[geometry] Add zero_simplex_manual_test (RobotLocomotion#20323)

This is a developer convenience for quick evaluation of volume meshes.

geometry/proximity/BUILD.bazel

@@ -1,5 +1,6 @@
 load(
     "//tools/skylark:drake_cc.bzl",
+    "drake_cc_binary",
     "drake_cc_googletest",
     "drake_cc_library",
     "drake_cc_package_library",
@@ -837,6 +838,26 @@ drake_cc_library(
     ],
 )
 
+drake_cc_binary(
+    name = "zero_simplex_manual_test",
+    testonly = 1,
+    srcs = ["test/zero_simplex_manual_test.cc"],
+    add_test_rule = 1,
+    data = [
+        "//geometry:test_vtk_files",
+    ],
+    test_rule_args = [
+        "--expect_fail",
+        "geometry/test/one_tetrahedron.vtk",
+    ],
+    deps = [
+        ":detect_zero_simplex",
+        ":vtk_to_volume_mesh",
+        "//common:add_text_logging_gflags",
+        "@gflags",
+    ],
+)
+
 drake_cc_googletest(
     name = "aabb_test",
     deps = [

geometry/proximity/test/zero_simplex_manual_test.cc

@@ -0,0 +1,48 @@
+#include <gflags/gflags.h>
+
+#include "drake/common/text_logging.h"
+#include "drake/geometry/proximity/detect_zero_simplex.h"
+#include "drake/geometry/proximity/vtk_to_volume_mesh.h"
+
+DEFINE_bool(expect_fail, false,
+            "expect to find zero simplices; reverses the success/fail logic");
+
+namespace drake {
+namespace geometry {
+namespace internal {
+namespace {
+
+int do_main(int argc, char* argv[]) {
+  gflags::SetUsageMessage(
+      "[INPUT-VTK-FILE]\n"
+      "Run zero simplex checks; summarize zero simplices;"
+      " fail if any are found unless --expect_fail is set");
+  gflags::ParseCommandLineFlags(&argc, &argv, true);
+  if (argc < 2) {
+    drake::log()->error("missing input filename");
+    return 1;
+  }
+
+  auto mesh = ReadVtkToVolumeMesh(argv[1]);
+  auto bad_tets = DetectTetrahedronWithAllBoundaryVertices(mesh);
+  auto bad_triangles = DetectInteriorTriangleWithAllBoundaryVertices(mesh);
+  auto bad_edges = DetectInteriorEdgeWithAllBoundaryVertices(mesh);
+
+  drake::log()->info(
+      "Found {} bad tetrahedra, {} bad triangles, and {} bad "
+      "edges from total {} tetrahedra.",
+      bad_tets.size(), bad_triangles.size(), bad_edges.size(),
+      mesh.num_elements());
+  bool found_bad =
+      (!bad_tets.empty() || !bad_triangles.empty() || !bad_edges.empty());
+  return found_bad ^ FLAGS_expect_fail;
+}
+
+}  // namespace
+}  // namespace internal
+}  // namespace geometry
+}  // namespace drake
+
+int main(int argc, char* argv[]) {
+  return drake::geometry::internal::do_main(argc, argv);
+}