Trade: convenience MeshData*D::has*() functions.

Makes it more intuitive (and shorter) than calling
`if(data.textureCoords2DArrayCount())`.

src/Trade/MeshData2D.h

@@ -83,7 +83,11 @@ class MAGNUM_EXPORT MeshData2D {
         std::vector<UnsignedInt>& indices();
         const std::vector<UnsignedInt>& indices() const; /**< @overload */
 
-        /** @brief Count of position arrays */
+        /**
+         * @brief Count of position arrays
+         *
+         * There is always at least one.
+         */
         UnsignedInt positionArrayCount() const { return _positions.size(); }
 
         /**
@@ -95,6 +99,9 @@ class MAGNUM_EXPORT MeshData2D {
         std::vector<Vector2>& positions(UnsignedInt id);
         const std::vector<Vector2>& positions(UnsignedInt id) const; /**< @overload */
 
+        /** @brief Whether the data contain any 2D texture coordinates */
+        bool hasTextureCoords2D() const { return !_textureCoords2D.empty(); }
+
         /** @brief Count of 2D texture coordinate arrays */
         UnsignedInt textureCoords2DArrayCount() const { return _textureCoords2D.size(); }
 

src/Trade/MeshData3D.h

@@ -84,7 +84,11 @@ class MAGNUM_EXPORT MeshData3D {
         std::vector<UnsignedInt>& indices();
         const std::vector<UnsignedInt>& indices() const; /**< @overload */
 
-        /** @brief Count of position arrays */
+        /**
+         * @brief Count of position arrays
+         *
+         * There is always at least one.
+         */
         UnsignedInt positionArrayCount() const { return _positions.size(); }
 
         /**
@@ -96,6 +100,9 @@ class MAGNUM_EXPORT MeshData3D {
         std::vector<Vector3>& positions(UnsignedInt id);
         const std::vector<Vector3>& positions(UnsignedInt id) const; /**< @overload */
 
+        /** @brief Whether the data contain any normals */
+        bool hasNormals() const { return !_normals.empty(); }
+
         /** @brief Count of normal arrays */
         UnsignedInt normalArrayCount() const { return _normals.size(); }
 
@@ -108,6 +115,9 @@ class MAGNUM_EXPORT MeshData3D {
         std::vector<Vector3>& normals(UnsignedInt id);
         const std::vector<Vector3>& normals(UnsignedInt id) const; /**< @overload */
 
+        /** @brief Whether the data contain any 2D texture coordinates */
+        bool hasTextureCoords2D() const { return !_textureCoords2D.empty(); }
+
         /** @brief Count of 2D texture coordinate arrays */
         UnsignedInt textureCoords2DArrayCount() const { return _textureCoords2D.size(); }