new tentative

Author: panquez

src/geode/mesh/helpers/build_grid.cpp

@@ -42,15 +42,24 @@ namespace geode
         }
         const auto min_cell_length =
             std::pow( numerator / max_nb_cells, 1. / dimension );
-        const auto cell_length =
-            std::max( min_cell_length, target_cell_length );
+        const auto target_is_ok = target_cell_length < min_cell_length;
+        auto cell_length = std::max( min_cell_length, target_cell_length );
         std::array< index_t, dimension > cell_numbers;
         std::array< double, dimension > cell_lengths;
         for( const auto d : LRange{ dimension } )
         {
-            cell_numbers[d] = std::max( static_cast< index_t >( 1 ),
-                static_cast< index_t >(
-                    std::floor( diagonal.value( d ) / cell_length ) ) );
+            if( target_is_ok )
+            {
+                cell_numbers[d] = std::max( static_cast< index_t >( 1 ),
+                    static_cast< index_t >(
+                        std::ceil( diagonal.value( d ) / cell_length ) ) );
+            }
+            else
+            {
+                cell_numbers[d] = std::max( static_cast< index_t >( 1 ),
+                    static_cast< index_t >(
+                        std::floor( diagonal.value( d ) / cell_length ) ) );
+            }
             cell_lengths[d] = diagonal.value( d ) / cell_numbers[d];
         }
         return { bbox.min(), std::move( cell_numbers ),