Trade: usage docs for MaterialData.

doc/snippets/MagnumTrade.cpp

@@ -40,9 +40,13 @@
 #include "Magnum/Trade/AbstractImporter.h"
 #include "Magnum/Trade/AnimationData.h"
 #include "Magnum/Trade/ImageData.h"
+#include "Magnum/Trade/MaterialData.h"
 #include "Magnum/Trade/MeshData.h"
 #include "Magnum/Trade/ObjectData2D.h"
 #include "Magnum/Trade/MeshObjectData3D.h"
+#include "Magnum/Trade/PbrClearCoatMaterialData.h"
+#include "Magnum/Trade/PbrSpecularGlossinessMaterialData.h"
+#include "Magnum/Trade/PbrMetallicRoughnessMaterialData.h"
 #include "Magnum/Trade/PhongMaterialData.h"
 #ifdef MAGNUM_TARGET_GL
 #include "Magnum/GL/Texture.h"
@@ -61,6 +65,8 @@
 #include "Magnum/Trade/MeshData3D.h"
 #endif
 
+#define DOXYGEN_IGNORE(...) __VA_ARGS__
+
 using namespace Magnum;
 using namespace Magnum::Math::Literals;
 
@@ -248,6 +254,207 @@ for(auto&& row: data.mutablePixels<Color3ub>())
 /* [ImageData-usage-mutable] */
 }
 
+{
+/* [MaterialAttributeData-name] */
+Trade::MaterialAttributeData a{
+    Trade::MaterialAttribute::DiffuseColor, 0x3bd267ff_rgbaf};
+Trade::MaterialAttributeData b{"DiffuseColor", 0x3bd267ff_rgbaf};
+/* [MaterialAttributeData-name] */
+}
+
+{
+/* [MaterialData-usage] */
+Trade::MaterialData data = DOXYGEN_IGNORE(Trade::MaterialData{{}, {}});
+
+// Assumes the attribute exists
+Float roughness = data.attribute<Float>(Trade::MaterialAttribute::Roughness);
+
+// Optional access
+Color4 color = data.attributeOr(Trade::MaterialAttribute::BaseColor,
+                                0x3bd267ff_rgbaf);
+if(Containers::Optional<UnsignedInt> texture =
+   data.tryAttribute<UnsignedInt>(Trade::MaterialAttribute::BaseColorTexture))
+{
+    // ...
+}
+/* [MaterialData-usage] */
+static_cast<void>(roughness);
+static_cast<void>(color);
+}
+
+{
+Trade::MaterialData data{{}, {}};
+/* [MaterialData-usage-types] */
+/* Prefer a specular/roughness workflow, if present */
+if(data.types() & Trade::MaterialType::PbrSpecularGlossiness) {
+    const auto& pbr = data.as<Trade::PbrSpecularGlossinessMaterialData>();
+
+    Color4 diffuse = pbr.diffuseColor();
+    Color4 specular = pbr.specularColor();
+    Float glossiness = pbr.glossiness();
+
+    DOXYGEN_IGNORE(static_cast<void>(diffuse), static_cast<void>(specular), static_cast<void>(glossiness);)
+
+/* Otherwise use metallic/roughness (or defaults if no attributes present) */
+} else {
+    const auto& pbr = data.as<Trade::PbrMetallicRoughnessMaterialData>();
+
+    Color4 base = pbr.baseColor();
+    Float metalness = pbr.metalness();
+    Float roughness = pbr.roughness();
+
+    DOXYGEN_IGNORE(static_cast<void>(base), static_cast<void>(metalness), static_cast<void>(roughness);)
+}
+/* [MaterialData-usage-types] */
+}
+
+{
+/* [MaterialData-usage-packing] */
+Trade::PbrMetallicRoughnessMaterialData data = DOXYGEN_IGNORE(Trade::PbrMetallicRoughnessMaterialData{{}, {}});
+
+/* Use a shader that accepts a single packed metallic/roughness texture.
+   Querying any texture attributes will give the same values for both metalness
+   and roughness. */
+if(data.hasMetallicRoughnessTexture()) {
+    UnsignedInt metallicRoughness = data.metalnessTexture();
+
+    DOXYGEN_IGNORE(static_cast<void>(metallicRoughness);)
+
+/* Supply texture channels separately */
+} else {
+    UnsignedInt metalness = data.metalnessTexture();
+    UnsignedInt roughness = data.roughnessTexture();
+    Trade::MaterialTextureSwizzle metalnessSwizzle = data.metalnessTextureSwizzle();
+    Trade::MaterialTextureSwizzle roughnessSwizzle = data.roughnessTextureSwizzle();
+
+    DOXYGEN_IGNORE(static_cast<void>(metalness), static_cast<void>(roughness), static_cast<void>(metalnessSwizzle), static_cast<void>(roughnessSwizzle);)
+}
+/* [MaterialData-usage-packing] */
+}
+
+{
+Trade::MaterialData data{{}, {}};
+/* [MaterialData-usage-layers] */
+if(data.hasLayer(Trade::MaterialLayer::ClearCoat)) {
+    Float clearCoatFactor = data.attributeOr(Trade::MaterialLayer::ClearCoat,
+        Trade::MaterialAttribute::LayerFactor, 1.0f);
+    Float clearCoatRoughness = data.attributeOr(Trade::MaterialLayer::ClearCoat,
+        Trade::MaterialAttribute::Roughness, 0.0f);
+
+    DOXYGEN_IGNORE(static_cast<void>(clearCoatFactor), static_cast<void>(clearCoatRoughness);)
+}
+/* [MaterialData-usage-layers] */
+}
+
+{
+Trade::MaterialData data{{}, {}};
+/* [MaterialData-usage-layers-types] */
+if(data.types() & Trade::MaterialType::PbrClearCoat) {
+    const auto& clearCoat = data.as<Trade::PbrClearCoatMaterialData>();
+
+    Float clearCoatFactor = clearCoat.layerFactor();
+    Float clearCoatRoughness = clearCoat.roughness();
+
+    DOXYGEN_IGNORE(static_cast<void>(clearCoatFactor), static_cast<void>(clearCoatRoughness);)
+}
+/* [MaterialData-usage-layers-types] */
+}
+
+{
+/* [MaterialData-populating] */
+Trade::MaterialData data{Trade::MaterialType::PbrMetallicRoughness, {
+    {Trade::MaterialAttribute::DoubleSided, true},
+    {Trade::MaterialAttribute::BaseColor, 0x3bd267ff_srgbaf},
+    {Trade::MaterialAttribute::BaseColorTexture, 17u},
+    {Trade::MaterialAttribute::TextureMatrix, Matrix3::scaling({0.5f, 1.0f})}
+}};
+/* [MaterialData-populating] */
+}
+
+{
+/* [MaterialData-populating-non-owned] */
+using namespace Containers::Literals;
+
+constexpr Trade::MaterialAttributeData attributes[]{
+    {"DoubleSided"_s, true},
+    {"BaseColor"_s, Color4{0.043735f, 0.64448f, 0.135633f, 1.0f}},
+    {"BaseColorTexture"_s, 5u},
+    {"TextureMatrix"_s, Matrix3{{0.5f, 0.0f, 0.0f},
+                                {0.0f, 1.0f, 0.0f},
+                                {0.0f, 0.0f, 1.0f}}}
+};
+
+Trade::MaterialData data{Trade::MaterialType::Phong, {}, attributes};
+/* [MaterialData-populating-non-owned] */
+}
+
+#ifdef MAGNUM_TARGET_GL
+{
+GL::Texture2D baseColorTexture;
+/* [MaterialData-populating-custom] */
+Trade::MaterialData data{Trade::MaterialType::PbrMetallicRoughness, {
+    {Trade::MaterialAttribute::BaseColor, 0x3bd267ff_srgbaf},
+    {Trade::MaterialAttribute::TextureMatrix, Matrix3::scaling({0.5f, 1.0f})},
+    {"baseColorTexturePointer", &baseColorTexture},
+    {"highlightColor", 0x00ffff_srgbf},
+    {"name", "Canary Green Plastic, really ugly"}
+}};
+
+// Retrieving the texture pointer
+GL::Texture2D* texture = data.attribute<GL::Texture2D*>("baseColorTexturePointer");
+/* [MaterialData-populating-custom] */
+static_cast<void>(texture);
+}
+#endif
+
+{
+/* [MaterialData-populating-layers] */
+Trade::MaterialData data{
+    Trade::MaterialType::PbrMetallicRoughness|Trade::MaterialType::PbrClearCoat,
+    {
+        {Trade::MaterialAttribute::BaseColor, 0xffcc33_srgbf},
+        {Trade::MaterialAttribute::MetallicRoughnessTexture, 0u},
+
+        {Trade::MaterialLayer::ClearCoat},
+        {Trade::MaterialAttribute::LayerFactorTexture, 1u},
+        {Trade::MaterialAttribute::RoughnessTexture,  1u},
+        {Trade::MaterialAttribute::RoughnessTextureSwizzle,
+            Trade::MaterialTextureSwizzle::G}
+    },
+
+    {2, 6}
+};
+/* [MaterialData-populating-layers] */
+}
+
+{
+UnsignedInt a, b, c, d, sandTile, grassTile, rockTile;
+/* [MaterialData-populating-layers-custom] */
+Trade::MaterialData proceduralLandscape{
+    Trade::MaterialTypes{}, // Doesn't match any builtin material type
+    {
+        // Rock layer
+        {Trade::MaterialAttribute::LayerFactorTexture, a},
+        {Trade::MaterialAttribute::BaseColorTexture, rockTile},
+
+        // Sand layer
+        {Trade::MaterialAttribute::LayerFactorTexture, b},
+        {"blendType", "mix"},
+        {Trade::MaterialAttribute::BaseColorTexture, sandTile},
+
+        // Grass layer
+        {Trade::MaterialAttribute::LayerFactorTexture, c},
+        {"blendType", "overlay"},
+        {"strandLengthTexture", d},
+        {Trade::MaterialAttribute::BaseColorTexture, grassTile},
+    },
+
+    // There's no base material, everything is in layers
+    {0, 2, 5, 9}
+};
+/* [MaterialData-populating-layers-custom] */
+}
+
 {
 /* [MeshIndexData-usage] */
 Containers::ArrayView<const UnsignedShort> indices;

src/Magnum/Trade/FlatMaterialData.h

@@ -38,8 +38,12 @@ namespace Magnum { namespace Trade {
 @brief Flat material data
 @m_since_latest
 
-@see @ref AbstractImporter::material(), @ref PbrMetallicRoughnessMaterialData,
+See @ref Trade-MaterialData-usage-types for more information about how to use
-    @ref PbrSpecularGlossinessMaterialData, @ref PhongMaterialData
+this class.
+@see @ref AbstractImporter::material(), @ref PhongMaterialData,
+    @ref PbrMetallicRoughnessMaterialData,
+    @ref PbrSpecularGlossinessMaterialData, @ref PbrClearCoatMaterialData,
+    @ref MaterialType::Flat
 */
 class MAGNUM_TRADE_EXPORT FlatMaterialData: public MaterialData {
     public:

src/Magnum/Trade/MaterialData.h

@@ -1341,8 +1341,168 @@ MAGNUM_TRADE_EXPORT Debug& operator<<(Debug& debug, MaterialAlphaMode value);
 @brief Material data
 @m_since_latest
 
-Key-value store for material attributes in one of the types defined by
+Key-value store for builtin as well as custom material attributes, with an
-@ref MaterialAttributeType.
+ability to define additional layers further affecting the base material.
+Populated instances of this class are returned from
+@ref AbstractImporter::material().
+
+@section Trade-MaterialData-usage Usage
+
+The simplest usage is through templated @ref attribute() functions, which take
+a string attribute name or one of the pre-defined @ref MaterialAttribute
+values. You're expected to check for attribute presence first with
+@ref hasAttribute(), and the requested type has to match @ref attributeType().
+To make things easier, each of the attributes defined in @ref MaterialAttribute
+has a strictly defined type, so you can safely assume the type when requesting
+those. In addition there's @ref tryAttribute() and @ref attributeOr() that
+return a @ref Containers::NullOpt or a default value in case given attribute is
+not found.
+
+@snippet MagnumTrade.cpp MaterialData-usage
+
+It's also possible to iterate through all attributes using @ref attributeName(),
+@ref attributeType() and @ref attribute() taking indices instead of names, with
+@ref attributeCount() returning the total attribute count.
+
+@subsection Trade-MaterialData-usage-types Material types and cnvenience accessors
+
+A material usually consists of a set of attributes for a particular rendering
+workflow --- PBR metallic/roughness, Phong or for example flat-shaded
+materials. To hint what the material contains, @ref types() returns a set of
+@ref MaterialType values. It's not just a single value as the data can define
+attributes for more than one material type (for example both metallic/roughness
+and specular/glossiness PBR workflow), allowing the application to pick the
+best type for a particular use case.
+
+Because retrieving everything through the @ref attribute() APIs can get verbose
+and complex, the @ref Trade library provides a set of accessor APIs for common
+material types such as @ref FlatMaterialData, @ref PhongMaterialData,
+@ref PbrMetallicRoughnessMaterialData or @ref PbrSpecularGlossinessMaterialData.
+Using @ref as() you can convert any @ref MaterialData instance to a reference
+to one of those. These convenience APIs then take care of default values when
+an attribute isn't present or handle fallbacks when an attribute can be defined
+in multiple ways:
+
+@snippet MagnumTrade.cpp MaterialData-usage-types
+
+Each @ref MaterialAttribute is exposed through one or more of those convenience
+APIs, see the documentation of of a particular enum value for more information.
+
+@subsection Trade-MaterialData-usage-packing Texture packing
+
+Especially for single- and two-channel texture maps it's common to have more
+than one map packed into a single texture. Such packing is expressed through
+various @ref MaterialTextureSwizzle attributes such as
+@ref MaterialAttribute::MetalnessTextureSwizzle. While this provides an almost
+endless variability, real-world textures are in just a few common packing
+schemes. For convenience these have dedicated attributes such as
+@ref MaterialAttribute::MetallicRoughnessTexture and can also be checked for
+with for example @ref PbrMetallicRoughnessMaterialData::hasMetallicRoughnessTexture():
+
+@snippet MagnumTrade.cpp MaterialData-usage-packing
+
+@subsection Trade-MaterialData-usage-layers Material layers
+
+In addition to the base material, there can be material layers. While a
+material attribute can be specified only once for a particular layer, multiple
+layers can use the same attribute name for different purpose. Layers are
+commonly used in PBR workflows to describe lacquered wood, metallic paint or
+for example a thin film on leather surfaces. You can enumerate and query layers
+using @ref layerCount(), @ref layerName() and @ref hasLayer(), layer-specific
+attributes are retrieved by passing layer ID or name as the first parameter to
+the @ref attribute() family of APIs.
+
+For each layer there can be predefined @ref layerFactor(),
+@ref layerFactorTexture() and other texture-related attributes which define how
+much the layer affects the underlying material, but the exact semantics of how
+the factor is applied is left to the layer implementation.
+
+Here's an example showing retrieval of a clear coat layer parameters, if
+present:
+
+@snippet MagnumTrade.cpp MaterialData-usage-layers
+
+Like with base material attributes, builtin layers also have convenience
+accessor APIs. The above can be written in a more compact way using
+@link PbrClearCoatMaterialData @endlink:
+
+@snippet MagnumTrade.cpp MaterialData-usage-layers-types
+
+@section Trade-MaterialData-populating Populating an instance
+
+A @ref MaterialData instance by default takes over ownership of an
+@ref Corrade::Containers::Array containing @ref MaterialAttributeData
+instances, together with @ref MaterialTypes suggesting available material types
+(or an empty set, in case of a fully custom material). Attribute values can be
+in one of the types from @ref MaterialAttributeType, and the type is in most
+cases inferred implicitly. The class internally uses strings for attribute
+names, but you're encouraged to use the predefined names from
+@ref MaterialAttribute --- with those, the attribute gets checked additionally
+that it's in an expected type. Attribute order doesn't matter, the array gets
+internally sorted by name to allow a @f$ \mathcal{O}(\log n) @f$ lookup.
+
+@snippet MagnumTrade.cpp MaterialData-populating
+
+In addition to passing ownership of an array it's also possible to have the
+@ref MaterialData instance refer to external data (for example in a
+memory-mapped file, constant memory etc.). The additional second argument is
+@ref DataFlags that's used only for safely disambiguating from the owning
+constructor, and you'll pass a @ref Corrade::Containers::ArrayView instead of
+an @ref Corrade::Containers::Array. Note that in this case, since the attribute
+data is treated as immutable, you *have to* ensure the list is sorted by name.
+
+@snippet MagnumTrade.cpp MaterialData-populating-non-owned
+
+<b></b>
+
+@m_class{m-note m-info}
+
+@par
+    Additionally, as shown above, in order to create a @cpp constexpr @ce
+    @ref MaterialAttributeData array, you need to use
+    @ref Corrade::Containers::StringView literals instead of plain C strings
+    or the @ref MaterialAttribute enum, and be sure to call only
+    @cpp constexpr @ce-enabled constructors of stored data types.
+
+@subsection Trade-MaterialData-populating-custom Custom material attributes
+
+While attribute names beginning with uppercase letters are reserved for builtin
+Magnum attributes, anything beginning with a lowercase letter can be a custom
+attribute. For greater flexibility, custom attributes can be also strings or
+pointers, allowing you to store arbitrary properties or direct texture pointers
+instead of IDs:
+
+@snippet MagnumTrade.cpp MaterialData-populating-custom
+
+@subsection Trade-MaterialData-populating-layers Adding material layers
+
+Material layers are internally represented as ranges of the attribute array and
+by default the whole attribute array is treated as a base material. The actual
+split into layers can be described using an additionaly offset array passed to
+@ref MaterialData(MaterialTypes, Containers::Array<MaterialAttributeData>&&, Containers::Array<UnsignedInt>&&, const void*),
+where entry *i* specifies the end offset of layer *i* --- in the following
+snippet we have two layers (one base material and one clear coat layer), the
+base material being the first two attributes and the clear coat layer being
+attributes in range @cpp 2 @ce to @cpp 6 @ce (thus four attributes):
+
+@snippet MagnumTrade.cpp MaterialData-populating-layers
+
+Like with just a base material, the attributes get sorted for a
+@f$ \mathcal{O}(\log n) @f$ lookup --- but not as a whole, each layer
+separately. In contrary, because layer order matters, those are not reordered
+(and thus their lookup is @f$ \mathcal{O}(n) @f$, however it isn't expected to
+have that many layers for this to matter). The layers can be named by supplying
+a @ref MaterialAttribute::LayerName attribute (or, like shown above, by using
+the convenience @ref MaterialAttributeData::MaterialAttributeData(MaterialLayer)
+constructor) but don't have to --- if a layer doesn't have a name, it can be
+only looked up by its index, not by a name.
+
+Apart from builtin layers, there's no limit in what the layers can be used for
+--- the data can for example describe a completely custom landscape from a set
+of authored `rockTile`, `sandTile`, `grassTile` textures and procedurally
+generated blend factors `a`, `b`, `c`, `d`:
+
+@snippet MagnumTrade.cpp MaterialData-populating-layers-custom
 
 @section Trade-MaterialData-representation Internal representation
 
@@ -1923,16 +2083,16 @@ class MAGNUM_TRADE_EXPORT MaterialData {
          * The @p layer is expected to be smaller than @ref layerCount() const
          * and @p id is expected to be smaller than @ref attributeCount(UnsignedInt) const
          * in that layer. Cast the pointer to a concrete type based on
-         * @ref type(). Note that in case of a
+         * @ref type().
-         * @ref MaterialAttributeType::Pointer or a
+         *
+         * -    In case of a @ref MaterialAttributeType::Pointer or a
          *      @ref MaterialAttributeType::MutablePointer, returns a
          *      *pointer to a pointer*, not the pointer value itself.
-         *
+         * -    In case of a @ref MaterialAttributeType::String returns a
-         * In case of a @ref MaterialAttributeType::String returns a
          *      null-terminated @cpp const char* @ce (not a pointer to
          *      @ref Containers::StringView). This doesn't preserve the actual
-         * string size in case the string data contain zero bytes, thus prefer
+         *      string size in case the string data contain zero bytes, thus
-         * to use typed access in that case.
+         *      prefer to use typed access in that case.
          */
         const void* attribute(UnsignedInt layer, UnsignedInt id) const;
 
@@ -1941,16 +2101,17 @@ class MAGNUM_TRADE_EXPORT MaterialData {
          *
          * The @p layer is expected to be smaller than @ref layerCount() const
          * and @p name is expected to exist in that layer. Cast the pointer to
-         * a concrete type based on @ref attributeType(). Note that
+         * a concrete type based on @ref attributeType().
-         * in case of a @ref MaterialAttributeType::Pointer or a
+         *
+         * -    In case of a @ref MaterialAttributeType::Pointer or a
          *      @ref MaterialAttributeType::MutablePointer, returns a
          *      *pointer to a pointer*, not the pointer value itself.
-         *
+         * -    In case of a @ref MaterialAttributeType::String returns a
-         * In case of a @ref MaterialAttributeType::String returns a
          *      null-terminated @cpp const char* @ce (not a pointer to
          *      @ref Containers::StringView). This doesn't preserve the actual
          *      string size in case the string data contain zero bytes, thus prefer
          *      to use typed access in that case.
+         *
          * @see @ref hasAttribute(), @ref tryAttribute(), @ref attributeOr()
          */
         const void* attribute(UnsignedInt layer, Containers::StringView name) const;
@@ -1961,16 +2122,17 @@ class MAGNUM_TRADE_EXPORT MaterialData {
          *
          * The @p layer is expected to exist and the @p id is expected to be smaller than @ref attributeCount(UnsignedInt) const
          * in that layer. Cast the pointer to a concrete type based on
-         * @ref attributeType(). Note that in case of a
+         * @ref attributeType().
-         * @ref MaterialAttributeType::Pointer or a
+         *
+         * -    In case of a @ref MaterialAttributeType::Pointer or a
          *      @ref MaterialAttributeType::MutablePointer, returns a
          *      *pointer to a pointer*, not the pointer value itself.
-         *
+         * -    In case of a @ref MaterialAttributeType::String returns a
-         * In case of a @ref MaterialAttributeType::String returns a
          *      null-terminated @cpp const char* @ce (not a pointer to
          *      @ref Containers::StringView). This doesn't preserve the actual
          *      string size in case the string data contain zero bytes, thus prefer
          *      to use typed access in that case.
+         *
          * @see @ref hasLayer()
          */
         const void* attribute(Containers::StringView layer, UnsignedInt id) const;
@@ -1981,16 +2143,17 @@ class MAGNUM_TRADE_EXPORT MaterialData {
          *
          * The @p layer is expected to exist and @p name is expected to exist
          * in that layer. Cast the pointer to a concrete type based on
-         * @ref attributeType(). Note that in case of a
+         * @ref attributeType().
-         * @ref MaterialAttributeType::Pointer or a
+         *
+         * -    In case of a @ref MaterialAttributeType::Pointer or a
          *      @ref MaterialAttributeType::MutablePointer, returns a
          *      *pointer to a pointer*, not the pointer value itself.
-         *
+         * -    In case of a @ref MaterialAttributeType::String returns a
-         * In case of a @ref MaterialAttributeType::String returns a
          *      null-terminated @cpp const char* @ce (not a pointer to
          *      @ref Containers::StringView). This doesn't preserve the actual
-         * string size in case the string data contain zero bytes, thus prefer
+         *      string size in case the string data contain zero bytes, thus
-         * to use typed access in that case.
+         *      prefer to use typed access in that case.
+         *
          * @see @ref hasLayer(), @ref hasAttribute()
          */
         const void* attribute(Containers::StringView layer, Containers::StringView name) const;

src/Magnum/Trade/MaterialLayerData.h

@@ -41,7 +41,8 @@ namespace Magnum { namespace Trade {
 
 Convenience wrapper that re-routes all @ref MaterialData base material layer
 and attribute accessors APIS from to a layer specified in the @p layer template
-parameter. All APIs expect that given layer exists.
+parameter. All APIs expect that given layer exists. See
+@ref Trade-MaterialData-usage-layers for more information.
 */
 template<MaterialLayer layer> class MaterialLayerData: public MaterialData {
     public:

src/Magnum/Trade/PbrClearCoatMaterialData.h

@@ -39,8 +39,11 @@ namespace Magnum { namespace Trade {
 @m_since_latest
 
 Exposes properties of a @ref MaterialLayer::ClearCoat layer. All APIs expect
-that the layer is present in the material.
+that the layer is present in the material. See @ref Trade-MaterialData-usage-types
-@see @ref AbstractImporter::material(), @ref MaterialType::PbrClearCoat
+for more information about how to use this class.
+@see @ref AbstractImporter::material(), @ref FlatMaterialData,
+    @ref PhongMaterialData, @ref PbrMetallicRoughnessMaterialData,
+    @ref PbrSpecularGlossinessMaterialData, @ref MaterialType::PbrClearCoat
 */
 class MAGNUM_TRADE_EXPORT PbrClearCoatMaterialData: public MaterialLayerData<MaterialLayer::ClearCoat> {
     public:

src/Magnum/Trade/PbrMetallicRoughnessMaterialData.h

@@ -38,8 +38,11 @@ namespace Magnum { namespace Trade {
 @brief PBR metallic/roughness material data
 @m_since_latest
 
-@see @ref AbstractImporter::material(), @ref PbrSpecularGlossinessMaterialData,
+See @ref Trade-MaterialData-usage-types for more information about how to use
-    @ref PhongMaterialData, @ref FlatMaterialData
+this class.
+@see @ref AbstractImporter::material(), @ref FlatMaterialData,
+    @ref PhongMaterialData, @ref PbrSpecularGlossinessMaterialData,
+    @ref PbrClearCoatMaterialData, @ref MaterialType::PbrMetallicRoughness
 */
 class MAGNUM_TRADE_EXPORT PbrMetallicRoughnessMaterialData: public MaterialData {
     public:

src/Magnum/Trade/PbrSpecularGlossinessMaterialData.h

@@ -38,8 +38,11 @@ namespace Magnum { namespace Trade {
 @brief PBR specular/glossiness material data
 @m_since_latest
 
-@see @ref AbstractImporter::material(), @ref PbrMetallicRoughnessMaterialData,
+See @ref Trade-MaterialData-usage-types for more information about how to use
-    @ref PhongMaterialData, @ref FlatMaterialData
+this class.
+@see @ref AbstractImporter::material(), @ref PhongMaterialData,
+    @ref FlatMaterialData, @ref PbrMetallicRoughnessMaterialData,
+    @ref PbrClearCoatMaterialData, @ref MaterialType::PbrSpecularGlossiness
 */
 class MAGNUM_TRADE_EXPORT PbrSpecularGlossinessMaterialData: public MaterialData {
     public:

src/Magnum/Trade/PhongMaterialData.h

@@ -37,8 +37,11 @@ namespace Magnum { namespace Trade {
 /**
 @brief Phong material data
 
-@see @ref AbstractImporter::material(), @ref PbrMetallicRoughnessMaterialData,
+See @ref Trade-MaterialData-usage-types for more information about how to use
-    @ref PbrSpecularGlossinessMaterialData, @ref FlatMaterialData
+this class.
+@see @ref AbstractImporter::material(), @ref FlatMaterialData,
+    @ref PbrMetallicRoughnessMaterialData,
+    @ref PbrSpecularGlossinessMaterialData, @ref PbrClearCoatMaterialData
 */
 class MAGNUM_TRADE_EXPORT PhongMaterialData: public MaterialData {
     public: