Enhance material views with iterators to traverse zone id/vf data.

RELEASE-NOTES.md

@@ -33,6 +33,14 @@ The Axom project release numbers follow [Semantic Versioning](http://semver.org/
 - The maximum number of vertices allowed in polygon primitives can now be passed as a template
   argument to `axom::bump::TopologyMapper`, `axom::bump::PrimalAdaptor`, and
   `axom::mir::ElviraAlgorithm`.
+- Material views in `axom::bump::views` were enhanced with `iterator` classes that
+  enable traversal of material data for zones so kernels do not need to use large fixed size
+  buffers inside kernels.
+- Material views in `axom::bump::views` were enhanced with an overloaded `zoneMaterials()`
+  method that allows data to be gathered into `axom::ArrayView` objects.
+- A new `heavily_mixed` example program was added in `axom::mir` to demonstrate running MIR on
+  meshes with heavily mixed zones.
+
 ###  Fixed
 
 ###  Deprecated

src/axom/bump/MatsetSlicer.hpp

@@ -112,15 +112,12 @@ class MatsetSlicer
         const auto size = static_cast<int>(sizesView[index]);
         const auto offset = offsetsView[index];
 
-        typename MatsetView::IDList ids;
-        typename MatsetView::VFList vfs;
-        deviceMatsetView.zoneMaterials(deviceSelectedZonesView[index], ids, vfs);
-
-        for(int i = 0; i < size; i++)
+        auto zoneMat = deviceMatsetView.beginZone(deviceSelectedZonesView[index]);
+        for(int i = 0; i < size; i++, zoneMat++)
         {
           const auto destIndex = offset + i;
-          materialIdsView[destIndex] = ids[i];
-          volumeFractionsView[destIndex] = vfs[i];
+          materialIdsView[destIndex] = zoneMat.material_id();
+          volumeFractionsView[destIndex] = zoneMat.volume_fraction();
           indicesView[destIndex] = destIndex;
         }
       });

src/axom/bump/MergeMeshes.hpp

@@ -1811,8 +1811,6 @@ class MergeMeshesAndMatsets : public MergeMeshes<ExecSpace>
                         axom::IndexType nzones,
                         axom::IndexType zOffset) const
   {
-    using IDList = typename decltype(matsetView)::IDList;
-    using VFList = typename decltype(matsetView)::VFList;
     using MatID = typename decltype(matsetView)::IndexType;
 
     // Make some maps for renumbering material numbers.
@@ -1844,19 +1842,18 @@ class MergeMeshesAndMatsets : public MergeMeshes<ExecSpace>
       nzones,
       AXOM_LAMBDA(axom::IndexType zoneIndex) {
         // Get this zone's materials.
-        IDList ids;
-        VFList vfs;
-        matsetView.zoneMaterials(zoneIndex, ids, vfs);
+        auto zoneMat = matsetView.beginZone(zoneIndex);
+        const auto nmats = zoneMat.size();
 
         // Store the materials in the new material.
         const auto zoneStart = offsetsView[zOffset + zoneIndex];
-        for(axom::IndexType mi = 0; mi < ids.size(); mi++)
+        for(axom::IndexType mi = 0; mi < nmats; mi++, zoneMat++)
         {
           const auto destIndex = zoneStart + mi;
-          volumeFractionsView[destIndex] = vfs[mi];
+          volumeFractionsView[destIndex] = zoneMat.volume_fraction();
 
           // Get the index of the material number in the local map.
-          const auto mapIndex = axom::utilities::binary_search(localView, ids[mi]);
+          const auto mapIndex = axom::utilities::binary_search(localView, zoneMat.material_id());
           SLIC_ASSERT(mapIndex != -1);
           // We'll store the all materials number.
           const auto allMatno = allView[mapIndex];

src/axom/bump/TopologyMapper.hpp

@@ -656,11 +656,9 @@ class TopologyMapper
 
             // Get the src material - there should just be one because we assume
             // that a clean matset is being mapped.
-            typename SrcMatsetView::IDList zoneMatIds;
-            typename SrcMatsetView::VFList zoneMatVFs;
-            srcMatsetView.zoneMaterials(srcZone, zoneMatIds, zoneMatVFs);
-            SLIC_ASSERT(zoneMatIds.size() == 1);
-            const auto mat = zoneMatIds[0];
+            auto zoneMat = srcMatsetView.beginZone(srcZone);
+            SLIC_ASSERT(zoneMat.size() == 1);
+            const auto mat = zoneMat.material_id();
 
 #if defined(AXOM_DEBUG_TOPOLOGY_MAPPER) && !defined(AXOM_DEVICE_CODE)
             std::cout << "\tintersection:" << std::endl

src/axom/bump/tests/bump_views.cpp

@@ -658,6 +658,78 @@ struct test_braid2d_mat
     {
       EXPECT_EQ(results[i], resultsHost[i]);
     }
+
+    // Test iterators.
+    test_matsetview_iterators(matsetView, allocatorID);
+  }
+
+  template <typename MatsetView>
+  static void test_matsetview_iterators(MatsetView matsetView, int allocatorID)
+  {
+    using ZoneIndex = typename MatsetView::ZoneIndex;
+    // Allocate results array on device.
+    const int nResults = matsetView.numberOfZones();
+    axom::Array<int> resultsArrayDevice(nResults, nResults, allocatorID);
+    auto resultsView = resultsArrayDevice.view();
+
+    axom::for_all<ExecSpace>(
+      matsetView.numberOfZones(),
+      AXOM_LAMBDA(axom::IndexType index) {
+        typename MatsetView::IDList ids {};
+        typename MatsetView::VFList vfs {};
+        matsetView.zoneMaterials(index, ids, vfs);
+
+        // Get the end iterator for the zone.
+        const auto end = matsetView.endZone(index);
+
+        int eq_count = 0;
+        int count = 0;
+
+        // Make sure the iterator is for the right zone.
+        eq_count += (end.zoneIndex() == static_cast<ZoneIndex>(index)) ? 1 : 0;
+        count++;
+
+        // Make sure incrementing the last iterator has no effect.
+        auto end2 = end;
+        end2++;
+        eq_count += (end == end2) ? 1 : 0;
+        count++;
+
+        // Make sure the iterator order is the same as for the values we got from zoneMaterials().
+        int i = 0;
+        for(auto it = matsetView.beginZone(index); it != end; it++, i++)
+        {
+          eq_count += (vfs[i] == it.volume_fraction() && ids[i] == it.material_id()) ? 1 : 0;
+          count++;
+        }
+
+        // Test ArrayView version of zoneMaterials().
+        using IndexType = typename MatsetView::IndexType;
+        using FloatType = typename MatsetView::FloatType;
+        constexpr int ARRAY_SIZE = 10;
+        IndexType idStorage[ARRAY_SIZE];
+        FloatType vfStorage[ARRAY_SIZE];
+        axom::ArrayView<IndexType> idView(idStorage, ARRAY_SIZE);
+        axom::ArrayView<FloatType> vfView(vfStorage, ARRAY_SIZE);
+        const auto nmats = matsetView.zoneMaterials(index, idView, vfView);
+        eq_count += (nmats == ids.size()) ? 1 : 0;
+        count++;
+        for(axom::IndexType j = 0; j < nmats; j++)
+        {
+          eq_count += (vfs[j] == vfView[j] && ids[j] == idView[j]) ? 1 : 0;
+          count++;
+        }
+
+        resultsView[index] = (eq_count == count) ? 1 : 0;
+      });
+
+    // Get containsView data to the host and compare results
+    std::vector<int> resultsHost(nResults);
+    axom::copy(resultsHost.data(), resultsView.data(), sizeof(int) * nResults);
+    for(int i = 0; i < nResults; i++)
+    {
+      EXPECT_EQ(resultsHost[i], 1);
+    }
   }
 };