Trade: add a query for packed clearcoat factor/roughness texture.

glTF, always some surprise waiting around the corner.

src/Magnum/Trade/PbrClearCoatMaterialData.cpp

@@ -27,6 +27,16 @@
 
 namespace Magnum { namespace Trade {
 
+bool PbrClearCoatMaterialData::hasLayerFactorRoughnessTexture() const {
+    return hasAttribute(MaterialAttribute::LayerFactorTexture) &&
+        hasAttribute(MaterialAttribute::RoughnessTexture) &&
+        attribute<UnsignedInt>(MaterialAttribute::LayerFactorTexture) == attribute<UnsignedInt>(MaterialAttribute::RoughnessTexture) &&
+        layerFactorTextureSwizzle() == MaterialTextureSwizzle::R &&
+        roughnessTextureSwizzle() == MaterialTextureSwizzle::G &&
+        layerFactorTextureMatrix() == roughnessTextureMatrix() &&
+        layerFactorTextureCoordinates() == roughnessTextureCoordinates();
+}
+
 bool PbrClearCoatMaterialData::hasTextureTransformation() const {
     return hasAttribute(MaterialAttribute::LayerFactorTextureMatrix) ||
         hasAttribute(MaterialAttribute::RoughnessTextureMatrix) ||

src/Magnum/Trade/PbrClearCoatMaterialData.h

@@ -56,6 +56,36 @@ class MAGNUM_TRADE_EXPORT PbrClearCoatMaterialData: public MaterialLayerData<Mat
         using MaterialLayerData<MaterialLayer::ClearCoat>::MaterialLayerData;
         #endif
 
+        /**
+         * @brief Whether the material has a combined layer factor / roughness texture
+         *
+         * Returns @cpp true @ce if both
+         * @ref MaterialAttribute::LayerFactorTexture and
+         * @ref MaterialAttribute::RoughnessTexture attributes are present,
+         * point to the same texture ID,
+         * @ref MaterialAttribute::LayerFactorTextureSwizzle is either not
+         * present or set to @ref MaterialTextureSwizzle::R and
+         * @ref MaterialAttribute::RoughnessTextureSwizzle is set to
+         * @ref MaterialTextureSwizzle::G, and additionally
+         * @ref MaterialAttribute::LayerFactorTextureMatrix and
+         * @ref MaterialAttribute::RoughnessTextureMatrix are both either not
+         * present or have the same value, and
+         * @ref MaterialAttribute::LayerFactorTextureCoordinates and
+         * @ref MaterialAttribute::RoughnessTextureCoordinates are both either
+         * not present or have the smae value; @cpp false @ce otherwise.
+         *
+         * In other words, if this function returns @cpp true @ce,
+         * @ref layerFactorTexture(), @ref layerFactorTextureMatrix() and
+         * @ref layerFactorTextureCoordinates() return values common for both
+         * layer factor and roughness texture, and the two are packed together
+         * with layer factor occupying the R channel and roughness the G
+         * channel. This check is present in order to provide support for the
+         * [KHR_materials_clearcoat](https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat/README.md)
+         * glTF extension.
+         * @see @ref hasAttribute()
+         */
+        bool hasLayerFactorRoughnessTexture() const;
+
         /**
          * @brief Whether the material has texture transformation
          *

src/Magnum/Trade/Test/MaterialDataTest.cpp

@@ -207,6 +207,7 @@ class MaterialDataTest: public TestSuite::Tester {
         void pbrClearCoatAccessDefaults();
         void pbrClearCoatAccessTextured();
         void pbrClearCoatAccessTexturedDefaults();
+        void pbrClearCoatAccessTexturedExplicitPackedLayerFactorRoughness();
         void pbrClearCoatAccessTexturedSingleMatrixCoordinates();
         void pbrClearCoatAccessTexturedBaseMaterialMatrixCoordinates();
         void pbrClearCoatAccessInvalidTextures();
@@ -465,6 +466,7 @@ MaterialDataTest::MaterialDataTest() {
               &MaterialDataTest::pbrClearCoatAccessDefaults,
               &MaterialDataTest::pbrClearCoatAccessTextured,
               &MaterialDataTest::pbrClearCoatAccessTexturedDefaults,
+              &MaterialDataTest::pbrClearCoatAccessTexturedExplicitPackedLayerFactorRoughness,
               &MaterialDataTest::pbrClearCoatAccessTexturedSingleMatrixCoordinates,
               &MaterialDataTest::pbrClearCoatAccessTexturedBaseMaterialMatrixCoordinates,
               &MaterialDataTest::pbrClearCoatAccessInvalidTextures,
@@ -4619,6 +4621,101 @@ void MaterialDataTest::pbrClearCoatAccessTexturedDefaults() {
     CORRADE_COMPARE(data.normalTextureCoordinates(), 0u);
 }
 
+void MaterialDataTest::pbrClearCoatAccessTexturedExplicitPackedLayerFactorRoughness() {
+    /* Just the texture ID and swizzles, the rest is implicit */
+    {
+        PbrClearCoatMaterialData data{{}, {
+            {MaterialLayer::ClearCoat},
+            {MaterialAttribute::LayerFactorTexture, 2u},
+            {MaterialAttribute::RoughnessTexture, 2u},
+            {MaterialAttribute::RoughnessTextureSwizzle, MaterialTextureSwizzle::G}
+        }, {0, 4}};
+        CORRADE_VERIFY(data.hasLayerFactorRoughnessTexture());
+        CORRADE_COMPARE(data.layerFactorTexture(), 2);
+        CORRADE_COMPARE(data.layerFactorTextureMatrix(), Matrix3{});
+        CORRADE_COMPARE(data.layerFactorTextureCoordinates(), 0);
+        CORRADE_COMPARE(data.roughnessTexture(), 2);
+        CORRADE_COMPARE(data.roughnessTextureSwizzle(), MaterialTextureSwizzle::G);
+        CORRADE_COMPARE(data.roughnessTextureMatrix(), Matrix3{});
+        CORRADE_COMPARE(data.roughnessTextureCoordinates(), 0);
+
+    /* Explicit parameters for everything, but all the same */
+    } {
+        PbrClearCoatMaterialData data{{}, {
+            {MaterialLayer::ClearCoat},
+            {MaterialAttribute::LayerFactorTexture, 2u},
+            {MaterialAttribute::LayerFactorTextureSwizzle, MaterialTextureSwizzle::R},
+            {MaterialAttribute::LayerFactorTextureMatrix, Matrix3::scaling({0.5f, 0.5f})},
+            {MaterialAttribute::LayerFactorTextureCoordinates, 3u},
+            {MaterialAttribute::RoughnessTexture, 2u},
+            {MaterialAttribute::RoughnessTextureSwizzle, MaterialTextureSwizzle::G},
+            {MaterialAttribute::RoughnessTextureMatrix, Matrix3::scaling({0.5f, 0.5f})},
+            {MaterialAttribute::RoughnessTextureCoordinates, 3u}
+        }, {0, 9}};
+        CORRADE_VERIFY(data.hasLayerFactorRoughnessTexture());
+        CORRADE_COMPARE(data.layerFactorTexture(), 2);
+        CORRADE_COMPARE(data.layerFactorTextureMatrix(), Matrix3::scaling({0.5f, 0.5f}));
+        CORRADE_COMPARE(data.layerFactorTextureCoordinates(), 3);
+        CORRADE_COMPARE(data.roughnessTexture(), 2);
+        CORRADE_COMPARE(data.roughnessTextureSwizzle(), MaterialTextureSwizzle::G);
+        CORRADE_COMPARE(data.roughnessTextureMatrix(), Matrix3::scaling({0.5f, 0.5f}));
+        CORRADE_COMPARE(data.roughnessTextureCoordinates(), 3);
+
+    /* Different texture ID */
+    } {
+        PbrClearCoatMaterialData data{{}, {
+            {MaterialLayer::ClearCoat},
+            {MaterialAttribute::LayerFactorTexture, 2u},
+            {MaterialAttribute::RoughnessTexture, 3u},
+            {MaterialAttribute::RoughnessTextureSwizzle, MaterialTextureSwizzle::G},
+        }, {0, 4}};
+        CORRADE_VERIFY(!data.hasLayerFactorRoughnessTexture());
+
+    /* Unexpected swizzle 1 */
+    } {
+        PbrClearCoatMaterialData data{{}, {
+            {MaterialLayer::ClearCoat},
+            {MaterialAttribute::LayerFactorTexture, 2u},
+            {MaterialAttribute::LayerFactorTextureSwizzle, MaterialTextureSwizzle::B},
+            {MaterialAttribute::RoughnessTexture, 2u},
+            {MaterialAttribute::RoughnessTextureSwizzle, MaterialTextureSwizzle::G},
+        }, {0, 5}};
+        CORRADE_VERIFY(!data.hasLayerFactorRoughnessTexture());
+
+    /* Unexpected swizzle 2 */
+    } {
+        PbrClearCoatMaterialData data{{}, {
+            {MaterialLayer::ClearCoat},
+            {MaterialAttribute::LayerFactorTexture, 2u},
+            {MaterialAttribute::RoughnessTexture, 2u},
+            {MaterialAttribute::RoughnessTextureSwizzle, MaterialTextureSwizzle::B}
+        }, {0, 4}};
+        CORRADE_VERIFY(!data.hasLayerFactorRoughnessTexture());
+
+    /* Unexpected texture matrix */
+    } {
+        PbrClearCoatMaterialData data{{}, {
+            {MaterialLayer::ClearCoat},
+            {MaterialAttribute::LayerFactorTexture, 2u},
+            {MaterialAttribute::LayerFactorTextureMatrix, Matrix3::scaling({0.5f, 1.0f})},
+            {MaterialAttribute::RoughnessTexture, 2u},
+            {MaterialAttribute::RoughnessTextureSwizzle, MaterialTextureSwizzle::G}
+        }, {0, 5}};
+        CORRADE_VERIFY(!data.hasLayerFactorRoughnessTexture());
+
+    /* Unexpected texture coordinates */
+    } {
+        PbrClearCoatMaterialData data{{}, {
+            {MaterialLayer::ClearCoat},
+            {MaterialAttribute::LayerFactorTexture, 2u},
+            {MaterialAttribute::RoughnessTexture, 2u},
+            {MaterialAttribute::RoughnessTextureSwizzle, MaterialTextureSwizzle::G},
+            {MaterialAttribute::RoughnessTextureCoordinates, 1u}
+        }, {0, 5}};
+        CORRADE_VERIFY(!data.hasLayerFactorRoughnessTexture());
+    }
+}
+
 void MaterialDataTest::pbrClearCoatAccessTexturedSingleMatrixCoordinates() {
     PbrClearCoatMaterialData data{{}, {
         {MaterialLayer::ClearCoat},