# Function gamer::getTangent(const SurfaceMesh&, SurfaceMesh::SimplexID<1>)¶

## Function Documentation¶

tensor<double, 3, 2> gamer::getTangent(const SurfaceMesh &mesh, SurfaceMesh::SimplexID<1> vertexID)

Compute the tangent to a vertex.

The vertex normal is defined as the mean of incident triangle normals as follows, $$\mathbf{n} = \frac{1}{N} \sum_{i=0}^{N, \textrm{incident triangle}} n_t$$. where $$\mathbf{n}$$ is the vertex normal, $$N$$ is the number of incident faces, and $$n_i$$ is the normal of incident triangle $$i$$.

Return

Returns a 2-tensor representing the tangent plane.

Parameters
• [in] mesh: SurfaceMesh of interest.

• [in] vertexID: SimplexID of the vertex to get the tangent of.