Building igl statically and moving to the dep scripts

Fixing dep build script on Windows and removing some warnings.

Use bundled igl by default.

Not building with the dependency scripts if not explicitly stated. This way, it will stay in
Fix the libigl patch to include C source files in header only mode.

src/libigl/igl/parallel_for.h

@@ -0,0 +1,188 @@
+// This file is part of libigl, a simple c++ geometry processing library.
+// 
+// Copyright (C) 2016 Alec Jacobson <alecjacobson@gmail.com>
+// 
+// This Source Code Form is subject to the terms of the Mozilla Public License 
+// v. 2.0. If a copy of the MPL was not distributed with this file, You can 
+// obtain one at http://mozilla.org/MPL/2.0/.
+#ifndef IGL_PARALLEL_FOR_H
+#define IGL_PARALLEL_FOR_H
+#include "igl_inline.h"
+#include <functional>
+
+//#warning "Defining IGL_PARALLEL_FOR_FORCE_SERIAL"
+//#define IGL_PARALLEL_FOR_FORCE_SERIAL
+
+namespace igl
+{
+  // PARALLEL_FOR Functional implementation of a basic, open-mp style, parallel
+  // for loop. If the inner block of a for-loop can be rewritten/encapsulated in
+  // a single (anonymous/lambda) function call `func` so that the serial code
+  // looks like:
+  // 
+  //     for(int i = 0;i<loop_size;i++)
+  //     {
+  //       func(i);
+  //     }
+  //
+  // then `parallel_for(loop_size,func,min_parallel)` will use as many threads as
+  // available on the current hardware to parallelize this for loop so long as
+  // loop_size<min_parallel, otherwise it will just use a serial for loop.
+  //
+  // Inputs:
+  //   loop_size  number of iterations. I.e. for(int i = 0;i<loop_size;i++) ...
+  //   func  function handle taking iteration index as only argument to compute
+  //     inner block of for loop I.e. for(int i ...){ func(i); }
+  //   min_parallel  min size of loop_size such that parallel (non-serial)
+  //     thread pooling should be attempted {0}
+  // Returns true iff thread pool was invoked
+  template<typename Index, typename FunctionType >
+  inline bool parallel_for(
+    const Index loop_size, 
+    const FunctionType & func,
+    const size_t min_parallel=0);
+  // PARALLEL_FOR Functional implementation of an open-mp style, parallel for
+  // loop with accumulation. For example, serial code separated into n chunks
+  // (each to be parallelized with a thread) might look like:
+  //     
+  //     Eigen::VectorXd S;
+  //     const auto & prep_func = [&S](int n){ S = Eigen:VectorXd::Zero(n); };
+  //     const auto & func = [&X,&S](int i, int t){ S(t) += X(i); };
+  //     const auto & accum_func = [&S,&sum](int t){ sum += S(t); };
+  //     prep_func(n);
+  //     for(int i = 0;i<loop_size;i++)
+  //     {
+  //       func(i,i%n);
+  //     }
+  //     double sum = 0;
+  //     for(int t = 0;t<n;t++)
+  //     {
+  //       accum_func(t);
+  //     }
+  // 
+  // Inputs:
+  //   loop_size  number of iterations. I.e. for(int i = 0;i<loop_size;i++) ...
+  //   prep_func function handle taking n >= number of threads as only
+  //     argument 
+  //   func  function handle taking iteration index i and thread id t as only
+  //     arguments to compute inner block of for loop I.e. 
+  //     for(int i ...){ func(i,t); }
+  //   accum_func  function handle taking thread index as only argument, to be
+  //     called after all calls of func, e.g., for serial accumulation across
+  //     all n (potential) threads, see n in description of prep_func.
+  //   min_parallel  min size of loop_size such that parallel (non-serial)
+  //     thread pooling should be attempted {0}
+  // Returns true iff thread pool was invoked
+  template<
+    typename Index, 
+    typename PrepFunctionType, 
+    typename FunctionType, 
+    typename AccumFunctionType 
+    >
+  inline bool parallel_for(
+    const Index loop_size, 
+    const PrepFunctionType & prep_func,
+    const FunctionType & func,
+    const AccumFunctionType & accum_func,
+    const size_t min_parallel=0);
+}
+
+// Implementation
+
+#include <cmath>
+#include <cassert>
+#include <thread>
+#include <vector>
+#include <algorithm>
+
+template<typename Index, typename FunctionType >
+inline bool igl::parallel_for(
+  const Index loop_size, 
+  const FunctionType & func,
+  const size_t min_parallel)
+{
+  using namespace std;
+  // no op preparation/accumulation
+  const auto & no_op = [](const size_t /*n/t*/){};
+  // two-parameter wrapper ignoring thread id
+  const auto & wrapper = [&func](Index i,size_t /*t*/){ func(i); };
+  return parallel_for(loop_size,no_op,wrapper,no_op,min_parallel);
+}
+
+template<
+  typename Index, 
+  typename PreFunctionType,
+  typename FunctionType, 
+  typename AccumFunctionType>
+inline bool igl::parallel_for(
+  const Index loop_size, 
+  const PreFunctionType & prep_func,
+  const FunctionType & func,
+  const AccumFunctionType & accum_func,
+  const size_t min_parallel)
+{
+  assert(loop_size>=0);
+  if(loop_size==0) return false;
+  // Estimate number of threads in the pool
+  // http://ideone.com/Z7zldb
+  const static size_t sthc = std::thread::hardware_concurrency();
+  const size_t nthreads = 
+#ifdef IGL_PARALLEL_FOR_FORCE_SERIAL
+    0;
+#else
+    loop_size<min_parallel?0:(sthc==0?8:sthc);
+#endif
+  if(nthreads==0)
+  {
+    // serial
+    prep_func(1);
+    for(Index i = 0;i<loop_size;i++) func(i,0);
+    accum_func(0);
+    return false;
+  }else
+  {
+    // Size of a slice for the range functions
+    Index slice = 
+      std::max(
+        (Index)std::round((loop_size+1)/static_cast<double>(nthreads)),(Index)1);
+ 
+    // [Helper] Inner loop
+    const auto & range = [&func](const Index k1, const Index k2, const size_t t)
+    {
+      for(Index k = k1; k < k2; k++) func(k,t);
+    };
+    prep_func(nthreads);
+    // Create pool and launch jobs
+    std::vector<std::thread> pool;
+    pool.reserve(nthreads);
+    // Inner range extents
+    Index i1 = 0;
+    Index i2 = std::min(0 + slice, loop_size);
+    {
+      size_t t = 0;
+      for (; t+1 < nthreads && i1 < loop_size; ++t)
+      {
+        pool.emplace_back(range, i1, i2, t);
+        i1 = i2;
+        i2 = std::min(i2 + slice, loop_size);
+      }
+      if (i1 < loop_size)
+      {
+        pool.emplace_back(range, i1, loop_size, t);
+      }
+    }
+    // Wait for jobs to finish
+    for (std::thread &t : pool) if (t.joinable()) t.join();
+    // Accumulate across threads
+    for(size_t t = 0;t<nthreads;t++)
+    {
+      accum_func(t);
+    }
+    return true;
+  }
+}
+ 
+//#ifndef IGL_STATIC_LIBRARY
+//#include "parallel_for.cpp"
+//#endif
+#endif