Cook Torrance 模型將物體粗糙表面看做很多微小平面組成，每一個(gè)微小平面都被看做一個(gè)理想的鏡面反射，物體表面粗糙程度由微平面斜率的變化來(lái)衡量，一個(gè)粗糙表面由一些列斜率變化很大的微平面組成，而相對(duì)平滑的微平面斜率變化很小，
Vertex shader:
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uniform vec3 lightposition;//光源為位置
2uniform vec3 eyeposition;//相機(jī)位置
3varying float NdotL, NdotH, NdotV, VdotH ;
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void main(void)
{
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6 vec3 objPosition = vec3 (gl_ModelViewMatrix * gl_Vertex);
7 vec3 Normal = normalize (gl_NormalMatrix * gl_Normal);
8 vec3 LightDir = normalize (lightposition - objPosition);
9 vec3 EyeDir = normalize (eyeposition - objPosition);
10 vec3 HalfVec = normalize (LightDir + EyeDir);
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12 NdotL = max(dot(Normal, LightDir), 0.0);
13 NdotH = max(dot(Normal, HalfVec), 0.0);
14 NdotV = max(dot(Normal, EyeDir), 0.0);
15 VdotH = max(dot(EyeDir, HalfVec), 0.0);
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17 gl_Position = ftransform();
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} Frag Shader:
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uniform sampler2D tex;
2uniform vec4 ambient;//環(huán)境光顏色
3uniform vec4 DiffuseLightColor;//漫反射光源顏色
4uniform vec4 SpecularLightColor;//specular光源顏色
5varying float NdotL, NdotH, NdotV, VdotH ;
6float diff=0.1;
7float spec=1.0;
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void main(void){
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float m = 0.6;//物體表面粗超程度
10 float f0 = 0.9;//入射角接近0時(shí)候的菲涅爾反射系數(shù)
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12 float Fresnel = f0 + (1.0 - f0) * pow((1.0 - VdotH), 5.0);
13 float Droughness = (pow(NdotH, 2.0)-1.0) / (m * m * pow(NdotH,2.0));
14 float Drough = (1.0 / m * m * pow(NdotH,4.0)) * exp(Droughness);
15 float G1 = (2.0 * NdotH * NdotL) / VdotH;
16 float G2 = (2.0 * NdotH * NdotV) / VdotH;
17 float Geometric= min(1.0, min(G1, G2));
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19 float Rs = (Fresnel * Drough * Geometric) / (NdotV * NdotL);
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21 vec3 diffuse = diff * vec3(DiffuseLightColor) * NdotL;
22 vec3 specular = spec * vec3(SpecularLightColor) * Rs;
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24 vec4 Color = vec4((diffuse + specular),1.0);
25 gl_FragColor = Color;
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} f0系數(shù)的設(shè)置對(duì)反射的亮度有一定的影響。 此處設(shè)置的比較大，一般近似取f0=
pow((1.0 - VdotH), 4.0);
Effect:
Object1