Modified MeshTools::interleave() to support any STL container type.

src/MeshTools/Interleave.h

@@ -36,7 +36,7 @@ class Interleave {
     public:
         inline Interleave(): _attributeCount(0), _stride(0), _data(nullptr) {}
 
-        template<class ...T> std::tuple<size_t, size_t, char*> operator()(const std::vector<T>&... attributes) {
+        template<class ...T> std::tuple<size_t, size_t, char*> operator()(const T&... attributes) {
             /* Compute buffer size and stride */
             _attributeCount = attributeCount(attributes...);
             if(_attributeCount) {
@@ -52,7 +52,7 @@ class Interleave {
             return std::make_tuple(_attributeCount, _stride, _data);
         }
 
-        template<class ...T> void operator()(Mesh* mesh, Buffer* buffer, Buffer::Usage usage, const std::vector<T>&... attributes) {
+        template<class ...T> void operator()(Mesh* mesh, Buffer* buffer, Buffer::Usage usage, const T&... attributes) {
             CORRADE_ASSERT(mesh->isInterleaved(buffer), "MeshTools::interleave(): the buffer is not interleaved, nothing done", )
 
             operator()(attributes...);
@@ -63,23 +63,24 @@ class Interleave {
             delete[] _data;
         }
 
-        template<class T, class ...U> inline static size_t attributeCount(const std::vector<T>& first, const std::vector<U>&... next) {
+        template<class T, class ...U> inline static size_t attributeCount(const T& first, const U&... next) {
             CORRADE_ASSERT(sizeof...(next) == 0 || attributeCount(next...) == first.size(), "MeshTools::interleave(): attribute arrays don't have the same length, nothing done.", 0)
 
             return first.size();
         }
 
-        template<class T, class ...U> inline static size_t stride(const std::vector<T>& first, const std::vector<U>&... next) {
-            return sizeof(T) + stride(next...);
+        template<class T, class ...U> inline static size_t stride(const T& first, const U&... next) {
+            return sizeof(typename T::value_type) + stride(next...);
         }
 
     private:
-        template<class T, class ...U> void write(char* startingOffset, const std::vector<T>& first, const std::vector<U>&... next) {
+        template<class T, class ...U> void write(char* startingOffset, const T& first, const U&... next) {
             /* Copy the data to the buffer */
-            for(size_t i = 0; i != _attributeCount; ++i)
-                memcpy(startingOffset+i*_stride, reinterpret_cast<const char*>(&first[i]), sizeof(T));
+            auto it = first.begin();
+            for(size_t i = 0; i != _attributeCount; ++i, ++it)
+                memcpy(startingOffset+i*_stride, reinterpret_cast<const char*>(&*it), sizeof(typename T::value_type));
 
-            write(startingOffset+sizeof(T), next...);
+            write(startingOffset+sizeof(typename T::value_type), next...);
         }
 
         /* Terminator functions for recursive calls */
@@ -101,7 +102,8 @@ class Interleave {
 
 /**
 @brief %Interleave vertex attributes
-@param attributes   Attribute arrays
+@param attribute    First attribute array
+@param attributes   Next attribute arrays
 @return Attribute count, stride and interleaved attribute array. Deleting the
     array is user responsibility.
 
@@ -110,23 +112,31 @@ so data for each attribute are in continuous place in memory. Size of the data
 buffer can be computed from attribute count and stride, as shown below. Example
 usage:
 @code
+std::vector<Vector4> vertices;
+std::vector<Vector2> textureCoordinates;
 size_t attributeCount;
 size_t stride;
 char* data;
-std::tie(attributeCount, stride, data) = MeshTools::interleave(attributes);
+std::tie(attributeCount, stride, data) = MeshTools::interleave(vertices, textureCoordinates);
 size_t dataSize = attributeCount*stride;
 // ...
 delete[] data;
 @endcode
 
+The only requirements to attribute array type is that it must have typedef
+`T::value_type`, forward iterator (to be used with range-based for) and
+function `size()` returning count of elements. In most cases it will be
+`std::vector` or `std::array`.
+
 See also interleave(Mesh*, Buffer*, Buffer::Usage, const std::vector<T>&...),
 which writes the interleaved array directly into buffer of given mesh.
 
-@attention Each vector should have the same size, if not, resulting array has
-    zero length.
+@attention Each passed array should have the same size, if not, resulting
+    array has zero length.
 */
-template<class ...T> inline std::tuple<size_t, size_t, char*> interleave(const std::vector<T>&... attributes) {
-    return Implementation::Interleave()(attributes...);
+/* enable_if to avoid clash with overloaded function below */
+template<class T, class ...U> inline typename std::enable_if<!std::is_convertible<T, Mesh*>::value, std::tuple<size_t, size_t, char*>>::type interleave(const T& attribute, const U&... attributes) {
+    return Implementation::Interleave()(attribute, attributes...);
 }
 
 /**
@@ -136,15 +146,14 @@ template<class ...T> inline std::tuple<size_t, size_t, char*> interleave(const s
 @param buffer       Output array buffer
 @param usage        Array buffer usage
 
-The same as interleave(const std::vector<T>&...), but this function writes
-the output to given array buffer and updates vertex count in the mesh
-accordingly.
+The same as interleave(const T&...), but this function writes the output to
+given array buffer and updates vertex count in the mesh accordingly.
 
 @attention The buffer must be set as interleaved (see Mesh::addBuffer()),
     otherwise this function does nothing. Binding the attributes to shader is
     left to user.
 */
-template<class ...T> inline void interleave(Mesh* mesh, Buffer* buffer, Buffer::Usage usage, const std::vector<T>&... attributes) {
+template<class ...T> inline void interleave(Mesh* mesh, Buffer* buffer, Buffer::Usage usage, const T&... attributes) {
     return Implementation::Interleave()(mesh, buffer, usage, attributes...);
 }