EMSUSD-612 - Add support for MaterialX 1.38.8

lib/mayaUsd/render/MaterialXGenOgsXml/CMakeLists.txt

@@ -87,6 +87,17 @@ if(MaterialX_VERSION VERSION_LESS "1.38.4")
             DESTINATION ${CMAKE_INSTALL_PREFIX}/libraries/pbrlib/genglsl/ogsxml
         )
     endforeach()
+elseif(MaterialX_VERSION VERSION_LESS "1.38.8")
+    MESSAGE(STATUS "Using 1.38.[4-7] libraries with MaterialX ${MaterialX_VERSION}")
+    install(FILES ${NODE_GLSL_IMPLEMENTATIONS_VERSIONED}
+        DESTINATION ${CMAKE_INSTALL_PREFIX}/libraries/adsk/maya/genglsl
+    )
+    foreach(MTLX_FILE ${LIGHT_IMPLEMENTATIONS})
+        string(REPLACE "libraries/" "libraries/1.38.7/" MTLX_FILE ${MTLX_FILE})
+        install(FILES "${MTLX_FILE}"
+            DESTINATION ${CMAKE_INSTALL_PREFIX}/libraries/pbrlib/genglsl/ogsxml
+        )
+    endforeach()
 else()
     MESSAGE(STATUS "Using latest libraries with MaterialX ${MaterialX_VERSION}")
     install(FILES ${NODE_GLSL_IMPLEMENTATIONS_VERSIONED}

lib/mayaUsd/render/MaterialXGenOgsXml/libraries/1.38.7/mx_lighting_maya_none.glsl

@@ -0,0 +1,19 @@
+// This is the same algorithm as found in libraries\pbrlib\genglsl\lib\mx_environment_prefilter.glsl
+// but adjusted for Maya. At this time we will compute a roughness based on the radiance and
+// irradiance samples, so materials with small amount of roughness will look wrong.
+//
+// A more precise roughness computation can be done using Maya samplers, but this requires
+// knowing that the Maya sampling functions are there, otherwise compilation will fail unless
+// there is an IBL active in the Maya lighting.
+
+#include "libraries/pbrlib/genglsl/lib/mx_microfacet_specular.glsl"
+
+vec3 mx_environment_irradiance(vec3 N)
+{
+    return vec3(0);
+}
+
+vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distribution, FresnelData fd)
+{
+    return vec3(0);
+}

lib/mayaUsd/render/MaterialXGenOgsXml/libraries/1.38.7/mx_lighting_maya_v1.glsl

@@ -0,0 +1,27 @@
+// This is the same algorithm as found in libraries\pbrlib\genglsl\lib\mx_environment_prefilter.glsl
+// but adjusted for Maya. At this time we will compute a roughness based on the radiance and
+// irradiance samples, so materials with small amount of roughness will look wrong.
+//
+// A more precise roughness computation can be done using Maya samplers, but this requires
+// knowing that the Maya sampling functions are there, otherwise compilation will fail unless
+// there is an IBL active in the Maya lighting.
+
+#include "libraries/pbrlib/genglsl/lib/mx_microfacet_specular.glsl"
+
+vec3 mx_environment_irradiance(vec3 N)
+{
+    return g_diffuseI;
+}
+
+vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distribution, FresnelData fd)
+{
+    N = mx_forward_facing_normal(N, V);
+    vec3 L = reflect(-V, N);
+    float NdotV = clamp(dot(N, V), M_FLOAT_EPS, 1.0);
+    float avgAlpha = mx_average_alpha(alpha);
+    vec3 F = mx_compute_fresnel(NdotV, fd);
+    float G = mx_ggx_smith_G2(NdotV, NdotV, avgAlpha);
+    vec3 comp = mx_ggx_energy_compensation(NdotV, avgAlpha, F);
+    vec3 Li = mix(g_specularI, g_diffuseI, avgAlpha);
+    return Li * F * G * comp;
+}

lib/mayaUsd/render/MaterialXGenOgsXml/libraries/1.38.7/mx_lighting_maya_v2.glsl

@@ -0,0 +1,27 @@
+// This is the same algorithm as found in libraries\pbrlib\genglsl\lib\mx_environment_prefilter.glsl
+// but adjusted for Maya.
+//
+// Since we are on a more recent versions of Maya, we have external lighting functions that can be
+// called to fetch environment samples:
+
+#include "libraries/pbrlib/genglsl/lib/mx_microfacet_specular.glsl"
+
+vec3 mx_environment_irradiance(vec3 N)
+{
+    return mayaGetIrradianceEnvironment(N);
+}
+
+vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distribution, FresnelData fd)
+{
+    N = mx_forward_facing_normal(N, V);
+    vec3 L = reflect(-V, N);
+    float NdotV = clamp(dot(N, V), M_FLOAT_EPS, 1.0);
+    float avgAlpha = mx_average_alpha(alpha);
+    vec3 F = mx_compute_fresnel(NdotV, fd);
+    float G = mx_ggx_smith_G2(NdotV, NdotV, avgAlpha);
+    vec3 comp = mx_ggx_energy_compensation(NdotV, avgAlpha, F);
+    float phongExp = mayaRoughnessToPhongExp(sqrt(avgAlpha));
+    vec3 Li = mayaGetSpecularEnvironment(N, V, phongExp);
+
+    return Li * F * G * comp;
+}

lib/mayaUsd/render/MaterialXGenOgsXml/libraries/1.38.7/mx_lighting_maya_v3.glsl

@@ -0,0 +1,82 @@
+// This is the same algorithm as found in libraries\pbrlib\genglsl\lib\mx_environment_fis.glsl
+// but adjusted for Maya.
+//
+// Since we are on a more recent versions of Maya, we have external lighting functions that can be
+// called to fetch environment samples:
+#include "libraries/pbrlib/genglsl/lib/mx_microfacet_specular.glsl"
+
+// https://developer.nvidia.com/gpugems/GPUGems3/gpugems3_ch20.html
+// Section 20.4 Equation 13
+float mx_latlong_compute_lod(vec3 dir, float pdf, float maxMipLevel, int envSamples)
+{
+    const float MIP_LEVEL_OFFSET = 1.5;
+    float effectiveMaxMipLevel = maxMipLevel - MIP_LEVEL_OFFSET;
+    float distortion = sqrt(1.0 - mx_square(dir.y));
+    return max(effectiveMaxMipLevel - 0.5 * log2(float(envSamples) * pdf * distortion), 0.0);
+}
+
+vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distribution, FresnelData fd)
+{
+    if (mayaGetSpecularEnvironmentNumLOD() == 0) {
+        return vec3(0);
+    }
+
+    // Generate tangent frame.
+    vec3 Y = normalize(cross(N, X));
+    X = cross(Y, N);
+    mat3 tangentToWorld = mat3(X, Y, N);
+
+    // Transform the view vector to tangent space.
+    V = vec3(dot(V, X), dot(V, Y), dot(V, N));
+
+    // Compute derived properties.
+    float NdotV = clamp(V.z, M_FLOAT_EPS, 1.0);
+    float avgAlpha = mx_average_alpha(alpha);
+
+    // Integrate outgoing radiance using filtered importance sampling.
+    // http://cgg.mff.cuni.cz/~jaroslav/papers/2008-egsr-fis/2008-egsr-fis-final-embedded.pdf
+    vec3 radiance = vec3(0.0);
+    for (int i = 0; i < MX_NUM_FIS_SAMPLES; i++)
+    {
+        vec2 Xi = mx_spherical_fibonacci(i, MX_NUM_FIS_SAMPLES);
+
+        // Compute the half vector and incoming light direction.
+        vec3 H = mx_ggx_importance_sample_NDF(Xi, alpha);
+        vec3 L = -reflect(V, H);
+
+        // Compute dot products for this sample.
+        float NdotH = clamp(H.z, M_FLOAT_EPS, 1.0);
+        float NdotL = clamp(L.z, M_FLOAT_EPS, 1.0);
+        float VdotH = clamp(dot(V, H), M_FLOAT_EPS, 1.0);
+        float LdotH = VdotH;
+
+        // Sample the environment light from the given direction.
+        vec3 Lw = tangentToWorld * L;
+        float pdf = mx_ggx_PDF(H, LdotH, alpha);
+        float lod = mx_latlong_compute_lod(Lw, pdf, float(mayaGetSpecularEnvironmentNumLOD() - 1), MX_NUM_FIS_SAMPLES);
+        vec3 sampleColor = mayaSampleSpecularEnvironmentAtLOD(Lw, lod);
+
+        // Compute the Fresnel term.
+        vec3 F = mx_compute_fresnel(VdotH, fd);
+
+        // Compute the geometric term.
+        float G = mx_ggx_smith_G2(NdotL, NdotV, avgAlpha);
+
+        // Add the radiance contribution of this sample.
+        // From https://cdn2.unrealengine.com/Resources/files/2013SiggraphPresentationsNotes-26915738.pdf
+        //   incidentLight = sampleColor * NdotL
+        //   microfacetSpecular = D * F * G / (4 * NdotL * NdotV)
+        //   pdf = D * NdotH / (4 * VdotH)
+        //   radiance = incidentLight * microfacetSpecular / pdf
+        radiance += sampleColor * F * G * VdotH / (NdotV * NdotH);
+    }
+
+    // Normalize and return the final radiance.
+    radiance /= float(MX_NUM_FIS_SAMPLES);
+    return radiance;
+}
+
+vec3 mx_environment_irradiance(vec3 N)
+{
+    return mayaGetIrradianceEnvironment(N);
+}

lib/mayaUsd/render/MaterialXGenOgsXml/libraries/mx_lighting_maya_none.glsl

@@ -10,10 +10,10 @@
 
 vec3 mx_environment_irradiance(vec3 N)
 {
-    return vec3(0);
+    return vec3(0.0);
 }
 
-vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distribution, FresnelData fd)
+vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 roughness, int distribution, FresnelData fd)
 {
-    return vec3(0);
+    return vec3(0.0);
 }

lib/mayaUsd/render/MaterialXGenOgsXml/libraries/mx_lighting_maya_v1.glsl

@@ -16,12 +16,12 @@ vec3 mx_environment_irradiance(vec3 N)
 vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distribution, FresnelData fd)
 {
     N = mx_forward_facing_normal(N, V);
-    vec3 L = reflect(-V, N);
+    vec3 L = fd.refraction ? mx_refraction_solid_sphere(-V, N, fd.ior.x) : -reflect(V, N);
     float NdotV = clamp(dot(N, V), M_FLOAT_EPS, 1.0);
     float avgAlpha = mx_average_alpha(alpha);
     vec3 F = mx_compute_fresnel(NdotV, fd);
     float G = mx_ggx_smith_G2(NdotV, NdotV, avgAlpha);
-    vec3 comp = mx_ggx_energy_compensation(NdotV, avgAlpha, F);
+    vec3 FG = fd.refraction ? vec3(1.0) - (F * G) : F * G;
     vec3 Li = mix(g_specularI, g_diffuseI, avgAlpha);
-    return Li * F * G * comp;
+    return Li * FG;
 }

lib/mayaUsd/render/MaterialXGenOgsXml/libraries/mx_lighting_maya_v2.glsl

@@ -14,14 +14,13 @@ vec3 mx_environment_irradiance(vec3 N)
 vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distribution, FresnelData fd)
 {
     N = mx_forward_facing_normal(N, V);
-    vec3 L = reflect(-V, N);
+    vec3 L = fd.refraction ? mx_refraction_solid_sphere(-V, N, fd.ior.x) : -reflect(V, N);
     float NdotV = clamp(dot(N, V), M_FLOAT_EPS, 1.0);
     float avgAlpha = mx_average_alpha(alpha);
     vec3 F = mx_compute_fresnel(NdotV, fd);
     float G = mx_ggx_smith_G2(NdotV, NdotV, avgAlpha);
-    vec3 comp = mx_ggx_energy_compensation(NdotV, avgAlpha, F);
+    vec3 FG = fd.refraction ? vec3(1.0) - (F * G) : F * G;
     float phongExp = mayaRoughnessToPhongExp(sqrt(avgAlpha));
     vec3 Li = mayaGetSpecularEnvironment(N, V, phongExp);
-
-    return Li * F * G * comp;
+    return Li * FG;
 }

lib/mayaUsd/render/MaterialXGenOgsXml/libraries/mx_lighting_maya_v3.glsl

@@ -22,8 +22,8 @@ vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distributio
     }
 
     // Generate tangent frame.
-    vec3 Y = normalize(cross(N, X));
-    X = cross(Y, N);
+    X = normalize(X - dot(X, N) * N);
+    vec3 Y = cross(N, X);
     mat3 tangentToWorld = mat3(X, Y, N);
 
     // Transform the view vector to tangent space.
@@ -32,6 +32,7 @@ vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distributio
     // Compute derived properties.
     float NdotV = clamp(V.z, M_FLOAT_EPS, 1.0);
     float avgAlpha = mx_average_alpha(alpha);
+    float G1V = mx_ggx_smith_G1(NdotV, avgAlpha);
 
     // Integrate outgoing radiance using filtered importance sampling.
     // http://cgg.mff.cuni.cz/~jaroslav/papers/2008-egsr-fis/2008-egsr-fis-final-embedded.pdf
@@ -41,18 +42,16 @@ vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distributio
         vec2 Xi = mx_spherical_fibonacci(i, MX_NUM_FIS_SAMPLES);
 
         // Compute the half vector and incoming light direction.
-        vec3 H = mx_ggx_importance_sample_NDF(Xi, alpha);
-        vec3 L = -reflect(V, H);
+        vec3 H = mx_ggx_importance_sample_VNDF(Xi, V, alpha);
+        vec3 L = fd.refraction ? mx_refraction_solid_sphere(-V, H, fd.ior.x) : -reflect(V, H);
 
         // Compute dot products for this sample.
-        float NdotH = clamp(H.z, M_FLOAT_EPS, 1.0);
         float NdotL = clamp(L.z, M_FLOAT_EPS, 1.0);
         float VdotH = clamp(dot(V, H), M_FLOAT_EPS, 1.0);
-        float LdotH = VdotH;
 
         // Sample the environment light from the given direction.
         vec3 Lw = tangentToWorld * L;
-        float pdf = mx_ggx_PDF(H, LdotH, alpha);
+        float pdf = mx_ggx_NDF(H, alpha) * G1V / (4.0 * NdotV);
         float lod = mx_latlong_compute_lod(Lw, pdf, float(mayaGetSpecularEnvironmentNumLOD() - 1), MX_NUM_FIS_SAMPLES);
         vec3 sampleColor = mayaSampleSpecularEnvironmentAtLOD(Lw, lod);
 
@@ -62,17 +61,22 @@ vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distributio
         // Compute the geometric term.
         float G = mx_ggx_smith_G2(NdotL, NdotV, avgAlpha);
 
+        // Compute the combined FG term, which is inverted for refraction.
+        vec3 FG = fd.refraction ? vec3(1.0) - (F * G) : F * G;
+
         // Add the radiance contribution of this sample.
         // From https://cdn2.unrealengine.com/Resources/files/2013SiggraphPresentationsNotes-26915738.pdf
         //   incidentLight = sampleColor * NdotL
         //   microfacetSpecular = D * F * G / (4 * NdotL * NdotV)
-        //   pdf = D * NdotH / (4 * VdotH)
+        //   pdf = D * G1V / (4 * NdotV);
         //   radiance = incidentLight * microfacetSpecular / pdf
-        radiance += sampleColor * F * G * VdotH / (NdotV * NdotH);
+        radiance += sampleColor * FG;
     }
 
-    // Normalize and return the final radiance.
-    radiance /= float(MX_NUM_FIS_SAMPLES);
+    // Apply the global component of the geometric term and normalize.
+    radiance /= G1V * float(MX_NUM_FIS_SAMPLES);
+
+    // Return the final radiance.
     return radiance;
 }
 

test/lib/mayaUsd/render/vp2RenderDelegate/testVP2RenderDelegateMaterialX.py

@@ -94,6 +94,10 @@ def testMayaSurfaces(self):
         if os.getenv('MAYA_HAS_COLOR_MANAGEMENT_SUPPORT_API', 'FALSE') == 'TRUE':
             suffix = "_ocio"
 
+        # MaterialX 1.38.8 has a new triplanar node with superior blending
+        if os.getenv('MATERIALX_VERSION', '1.38.0') >= '1.38.8':
+            suffix += "_blended"
+
         mayaUtils.loadPlugin("mayaUsdPlugin")
         panel = mayaUtils.activeModelPanel()
         cmds.modelEditor(panel, edit=True, displayTextures=True)