feat: proper metalness

Latios96 · Oct 19, 2024 · 112274e · 112274e
1 parent bacd404
commit 112274e
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Showing 7 changed files with 76 additions and 8 deletions.
diff --git a/.../integrationTests/UsdPreviewSurface/SimpleMetalMaterial/SimpleMetalMaterial.png b/.../integrationTests/UsdPreviewSurface/SimpleMetalMaterial/SimpleMetalMaterial.png
diff --git a/src/crayg/integrationTests/UsdPreviewSurface/SimpleMetalMaterial/SimpleMetalMaterial.usda b/src/crayg/integrationTests/UsdPreviewSurface/SimpleMetalMaterial/SimpleMetalMaterial.usda
@@ -0,0 +1,25 @@
+#usda 1.0
+(
+    subLayers = [
+        @./../_base_scene/_base_scene.usda@
+    ]
+)
+
+
+
+over "Knob"
+{
+    over "Looks"
+    {
+        over "MaterialUnderTestSG"
+        {
+            over "MaterialUnderTest"
+            {
+                color3f inputs:diffuseColor = (0.5,0.5,0.5)
+                color3f inputs:specularColor = (0.95, 0.95, 0.95)
+                int inputs:useSpecularWorkflow = 0
+                float inputs:metallic = 1
+            }
+        }
+    }
+}
diff --git a/src/crayg/integrationTests/cato.json b/src/crayg/integrationTests/cato.json
@@ -243,6 +243,12 @@
           "comparisonSettings": {
             "threshold": 0.15
           }
+        },
+        {
+          "name": "SimpleMetalMaterial",
+          "comparisonSettings": {
+            "threshold": 0.15
+          }
         }
       ]
     }

diff --git a/src/crayg/src/integrators/RaytracingIntegrator.cpp b/src/crayg/src/integrators/RaytracingIntegrator.cpp
@@ -38,6 +38,16 @@ Color RaytracingIntegrator::integrate(const Ray &ray, int recursionDepth) {
 
     Color lobesResult = Color::createBlack();
     int contributingLobes = 0;
+
+    if (!lobes.metallic.weight.isBlack()) {
+        lobesResult += lobes.metallic.weight * integratorContext.integrateRay(lobes.metallic.sampleDirection);
+        contributingLobes++;
+    }
+
+    if (!lobes.specular.weight.isBlack()) {
+        lobesResult += lobes.specular.weight * integratorContext.integrateRay(lobes.specular.sampleDirection);
+        contributingLobes++;
+    }
     if (!lobes.specular.weight.isBlack()) {
         lobesResult += lobes.specular.weight * integratorContext.integrateRay(lobes.specular.sampleDirection);
         contributingLobes++;

diff --git a/src/crayg/src/scene/shadingnetworks/materials/Material.h b/src/crayg/src/scene/shadingnetworks/materials/Material.h
@@ -14,6 +14,7 @@ struct Lobe {
 };
 
 struct Lobes {
+    Lobe metallic;
     Lobe specular;
     Lobe diffuse;
 };

diff --git a/src/crayg/src/scene/shadingnetworks/materials/UsdPreviewSurface.cpp b/src/crayg/src/scene/shadingnetworks/materials/UsdPreviewSurface.cpp
@@ -43,7 +43,19 @@ float F_schlick(float ior, const Vector3f &view, const Vector3f &halfVector) {
 }
 
 void UsdPreviewSurface::getLobes(const SurfaceInteraction &surfaceInteraction, Lobes &lobes) {
-    lobes.specular.weight = getReflectivity(surfaceInteraction);
+    const Color evaluatedDiffuse = diffuseColor.evaluate(surfaceInteraction);
+    const float evaluatedMetallic = metallic.evaluate(surfaceInteraction);
+
+    if (evaluatedMetallic > 0.f) {
+        lobes.metallic.weight = Color::createGrey(evaluatedMetallic) * evaluatedDiffuse;
+        lobes.metallic.sampleDirection = surfaceInteraction.spawnReflectionRayFromSurface();
+    }
+
+    if (evaluatedMetallic >= 1.f) {
+        return;
+    }
+
+    lobes.specular.weight = specularColor.evaluate(surfaceInteraction) * (1.f - evaluatedMetallic);
     const Vector3f halfVector =
         (lobes.specular.sampleDirection.direction + surfaceInteraction.ray.direction).normalize();
 
@@ -54,8 +66,7 @@ void UsdPreviewSurface::getLobes(const SurfaceInteraction &surfaceInteraction, L
         reflectance = F_schlick(evaluatedIor, surfaceInteraction.ray.direction, halfVector);
     }
 
-    lobes.diffuse.weight =
-        (Color::createWhite() - lobes.specular.weight * reflectance) * diffuseColor.evaluate(surfaceInteraction);
+    lobes.diffuse.weight = (Color::createWhite() - lobes.specular.weight * reflectance) * evaluatedDiffuse;
     if (!lobes.diffuse.weight.isBlack()) {
         const Vector3f randomDirOnHemisphere = Sampling::uniformSampleHemisphere();
         auto orthonormalBasis = surfaceInteraction.getOrthonormalBasis();

diff --git a/src/crayg/tests/TestUsdPreviewSurface.cpp b/src/crayg/tests/TestUsdPreviewSurface.cpp
@@ -18,17 +18,32 @@ TEST_CASE("UsdPreviewSurface::evaluate") {
 
         REQUIRE(lobes.diffuse.weight == Color::createGrey(0.5f));
         REQUIRE(lobes.specular.weight == Color::createBlack());
+        REQUIRE(lobes.metallic.weight == Color::createBlack());
     }
 
-    SECTION("should return weighted reflection") {
-        UsdPreviewSurface usdPreviewSurface(Color::createBlack());
-        usdPreviewSurface.metallic = 0.5;
+    SECTION("should return diffuse and spec for dielectric") {
+        UsdPreviewSurface usdPreviewSurface(Color::createGrey(0.5f));
+        usdPreviewSurface.specularColor = Color::createWhite();
+        usdPreviewSurface.metallic = 0;
 
         Lobes lobes;
         usdPreviewSurface.getLobes(surfaceInteraction, lobes);
 
-        REQUIRE(lobes.diffuse.weight == Color::createGrey(0));
-        REQUIRE(lobes.specular.weight == Color::createGrey(0.5));
+        REQUIRE(lobes.diffuse.weight == Color::createGrey(0.48585278f));
+        REQUIRE(lobes.specular.weight == Color::createWhite());
+        REQUIRE(lobes.metallic.weight == Color::createBlack());
+    }
+
+    SECTION("should return only metal for conductor") {
+        UsdPreviewSurface usdPreviewSurface(Color::createGrey(0.5f));
+        usdPreviewSurface.metallic = 1;
+
+        Lobes lobes;
+        usdPreviewSurface.getLobes(surfaceInteraction, lobes);
+
+        REQUIRE(lobes.diffuse.weight == Color::createBlack());
+        REQUIRE(lobes.specular.weight == Color::createBlack());
+        REQUIRE(lobes.metallic.weight == Color::createGrey(0.5));
     }
 }