-double graph_layout_energy(const Layout *g) {
- /* For each (vi,vj) computes shortest path pij = vi..vj along edges,
- * and actual distance dij = vi-vj.
+double graph_layout_cost(const Layout *g, const double vertex_areas[N]) {
+ /* For each (vi,vj) computes shortest path s_ij = |vi..vj|
+ * along edges, and actual distance d_ij = |vi-vj|.
+ *
+ * We will also use the `vertex areas': for each vertex vi the
+ * vertex area a_vi is the mean area of the incident triangles.
+ * This is computed elsewhere.