首先声明以下素材和shader代码都来自Kerry佬，我只做整理和学习之用，写此随笔是为了做个笔记方便以后查阅。
IBL，英文全称Image Based Lighting，即基于图像的照明，是一种通过采样图片从而模拟出光照的技术。
IBL不需要在shader中进行直接光源的光照计算，而是将周围环境提前做成一个CubeMap，或者用反射探针在unity中烘焙好。
采样CubeMap时，可根据粗糙度贴图等生成动态mipmap值，根据mipmap值来采样CubeMap，从而模拟出如金属表面有污渍的效果。
IBL镜面反射和漫反射都可模拟，两者区别在于：
1. 如下图，镜面反射选择Specular，漫反射选择Diffuse。
2. 当采样CubeMap时，镜面反射还是用视角方向基于法线的反射向量来采样，漫反射则可使用法线方向来采样。
shader如下：
1 Shader "MyURP/Kerry/IBL/URPIBLProbe"
2 {
3 Properties
4 {
5 //_MainTex ("Texture", 2D) = "white" {}
6 _CubeMap("Cube Map",Cube) = "white"{}
7 _Tint("Tint",Color) = (1,1,1,1)
8 _Expose("Expose",Float) = 1.0
9 _Rotate("Rotate",Range(0,360)) = 0
10 _NormalMap("Normal Map",2D) = "bump"{}
11 _NormalIntensity("Normal Intensity",Float) = 1.0
12 _AOMap("AO Map",2D) = "white"{}
13 _AOAdjust("AO Adjust",Range(0,1)) = 1
14 _RoughnessMap("Roughness Map",2D) = "black"{}
15 _RoughnessContrast("Roughness Contrast",Range(0.01,10)) = 1
16 _RoughnessBrightness("Roughness Brightness",Float) = 1
17 _RoughnessMin("Rough Min",Range(0,1)) = 0
18 _RoughnessMax("Rough Max",Range(0,1)) = 1
19 }
20 SubShader
21 {
22 Tags
23 {
24 "RenderType" = "Opaque"
25 "RenderPipeling" = "UniversalPipeline"
26 }
27 LOD 100
28
29 Pass
30 {
31 HLSLPROGRAM
32 #pragma vertex vert
33 #pragma fragment frag
34 #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
35 #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
36
37 struct appdata
38 {
39 float4 vertex : POSITION;
40 float2 texcoord : TEXCOORD0;
41 float3 normal : NORMAL;
42 float4 tangent : TANGENT;
43 };
44
45 struct v2f
46 {
47 float2 uv : TEXCOORD0;
48 float4 pos : SV_POSITION;
49 float3 normal_world : TEXCOORD1;
50 float3 pos_world : TEXCOORD2;
51 float3 tangent_world : TEXCOORD3;
52 float3 binormal_world : TEXCOORD4;
53 };
54
55 //sampler2D _MainTex;
56 //float4 _MainTex_ST;
57 TEXTURECUBE(_CubeMap); SAMPLER(sampler_CubeMap);
58 float4 _Tint;
59 float _Expose;
60
61 TEXTURE2D(_NormalMap); SAMPLER(sampler_NormalMap);
62 float4 _NormalMap_ST;
63 float _NormalIntensity;
64 TEXTURE2D(_AOMap); SAMPLER(sampler_AOMap);
65 float _AOAdjust;
66 float _Rotate;
67 float _Roughness;
68 TEXTURE2D(_RoughnessMap); SAMPLER(sampler_RoughnessMap);
69 float _RoughnessContrast;
70 float _RoughnessBrightness;
71 float _RoughnessMin;
72 float _RoughnessMax;
73
74 float3 RotateAround(float degree, float3 target)
75 {
76 float rad = degree * PI / 180;
77 float2x2 m_rotate = float2x2(cos(rad), -sin(rad),
78 sin(rad), cos(rad));
79 float2 dir_rotate = mul(m_rotate, target.xz);
80 target = float3(dir_rotate.x, target.y, dir_rotate.y);
81 return target;
82 }
83
84 inline float3 ACES_Tonemapping(float3 x)
85 {
86 float a = 2.51f;
87 float b = 0.03f;
88 float c = 2.43f;
89 float d = 0.59f;
90 float e = 0.14f;
91 float3 encode_color = saturate((x*(a*x + b)) / (x*(c*x + d) + e));
92 return encode_color;
93 };
94
95 v2f vert (appdata v)
96 {
97 v2f o;
98 o.pos = TransformObjectToHClip(v.vertex.xyz);
99 o.uv = v.texcoord * _NormalMap_ST.xy + _NormalMap_ST.zw;
100 o.pos_world = mul(unity_ObjectToWorld, v.vertex).xyz;
101 o.normal_world = normalize(mul(float4(v.normal, 0.0), unity_WorldToObject).xyz);
102 o.tangent_world = normalize(mul(unity_ObjectToWorld, float4(v.tangent.xyz, 0.0)).xyz);
103 o.binormal_world = normalize(cross(o.normal_world, o.tangent_world)) * v.tangent.w;
104 return o;
105 }
106
107 half4 frag (v2f i) : SV_Target
108 {
109 half3 normal_dir = normalize(i.normal_world);
110 half3 normaldata = UnpackNormal(SAMPLE_TEXTURE2D(_NormalMap,sampler_NormalMap,i.uv));
111 normaldata.xy = normaldata.xy* _NormalIntensity;
112 half3 tangent_dir = normalize(i.tangent_world);
113 half3 binormal_dir = normalize(i.binormal_world);
114 normal_dir = normalize(tangent_dir * normaldata.x + binormal_dir * normaldata.y + normal_dir * normaldata.z);
115
116 half ao = SAMPLE_TEXTURE2D(_AOMap, sampler_AOMap, i.uv).r;
117 ao = lerp(1.0,ao, _AOAdjust);
118 half3 view_dir = GetWorldSpaceNormalizeViewDir(i.pos_world);
119 half3 reflect_dir = reflect(-view_dir, normal_dir);
120
121 reflect_dir = RotateAround(_Rotate, reflect_dir);
122
123 float roughness = SAMPLE_TEXTURE2D(_RoughnessMap, sampler_RoughnessMap, i.uv).r;
124 roughness = saturate(pow(roughness, _RoughnessContrast) * _RoughnessBrightness);
125 roughness = lerp(_RoughnessMin, _RoughnessMax, roughness);
126 roughness = roughness * (1.7 - 0.7 * roughness);
127 float mip_level = roughness * 6.0;
128
129 half4 color_cubemap = SAMPLE_TEXTURECUBE_LOD(unity_SpecCube0, samplerunity_SpecCube0, reflect_dir, mip_level);
130 half3 env_color = DecodeHDREnvironment(color_cubemap, unity_SpecCube0_HDR);//确保在移动端能拿到HDR信息
131 half3 final_color = env_color * ao * _Tint.rgb * _Tint.rgb * _Expose;
132 //half3 final_color_linear = pow(final_color, 2.2);
133 //final_color = ACES_Tonemapping(final_color_linear);
134 //half3 final_color_gamma = pow(final_color, 1.0 / 2.2);
135
136 return float4(final_color, 1.0);
137 }
138 ENDHLSL
139 }
140 }
141 FallBack "Hidden/Universal Render Pipeline/FallbackError"
142 }
效果如下：
转载请注明出处：https://www.cnblogs.com/jietian331/p/17027723.html
标签：IBL,color,float,Shader,half3,Unity,world,dir,float3 From： https://www.cnblogs.com/jietian331/p/17027723.html