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Merge pull request #362 from emackey/pbr-lighting
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Update PBR lighting
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@lilleyse
lilleyse committed Apr 27, 2018
2 parents 8afa31a + d372833 commit 666dbc4
Showing 1 changed file with 42 additions and 18 deletions.
60 changes: 42 additions & 18 deletions lib/processPbrMetallicRoughness.js
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Original file line number Diff line number Diff line change
Expand Up @@ -381,9 +381,9 @@ function generateTechnique(gltf, material, materialIndex, options) {
// Fragment shader lighting
fragmentShader += 'const float M_PI = 3.141592653589793;\n';

fragmentShader += 'vec3 lambertianDiffuse(vec3 baseColor) \n' +
fragmentShader += 'vec3 lambertianDiffuse(vec3 diffuseColor) \n' +
'{\n' +
' return baseColor / M_PI;\n' +
' return diffuseColor / M_PI;\n' +
'}\n\n';

fragmentShader += 'vec3 fresnelSchlick2(vec3 f0, vec3 f90, float VdotH) \n' +
Expand Down Expand Up @@ -414,6 +414,22 @@ function generateTechnique(gltf, material, materialIndex, options) {
' return roughnessSquared / (M_PI * f * f);\n' +
'}\n\n';

fragmentShader += 'vec3 SRGBtoLINEAR3(vec3 srgbIn) \n' +
'{\n' +
' return pow(srgbIn, vec3(2.2));\n' +
'}\n\n';

fragmentShader += 'vec4 SRGBtoLINEAR4(vec4 srgbIn) \n' +
'{\n' +
' vec3 linearOut = pow(srgbIn.rgb, vec3(2.2));\n' +
' return vec4(linearOut, srgbIn.a);\n' +
'}\n\n';

fragmentShader += 'vec3 LINEARtoSRGB(vec3 linearIn) \n' +
'{\n' +
' return pow(linearIn, vec3(1.0/2.2));\n' +
'}\n\n';

fragmentShader += 'void main(void) \n{\n';

// Add normal mapping to fragment shader
Expand Down Expand Up @@ -462,7 +478,7 @@ function generateTechnique(gltf, material, materialIndex, options) {

// Add base color to fragment shader
if (defined(parameterValues.baseColorTexture)) {
fragmentShader += ' vec4 baseColorWithAlpha = texture2D(u_baseColorTexture, ' + v_texcoord + ');\n';
fragmentShader += ' vec4 baseColorWithAlpha = SRGBtoLINEAR4(texture2D(u_baseColorTexture, ' + v_texcoord + '));\n';
if (defined(parameterValues.baseColorFactor)) {
fragmentShader += ' baseColorWithAlpha *= u_baseColorFactor;\n';
}
Expand Down Expand Up @@ -505,10 +521,12 @@ function generateTechnique(gltf, material, materialIndex, options) {
fragmentShader += ' vec3 v = -normalize(v_positionEC);\n';

// Generate fragment shader's lighting block
fragmentShader += ' vec3 lightColor = vec3(1.0, 1.0, 1.0);\n';
if (optimizeForCesium) {
// The Sun is brighter than your average light source, and has a yellowish tint balanced by the Earth's ambient blue.
fragmentShader += ' vec3 lightColor = vec3(1.5, 1.4, 1.2);\n';
fragmentShader += ' vec3 l = normalize(czm_sunDirectionEC);\n';
} else {
fragmentShader += ' vec3 lightColor = vec3(1.0, 1.0, 1.0);\n';
fragmentShader += ' vec3 l = vec3(0.0, 0.0, 1.0);\n';
}
fragmentShader += ' vec3 h = normalize(v + l);\n';
Expand All @@ -517,7 +535,7 @@ function generateTechnique(gltf, material, materialIndex, options) {
// Figure out if the reflection vector hits the ellipsoid
fragmentShader += ' czm_ellipsoid ellipsoid = czm_getWgs84EllipsoidEC();\n';
fragmentShader += ' float vertexRadius = length(v_positionWC);\n';
fragmentShader += ' float horizonDotNadir = 1.0 - ellipsoid.radii.x / vertexRadius;\n';
fragmentShader += ' float horizonDotNadir = 1.0 - min(1.0, ellipsoid.radii.x / vertexRadius);\n';
fragmentShader += ' float reflectionDotNadir = dot(r, normalize(v_positionWC));\n';
// Flipping the X vector is a cheap way to get the inverse of czm_temeToPseudoFixed, since that's a rotation about Z.
fragmentShader += ' r.x = -r.x;\n';
Expand All @@ -534,7 +552,7 @@ function generateTechnique(gltf, material, materialIndex, options) {

fragmentShader += ' vec3 f0 = vec3(0.04);\n';
fragmentShader += ' float alpha = roughness * roughness;\n';
fragmentShader += ' vec3 diffuseColor = baseColor * (1.0 - metalness);\n';
fragmentShader += ' vec3 diffuseColor = baseColor * (1.0 - metalness) * (1.0 - f0);\n';
fragmentShader += ' vec3 specularColor = mix(f0, baseColor, metalness);\n';
fragmentShader += ' float reflectance = max(max(specularColor.r, specularColor.g), specularColor.b);\n';
fragmentShader += ' vec3 r90 = vec3(clamp(reflectance * 25.0, 0.0, 1.0));\n';
Expand All @@ -544,44 +562,49 @@ function generateTechnique(gltf, material, materialIndex, options) {
fragmentShader += ' float G = smithVisibilityGGX(alpha, NdotL, NdotV);\n';
fragmentShader += ' float D = GGX(alpha, NdotH);\n';

fragmentShader += ' vec3 diffuseContribution = (1.0 - F) * lambertianDiffuse(baseColor);\n';
fragmentShader += ' vec3 diffuseContribution = (1.0 - F) * lambertianDiffuse(diffuseColor);\n';
fragmentShader += ' vec3 specularContribution = F * G * D / (4.0 * NdotL * NdotV);\n';
fragmentShader += ' vec3 color = NdotL * lightColor * (diffuseContribution + specularContribution);\n';

if (optimizeForCesium) {
fragmentShader += ' float inverseRoughness = 1.0 - roughness;\n';
fragmentShader += ' float inverseRoughness = 1.04 - roughness;\n';
fragmentShader += ' inverseRoughness *= inverseRoughness;\n';
fragmentShader += ' vec3 sceneSkyBox = textureCube(czm_environmentMap, r).rgb * inverseRoughness;\n';

fragmentShader += ' float atmosphereHeight = 0.05;\n';
fragmentShader += ' float blendRegionSize = 0.1 * ((1.0 - inverseRoughness) * 8.0 + 1.1 - horizonDotNadir);\n';
fragmentShader += ' float farAboveHorizon = clamp(horizonDotNadir - blendRegionSize * 0.5, 1.0e-10 - blendRegionSize, 0.99999);\n';
fragmentShader += ' float blendRegionOffset = roughness * -1.0;\n';
fragmentShader += ' float farAboveHorizon = clamp(horizonDotNadir - blendRegionSize * 0.5 + blendRegionOffset, 1.0e-10 - blendRegionSize, 0.99999);\n';
fragmentShader += ' float aroundHorizon = clamp(horizonDotNadir + blendRegionSize * 0.5, 1.0e-10 - blendRegionSize, 0.99999);\n';
fragmentShader += ' float farBelowHorizon = clamp(horizonDotNadir + blendRegionSize * 1.5, 1.0e-10 - blendRegionSize, 0.99999);\n';
fragmentShader += ' float smoothstepHeight = smoothstep(0.0, atmosphereHeight, horizonDotNadir);\n';
fragmentShader += ' float lightScale = smoothstepHeight * 1.5 + 1.0;\n';

fragmentShader += ' vec3 diffuseIrradiance = mix(vec3(0.5), vec3(0.05), smoothstepHeight);\n';
fragmentShader += ' vec3 belowHorizonColor = mix(vec3(0.1, 0.2, 0.4), vec3(0.2, 0.5, 0.7), smoothstepHeight);\n';
fragmentShader += ' vec3 belowHorizonColor = mix(vec3(0.1, 0.15, 0.25), vec3(0.4, 0.7, 0.9), smoothstepHeight);\n';
fragmentShader += ' vec3 nadirColor = belowHorizonColor * 0.5;\n';
fragmentShader += ' vec3 aboveHorizonColor = vec3(0.8, 0.9, 0.95);\n';
fragmentShader += ' vec3 blueSkyColor = mix(vec3(0.09, 0.13, 0.24), aboveHorizonColor, reflectionDotNadir * inverseRoughness * 0.5 + 0.5);\n';
fragmentShader += ' vec3 aboveHorizonColor = mix(vec3(0.9, 1.0, 1.2), belowHorizonColor, roughness * 0.5);\n';
fragmentShader += ' vec3 blueSkyColor = mix(vec3(0.18, 0.26, 0.48), aboveHorizonColor, reflectionDotNadir * inverseRoughness * 0.5 + 0.75);\n';
fragmentShader += ' vec3 zenithColor = mix(blueSkyColor, sceneSkyBox, smoothstepHeight);\n';

fragmentShader += ' vec3 specularIrradiance = mix(zenithColor, aboveHorizonColor, smoothstep(farAboveHorizon, aroundHorizon, reflectionDotNadir) * inverseRoughness);\n';
fragmentShader += ' vec3 blueSkyDiffuseColor = vec3(0.7, 0.85, 0.9);\n';
fragmentShader += ' float diffuseIrradianceFromEarth = (1.0 - horizonDotNadir) * (reflectionDotNadir * 0.25 + 0.75) * smoothstepHeight;\n';
fragmentShader += ' float diffuseIrradianceFromSky = (1.0 - smoothstepHeight) * (1.0 - (reflectionDotNadir * 0.25 + 0.25));\n';
fragmentShader += ' vec3 diffuseIrradiance = blueSkyDiffuseColor * clamp(diffuseIrradianceFromEarth + diffuseIrradianceFromSky, 0.0, 1.0);\n';

fragmentShader += ' float notDistantRough = (1.0 - horizonDotNadir * roughness * 0.8);\n';
fragmentShader += ' vec3 specularIrradiance = mix(zenithColor, aboveHorizonColor, smoothstep(farAboveHorizon, aroundHorizon, reflectionDotNadir) * notDistantRough);\n';
fragmentShader += ' specularIrradiance = mix(specularIrradiance, belowHorizonColor, smoothstep(aroundHorizon, farBelowHorizon, reflectionDotNadir) * inverseRoughness);\n';
fragmentShader += ' specularIrradiance = mix(specularIrradiance, nadirColor, smoothstep(farBelowHorizon, 1.0, reflectionDotNadir) * inverseRoughness);\n';

fragmentShader += ' vec2 brdfLut = texture2D(czm_brdfLut, vec2(NdotV, 1.0 - roughness)).rg;\n';
fragmentShader += ' vec3 IBLColor = (diffuseIrradiance * diffuseColor) + (specularIrradiance * (specularColor * brdfLut.x + brdfLut.y));\n';
fragmentShader += ' color = color * lightScale + IBLColor;\n';
fragmentShader += ' vec3 IBLColor = (diffuseIrradiance * diffuseColor) + (specularIrradiance * SRGBtoLINEAR3(specularColor * brdfLut.x + brdfLut.y));\n';
fragmentShader += ' color += IBLColor;\n';
}

if (defined(parameterValues.occlusionTexture)) {
fragmentShader += ' color *= texture2D(u_occlusionTexture, ' + v_texcoord + ').r;\n';
}
if (defined(parameterValues.emissiveTexture)) {
fragmentShader += ' vec3 emissive = texture2D(u_emissiveTexture, ' + v_texcoord + ').rgb;\n';
fragmentShader += ' vec3 emissive = SRGBtoLINEAR3(texture2D(u_emissiveTexture, ' + v_texcoord + ').rgb);\n';
if (defined(parameterValues.emissiveFactor)) {
fragmentShader += ' emissive *= u_emissiveFactor;\n';
}
Expand All @@ -594,6 +617,7 @@ function generateTechnique(gltf, material, materialIndex, options) {
}

// Final color
fragmentShader += ' color = LINEARtoSRGB(color);\n';
var alphaMode = material.alphaMode;
if (defined(alphaMode)) {
if (alphaMode === 'MASK') {
Expand Down

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