add back missing ddm function

Author: Alec Jacobson

src/direct_delta_mush.cpp

@@ -0,0 +1,109 @@
+#include <common.h>
+#include <npe.h>
+#include <typedefs.h>
+#include <igl/direct_delta_mush.h>
+
+const char* ds_direct_delta_mush = R"igl_Qu8mg5v7(
+Perform Direct Delta Mush Skinning. 
+Computes Direct Delta Mesh Skinning (Variant 0) from 
+"Direct Delta Mush Skinning and Variants"
+
+Parameters
+----------
+v  #V by 3 list of rest pose vertex positions
+t  #E*4 by 3 list of bone pose transformations
+omega #V by #E*10 list of precomputated matrix values
+
+Returns
+-------
+u  #V by 3 list of output vertex positions
+
+See also
+--------
+
+
+Notes
+-----
+None
+
+Examples
+--------
+)igl_Qu8mg5v7";
+
+npe_function(direct_delta_mush)
+npe_doc(ds_direct_delta_mush)
+
+npe_arg(v, dense_double)
+npe_arg(t, dense_double)
+npe_arg(omega, dense_double)
+
+npe_begin_code()
+  assert_cols_equals(v, 3, "v");
+  assert_valid_bone_transforms(t, "t");
+  assert_rows_equals(t, (omega.cols() * 4) / 10, "t");
+
+  std::vector<Eigen::Affine3d, Eigen::aligned_allocator<Eigen::Affine3d>> 
+      t_affine(t.rows() / 4);
+  
+  for(int bone = 0; bone < t_affine.size(); ++bone)
+  {
+    t_affine[bone] = Eigen::Affine3d::Identity();
+    t_affine[bone].matrix().block(0, 0, 3, 4) = t.block(bone * 4, 0, 4, 3).transpose();
+  }
+
+  EigenDenseLike<npe_Matrix_v> u;
+  igl::direct_delta_mush(v, t_affine, omega, u);
+  return npe::move(u);
+
+npe_end_code()
+
+const char* ds_direct_delta_mush_precomp = R"igl_Qu8mg5v7(
+Do the Omega precomputation necessary for Direct Delta Mush Skinning.
+
+Parameters
+----------
+v  #V by 3 list of rest pose vertex positions
+f  #F by 3 list of triangle indices into rows of V
+w  #V by #Edges list of weights
+p  number of smoothing iterations
+lambda  rotation smoothing step size
+kappa   translation smoothness step size
+alpha   translation smoothness blending weight
+
+Returns
+-------
+omega : #V by #E*10 list of precomputated matrix values
+
+See also
+--------
+
+
+Notes
+-----
+None
+
+Examples
+--------
+)igl_Qu8mg5v7";
+
+npe_function(direct_delta_mush_precomputation)
+npe_doc(ds_direct_delta_mush_precomp)
+
+npe_arg(v, dense_double)
+npe_arg(f, dense_int, dense_long, dense_longlong)
+npe_arg(w, npe_matches(v))
+npe_arg(p, int)
+npe_arg(lambda, double)
+npe_arg(kappa, double)
+npe_arg(alpha, double)
+
+npe_begin_code()
+  assert_valid_3d_tri_mesh(v, f);
+
+  Eigen::MatrixXd w_copy = w.template cast<double>();
+
+  EigenDenseLike<npe_Matrix_v> omega;
+  igl::direct_delta_mush_precomputation(v, f, w_copy, p, lambda, kappa, alpha, omega);
+  return npe::move(omega);
+  
+npe_end_code()