1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
| // PBR光照计算函数库
CCProgram pbr-lighting %{
struct MaterialData {
vec3 albedo;
float metallic;
float roughness;
vec3 normal;
vec3 emission;
float ao;
};
struct LightData {
vec3 direction;
vec3 color;
float intensity;
};
// 菲涅尔反射(Fresnel)
vec3 fresnelSchlick(float cosTheta, vec3 F0) {
return F0 + (1.0 - F0) * pow(1.0 - cosTheta, 5.0);
}
vec3 fresnelSchlickRoughness(float cosTheta, vec3 F0, float roughness) {
return F0 + (max(vec3(1.0 - roughness), F0) - F0) * pow(1.0 - cosTheta, 5.0);
}
// 法线分布函数 (Normal Distribution Function - GGX/Trowbridge-Reitz)
float distributionGGX(vec3 N, vec3 H, float roughness) {
float a = roughness * roughness;
float a2 = a * a;
float NdotH = max(dot(N, H), 0.0);
float NdotH2 = NdotH * NdotH;
float num = a2;
float denom = (NdotH2 * (a2 - 1.0) + 1.0);
denom = PI * denom * denom;
return num / denom;
}
// 几何遮蔽函数 (Geometry Function)
float geometrySchlickGGX(float NdotV, float roughness) {
float r = (roughness + 1.0);
float k = (r * r) / 8.0;
float num = NdotV;
float denom = NdotV * (1.0 - k) + k;
return num / denom;
}
float geometrySmith(vec3 N, vec3 V, vec3 L, float roughness) {
float NdotV = max(dot(N, V), 0.0);
float NdotL = max(dot(N, L), 0.0);
float ggx2 = geometrySchlickGGX(NdotV, roughness);
float ggx1 = geometrySchlickGGX(NdotL, roughness);
return ggx1 * ggx2;
}
// PBR BRDF计算
vec3 calculatePBR(MaterialData material, LightData light, vec3 viewDir) {
vec3 lightDir = normalize(-light.direction);
vec3 halfwayDir = normalize(lightDir + viewDir);
// 基础反射率
vec3 F0 = mix(vec3(0.04), material.albedo, material.metallic);
// Cook-Torrance BRDF
float NDF = distributionGGX(material.normal, halfwayDir, material.roughness);
float G = geometrySmith(material.normal, viewDir, lightDir, material.roughness);
vec3 F = fresnelSchlick(max(dot(halfwayDir, viewDir), 0.0), F0);
vec3 kS = F;
vec3 kD = vec3(1.0) - kS;
kD *= 1.0 - material.metallic;
vec3 numerator = NDF * G * F;
float denominator = 4.0 * max(dot(material.normal, viewDir), 0.0) * max(dot(material.normal, lightDir), 0.0) + 0.001;
vec3 specular = numerator / denominator;
float NdotL = max(dot(material.normal, lightDir), 0.0);
vec3 diffuse = kD * material.albedo / PI;
return (diffuse + specular) * light.color * light.intensity * NdotL;
}
// 环境光照计算
vec3 calculateAmbientLighting(MaterialData material, vec3 viewDir, samplerCube irradianceMap, samplerCube prefilterMap, sampler2D brdfLUT) {
vec3 F0 = mix(vec3(0.04), material.albedo, material.metallic);
vec3 F = fresnelSchlickRoughness(max(dot(material.normal, viewDir), 0.0), F0, material.roughness);
vec3 kS = F;
vec3 kD = 1.0 - kS;
kD *= 1.0 - material.metallic;
// 漫反射环境光
vec3 irradiance = textureCube(irradianceMap, material.normal).rgb;
vec3 diffuse = irradiance * material.albedo;
// 镜面反射环境光
vec3 reflectionDir = reflect(-viewDir, material.normal);
float maxReflectionLOD = 4.0; // 预滤波贴图的最大LOD
vec3 prefilteredColor = textureLod(prefilterMap, reflectionDir, material.roughness * maxReflectionLOD).rgb;
vec2 brdf = texture(brdfLUT, vec2(max(dot(material.normal, viewDir), 0.0), material.roughness)).rg;
vec3 specular = prefilteredColor * (F * brdf.x + brdf.y);
vec3 ambient = (kD * diffuse + specular) * material.ao;
return ambient;
}
}%
|
