Assimp support and GridIn::read_assimp. #5095

luca-heltai · 2017-09-16T14:56:32Z

Added support for the Open Asset Library (http://assimp.sourceforge.net/).

This can be used by invoking the (new) GridIn::read_assimp() function, that translates one of the graphical formats supported by Assimp into a deal.II compatible grid.

The most reliable format so far is the Wavefront .obj format, to which most opensource graphical softwares can export to (Blender, for example, can http://www.blender.org).

As soon as I find the time, I'll make a video tutorial using Blender to create a complex Triangulation<2,3> grid that exploits some of the (many) functionalities of Blender.

davydden · 2017-09-16T15:11:59Z

As soon as I find the time, I'll make a video tutorial using Blender to create a complex Triangulation<2,3> grid that exploits some of the (many) functionalities of Blender.

looking forward to that, i used Blender some 10 years ago as a 3dmax like rendering program.

davydden · 2017-09-16T15:14:18Z

include/deal.II/grid/grid_in.h

+   * the given index will be extracted, otherwise all meshes which are
+   * present in the file will be used to generate the Triangulation.
+   *
+   * This function can only be used to read two-dimensional meshes (possibly


I don't know if .obj supports volume information... so far I could only make it work with surface one. I know it's a pity, but there is a lot of BEM and shell models that would benefit from this anyway. :)

davydden · 2017-09-16T15:14:37Z

include/deal.II/grid/grid_in.h

+   *
+   * This function can only be used to read two-dimensional meshes (possibly
+   * embedded in three dimensions), as this is the only format supported
+   * by the supported graphical formats.


supported by the supported

maybe reword

davydden · 2017-09-16T15:16:09Z

include/deal.II/grid/grid_in.h

+   * `ignore_unsupported_element_types`, all the other element types are simply
+   * ignored by this algorithm. If your mesh contains a mixture of triangles
+   * and quadrilaterals, for example, only the quadrilaterals will be
+   * extracted. Careful that your mesh may not make any sense if you are mixing


maybe: ~~Careful that~~ Your mesh...

luca-heltai · 2017-09-17T19:57:01Z

/run_tests

tjhei · 2017-09-18T13:17:24Z

/run_tests

/run-tests (with a dash)

bangerth · 2017-09-18T13:47:38Z

include/deal.II/grid/grid_in.h

- * @ref GlossBoundaryIndicator "this"
- * glossary entry for more information).
+ * boundary ids to cells or faces (see @ref GlossMaterialId "this" and @ref
+ * GlossBoundaryIndicator "this" glossary entry for more information).


Can you undo the change in formatting?

bangerth · 2017-09-18T14:51:47Z

include/deal.II/grid/grid_in.h

+   * `ignore_unsupported_element_types`, all the other element types are simply
+   * ignored by this algorithm. If your mesh contains a mixture of triangles
+   * and quadrilaterals, for example, only the quadrilaterals will be
+   * extracted. Your mesh may not make any sense if you are mixing compatible


To avoid confusing between the use of "your mesh" in this sentence and the one in the previous sentence, how about writing "The resulting mesh (as represented in the Triangulation object) may not make ..." in the second sentence?

bangerth · 2017-09-18T14:53:09Z

source/grid/grid_in.cc

+DEAL_II_ENABLE_EXTRA_DIAGNOSTICS
+
+#undef AI_CONFIG_PP_RVC_FLAGS
+#define AI_CONFIG_PP_RVC_FLAGS           \


could this be done with a local variable in the function that uses it, instead of a global preprocessor define?

bangerth · 2017-09-18T14:53:56Z

source/grid/grid_in.cc

+  // Only good for surface grids.
+  AssertThrow(dim<3, ExcImpossibleInDim(dim));
+
+  // Create an istance of the Importer class


-> instance

bangerth · 2017-09-18T14:54:57Z

source/grid/grid_in.cc

+  Assimp::Importer importer;
+
+  // And have it read the given file with some  postprocessing
+  const aiScene *scene = importer.ReadFile( filename.c_str(),


are you creating a memory leak here? Or is the memory managed by the importer object?

It is managed by the importer object:

Create an object of this class and call ReadFile() to import a file. If the import succeeds, the function returns a pointer to the imported data. The data remains property of the object, it is intended to be accessed read-only. The imported data will be destroyed along with the Importer object. If the import fails, ReadFile() returns a NULL pointer. In this case you can retrieve a human-readable error description be calling GetErrorString(). You can call ReadFile() multiple times with a single Importer instance. Actually, constructing Importer objects involves quite many allocations and may take some time, so it's better to reuse them as often as possible.

bangerth · 2017-09-18T14:59:17Z

source/grid/grid_in.cc

+          std::stringstream s;
+          s << "Incompatible mesh "  << m
+            << "/" << scene->mNumMeshes;
+          AssertThrow(ignore_unsupported_types, ExcMessage(s.str()));


bangerth · 2017-09-18T15:00:21Z

source/grid/grid_in.cc

+                << m << " has " << mFaces[i].mNumIndices
+                << " vertices. We expected only "
+                << GeometryInfo<dim>::vertices_per_cell;
+              AssertThrow(ignore_unsupported_types, ExcMessage(s.str()));


bangerth · 2017-09-18T15:00:37Z

source/grid/grid_in.cc

+        }
+      cells.resize(valid_cell);
+
+      // The vertices are added all at once. Cells are check for


bangerth · 2017-09-18T15:02:17Z

source/grid/grid_in.cc

                               "functions, instead."));
      return;

    case tecplot:
      read_tecplot (in);
      return;

+    case assimp:
+      Assert(false, ExcMessage("There is no read_assimp(istream &) function. "
+                               "Use the read_netcdf)(string &filename, ...) "


-> read_assimp

bangerth · 2017-09-18T15:02:28Z

source/grid/grid_in.cc

@@ -2820,14 +3000,20 @@ void GridIn<dim, spacedim>::read (std::istream &in,

    case netcdf:
      Assert(false, ExcMessage("There is no read_netcdf(istream &) function. "
-                               "Use the read(_netcdf)(string &filename) "
+                               "Use the read_netcdf)(string &filename) "


remove the stray closing parenthesis

luca-heltai · 2017-09-21T07:54:56Z

ping @bangerth

bangerth · 2017-09-21T14:49:31Z

This new additional external dependency also still needs an entry in readme.html. Can you please put that on your list as well?

davydden · 2017-09-25T06:21:35Z

@luca-heltai btw, the up-to-date homepage is http://www.assimp.org

tamiko · 2017-09-25T13:36:18Z

cmake/modules/FindASSIMP.cmake

+	PATH_SUFFIXES lib${LIB_SUFFIX} lib64 lib
+  )
+
+SET(ASSIMP_INC "${ASSIMP_DIR}/include")


@luca-heltai The include directory does not need to be ${ASSIMP_DIR}/include. I will make a pull request (later today) to clean up this file.

luca-heltai added 4 commits September 16, 2017 16:57

Added assimp detection.

12f56a3

GridIn::read_assimp + test.

912fef0

Add quick-test for Assimp.

b5ad63e

ChangeLog.

0d1633e

luca-heltai force-pushed the assimp-detection branch from 13237cf to 0d1633e Compare September 16, 2017 14:57

davydden reviewed Sep 16, 2017

View reviewed changes

luca-heltai added 2 commits September 16, 2017 17:36

Fixed comments by Denis.

5447a0e

Fixed compilation when Assimp is not available.

ffa0f71

bangerth reviewed Sep 18, 2017

View reviewed changes

luca-heltai added 2 commits September 18, 2017 19:46

WB's comments.

730373d

WB's comments part II.

b222918

bangerth merged commit b313294 into dealii:master Sep 21, 2017

tamiko reviewed Sep 25, 2017

View reviewed changes

tjhei mentioned this pull request Feb 3, 2018

add assimp v3.3.1 dealii/candi#64

Merged

luca-heltai deleted the assimp-detection branch December 18, 2019 08:32

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Assimp support and GridIn::read_assimp. #5095

Assimp support and GridIn::read_assimp. #5095

luca-heltai commented Sep 16, 2017 •

edited

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tamiko Sep 25, 2017

Assimp support and GridIn::read_assimp. #5095

Assimp support and GridIn::read_assimp. #5095

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luca-heltai commented Sep 16, 2017 • edited

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luca-heltai commented Sep 21, 2017

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luca-heltai commented Sep 16, 2017 •

edited