WebGL is a PBR Viewer parser

Viewer address

Initial color vs. texture color vs. vertex color

Multiple colors (default color, map color, vertex color)
Default color x Map color x vertex color

vec4 baseColor = getBaseColor();

vec4 getBaseColor() {
    // Default eyes
    vec4 baseColor = vec4(1);
    #if defined(MATERIAL_SPECULARGLOSSINESS) // High optical flow
        baseColor = u_DiffuseFactor;  //diffuse
    #elif defined(MATERIAL_METALLICROUGHNESS) // Metal flow
        baseColor = u_BaseColorFactor; // Metal 1, 1, 1, 1
    #endif
    
    // Color map
    #if defined(MATERIAL_SPECULARGLOSSINESS) && defined(HAS_DIFFUSE_MAP)
        baseColor *= texture(u_DiffuseSampler, getDiffuseUV());
    #elif defined(MATERIAL_METALLICROUGHNESS) && defined(HAS_BASE_COLOR_MAP)
        baseColor *= texture(u_BaseColorSampler, getBaseColorUV());
    #endif
    
    // Vertex color
    return baseColor * getVertexColor(); // Just multiply
}
Copy the code

Here you can set the opacity to 1.0

#if ALPHAMODE == ALPHAMODE_OPAQUE
    baseColor.a = 1.0;
#endif
Copy the code

This is linear SRGB special case

#ifdef MATERIAL_UNLIT
    g_finalColor = (vec4(linearTosRGB(baseColor.rgb), baseColor.a));
    return;
#endif
const float GAMMA = 2.2;
const float INV_GAMMA = 1.0 / GAMMA;
// see http://chilliant.blogspot.com/2012/08/srgb-approximations-for-hlsl.html
vec3 linearTosRGB(vec3 color) {
    return pow(color, vec3(INV_GAMMA));
}
Copy the code

The normal information

vec3 v = normalize(u_Camera - v_Position); //view
NormalInfo normalInfo = getNormalInfo(v); // Tangent space
vec3 n = normalInfo.n;    / / normal
vec3 t = normalInfo.t;    / / are tangent
vec3 b = normalInfo.b;    / / deputy tangent
float NdotV = clampedDot(n, v); // Normals and angles
float TdotV = clampedDot(t, v); It's no use / /
float BdotV = clampedDot(b, v); It's no use / /

// Get normal, tangent and bitangent vectors.
NormalInfo getNormalInfo(vec3 v)
{
    vec2 UV = getNormalUV();
    vec3 uv_dx = dFdx(vec3(UV, 0.0));
    vec3 uv_dy = dFdy(vec3(UV, 0.0));
    vec3 t_ = (uv_dy.t * dFdx(v_Position) - uv_dx.t * dFdy(v_Position)) /
        (uv_dx.s * uv_dy.t - uv_dy.s * uv_dx.t); //how to do it 
    vec3 n, t, b, ng;
    // Compute geometrical TBN: if exists TBN
    #ifdef HAS_TANGENT_VEC4
        // Trivial TBN computation, present as vertex attribute.
        // Normalize eigenvectors as matrix is linearly interpolated.
        t = normalize(v_TBN[0]);
        b = normalize(v_TBN[1]);
        ng = normalize(v_TBN[2]);
    #else
        // Normals are either present as vertex attributes or approximated.
        #ifdef HAS_NORMAL_VEC3 // 
            ng = normalize(v_Normal);
        #else  
            ng = normalize(cross(dFdx(v_Position), dFdy(v_Position)));//cross ng
        #endif
        t = normalize(t_ - ng * dot(ng, t_)); / /??
        b = cross(ng, t);  //cross
    #endif 
    
    // For a back-facing surface, the tangential basis vectors are negated.
    if (gl_FrontFacing= =false) //false
    {
        t *= 1.0;
        b *= 1.0;
        ng *= 1.0;
    }
    
    // Compute pertubed normals:
    #ifdef HAS_NORMAL_MAP //
        n = texture(u_NormalSampler, UV).rgb * 2.0 - vec3(1.0); // From 0 to -1 to -1
        n *= vec3(u_NormalScale, u_NormalScale, 1.0); // NormalScale is multiplied only by the first two
        n = mat3(t, b, ng) * normalize(n); // Unit vector * tangent space time space normal line
    #else
        n = ng; / / normal
    #endif
    NormalInfo info;
    info.ng = ng; // The normal line perpendicular to the surface
    info.t = t;
    info.b = b;
    info.n = n;
    return info;
}
// Get the normal uv
vec2 getNormalUV()
{
    vec3 uv = vec3(u_NormalUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0); // There are two sets of UVs, so treat them differently
    #ifdef HAS_NORMAL_UV_TRANSFORM // Shift rotation scale
        uv = u_NormalUVTransform * uv;
    #endif
    return uv.xy;
}
Copy the code

Ior baseColor F0 specularWeight Basic computation

Associated with the Transmission

MaterialInfo materialInfo;
materialInfo.baseColor = baseColor.rgb; // Put RGB first
materialInfo.ior = 1.5;  / / the default
materialInfo.f0 = vec3(0.04); / / the default
materialInfo.specularWeight = 1.0;
#ifdef MATERIAL_IOR // If there is ior, calculate F0 if there is no IOR, 0.04 by default this is a metal flow
    materialInfo = getIorInfo(materialInfo);
#endif
#ifdef MATERIAL_IOR
    MaterialInfo getIorInfo(MaterialInfo info) {
        info.f0 = vec3(pow(( u_Ior - 1.0) /  (u_Ior + 1.0), 2.0)); //f0 is calculated by ior
        info.ior = u_Ior;
        return info;
    }
#endif
Copy the code

Roughness evaluation (RGB Roughness Evaluation A)

The roughness is in a
F0 is in RGB
* basecolor c_diff is (1 – FO)

#ifdef MATERIAL_SPECULARGLOSSINESS
    materialInfo = getSpecularGlossinessInfo(materialInfo);
#endif

#ifdef MATERIAL_SPECULARGLOSSINESS
    MaterialInfo getSpecularGlossinessInfo(MaterialInfo info) {
        info.f0 = u_SpecularFactor; //Factor
        info.perceptualRoughness = u_GlossinessFactor; //Factor
        #ifdef HAS_SPECULAR_GLOSSINESS_MAP
            vec4 sgSample = texture(u_SpecularGlossinessSampler, getSpecularGlossinessUV());  //UV offset, etc
            info.perceptualRoughness *= sgSample.a ; // Glossiness to roughness multiplication
            info.f0 *= sgSample.rgb; / / RGB is f0
        #endif 
        
        info.perceptualRoughness = 1.0 - info.perceptualRoughness; // 1 - glossiness
        info.c_diff = info.baseColor.rgb * (1.0 - max(max(info.f0.r, info.f0.g), info.f0.b));
        return info;
    }
#endif
#ifdef MATERIAL_SPECULARGLOSSINESS
    uniform sampler2D u_DiffuseSampler;
    uniform int u_DiffuseUVSet;
    uniform mat3 u_DiffuseUVTransform;
    uniform sampler2D u_SpecularGlossinessSampler;
    uniform int u_SpecularGlossinessUVSet;
    uniform mat3 u_SpecularGlossinessUVTransform;
    vec2 getSpecularGlossinessUV() { // Also two sets of UV
        vec3 uv = vec3(u_SpecularGlossinessUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_SPECULARGLOSSINESS_UV_TRANSFORM
            uv = u_SpecularGlossinessUVTransform * uv;
        #endif
        return uv.xy;
    }
    vec2 getDiffuseUV() {
        vec3 uv = vec3(u_DiffuseUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_DIFFUSE_UV_TRANSFORM
            uv = u_DiffuseUVTransform * uv;
        #endif
        return uv.xy;
    }
#endif
Copy the code

Metal flow gets F0 Diffusecolor

Roughness in g
B
diffuse basecolor * (1 – f0) * (1 – metallic)
F0 f0 * (1 – metallic) + basecolor * metallic

#ifdef MATERIAL_METALLICROUGHNESS
    materialInfo = getMetallicRoughnessInfo(materialInfo);
#endif
#ifdef MATERIAL_METALLICROUGHNESS
    MaterialInfo getMetallicRoughnessInfo(MaterialInfo info) {
        info.metallic = u_MetallicFactor;  //factor
        info.perceptualRoughness = u_RoughnessFactor; //factor
        #ifdef HAS_METALLIC_ROUGHNESS_MAP
            // Roughness is stored in the 'g' channel, metallic is stored in the 'b' channel.
            // This layout intentionally reserves the 'r' channel for (optional) occlusion map data
            vec4 mrSample = texture(u_MetallicRoughnessSampler, getMetallicRoughnessUV());
            info.perceptualRoughness *= mrSample.g; 
            info.metallic *= mrSample.b;
        #endif
        
        // Achromatic f0 based on IOR.
        info.c_diff = mix(info.baseColor.rgb * (vec3(1.0) - info.f0), vec3(0), info.metallic);
        info.f0 = mix(info.f0, info.baseColor.rgb, info.metallic);
        return info;
    }
#endif
Copy the code

Sheen Information Collection

Sheen Color texture RGB
Sheen Roughness Map A

#ifdef MATERIAL_SHEEN
    materialInfo = getSheenInfo(materialInfo);
#endif
#ifdef MATERIAL_SHEEN
    MaterialInfo getSheenInfo(MaterialInfo info) {
        info.sheenColorFactor = u_SheenColorFactor;
        info.sheenRoughnessFactor = u_SheenRoughnessFactor;
        #ifdef HAS_SHEEN_COLOR_MAP
            vec4 sheenColorSample = texture(u_SheenColorSampler, getSheenColorUV());
            info.sheenColorFactor *= sheenColorSample.rgb;
        #endif
        
        #ifdef HAS_SHEEN_ROUGHNESS_MAP
            vec4 sheenRoughnessSample = texture(u_SheenRoughnessSampler, getSheenRoughnessUV());
            info.sheenRoughnessFactor *= sheenRoughnessSample.a;
        #endif
        return info;
    }
#endif
Copy the code

Clearcoat collects information

ClearcoatF0 is f0
ClearcoatF90 1.0
Clearcoat takes the r of the map
Step 6. ClearcoatRoughness step 6

#ifdef MATERIAL_CLEARCOAT
    materialInfo = getClearCoatInfo(materialInfo, normalInfo);
#endif

#ifdef MATERIAL_CLEARCOAT
    MaterialInfo getClearCoatInfo(MaterialInfo info, NormalInfo normalInfo) {
        info.clearcoatFactor = u_ClearcoatFactor;
        info.clearcoatRoughness = u_ClearcoatRoughnessFactor;
        info.clearcoatF0 = vec3(info.f0); //f0
        info.clearcoatF90 = vec3(1.0);  //F90
        #ifdef HAS_CLEARCOAT_MAP
            vec4 clearcoatSample = texture(u_ClearcoatSampler, getClearcoatUV());
            info.clearcoatFactor *= clearcoatSample.r;
        #endif
        
        #ifdef HAS_CLEARCOAT_ROUGHNESS_MAP
            vec4 clearcoatSampleRoughness = texture(u_ClearcoatRoughnessSampler, getClearcoatRoughnessUV());
            info.clearcoatRoughness *= clearcoatSampleRoughness.g;
        #endif
        
        info.clearcoatNormal = getClearcoatNormal(normalInfo);
        info.clearcoatRoughness = clamp(info.clearcoatRoughness, 0.0.1.0);
        return info;
    }
#endif
Copy the code

Specular highlights flow

Specular a
SpecularColor Fetch map RGB
DielectricSpecularF0 f0 * specularColor
F0 dielectricSpecularF0 * (1-metallic) + basecolor.rgb * metallic
specularWeight
C_diff basecolor * (1.0-max3 (dielectricSpecularF0)) * (1-metallic) c_diff basecolor * (1.0-max3 (dielectricSpecularF0)) * (1-metallic)

#ifdef MATERIAL_SPECULAR
    materialInfo = getSpecularInfo(materialInfo);
#endif
#ifdef MATERIAL_SPECULAR
    MaterialInfo getSpecularInfo(MaterialInfo info) {
        vec4 specularTexture = vec4(1.0);
        #ifdef HAS_SPECULAR_MAP
            specularTexture.a = texture(u_SpecularSampler, getSpecularColorUV()).a;
        #endif
        #ifdef HAS_SPECULAR_COLOR_MAP
            specularTexture.rgb = texture(u_SpecularColorSampler, getSpecularUV()).rgb;
        #endif
        
        vec3 dielectricSpecularF0 = min(info.f0 * u_KHR_materials_specular_specularColorFactor * specularTexture.rgb, vec3(1.0));
        info.f0 = mix(dielectricSpecularF0, info.baseColor.rgb, info.metallic);
        info.specularWeight = u_KHR_materials_specular_specularFactor * specularTexture.a;
        info.c_diff = mix(info.baseColor.rgb * (1.0 - max3(dielectricSpecularF0)), vec3(0), info.metallic);
        return info;
    }
#endif
Copy the code

TRANSMISSION

The R in TRANSMISSION map

#ifdef MATERIAL_TRANSMISSION
    materialInfo = getTransmissionInfo(materialInfo);
#endif
#ifdef MATERIAL_TRANSMISSION
    MaterialInfo getTransmissionInfo(MaterialInfo info) {
        info.transmissionFactor = u_TransmissionFactor;
        #ifdef HAS_TRANSMISSION_MAP
            vec4 transmissionSample = texture(u_TransmissionSampler, getTransmissionUV());
            info.transmissionFactor *= transmissionSample.r;
        #endif
        return info;
    }
#endif
Copy the code

Volume

#ifdef MATERIAL_VOLUME
    materialInfo = getVolumeInfo(materialInfo);
#endif
#ifdef MATERIAL_VOLUME
    MaterialInfo getVolumeInfo(MaterialInfo info) {
        info.thickness = u_ThicknessFactor;
        info.attenuationColor = u_AttenuationColor;
        info.attenuationDistance = u_AttenuationDistance;
        #ifdef HAS_THICKNESS_MAP
            vec4 thicknessSample = texture(u_ThicknessSampler, getThicknessUV());
            info.thickness *= thicknessSample.g;
        #endif
        return info;
    }
#endif
Copy the code

PBR Basic information

AlphaRoughness roughness squared
Reflectance is set to the maximum value of F0
F90 is still going to be 1

materialInfo.perceptualRoughness = clamp(materialInfo.perceptualRoughness, 0.0.1.0);
materialInfo.metallic = clamp(materialInfo.metallic, 0.0.1.0);

// Roughness is authored as perceptual roughness; as is convention, // convert to material roughness by squaring the perceptual roughness.
materialInfo.alphaRoughness = materialInfo.perceptualRoughness * materialInfo.perceptualRoughness;

// Compute reflectance.
float reflectance = max(max(materialInfo.f0.r, materialInfo.f0.g), materialInfo.f0.b);

// Anything less than 2% is physically impossible and is instead considered to be shadowing. Compare to "Real-Time-Rendering" 4th editon on page 325.
materialInfo.f90 = vec3(1.0);
// LIGHTING

vec3 f_specular = vec3(0.0);
vec3 f_diffuse = vec3(0.0);
vec3 f_emissive = vec3(0.0);
vec3 f_clearcoat = vec3(0.0);
vec3 f_sheen = vec3(0.0);
vec3 f_transmission = vec3(0.0);
float albedoSheenScaling = 1.0;
Copy the code

IBL Sheen Clearcoat

IBL is a five-part Specular Diffuse Clearcoat Sheen
specularLight * (specularColor * brdf.x + brdf.y)

f_specular += getIBLRadianceGGX(n, v, materialInfo.perceptualRoughness, materialInfo.f0, materialInfo.specularWeight);
vec3 getIBLRadianceGGX(vec3 n, vec3 v, float roughness, vec3 F0, float specularWeight) {
    float NdotV = clampedDot(n, v);
    float lod = roughness * float(u_MipCount - 1);
    vec3 reflection = normalize(reflect(-v, n));
    vec2 brdfSamplePoint = clamp(vec2(NdotV, roughness), vec2(0.0.0.0), vec2(1.0.1.0));
    vec2 f_ab = texture(u_GGXLUT, brdfSamplePoint).rg;
    vec4 specularLight = getSpecularSample(reflection, lod).rgb;
    
    // see https://bruop.github.io/ibl/#single_scattering_results at Single Scattering Results
    
    // Roughness dependent fresnel, from Fdez-Aguera
    vec3 Fr = max(vec3(1.0 - roughness), F0) - F0;
    vec3 k_S = F0 + Fr * pow(1.0 - NdotV, 5.0);
    vec3 FssEss = k_S * f_ab.x + f_ab.y;
    return specularWeight * specularLight * FssEss;
}
vec4 getSpecularSample(vec3 reflection, float lod) {
    return textureLod(u_GGXEnvSampler, u_EnvRotation * reflection, lod);
}
Copy the code

I don’t understand this calculation

f_diffuse += getIBLRadianceLambertian(n, v, materialInfo.perceptualRoughness, materialInfo.c_diff, materialInfo.f0, materialInfo.specularWeight);
vec3 getIBLRadianceLambertian(vec3 n, vec3 v, float roughness, vec3 diffuseColor, vec3 F0, float specularWeight) {
    float NdotV = clampedDot(n, v);
    vec2 brdfSamplePoint = clamp(vec2(NdotV, roughness), vec2(0.0.0.0), vec2(1.0.1.0));
    vec2 f_ab = texture(u_GGXLUT, brdfSamplePoint).rg;
    vec3 irradiance = getDiffuseLight(n);
    
    // see https://bruop.github.io/ibl/#single_scattering_results at Single Scattering Results
    
    // Roughness dependent fresnel, from Fdez-Aguera
    
    vec3 Fr = max(vec3(1.0 - roughness), F0) - F0;
    vec3 k_S = F0 + Fr * pow(1.0 - NdotV, 5.0);
    vec3 FssEss = specularWeight * k_S * f_ab.x + f_ab.y; // <--- GGX / specular light contribution (scale it down if the specularWeight is low)
    
    
    // Multiple scattering, from Fdez-Aguera
    float Ems = (1.0 - (f_ab.x + f_ab.y));
    vec3 F_avg = specularWeight * (F0 + (1.0 - F0) / 21.0);
    vec3 FmsEms = Ems * FssEss * F_avg / (1.0 - F_avg * Ems);
    vec3 k_D = diffuseColor * (1.0 - FssEss + FmsEms); // we use +FmsEms as indicated by the formula in the blog post (might be a typo in the implementation)
    
    
    return (FmsEms + k_D) * irradiance;
}
vec3 getDiffuseLight(vec3 n) {
    return texture(u_LambertianEnvSampler, u_EnvRotation * n).rgb;
}
Copy the code

It’s highlighted in the same way

f_clearcoat += getIBLRadianceGGX(materialInfo.clearcoatNormal, v, materialInfo.clearcoatRoughness, materialInfo.clearcoatF0, 1.0);
Copy the code

sheenLight * sheenColor * brdf

f_sheen += getIBLRadianceCharlie(n, v, materialInfo.sheenRoughnessFactor, materialInfo.sheenColorFactor);
vec3 getIBLRadianceCharlie(vec3 n, vec3 v, float sheenRoughness, vec3 sheenColor) {
    float NdotV = clampedDot(n, v);
    float lod = sheenRoughness * float(u_MipCount - 1);
    vec3 reflection = normalize(reflect(-v, n));
    vec2 brdfSamplePoint = clamp(vec2(NdotV, sheenRoughness), vec2(0.0.0.0), vec2(1.0.1.0));
    float brdf = texture(u_CharlieLUT, brdfSamplePoint).b;
    vec4 sheenSample = getSheenSample(reflection, lod);
    vec3 sheenLight = sheenSample.rgb;
    return sheenLight * sheenColor * brdf;
}
Copy the code

transmission

Different from the PBR at the back see

#if (defined(MATERIAL_TRANSMISSION) || defined(MATERIAL_VOLUME)) && (defined(USE_PUNCTUAL) || defined(USE_IBL))
    f_transmission += materialInfo.transmissionFactor * getIBLVolumeRefraction(
    n, v, materialInfo.perceptualRoughness, materialInfo.baseColor, materialInfo.f0, materialInfo.f90, v_Position, u_ModelMatrix, u_ViewMatrix, u_ProjectionMatrix, materialInfo.ior, materialInfo.thickness, materialInfo.attenuationColor, materialInfo.attenuationDistance);
#endif
Copy the code

OA

float ao = 1.0;
// Apply optional PBR terms for additional (optional) shading

#ifdef HAS_OCCLUSION_MAP
    ao = texture(u_OcclusionSampler, getOcclusionUV()).r;
    f_diffuse = mix(f_diffuse, f_diffuse * ao, u_OcclusionStrength);
    // apply ambient occlusion to all lighting that is not punctual

    f_specular = mix(f_specular, f_specular * ao, u_OcclusionStrength);
    f_sheen = mix(f_sheen, f_sheen * ao, u_OcclusionStrength);
    f_clearcoat = mix(f_clearcoat, f_clearcoat * ao, u_OcclusionStrength);
#endif
Copy the code

Direct sunlight

#ifdef USE_PUNCTUAL
    for (int i = 0; i < LIGHT_COUNT; ++i) {
        Light light = u_Lights[i];
        vec3 pointToLight;
        if (light.type ! = LightType_Directional) {
            pointToLight = light.position - v_Position;
        }
        else {
            pointToLight = -light.direction;
        }
        // BSTF
        vec3 l = normalize(pointToLight);   // Direction from surface point to light

        vec3 h = normalize(l + v);          // Direction of the vector between l and v, called halfway vector

        float NdotL = clampedDot(n, l);
        float NdotV = clampedDot(n, v);
        float NdotH = clampedDot(n, h);
        float LdotH = clampedDot(l, h);
        float VdotH = clampedDot(v, h);
        if (NdotL > 0.0 || NdotV > 0.0) {
            // Calculation of analytical light
            / / https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#acknowledgments AppendixB
            vec3 intensity = getLighIntensity(light, pointToLight);
            f_diffuse += intensity * NdotL *  BRDF_lambertian(materialInfo.f0, materialInfo.f90, materialInfo.c_diff, materialInfo.specularWeight, VdotH);
            f_specular += intensity * NdotL * BRDF_specularGGX(materialInfo.f0, materialInfo.f90, materialInfo.alphaRoughness, materialInfo.specularWeight, VdotH, NdotL, NdotV, NdotH);
            #ifdef MATERIAL_SHEEN
                f_sheen += intensity * getPunctualRadianceSheen(materialInfo.sheenColorFactor, materialInfo.sheenRoughnessFactor, NdotL, NdotV, NdotH);
                albedoSheenScaling = min(1.0 - max3(materialInfo.sheenColorFactor) * albedoSheenScalingLUT(NdotV, materialInfo.sheenRoughnessFactor), 1.0 - max3(materialInfo.sheenColorFactor) * albedoSheenScalingLUT(NdotL, materialInfo.sheenRoughnessFactor));
            #endif

            #ifdef MATERIAL_CLEARCOAT
                f_clearcoat += intensity * getPunctualRadianceClearCoat(materialInfo.clearcoatNormal, v, l, h, VdotH, materialInfo.clearcoatF0, materialInfo.clearcoatF90, materialInfo.clearcoatRoughness);
            #endif
        }
        // BDTF
        #ifdef MATERIAL_TRANSMISSION
            // If the light ray travels through the geometry, use the point it exits the geometry again.
            // That will change the angle to the light source, if the material refracts the light ray.
            vec3 transmissionRay = getVolumeTransmissionRay(n, v, materialInfo.thickness, materialInfo.ior, u_ModelMatrix);
            pointToLight -= transmissionRay;
            l = normalize(pointToLight);
            vec3 intensity = getLighIntensity(light, pointToLight);
            vec3 transmittedLight = intensity * getPunctualRadianceTransmission(n, v, l, materialInfo.alphaRoughness, materialInfo.f0, materialInfo.f90, materialInfo.baseColor, materialInfo.ior);
            #ifdef MATERIAL_VOLUME
                transmittedLight = applyVolumeAttenuation(transmittedLight, length(transmissionRay), materialInfo.attenuationColor, materialInfo.attenuationDistance);
            #endif

            f_transmission += materialInfo.transmissionFactor * transmittedLight;
        #endif
    }
#endif
Copy the code

final

f_emissive = u_EmissiveFactor;
#ifdef HAS_EMISSIVE_MAP
    f_emissive *= texture(u_EmissiveSampler, getEmissiveUV()).rgb;
#endif

vec3 color = vec3(0);

// Layer blending


float clearcoatFactor = 0.0;
vec3 clearcoatFresnel = vec3(0);
#ifdef MATERIAL_CLEARCOAT
    clearcoatFactor = materialInfo.clearcoatFactor;
    clearcoatFresnel = F_Schlick(materialInfo.clearcoatF0, materialInfo.clearcoatF90, clampedDot(materialInfo.clearcoatNormal, v));
    f_clearcoat = f_clearcoat * clearcoatFactor;
#endif

#ifdef MATERIAL_TRANSMISSION
    vec3 diffuse = mix(f_diffuse, f_transmission, materialInfo.transmissionFactor);
#else
    vec3 diffuse = f_diffuse;
#endif

color = f_emissive + diffuse + f_specular;
color = f_sheen + color * albedoSheenScaling;
color = color * (1.0 - clearcoatFactor * clearcoatFresnel) + f_clearcoat;
Copy the code

#if DEBUG == DEBUG_NONE

    #if ALPHAMODE == ALPHAMODE_MASK
        // Late discard to avoid samplig artifacts. See https://github.com/KhronosGroup/glTF-Sample-Viewer/issues/267
        if (baseColor.a < u_AlphaCutoff) {
            discard;
        }
        baseColor.a = 1.0;
    #endif

    #ifdef LINEAR_OUTPUT
        g_finalColor = vec4(color.rgb, baseColor.a);
    #else
        g_finalColor = vec4(toneMap(color), baseColor.a);
    #endif

#else
    g_finalColor.a = 1.0;
#endif

#if DEBUG == DEBUG_METALLIC
    g_finalColor.rgb = vec3(materialInfo.metallic);
#endif

#if DEBUG == DEBUG_ROUGHNESS
    g_finalColor.rgb = vec3(materialInfo.perceptualRoughness);
#endif

#if DEBUG == DEBUG_NORMAL
    #ifdef HAS_NORMAL_MAP
        g_finalColor.rgb = texture(u_NormalSampler, getNormalUV()).rgb;
    #else
        g_finalColor.rgb = vec3(0.5.0.5.1.0);
    #endif
#endif

#if DEBUG == DEBUG_NORMAL_GEOMETRY
    g_finalColor.rgb = (normalInfo.ng + 1.0) / 2.0;
#endif

#if DEBUG == DEBUG_NORMAL_WORLD
    g_finalColor.rgb = (n + 1.0) / 2.0;
#endif

#if DEBUG == DEBUG_TANGENT
    g_finalColor.rgb = t * 0.5 + vec3(0.5);
#endif

#if DEBUG == DEBUG_BITANGENT
    g_finalColor.rgb = b * 0.5 + vec3(0.5);
#endif

#if DEBUG == DEBUG_BASE_COLOR_SRGB
    g_finalColor.rgb = linearTosRGB(materialInfo.baseColor);
#endif

#if DEBUG == DEBUG_BASE_COLOR_LINEAR
    g_finalColor.rgb = materialInfo.baseColor;
#endif

#if DEBUG == DEBUG_OCCLUSION
    g_finalColor.rgb = vec3(ao);
#endif

#if DEBUG == DEBUG_F0
    g_finalColor.rgb = materialInfo.f0;
#endif

#if DEBUG == DEBUG_EMISSIVE_SRGB
    g_finalColor.rgb = linearTosRGB(f_emissive);
#endif

#if DEBUG == DEBUG_EMISSIVE_LINEAR
    g_finalColor.rgb = f_emissive;
#endif

#if DEBUG == DEBUG_SPECULAR_SRGB
    g_finalColor.rgb = linearTosRGB(f_specular);
#endif

#if DEBUG == DEBUG_DIFFUSE_SRGB
    g_finalColor.rgb = linearTosRGB(f_diffuse);
#endif

#if DEBUG == DEBUG_CLEARCOAT_SRGB
    g_finalColor.rgb = linearTosRGB(f_clearcoat);
#endif

#if DEBUG == DEBUG_SHEEN_SRGB
    g_finalColor.rgb = linearTosRGB(f_sheen);
#endif

#if DEBUG == DEBUG_TRANSMISSION_SRGB
    g_finalColor.rgb = linearTosRGB(f_transmission);
#endif

#if DEBUG == DEBUG_ALPHA
    g_finalColor.rgb = vec3(baseColor.a);
#endif
Copy the code

#version 300 es
#define HAS_NORMAL_MAP 1
#define HAS_OCCLUSION_MAP 1
#define HAS_EMISSIVE_MAP 1
#define HAS_BASE_COLOR_MAP 1
#define HAS_METALLIC_ROUGHNESS_MAP 1
#define ALPHAMODE_OPAQUE 0
#define ALPHAMODE_MASK 1
#define ALPHAMODE_BLEND 2
#define ALPHAMODE ALPHAMODE_OPAQUE
#define MATERIAL_METALLICROUGHNESS 1
#define HAS_NORMAL_VEC3 1
#define HAS_POSITION_VEC3 1
#define HAS_TEXCOORD_0_VEC2 1
#define USE_PUNCTUAL 1
#define LIGHT_COUNT 0
#define USE_IBL 1
#define DEBUG_NONE 0
#define DEBUG_NORMAL 1
#define DEBUG_NORMAL_WORLD 2
#define DEBUG_NORMAL_GEOMETRY 3
#define DEBUG_TANGENT 4
#define DEBUG_BITANGENT 5
#define DEBUG_ROUGHNESS 6
#define DEBUG_METALLIC 7
#define DEBUG_BASE_COLOR_SRGB 8
#define DEBUG_BASE_COLOR_LINEAR 9
#define DEBUG_OCCLUSION 10
#define DEBUG_EMISSIVE_SRGB 11
#define DEBUG_EMISSIVE_LINEAR 12
#define DEBUG_F0 13
#define DEBUG_ALPHA 14
#define DEBUG_DIFFUSE_SRGB 15
#define DEBUG_SPECULAR_SRGB 16
#define DEBUG_CLEARCOAT_SRGB 17
#define DEBUG_SHEEN_SRGB 18
#define DEBUG_TRANSMISSION_SRGB 19
#define DEBUG DEBUG_NONE
//
// This fragment shader defines a reference implementation for Physically Based Shading of
// a microfacet surface material defined by a glTF model.
//
// References:
// [1] Real Shading in Unreal Engine 4
// http://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_notes_v2.pdf
// [2] Physically Based Shading at Disney
// http://blog.selfshadow.com/publications/s2012-shading-course/burley/s2012_pbs_disney_brdf_notes_v3.pdf
// [3] README.md - Environment Maps
// https://github.com/KhronosGroup/glTF-WebGL-PBR/#environment-maps
// [4] "An Inexpensive BRDF Model for Physically based Rendering" by Christophe Schlick
// https://www.cs.virginia.edu/~jdl/bib/appearance/analytic%20models/schlick94b.pdf
// [5] "KHR_materials_clearcoat"
/ / https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat

precision highp float;
#define GLSLIFY 1

#define GLSLIFY 1
uniform float u_Exposure;
const float GAMMA = 2.2;
const float INV_GAMMA = 1.0 / GAMMA;

// sRGB = > XYZ = > D65_2_D60 = > AP1 = > RRT_SAT

const mat3 ACESInputMat = mat3
(
0.59719.0.07600.0.02840.0.35458.0.90834.0.13383.0.04823.0.01566.0.83777
);

// ODT_SAT = > XYZ = > D60_2_D65 = > sRGB

const mat3 ACESOutputMat = mat3
(
1.60475.0.10208.0.00327.0.53108.1.10813.0.07276.0.07367.0.00605.1.07602
);

// linear to sRGB approximation

// see http://chilliant.blogspot.com/2012/08/srgb-approximations-for-hlsl.html
vec3 linearTosRGB(vec3 color) {
    return pow(color, vec3(INV_GAMMA));
}
// sRGB to linear approximation
// see http://chilliant.blogspot.com/2012/08/srgb-approximations-for-hlsl.html
vec3 sRGBToLinear(vec3 srgbIn) {
    return vec3(pow(srgbIn.xyz, vec3(GAMMA)));
}
vec4 sRGBToLinear(vec4 srgbIn) {
    return vec4(sRGBToLinear(srgbIn.xyz), srgbIn.w);
}
// ACES tone map (faster approximation)
// see: https://knarkowicz.wordpress.com/2016/01/06/aces-filmic-tone-mapping-curve/
vec3 toneMapACES_Narkowicz(vec3 color) {
    const float A = 2.51;
    const float B = 0.03;
    const float C = 2.43;
    const float D = 0.59;
    const float E = 0.14;
    return clamp((color * (A * color + B)) / (color * (C * color + D) + E), 0.0.1.0);
}
// ACES filmic tone map approximation
// see https://github.com/TheRealMJP/BakingLab/blob/master/BakingLab/ACES.hlsl
vec3 RRTAndODTFit(vec3 color) {
    vec3 a = color * (color + 0.0245786) - 0.000090537;
    vec3 b = color * (0.983729 * color + 0.4329510) + 0.238081;
    return a / b;
}
// tone mapping 
vec3 toneMapACES_Hill(vec3 color) {
    color = ACESInputMat * color;
    
    // Apply RRT and ODT
    
    color = RRTAndODTFit(color);
    color = ACESOutputMat * color;
    
    // Clamp to [0, 1]
    
    color = clamp(color, 0.0.1.0);
    return color;
}
vec3 toneMap(vec3 color) {
    color *= u_Exposure;
    #ifdef TONEMAP_ACES_NARKOWICZ
        color = toneMapACES_Narkowicz(color);
    #endif
    
    #ifdef TONEMAP_ACES_HILL
        color = toneMapACES_Hill(color);
    #endif
    
    #ifdef TONEMAP_ACES_HILL_EXPOSURE_BOOST
        // boost exposure as discussed in https://github.com/mrdoob/three.js/pull/19621
        // this factor is based on the exposure correction of Krzysztof Narkowicz in his
        // implemetation of ACES tone mapping
        color /= 0.6;
        color = toneMapACES_Hill(color);
    #endif
    
    return linearTosRGB(color);
}
#define GLSLIFY 1
// IBL

uniform int u_MipCount;
uniform samplerCube u_LambertianEnvSampler;
uniform samplerCube u_GGXEnvSampler;
uniform sampler2D u_GGXLUT;
uniform samplerCube u_CharlieEnvSampler;
uniform sampler2D u_CharlieLUT;
uniform sampler2D u_SheenELUT;
uniform mat3 u_EnvRotation;

// General Material


uniform sampler2D u_NormalSampler;
uniform float u_NormalScale;
uniform int u_NormalUVSet;
uniform mat3 u_NormalUVTransform;
uniform vec3 u_EmissiveFactor;
uniform sampler2D u_EmissiveSampler;
uniform int u_EmissiveUVSet;
uniform mat3 u_EmissiveUVTransform;
uniform sampler2D u_OcclusionSampler;
uniform int u_OcclusionUVSet;
uniform float u_OcclusionStrength;
uniform mat3 u_OcclusionUVTransform;
in vec2 v_texcoord_0;
in vec2 v_texcoord_1;
vec2 getNormalUV() {
    vec3 uv = vec3(u_NormalUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
    #ifdef HAS_NORMAL_UV_TRANSFORM
        uv = u_NormalUVTransform * uv;
    #endif
    
    return uv.xy;
}
vec2 getEmissiveUV() {
    vec3 uv = vec3(u_EmissiveUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
    #ifdef HAS_EMISSIVE_UV_TRANSFORM
        uv = u_EmissiveUVTransform * uv;
    #endif
    
    return uv.xy;
}
vec2 getOcclusionUV() {
    vec3 uv = vec3(u_OcclusionUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
    #ifdef HAS_OCCLUSION_UV_TRANSFORM
        uv = u_OcclusionUVTransform * uv;
    #endif
    
    return uv.xy;
}
// Metallic Roughness Material

#ifdef MATERIAL_METALLICROUGHNESS
    
    uniform sampler2D u_BaseColorSampler;
    uniform int u_BaseColorUVSet;
    uniform mat3 u_BaseColorUVTransform;
    uniform sampler2D u_MetallicRoughnessSampler;
    uniform int u_MetallicRoughnessUVSet;
    uniform mat3 u_MetallicRoughnessUVTransform;
    vec2 getBaseColorUV() {
        vec3 uv = vec3(u_BaseColorUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_BASECOLOR_UV_TRANSFORM
            uv = u_BaseColorUVTransform * uv;
        #endif
        
        return uv.xy;
    }
    vec2 getMetallicRoughnessUV() {
        vec3 uv = vec3(u_MetallicRoughnessUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_METALLICROUGHNESS_UV_TRANSFORM
            uv = u_MetallicRoughnessUVTransform * uv;
        #endif
        
        return uv.xy;
    }
#endif

// Specular Glossiness Material

#ifdef MATERIAL_SPECULARGLOSSINESS
    
    uniform sampler2D u_DiffuseSampler;
    uniform int u_DiffuseUVSet;
    uniform mat3 u_DiffuseUVTransform;
    uniform sampler2D u_SpecularGlossinessSampler;
    uniform int u_SpecularGlossinessUVSet;
    uniform mat3 u_SpecularGlossinessUVTransform;
    vec2 getSpecularGlossinessUV() {
        vec3 uv = vec3(u_SpecularGlossinessUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_SPECULARGLOSSINESS_UV_TRANSFORM
            uv = u_SpecularGlossinessUVTransform * uv;
        #endif
        
        return uv.xy;
    }
    vec2 getDiffuseUV() {
        vec3 uv = vec3(u_DiffuseUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_DIFFUSE_UV_TRANSFORM
            uv = u_DiffuseUVTransform * uv;
        #endif
        
        return uv.xy;
    }
#endif

// Clearcoat Material

#ifdef MATERIAL_CLEARCOAT
    
    uniform sampler2D u_ClearcoatSampler;
    uniform int u_ClearcoatUVSet;
    uniform mat3 u_ClearcoatUVTransform;
    uniform sampler2D u_ClearcoatRoughnessSampler;
    uniform int u_ClearcoatRoughnessUVSet;
    uniform mat3 u_ClearcoatRoughnessUVTransform;
    uniform sampler2D u_ClearcoatNormalSampler;
    uniform int u_ClearcoatNormalUVSet;
    uniform mat3 u_ClearcoatNormalUVTransform;
    uniform float u_ClearcoatNormalScale;
    vec2 getClearcoatUV() {
        vec3 uv = vec3(u_ClearcoatUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_CLEARCOAT_UV_TRANSFORM
            uv = u_ClearcoatUVTransform * uv;
        #endif
        return uv.xy;
    }
    vec2 getClearcoatRoughnessUV() {
        vec3 uv = vec3(u_ClearcoatRoughnessUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_CLEARCOATROUGHNESS_UV_TRANSFORM
            uv = u_ClearcoatRoughnessUVTransform * uv;
        #endif
        return uv.xy;
    }
    vec2 getClearcoatNormalUV() {
        vec3 uv = vec3(u_ClearcoatNormalUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_CLEARCOATNORMAL_UV_TRANSFORM
            uv = u_ClearcoatNormalUVTransform * uv;
        #endif
        return uv.xy;
    }
#endif

// Sheen Material

#ifdef MATERIAL_SHEEN
    
    uniform sampler2D u_SheenColorSampler;
    uniform int u_SheenColorUVSet;
    uniform mat3 u_SheenColorUVTransform;
    uniform sampler2D u_SheenRoughnessSampler;
    uniform int u_SheenRoughnessUVSet;
    uniform mat3 u_SheenRoughnessUVTransform;
    vec2 getSheenColorUV() {
        vec3 uv = vec3(u_SheenColorUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_SHEENCOLOR_UV_TRANSFORM
            uv = u_SheenColorUVTransform * uv;
        #endif
        return uv.xy;
    }
    vec2 getSheenRoughnessUV() {
        vec3 uv = vec3(u_SheenRoughnessUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_SHEENROUGHNESS_UV_TRANSFORM
            uv = u_SheenRoughnessUVTransform * uv;
        #endif
        return uv.xy;
    }
#endif

// Specular Material

#ifdef MATERIAL_SPECULAR
    
    uniform sampler2D u_SpecularSampler;
    uniform int u_SpecularUVSet;
    uniform mat3 u_SpecularUVTransform;
    uniform sampler2D u_SpecularColorSampler;
    uniform int u_SpecularColorUVSet;
    uniform mat3 u_SpecularColorUVTransform;
    vec2 getSpecularUV() {
        vec3 uv = vec3(u_SpecularUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_SPECULAR_UV_TRANSFORM
            uv = u_SpecularUVTransform * uv;
        #endif
        return uv.xy;
    }
    vec2 getSpecularColorUV() {
        vec3 uv = vec3(u_SpecularColorUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_SPECULARCOLOR_UV_TRANSFORM
            uv = u_SpecularColorUVTransform * uv;
        #endif
        return uv.xy;
    }
#endif

// Transmission Material

#ifdef MATERIAL_TRANSMISSION
    
    uniform sampler2D u_TransmissionSampler;
    uniform int u_TransmissionUVSet;
    uniform mat3 u_TransmissionUVTransform;
    uniform sampler2D u_TransmissionFramebufferSampler;
    uniform ivec2 u_TransmissionFramebufferSize;
    vec2 getTransmissionUV() {
        vec3 uv = vec3(u_TransmissionUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_TRANSMISSION_UV_TRANSFORM
            uv = u_TransmissionUVTransform * uv;
        #endif
        return uv.xy;
    }
#endif

// Volume Material

#ifdef MATERIAL_VOLUME
    
    uniform sampler2D u_ThicknessSampler;
    uniform int u_ThicknessUVSet;
    uniform mat3 u_ThicknessUVTransform;
    vec2 getThicknessUV() {
        vec3 uv = vec3(u_ThicknessUVSet < 1 ? v_texcoord_0 : v_texcoord_1, 1.0);
        #ifdef HAS_THICKNESS_UV_TRANSFORM
            uv = u_ThicknessUVTransform * uv;
        #endif
        return uv.xy;
    }
#endif

#define GLSLIFY 1
const float M_PI = 3.141592653589793;
in vec3 v_Position;
#ifdef HAS_NORMAL_VEC3
    #ifdef HAS_TANGENT_VEC4
        in mat3 v_TBN;
    #else
        in vec3 v_Normal;
    #endif
#endif

#ifdef HAS_COLOR_0_VEC3
    in vec3 v_Color;
#endif
#ifdef HAS_COLOR_0_VEC4
    in vec4 v_Color;
#endif

vec4 getVertexColor() {
    vec4 color = vec4(1.0);
    #ifdef HAS_COLOR_0_VEC3
        color.rgb = v_Color.rgb;
    #endif
    #ifdef HAS_COLOR_0_VEC4
        color = v_Color;
    #endif
    
    return color;
}
struct NormalInfo {
    vec3 ng;   // Geometric normal
    
    vec3 n;    // Pertubed normal
    
    vec3 t;    // Pertubed tangent
    
    vec3 b;    // Pertubed bitangent
};
float clampedDot(vec3 x, vec3 y) {
    return clamp(dot(x, y), 0.0.1.0);
}
float max3(vec3 v) {
    return max(max(v.x, v.y), v.z);
}
float applyIorToRoughness(float roughness, float ior) {
    // Scale Roughness evaluation with IOR so that an IOR of 1.0 results in no microfacet refraction and
    // an IOR of 1.5 results in the default amount of microfacet refraction.
    return roughness * clamp(ior * 2.0 - 2.0.0.0.1.0);
}
#define GLSLIFY 1
//
// Fresnel
//
// http://graphicrants.blogspot.com/2013/08/specular-brdf-reference.html
// https://github.com/wdas/brdf/tree/master/src/brdfs
// https://google.github.io/filament/Filament.md.html
//

// The following equation models the Fresnel reflectance term of the spec equation (aka F())
// Implementation of fresnel from [4], Equation 15
vec3 F_Schlick(vec3 f0, vec3 f90, float VdotH) {
    return f0 + (f90 - f0) * pow(clamp(1.0 - VdotH, 0.0.1.0), 5.0);
}
// Smith Joint GGX
// Note: Vis = G / (4 * NdotL * NdotV)
// see Eric Heitz. 2014. Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs. Journal of Computer Graphics Techniques, 3
// see Real-Time Rendering. Page 331 to 336.
// see https://google.github.io/filament/Filament.md.html#materialsystem/specularbrdf/geometricshadowing(specularg)
float V_GGX(float NdotL, float NdotV, float alphaRoughness) {
    float alphaRoughnessSq = alphaRoughness * alphaRoughness;
    float GGXV = NdotL * sqrt(NdotV * NdotV * (1.0 - alphaRoughnessSq) + alphaRoughnessSq);
    float GGXL = NdotV * sqrt(NdotL * NdotL * (1.0 - alphaRoughnessSq) + alphaRoughnessSq);
    float GGX = GGXV + GGXL;
    if (GGX > 0.0) {
        return 0.5 / GGX;
    }
    return 0.0;
}
// The following equation(s) model the distribution of microfacet normals across the area being drawn (aka D())
// Implementation from "Average Irregularity Representation of a Roughened Surface for Ray Reflection" by T. S. Trowbridge, and K. P. Reitz
// Follows the distribution function recommended in the SIGGRAPH 2013 course notes from EPIC Games [1], Equation 3.
float D_GGX(float NdotH, float alphaRoughness) {
    float alphaRoughnessSq = alphaRoughness * alphaRoughness;
    float f = (NdotH * NdotH) * (alphaRoughnessSq - 1.0) + 1.0;
    return alphaRoughnessSq / (M_PI * f * f);
}
float lambdaSheenNumericHelper(float x, float alphaG) {
    float oneMinusAlphaSq = (1.0 - alphaG) * (1.0 - alphaG);
    float a = mix(21.5473.25.3245, oneMinusAlphaSq);
    float b = mix(3.82987.3.32435, oneMinusAlphaSq);
    float c = mix(0.19823.0.16801, oneMinusAlphaSq);
    float d = mix(1.97760.1.27393, oneMinusAlphaSq);
    float e = mix(4.32054.4.85967, oneMinusAlphaSq);
    return a / (1.0 + b * pow(x, c)) + d * x + e;
}
float lambdaSheen(float cosTheta, float alphaG) {
    if (abs(cosTheta) < 0.5) {
        return exp(lambdaSheenNumericHelper(cosTheta, alphaG));
    }
    else {
        return exp(2.0 * lambdaSheenNumericHelper(0.5, alphaG) - lambdaSheenNumericHelper(1.0- cosTheta, alphaG)); }}float V_Sheen(float NdotL, float NdotV, float sheenRoughness) {
    sheenRoughness = max(sheenRoughness, 0.000001); //clamp (0, 1]
    
    float alphaG = sheenRoughness * sheenRoughness;
    return clamp(1.0 / ((1.0 + lambdaSheen(NdotV, alphaG) + lambdaSheen(NdotL, alphaG)) *
    (4.0 * NdotV * NdotL)), 0.0.1.0);
}
//Sheen implementation-------------------------------------------------------------------------------------
// See  https://github.com/sebavan/glTF/tree/KHR_materials_sheen/extensions/2.0/Khronos/KHR_materials_sheen

// Estevez and Kulla http://www.aconty.com/pdf/s2017_pbs_imageworks_sheen.pdf
float D_Charlie(float sheenRoughness, float NdotH) {
    sheenRoughness = max(sheenRoughness, 0.000001); //clamp (0, 1]
    
    float alphaG = sheenRoughness * sheenRoughness;
    float invR = 1.0 / alphaG;
    float cos2h = NdotH * NdotH;
    float sin2h = 1.0 - cos2h;
    return (2.0 + invR) * pow(sin2h, invR * 0.5)/(2.0 * M_PI);
}
/ / https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#acknowledgments AppendixB
vec3 BRDF_lambertian(vec3 f0, vec3 f90, vec3 diffuseColor, float specularWeight, float VdotH) {
    // see https://seblagarde.wordpress.com/2012/01/08/pi-or-not-to-pi-in-game-lighting-equation/
    return (1.0 - specularWeight * F_Schlick(f0, f90, VdotH)) * (diffuseColor / M_PI);
}
//  https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#acknowledgments AppendixB
vec3 BRDF_specularGGX(vec3 f0, vec3 f90, float alphaRoughness, float specularWeight, float VdotH, float NdotL, float NdotV, float NdotH) {
    vec3 F = F_Schlick(f0, f90, VdotH);
    float Vis = V_GGX(NdotL, NdotV, alphaRoughness);
    float D = D_GGX(NdotH, alphaRoughness);
    return specularWeight * F * Vis * D;
}
// f_sheen
vec3 BRDF_specularSheen(vec3 sheenColor, float sheenRoughness, float NdotL, float NdotV, float NdotH) {
    float sheenDistribution = D_Charlie(sheenRoughness, NdotH);
    float sheenVisibility = V_Sheen(NdotL, NdotV, sheenRoughness);
    return sheenColor * sheenDistribution * sheenVisibility;
}
#define GLSLIFY 1
// KHR_lights_punctual extension.
/ / see https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
struct Light {
    vec3 direction;
    float range;
    vec3 color;
    float intensity;
    vec3 position;
    float innerConeCos;
    float outerConeCos;
    int type;
};
const int LightType_Directional = 0;
const int LightType_Point = 1;
const int LightType_Spot = 2;
#ifdef USE_PUNCTUAL
    uniform Light u_Lights[LIGHT_COUNT + 1]; //Array [0] is not allowed
    
#endif

/ / https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_lights_punctual/README.md#range-property
float getRangeAttenuation(float range, float distance) {
    if (range <= 0.0) {
        // negative range means unlimited
        return 1.0 / pow(distance.2.0);
    }
    return max(min(1.0 - pow(distance / range, 4.0), 1.0), 0.0) / pow(distance.2.0);
}
// https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_lights_punctual/README.md#inner-and-outer-co ne-angles
float getSpotAttenuation(vec3 pointToLight, vec3 spotDirection, float outerConeCos, float innerConeCos) {
    float actualCos = dot(normalize(spotDirection), normalize(-pointToLight));
    if (actualCos > outerConeCos) {
        if (actualCos < innerConeCos) {
            return smoothstep(outerConeCos, innerConeCos, actualCos);
        }
        return 1.0;
    }
    return 0.0;
}
vec3 getLighIntensity(Light light, vec3 pointToLight) {
    float rangeAttenuation = 1.0;
    float spotAttenuation = 1.0;
    if (light.type ! = LightType_Directional) {
        rangeAttenuation = getRangeAttenuation(light.range, length(pointToLight));
    }
    if (light.type == LightType_Spot) {
        spotAttenuation = getSpotAttenuation(pointToLight, light.direction, light.outerConeCos, light.innerConeCos);
    }
    return rangeAttenuation * spotAttenuation * light.intensity * light.color;
}
vec3 getPunctualRadianceTransmission(vec3 normal, vec3 view, vec3 pointToLight, float alphaRoughness, vec3 f0, vec3 f90, vec3 baseColor, float ior) {
    float transmissionRougness = applyIorToRoughness(alphaRoughness, ior);
    vec3 n = normalize(normal);           // Outward direction of surface point
    
    vec3 v = normalize(view);             // Direction from surface point to view
    
    vec3 l = normalize(pointToLight);
    vec3 l_mirror = normalize(l + 2.0*n*dot(-l, n));     // Mirror light reflection vector on surface
    
    vec3 h = normalize(l_mirror + v);            // Halfway vector between transmission light vector and v
    
    
    float D = D_GGX(clamp(dot(n, h), 0.0.1.0), transmissionRougness);
    vec3 F = F_Schlick(f0, f90, clamp(dot(v, h), 0.0.1.0));
    float Vis = V_GGX(clamp(dot(n, l_mirror), 0.0.1.0), clamp(dot(n, v), 0.0.1.0), transmissionRougness);
    
    // Transmission BTDF
    
    return (1.0 - F) * baseColor * D * Vis;
}
vec3 getPunctualRadianceClearCoat(vec3 clearcoatNormal, vec3 v, vec3 l, vec3 h, float VdotH, vec3 f0, vec3 f90, float clearcoatRoughness) {
    float NdotL = clampedDot(clearcoatNormal, l);
    float NdotV = clampedDot(clearcoatNormal, v);
    float NdotH = clampedDot(clearcoatNormal, h);
    return NdotL * BRDF_specularGGX(f0, f90, clearcoatRoughness * clearcoatRoughness, 1.0, VdotH, NdotL, NdotV, NdotH);
}
vec3 getPunctualRadianceSheen(vec3 sheenColor, float sheenRoughness, float NdotL, float NdotV, float NdotH) {
    return NdotL * BRDF_specularSheen(sheenColor, sheenRoughness, NdotL, NdotV, NdotH);
}
// Compute attenuated light as it travels through a volume.
vec3 applyVolumeAttenuation(vec3 radiance, float transmissionDistance, vec3 attenuationColor, float attenuationDistance) {
    if (attenuationDistance == 0.0) {
        // Anxious distance is +∞ (which we indicate by zero), i.e. the color is not attenuated at all.
        return radiance;
    }
    else {
        // Compute light attenuation using Beer's law.
        vec3 attenuationCoefficient = -log(attenuationColor) / attenuationDistance;
        vec3 transmittance = exp(-attenuationCoefficient * transmissionDistance); // Beer's law
        
        returntransmittance * radiance; }}vec3 getVolumeTransmissionRay(vec3 n, vec3 v, float thickness, float ior, mat4 modelMatrix) {
    // Direction of refracted light.
    vec3 refractionVector = refract(-v, normalize(n), 1.0 / ior);
    
    // Compute rotation-independant scaling of the model matrix.
    
    vec3 modelScale;
    modelScale.x = length(vec3(modelMatrix[0].xyz));
    modelScale.y = length(vec3(modelMatrix[1].xyz));
    modelScale.z = length(vec3(modelMatrix[2].xyz));
    
    // The thickness is specified in local space.
    
    return normalize(refractionVector) * thickness * modelScale;
}
#define GLSLIFY 1
vec3 getDiffuseLight(vec3 n) {
    return texture(u_LambertianEnvSampler, u_EnvRotation * n).rgb;
}
vec4 getSpecularSample(vec3 reflection, float lod) {
    return textureLod(u_GGXEnvSampler, u_EnvRotation * reflection, lod);
}
vec4 getSheenSample(vec3 reflection, float lod) {
    return textureLod(u_CharlieEnvSampler, u_EnvRotation * reflection, lod);
}
vec3 getIBLRadianceGGX(vec3 n, vec3 v, float roughness, vec3 F0, float specularWeight) {
    float NdotV = clampedDot(n, v);
    float lod = roughness * float(u_MipCount - 1);
    vec3 reflection = normalize(reflect(-v, n));
    vec2 brdfSamplePoint = clamp(vec2(NdotV, roughness), vec2(0.0.0.0), vec2(1.0.1.0));
    vec2 f_ab = texture(u_GGXLUT, brdfSamplePoint).rg;
    vec4 specularSample = getSpecularSample(reflection, lod);
    vec3 specularLight = specularSample.rgb;
    
    // see https://bruop.github.io/ibl/#single_scattering_results at Single Scattering Results
    
    // Roughness dependent fresnel, from Fdez-Aguera
    vec3 Fr = max(vec3(1.0 - roughness), F0) - F0;
    vec3 k_S = F0 + Fr * pow(1.0 - NdotV, 5.0);
    vec3 FssEss = k_S * f_ab.x + f_ab.y;
    return specularWeight * specularLight * FssEss;
}
#ifdef MATERIAL_TRANSMISSION
    vec3 getTransmissionSample(vec2 fragCoord, float roughness, float ior) {
        float framebufferLod = log2(float(u_TransmissionFramebufferSize.x)) * applyIorToRoughness(roughness, ior);
        vec3 transmittedLight = textureLod(u_TransmissionFramebufferSampler, fragCoord.xy, framebufferLod).rgb;
        return transmittedLight;
    }
#endif

#ifdef MATERIAL_TRANSMISSION
    vec3 getIBLVolumeRefraction(vec3 n, vec3 v, float perceptualRoughness, vec3 baseColor, vec3 f0, vec3 f90, vec3 position, mat4 modelMatrix, mat4 viewMatrix, mat4 projMatrix, float ior, float thickness, vec3 attenuationColor, float attenuationDistance) {
        vec3 transmissionRay = getVolumeTransmissionRay(n, v, thickness, ior, modelMatrix);
        vec3 refractedRayExit = position + transmissionRay;
        
        // Project refracted vector on the framebuffer, while mapping to normalized device coordinates.
        
        vec4 ndcPos = projMatrix * viewMatrix * vec4(refractedRayExit, 1.0);
        vec2 refractionCoords = ndcPos.xy / ndcPos.w;
        refractionCoords += 1.0;
        refractionCoords /= 2.0;
        
        // Sample framebuffer to get pixel the refracted ray hits.
        
        vec3 transmittedLight = getTransmissionSample(refractionCoords, perceptualRoughness, ior);
        vec3 attenuatedColor = applyVolumeAttenuation(transmittedLight, length(transmissionRay), attenuationColor, attenuationDistance);
        
        // Sample GGX LUT to get the specular component.
        
        float NdotV = clampedDot(n, v);
        vec2 brdfSamplePoint = clamp(vec2(NdotV, perceptualRoughness), vec2(0.0.0.0), vec2(1.0.1.0));
        vec2 brdf = texture(u_GGXLUT, brdfSamplePoint).rg;
        vec3 specularColor = f0 * brdf.x + f90 * brdf.y;
        return (1.0 - specularColor) * attenuatedColor * baseColor;
    }
#endif

// specularWeight is introduced with KHR_materials_specular
vec3 getIBLRadianceLambertian(vec3 n, vec3 v, float roughness, vec3 diffuseColor, vec3 F0, float specularWeight) {
    float NdotV = clampedDot(n, v);
    vec2 brdfSamplePoint = clamp(vec2(NdotV, roughness), vec2(0.0.0.0), vec2(1.0.1.0));
    vec2 f_ab = texture(u_GGXLUT, brdfSamplePoint).rg;
    vec3 irradiance = getDiffuseLight(n);
    
    // see https://bruop.github.io/ibl/#single_scattering_results at Single Scattering Results
    
    // Roughness dependent fresnel, from Fdez-Aguera
    
    vec3 Fr = max(vec3(1.0 - roughness), F0) - F0;
    vec3 k_S = F0 + Fr * pow(1.0 - NdotV, 5.0);
    vec3 FssEss = specularWeight * k_S * f_ab.x + f_ab.y; // <--- GGX / specular light contribution (scale it down if the specularWeight is low)
    
    
    // Multiple scattering, from Fdez-Aguera
    float Ems = (1.0 - (f_ab.x + f_ab.y));
    vec3 F_avg = specularWeight * (F0 + (1.0 - F0) / 21.0);
    vec3 FmsEms = Ems * FssEss * F_avg / (1.0 - F_avg * Ems);
    vec3 k_D = diffuseColor * (1.0 - FssEss + FmsEms); // we use +FmsEms as indicated by the formula in the blog post (might be a typo in the implementation)
    
    
    return (FmsEms + k_D) * irradiance;
}
vec3 getIBLRadianceCharlie(vec3 n, vec3 v, float sheenRoughness, vec3 sheenColor) {
    float NdotV = clampedDot(n, v);
    float lod = sheenRoughness * float(u_MipCount - 1);
    vec3 reflection = normalize(reflect(-v, n));
    vec2 brdfSamplePoint = clamp(vec2(NdotV, sheenRoughness), vec2(0.0.0.0), vec2(1.0.1.0));
    float brdf = texture(u_CharlieLUT, brdfSamplePoint).b;
    vec4 sheenSample = getSheenSample(reflection, lod);
    vec3 sheenLight = sheenSample.rgb;
    return sheenLight * sheenColor * brdf;
}
#define GLSLIFY 1
// Metallic Roughness
uniform float u_MetallicFactor;
uniform float u_RoughnessFactor;
uniform vec4 u_BaseColorFactor;

// Specular Glossiness

uniform vec3 u_SpecularFactor;
uniform vec4 u_DiffuseFactor;
uniform float u_GlossinessFactor;

// Sheen

uniform float u_SheenRoughnessFactor;
uniform vec3 u_SheenColorFactor;

// Clearcoat

uniform float u_ClearcoatFactor;
uniform float u_ClearcoatRoughnessFactor;

// Specular

uniform vec3 u_KHR_materials_specular_specularColorFactor;
uniform float u_KHR_materials_specular_specularFactor;

// Transmission

uniform float u_TransmissionFactor;

// Volume

uniform float u_ThicknessFactor;
uniform vec3 u_AttenuationColor;
uniform float u_AttenuationDistance;

//PBR Next IOR

uniform float u_Ior;

// Alpha mode

uniform float u_AlphaCutoff;
uniform vec3 u_Camera;
#ifdef MATERIAL_TRANSMISSION
    uniform ivec2 u_ScreenSize;
#endif

uniform mat4 u_ModelMatrix;
uniform mat4 u_ViewMatrix;
uniform mat4 u_ProjectionMatrix;
struct MaterialInfo {
    float ior;
    float perceptualRoughness;      // roughness value, as authored by the model creator (input to shader)
    
    vec3 f0;                        // full reflectance color (n incidence angle)
    
    
    float alphaRoughness;           // roughness mapped to a more linear change in the roughness (proposed by [2])
    
    vec3 c_diff;
    vec3 f90;                       // reflectance color at grazing angle
    
    float metallic;
    vec3 baseColor;
    float sheenRoughnessFactor;
    vec3 sheenColorFactor;
    vec3 clearcoatF0;
    vec3 clearcoatF90;
    float clearcoatFactor;
    vec3 clearcoatNormal;
    float clearcoatRoughness;
    
    // KHR_materials_specular
    
    float specularWeight; // product of specularFactor and specularTexture.a
    
    
    float transmissionFactor;
    float thickness;
    vec3 attenuationColor;
    float attenuationDistance;
};

// Get normal, tangent and bitangent vectors.

NormalInfo getNormalInfo(vec3 v) {
    vec2 UV = getNormalUV();
    vec3 uv_dx = dFdx(vec3(UV, 0.0));
    vec3 uv_dy = dFdy(vec3(UV, 0.0));
    vec3 t_ = (uv_dy.t * dFdx(v_Position) - uv_dx.t * dFdy(v_Position)) /
    (uv_dx.s * uv_dy.t - uv_dy.s * uv_dx.t);
    vec3 n, t, b, ng;
    
    // Compute geometrical TBN:
    
    #ifdef HAS_TANGENT_VEC4
        // Trivial TBN computation, present as vertex attribute.
        // Normalize eigenvectors as matrix is linearly interpolated.
        t = normalize(v_TBN[0]);
        b = normalize(v_TBN[1]);
        ng = normalize(v_TBN[2]);
    #else
        // Normals are either present as vertex attributes or approximated.
        #ifdef HAS_NORMAL_VEC3
            ng = normalize(v_Normal);
        #else
            ng = normalize(cross(dFdx(v_Position), dFdy(v_Position)));
        #endif
        t = normalize(t_ - ng * dot(ng, t_));
        b = cross(ng, t);
    #endif
    
    // For a back-facing surface, the tangential basis vectors are negated.
    if (gl_FrontFacing= =false) {
        t *= 1.0;
        b *= 1.0;
        ng *= 1.0;
    }
    // Compute pertubed normals:
    #ifdef HAS_NORMAL_MAP
        n = texture(u_NormalSampler, UV).rgb * 2.0 - vec3(1.0);
        n *= vec3(u_NormalScale, u_NormalScale, 1.0);
        n = mat3(t, b, ng) * normalize(n);
    #else
        n = ng;
    #endif
    
    NormalInfo info;
    info.ng = ng;
    info.t = t;
    info.b = b;
    info.n = n;
    return info;
}
vec3 getClearcoatNormal(NormalInfo normalInfo) {
    #ifdef HAS_CLEARCOAT_NORMAL_MAP
        vec3 n = texture(u_ClearcoatNormalSampler, getClearcoatNormalUV()).rgb * 2.0 - vec3(1.0);
        n *= vec3(u_ClearcoatNormalScale, u_ClearcoatNormalScale, 1.0);
        n = mat3(normalInfo.t, normalInfo.b, normalInfo.ng) * normalize(n);
        return n;
    #else
        return normalInfo.ng;
    #endif
}
vec4 getBaseColor() {
    vec4 baseColor = vec4(1);
    #if defined(MATERIAL_SPECULARGLOSSINESS)
        baseColor = u_DiffuseFactor;
        #elif defined(MATERIAL_METALLICROUGHNESS)
        baseColor = u_BaseColorFactor;
    #endif
    
    #if defined(MATERIAL_SPECULARGLOSSINESS) && defined(HAS_DIFFUSE_MAP)
        baseColor *= texture(u_DiffuseSampler, getDiffuseUV());
        #elif defined(MATERIAL_METALLICROUGHNESS) && defined(HAS_BASE_COLOR_MAP)
        baseColor *= texture(u_BaseColorSampler, getBaseColorUV());
    #endif
    
    return baseColor * getVertexColor();
}
#ifdef MATERIAL_SPECULARGLOSSINESS
    MaterialInfo getSpecularGlossinessInfo(MaterialInfo info) {
        info.f0 = u_SpecularFactor;
        info.perceptualRoughness = u_GlossinessFactor;
        #ifdef HAS_SPECULAR_GLOSSINESS_MAP
            vec4 sgSample = texture(u_SpecularGlossinessSampler, getSpecularGlossinessUV());
            info.perceptualRoughness *= sgSample.a ; // glossiness to roughness
            
            info.f0 *= sgSample.rgb; // specular
            
        #endif // ! HAS_SPECULAR_GLOSSINESS_MAP
        
        info.perceptualRoughness = 1.0 - info.perceptualRoughness; // 1 - glossiness
        
        info.c_diff = info.baseColor.rgb * (1.0 - max(max(info.f0.r, info.f0.g), info.f0.b));
        return info;
    }
#endif

#ifdef MATERIAL_METALLICROUGHNESS
    MaterialInfo getMetallicRoughnessInfo(MaterialInfo info) {
        info.metallic = u_MetallicFactor;
        info.perceptualRoughness = u_RoughnessFactor;
        #ifdef HAS_METALLIC_ROUGHNESS_MAP
            // Roughness is stored in the 'g' channel, metallic is stored in the 'b' channel.
            // This layout intentionally reserves the 'r' channel for (optional) occlusion map data
            vec4 mrSample = texture(u_MetallicRoughnessSampler, getMetallicRoughnessUV());
            info.perceptualRoughness *= mrSample.g;
            info.metallic *= mrSample.b;
        #endif
        
        // Achromatic f0 based on IOR.
        info.c_diff = mix(info.baseColor.rgb * (vec3(1.0) - info.f0), vec3(0), info.metallic);
        info.f0 = mix(info.f0, info.baseColor.rgb, info.metallic);
        return info;
    }
#endif

#ifdef MATERIAL_SHEEN
    MaterialInfo getSheenInfo(MaterialInfo info) {
        info.sheenColorFactor = u_SheenColorFactor;
        info.sheenRoughnessFactor = u_SheenRoughnessFactor;
        #ifdef HAS_SHEEN_COLOR_MAP
            vec4 sheenColorSample = texture(u_SheenColorSampler, getSheenColorUV());
            info.sheenColorFactor *= sheenColorSample.rgb;
        #endif
        
        #ifdef HAS_SHEEN_ROUGHNESS_MAP
            vec4 sheenRoughnessSample = texture(u_SheenRoughnessSampler, getSheenRoughnessUV());
            info.sheenRoughnessFactor *= sheenRoughnessSample.a;
        #endif
        return info;
    }
#endif

#ifdef MATERIAL_SPECULAR
    MaterialInfo getSpecularInfo(MaterialInfo info) {
        vec4 specularTexture = vec4(1.0);
        #ifdef HAS_SPECULAR_MAP
            specularTexture.a = texture(u_SpecularSampler, getSpecularColorUV()).a;
        #endif
        #ifdef HAS_SPECULAR_COLOR_MAP
            specularTexture.rgb = texture(u_SpecularColorSampler, getSpecularUV()).rgb;
        #endif
        
        vec3 dielectricSpecularF0 = min(info.f0 * u_KHR_materials_specular_specularColorFactor * specularTexture.rgb, vec3(1.0));
        info.f0 = mix(dielectricSpecularF0, info.baseColor.rgb, info.metallic);
        info.specularWeight = u_KHR_materials_specular_specularFactor * specularTexture.a;
        info.c_diff = mix(info.baseColor.rgb * (1.0 - max3(dielectricSpecularF0)), vec3(0), info.metallic);
        return info;
    }
#endif

#ifdef MATERIAL_TRANSMISSION
    MaterialInfo getTransmissionInfo(MaterialInfo info) {
        info.transmissionFactor = u_TransmissionFactor;
        #ifdef HAS_TRANSMISSION_MAP
            vec4 transmissionSample = texture(u_TransmissionSampler, getTransmissionUV());
            info.transmissionFactor *= transmissionSample.r;
        #endif
        return info;
    }
#endif

#ifdef MATERIAL_VOLUME
    MaterialInfo getVolumeInfo(MaterialInfo info) {
        info.thickness = u_ThicknessFactor;
        info.attenuationColor = u_AttenuationColor;
        info.attenuationDistance = u_AttenuationDistance;
        #ifdef HAS_THICKNESS_MAP
            vec4 thicknessSample = texture(u_ThicknessSampler, getThicknessUV());
            info.thickness *= thicknessSample.g;
        #endif
        return info;
    }
#endif

#ifdef MATERIAL_CLEARCOAT
    MaterialInfo getClearCoatInfo(MaterialInfo info, NormalInfo normalInfo) {
        info.clearcoatFactor = u_ClearcoatFactor;
        info.clearcoatRoughness = u_ClearcoatRoughnessFactor;
        info.clearcoatF0 = vec3(info.f0);
        info.clearcoatF90 = vec3(1.0);
        #ifdef HAS_CLEARCOAT_MAP
            vec4 clearcoatSample = texture(u_ClearcoatSampler, getClearcoatUV());
            info.clearcoatFactor *= clearcoatSample.r;
        #endif
        
        #ifdef HAS_CLEARCOAT_ROUGHNESS_MAP
            vec4 clearcoatSampleRoughness = texture(u_ClearcoatRoughnessSampler, getClearcoatRoughnessUV());
            info.clearcoatRoughness *= clearcoatSampleRoughness.g;
        #endif
        
        info.clearcoatNormal = getClearcoatNormal(normalInfo);
        info.clearcoatRoughness = clamp(info.clearcoatRoughness, 0.0.1.0);
        return info;
    }
#endif

#ifdef MATERIAL_IOR
    MaterialInfo getIorInfo(MaterialInfo info) {
        info.f0 = vec3(pow(( u_Ior - 1.0) /  (u_Ior + 1.0), 2.0));
        info.ior = u_Ior;
        return info;
    }
#endif

float albedoSheenScalingLUT(float NdotV, float sheenRoughnessFactor) {
    return texture(u_SheenELUT, vec2(NdotV, sheenRoughnessFactor)).r;
}
out vec4 g_finalColor;
Copy the code

Initial color vs. texture color vs. vertex color

Here you can set the opacity to 1.0

This is linear SRGB special case

The normal information

Ior baseColor F0 specularWeight Basic computation

Roughness evaluation (RGB Roughness Evaluation A)

Metal flow gets F0 Diffusecolor

Sheen Information Collection

Clearcoat collects information

Specular highlights flow

TRANSMISSION

Volume

PBR Basic information

IBL Sheen Clearcoat

transmission

OA

Direct sunlight

final

Related Posts

Secondary encapsulation of Axios in the Vue project

What is – closures

[], {}, () in js