float3 worldPos = _WorldSpaceCameraPos + linearDepth * i.interpolatedRay.xyz;
// 雾的浓度
float fogDensity = (_FogEnd - worldPos.y) / (_FogEnd - _FogStart);
// 限制到0~1之间
fogDensity = saturate(fogDensity * _FogDensity);
fixed4 finalColor = tex2D(_MainTex, i.uv);
// 雾的浓度=0的时候，显示原颜色
finalColor.rgb = lerp(finalColor.rgb, _FogColor.rgb, fogDensity);
return finalColor;
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ENDCG
Pass ｛
ZTest Always Cull Off ZWrite Off
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
ENDCG
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FallBack Off
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