Added dodecahedron object

src/polymesh/objects/dodecahedron.cc

+#include "dodecahedron.hh"
+
+#include <cmath> // std::sqrt
+
+polymesh::unique_array<polymesh::detail::pos3f> polymesh::detail::add_unit_dodecahedron_impl(polymesh::Mesh& m)
+{
+    polymesh::unique_array<pos3f> position(20);
+
+    auto const phi = (1 + std::sqrt(5.0f)) / 2.0f;
+    auto const phi_inv = 1 / phi;
+
+    pm::vertex_handle vs[20];
+    for (size_t i = 0; i < 20; ++i)
+        vs[i] = m.vertices().add();
+
+    position[0] = {1, 1, 1};
+    position[1] = {1, 1, -1};
+    position[2] = {1, -1, 1};
+    position[3] = {1, -1, -1};
+    position[4] = {-1, 1, 1};
+    position[5] = {-1, 1, -1};
+    position[6] = {-1, -1, 1};
+    position[7] = {-1, -1, -1};
+
+    position[8] = {0, phi, phi_inv};
+    position[9] = {0, phi, -phi_inv};
+    position[10] = {0, -phi, phi_inv};
+    position[11] = {0, -phi, -phi_inv};
+
+    position[12] = {phi_inv, 0, phi};
+    position[13] = {phi_inv, 0, -phi};
+    position[14] = {-phi_inv, 0, phi};
+    position[15] = {-phi_inv, 0, -phi};
+
+    position[16] = {phi, phi_inv, 0};
+    position[17] = {phi, -phi_inv, 0};
+    position[18] = {-phi, phi_inv, 0};
+    position[19] = {-phi, -phi_inv, 0};
+
+    m.faces().add({vs[8], vs[9], vs[5], vs[18], vs[4]});
+    m.faces().add({vs[9], vs[8], vs[0], vs[16], vs[1]});
+    m.faces().add({vs[8], vs[4], vs[14], vs[12], vs[0]});
+    m.faces().add({vs[9], vs[1], vs[13], vs[15], vs[5]});
+    m.faces().add({vs[4], vs[18], vs[19], vs[6], vs[14]});
+    m.faces().add({vs[5], vs[15], vs[7], vs[19], vs[18]});
+    m.faces().add({vs[13], vs[3], vs[11], vs[7], vs[15]});
+    m.faces().add({vs[16], vs[17], vs[3], vs[13], vs[1]});
+    m.faces().add({vs[0], vs[12], vs[2], vs[17], vs[16]});
+    m.faces().add({vs[14], vs[6], vs[10], vs[2], vs[12]});
+    m.faces().add({vs[19], vs[7], vs[11], vs[10], vs[6]});
+    m.faces().add({vs[17], vs[2], vs[10], vs[11], vs[3]});
+
+    return position;
+}

src/polymesh/objects/dodecahedron.hh

+#pragma once
+
+#include <polymesh/Mesh.hh>
+#include <polymesh/detail/math.hh>
+#include <polymesh/detail/unique_array.hh>
+#include <polymesh/fields.hh>
+
+namespace polymesh::detail
+{
+unique_array<pos3f> add_unit_dodecahedron_impl(Mesh& m);
+}
+
+namespace polymesh::objects
+{
+/// Adds a (subdivided) ico_sphere to the given mesh
+/// sf is called with (v, x, y, z), with vertex handle v and coordinates (x,y,z) on the unit sphere
+template <class SphereF>
+vertex_handle add_dodecahedron(Mesh& m, SphereF&& sf);
+
+/// same as add_cube but directly fills a position attribute
+template <class Pos3>
+vertex_handle add_dodecahedron(Mesh& m, vertex_attribute<Pos3>& pos);
+
+// ======== IMPLEMENTATION ========
+
+template <class SphereF>
+vertex_handle add_dodecahedron(Mesh& m, SphereF&& sf)
+{
+    auto const last_vertex_count = m.all_vertices().size();
+    auto const positions = detail::add_unit_dodecahedron_impl(m);
+    for (auto i = 0; i < 20; ++i)
+    {
+        sf(vertex_index(last_vertex_count + i).of(m), positions[i].x, positions[i].y, positions[i].z);
+    }
+    return vertex_index(last_vertex_count).of(m);
+}
+
+template <class Pos3>
+auto add_dodecahedron(Mesh& m, vertex_attribute<Pos3>& pos) -> vertex_handle
+{
+    return add_dodecahedron(m, [&](vertex_handle v, float x, float y, float z) { pos[v] = field3<Pos3>::make_pos(x, y, z); });
+}
+}