Add Healpix grid

.github/workflows/ci-additional.yml

@@ -33,6 +33,10 @@ jobs:
           environment-file: environment-python-dev.yml
           cache-environment: true
 
+      - name: Install Healpix
+        run: |
+          micromamba install healpix_cxx
+
       - name: Build and install Fastscapelib Python
         run: |
           python -m pip install . -v --no-build-isolation

.github/workflows/tests.yml

@@ -40,6 +40,11 @@ jobs:
           cache-environment: true
           cache-downloads: false
 
+      - name: Install Healpix (Linux and MacOS)
+        if: matrix.cfg.os != 'windows-latest'
+        run: |
+          micromamba install healpix_cxx
+
       - name: Configure Fastscapelib (CMake)
         run: |
           cmake -S . -B build \
@@ -78,6 +83,11 @@ jobs:
           create-args: >-
             python=${{ matrix.python-version }}
 
+      - name: Install Healpix (Linux and MacOS)
+        if: matrix.os != 'windows-latest'
+        run: |
+          micromamba install healpix_cxx
+
       - name: Build and install Fastscapelib Python
         run: |
           python -m pip install . -v --no-build-isolation
@@ -100,7 +110,7 @@ jobs:
 
       - name: Build and install Fastscapelib Python (Numpy 2.x)
         run: |
-          python -m pip install . --config-settings=cmake.define.FS_DOWNLOAD_XTENSOR_PYTHON=ON
+          python -m pip install . --config-settings=cmake.args="-DFS_DOWNLOAD_XTENSOR_PYTHON=ON;-DFS_WITH_HEALPIX=OFF"
 
       - name: Run tests (Numpy 1.xx)
         run: |

CMakeLists.txt

@@ -17,9 +17,14 @@ OPTION(FS_GTEST_SRC_DIR "Build gtest from local sources" OFF)
 OPTION(FS_BUILD_BENCHMARKS "Build fastscapelib benchmark suite" OFF)
 OPTION(FS_DOWNLOAD_GBENCHMARK "Build gbenchmark from downloaded sources" OFF)
 OPTION(FS_GBENCHMARK_SRC_DIR "Build gbenchmark from local sources" OFF)
+OPTION(FS_WITH_HEALPIX "Turn on support of Healpix grid" ON)
+
+if(WIN32)
+  set(FS_WITH_HEALPIX OFF CACHE BOOL "Healpix grid not supported on Windows" FORCE)
+endif()
 
 set(CMAKE_MODULE_PATH
-    ${CMAKE_SOURCE_DIR}/cmake
+    ${CMAKE_SOURCE_DIR}/cmake/modules
     ${CMAKE_MODULE_PATH})
 
 # Dependencies
@@ -76,6 +81,11 @@ endif()
 
 find_package(Threads REQUIRED)
 
+if(FS_WITH_HEALPIX)
+    find_package(healpix REQUIRED)
+    message(STATUS "Found healpix: ${healpix_INCLUDE_DIRS}/healpix_cxx")
+endif()
+
 # Installation directories
 # ========================
 
@@ -131,6 +141,10 @@ set(FASTSCAPELIB_HEADERS
   version.hpp
 )
 
+if(FS_WITH_HEALPIX)
+  list(APPEND FASTSCAPELIB_HEADERS grid/healpix_grid.hpp)
+endif()
+
 set(FASTSCAPELIB_TARGET fastscapelib)
 
 add_library(${FASTSCAPELIB_TARGET} INTERFACE)
@@ -143,6 +157,10 @@ target_include_directories(${FASTSCAPELIB_TARGET}
 
 target_link_libraries(${FASTSCAPELIB_TARGET} INTERFACE xtensor Threads::Threads)
 
+if(FS_WITH_HEALPIX)
+  target_link_libraries(${FASTSCAPELIB_TARGET} INTERFACE healpix)
+endif()
+
 target_compile_features(${FASTSCAPELIB_TARGET} INTERFACE cxx_std_17)
 
 # -- optional subdirectories

benchmark/benchmark_raster_grid.cpp

@@ -170,15 +170,18 @@ namespace fastscapelib
             auto n = static_cast<size_type>(state.range(0));
             std::array<size_type, 2> shape{ { n, n } };
 
+            const short d8_row_offsets[9] = { 0, -1, -1, 0, 1, 1, 1, 0, -1 };
+            const short d8_col_offsets[9] = { 0, 0, -1, -1, -1, 0, 1, 1, 1 };
+
             neighbors_offsets_type offsets(grid_type::n_neighbors_max());
 
-            auto get_neighbors_indices
-                = [&shape, &offsets](auto& r, auto& c) -> neighbors_offsets_type
+            auto get_neighbors_indices = [&shape, &offsets, &d8_row_offsets, &d8_col_offsets](
+                                             auto& r, auto& c) -> neighbors_offsets_type
             {
                 for (std::size_t k = 1; k <= grid_type::n_neighbors_max(); ++k)
                 {
-                    const index_t kr = r + fs::consts::d8_row_offsets[k];
-                    const index_t kc = c + fs::consts::d8_col_offsets[k];
+                    const index_t kr = r + d8_row_offsets[k];
+                    const index_t kc = c + d8_col_offsets[k];
 
                     offsets[k - 1] = std::array<std::ptrdiff_t, 2>({ kr, kc });
 

cmake/modules/Findhealpix.cmake

@@ -0,0 +1,77 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2024 Benoit Bovy
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+#
+# FindHealpix
+# -----------
+#
+# Find Healpix include directories and libraries.
+#
+# This module will set the following variables:
+#
+#  healpix_FOUND          - System has Healpix
+#  healpix_INCLUDE_DIRS   - The Healpix include directories
+#  healpix_LIBRARIES      - The libraries needed to use Healpix
+#
+
+include(FindPackageHandleStandardArgs)
+
+find_path(healpix_INCLUDE_DIR healpix_cxx
+  HINTS
+    ENV healpix_ROOT
+    ENV healpix_DIR
+    ENV CONDA_PREFIX
+    ${healpix_ROOT_DIR}
+  PATH_SUFFIXES
+    include
+  )
+
+find_library(healpix_LIBRARY
+  NAMES healpix_cxx
+  HINTS
+    ENV healpix_ROOT
+    ENV healpix_DIR
+    ENV CONDA_PREFIX
+    ${healpix_ROOT_DIR}
+  PATH_SUFFIXES
+    lib
+    libs
+    Library
+  )
+
+find_package_handle_standard_args(healpix
+  REQUIRED_VARS healpix_INCLUDE_DIR healpix_LIBRARY
+  )
+
+if(healpix_FOUND)
+  set(healpix_INCLUDE_DIRS ${healpix_INCLUDE_DIR})
+  set(healpix_LIBRARIES ${healpix_LIBRARY})
+
+  add_library(healpix SHARED IMPORTED)
+  set_target_properties(healpix PROPERTIES
+    INTERFACE_INCLUDE_DIRECTORIES ${healpix_INCLUDE_DIRS}
+    IMPORTED_LOCATION ${healpix_LIBRARIES}
+    IMPORTED_IMPLIB ${healpix_LIBRARIES}
+    )
+
+  mark_as_advanced(healpix_INCLUDE_DIRS healpix_LIBRARIES)
+endif()

doc/environment.yml

@@ -5,6 +5,7 @@ dependencies:
   - python=3.11
   - breathe
   - cmake
+  - healpix_cxx
   - xtensor-python
   - pybind11
   - scikit-build-core

environment-dev.yml

@@ -4,5 +4,3 @@ channels:
 dependencies:
   - xtensor
   - cmake
-  - gtest
-  - benchmark

include/fastscapelib/grid/base.hpp

@@ -44,7 +44,8 @@ namespace fastscapelib
         core = 0,           /**< Inner grid node */
         fixed_value = 1,    /**< Dirichlet boundary condition */
         fixed_gradient = 2, /**< Neumann boundary condition */
-        looped = 3          /**< Reflective boundaries */
+        looped = 3,         /**< Reflective boundaries */
+        ghost = 4           /**< Inactive grid node (outisde the domain) */
     };
 
     namespace detail