ADD massmatrix.

Author: petrasvestartas

environment.yml

@@ -1,11 +1,12 @@
+name: compas_libigl-dev
 channels:
   - conda-forge
+  - defaults
 dependencies:
-  - python>=3.9
-  - pip>=19.0
-  - git
-  - cmake>=3.14
+  - python <=3.12
+  - pip
+  - cmake
   - compas
-  - invoke
   - pip:
-      - -e .[dev]
+      - -r requirements-dev.txt
+      - .

src/compas.hpp

@@ -40,6 +40,8 @@
 
 #include <igl/isolines.h>
 
+#include <igl/massmatrix.h>
+
 #include <igl/map_vertices_to_circle.h>
 #include <igl/harmonic.h>
 #include <igl/doublearea.h>

src/compas_libigl/__init__.py

@@ -6,9 +6,8 @@
 from .geodistance import trimesh_geodistance
 from .intersections import intersection_ray_mesh, intersection_rays_mesh
 from .isolines import trimesh_isolines, groupsort_isolines
+from .massmatrix import trimesh_massmatrix
 
-
-# from .massmatrix import trimesh_massmatrix
 # from .meshing import trimesh_remesh_along_isoline
 # from .parametrisation import trimesh_harmonic, trimesh_lscm
 # from .planarize import quadmesh_planarize
@@ -89,7 +88,7 @@ def get_armadillo():
     "compas_libigl.geodistance",
     "compas_libigl.intersections",
     "compas_libigl.isolines",
-    # "compas_libigl.massmatrix",
+    "compas_libigl.massmatrix",
     # "compas_libigl.meshing",
     # "compas_libigl.parametrisation",
     # "compas_libigl.planarize",
@@ -113,7 +112,7 @@ def get_armadillo():
     "intersection_rays_mesh",
     "trimesh_isolines",
     "groupsort_isolines",
-    # "trimesh_massmatrix",
+    "trimesh_massmatrix",
     # "trimesh_remesh_along_isoline",
     # "trimesh_harmonic",
     # "trimesh_lscm",

src/compas_libigl/massmatrix.py

@@ -0,0 +1,37 @@
+import numpy as np
+from compas.plugins import plugin
+
+from compas_libigl import _massmatrix
+
+
+@plugin(category="trimesh")
+def trimesh_massmatrix(M):
+    """Compute massmatrix on a triangle mesh using a scalarfield of data points
+    assigned to its vertices.
+
+    Parameters
+    ----------
+    M : tuple or :class:`compas.datastructures.Mesh`
+        A mesh represented by a list of vertices and a list of faces
+        or by a COMPAS mesh object.
+
+    Returns
+    -------
+    array
+        The mass per vertex.
+
+    Examples
+    --------
+    >>> import compas
+    >>> import compas_libigl
+    >>> from compas.datastructures import Mesh
+    >>> mesh = Mesh.from_off(compas.get("tubemesh.off"))
+    >>> mesh.quads_to_triangles()
+    >>> M = mesh.to_vertices_and_faces()
+    >>> mass = compas_libigl.trimesh_massmatrix(M)
+
+    """
+    V, F = M
+    V = np.asarray(V, dtype=np.float64)
+    F = np.asarray(F, dtype=np.int32)
+    return _massmatrix.trimesh_massmatrix(V, F)

src/massmatrix.cpp

@@ -1,13 +1,20 @@
 #include "massmatrix.hpp"
 
-void function(const compas::RowMatrixXd& V, const compas::RowMatrixXi& F) {}
+Eigen::VectorXd trimesh_massmatrix(compas::RowMatrixXd V, compas::RowMatrixXi F) {
+  Eigen::SparseMatrix<double> M;
+  igl::massmatrix(V, F, igl::MASSMATRIX_TYPE_VORONOI, M);
+
+  Eigen::VectorXd mass = M.diagonal();
+
+  return mass;
+}
 
 NB_MODULE(_massmatrix, m) {
 
     m.def(
-        "function_name",
-        &function,
-        "Description.",
+        "trimesh_massmatrix",
+        &trimesh_massmatrix,
+        "Compute the mass matrix of a triangle mesh.",
         "V"_a,
         "F"_a);
 }