update gradle project, parallel for-loop based on std::thread on android, fix mipmaps on TextureManager

src/util.cpp

@@ -362,3 +362,58 @@ size_t curl_data_write(void *ptr, size_t size, size_t nmemb, FILE *stream)
     size_t written = fwrite(ptr, size, nmemb, stream);
     return written;
 }
+
+/// @param[in] nb_elements : size of your for loop
+/// @param[in] functor(start, end) :
+/// your function processing a sub chunk of the for loop.
+/// "start" is the first index to process (included) until the index "end"
+/// (excluded)
+/// @code
+///     for(int i = start; i < end; ++i)
+///         computation(i);
+/// @endcode
+/// @param use_threads : enable / disable threads.
+///
+///
+void parallel_for(unsigned nb_elements, std::function<void(int i)> functor, bool use_threads)
+{
+    // -------
+    unsigned nb_threads_hint = std::thread::hardware_concurrency();
+    unsigned nb_threads = nb_threads_hint == 0 ? 8 : (nb_threads_hint);
+
+    unsigned batch_size = nb_elements / nb_threads;
+    unsigned batch_remainder = nb_elements % nb_threads;
+
+    std::vector< std::thread > my_threads(nb_threads);
+
+    if (use_threads)
+    {
+        // Multithread execution
+        for (unsigned i = 0; i < nb_threads; ++i)
+        {
+            int start = i * batch_size;
+            my_threads[i] = std::thread([functor, start, batch_size]() {
+                for (int j = start; j < start + batch_size; j++)
+                    functor(j);
+            });
+        }
+    }
+    else
+    {
+        // Single thread execution (for easy debugging)
+        for (unsigned i = 0; i < nb_threads; ++i) {
+            int start = i * batch_size;
+            for (int j = start; j < start + batch_size; j++)
+                functor(j);
+        }
+    }
+
+    // Deform the elements left
+    int start = nb_threads * batch_size;
+    for (int j = start; j < start + batch_remainder; j++)
+        functor(j);
+
+    // Wait for the other thread to finish their task
+    if (use_threads)
+        std::for_each(my_threads.begin(), my_threads.end(), std::mem_fn(&std::thread::join));
+}