embed VAO caching mechanism into loadVertexArrayObject function

include/ACGL/OpenGL/Data/VertexArrayObjectLoadStore.hh

@@ -18,9 +18,15 @@ namespace OpenGL{
 //                                                                               generic load/save
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
+//! @brief
 //! Loads geometry data from a file and attaches the loaded array buffer data to a VertexArrayObject
 //! Tries to guess the file format from the file extension
-SharedVertexArrayObject loadVertexArrayObject(const std::string& _filename);
+//! @param _filename The name of the file to load relative to the Geometry load path
+//! @param _caching  If true, a disk caching mechanism is used to speed up future reading of the same file.
+//!                  When the file is loaded for the first time, a copy of the resulting VAO is stored in
+//!                  the binary VAO format next to the original file. Successive loadings of the same file
+//!                  will load the cached version if one is present.
+SharedVertexArrayObject loadVertexArrayObject(const std::string& _filename, bool _caching = false);
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 //                                                                           library specific load

src/ACGL/OpenGL/Data/VertexArrayObjectLoadStore.cc

@@ -15,30 +15,59 @@ using namespace ACGL::Utils;
 namespace ACGL{
 namespace OpenGL{
 
-SharedVertexArrayObject loadVertexArrayObject(const std::string& _filename)
+SharedVertexArrayObject loadVertexArrayObject(const std::string& _filename, bool _caching)
 {
-    // lower case file ending:
+    // Lower case file ending:
     std::string fileEnding = Base::FileHelpers::getFileEnding(_filename);
+    std::string loadFileName = _filename;
 
+    // Never cache VAO files
     if(fileEnding == "vao")
+        _caching = false;
+
+    bool saveCachedVAO = false;
+    if(_caching)
     {
-        return loadVertexArrayObjectVAO(_filename);
+        // See whether a cached version of the file is available
+        if(ACGL::Base::FileHelpers::fileExists(_filename + ".vao")
+        && ACGL::Base::FileHelpers::getFileModificationTime(_filename + ".vao") > ACGL::Base::FileHelpers::getFileModificationTime(_filename))
+        {
+            // If so, load the cached file instead
+            loadFileName = _filename + ".vao";
+            fileEnding = "vao";
+        }
+        else
+        {
+            // Otherwise, create a cached copy after loading
+            saveCachedVAO = true;
+        }
+    }
+
+    // Load the VAO
+    SharedVertexArrayObject vao;
+    if(fileEnding == "vao")
+    {
+        vao = loadVertexArrayObjectVAO(loadFileName);
     }
     else
     {
         // Generic load: Try to load the file as an ArrayBuffer and attach it to a VAO
-        SharedArrayBuffer ab = loadArrayBuffer(_filename);
+        SharedArrayBuffer ab = loadArrayBuffer(loadFileName);
         if(ab)
         {
-            SharedVertexArrayObject vao(new VertexArrayObject);
+            vao = SharedVertexArrayObject(new VertexArrayObject);
             vao->attachAllAttributes(ab);
-            return vao;
-        }
-        else
-        {
-            return SharedVertexArrayObject();
         }
     }
+
+    // If necessary, store a cached copy to disk
+    if(vao && saveCachedVAO)
+    {
+        ACGL::Utils::debug() << "Saving a cached copy of " << _filename << " ..." << std::endl;
+        saveVertexArrayObjectToVAO(vao, _filename + ".vao");
+    }
+
+    return vao;
 }
 
 }