message: demo: Allow -d option with no extra arguments
  We create a tessellated plane in this case similarly to how we handle
  this without -d. Also reduce the plane width to 200 quads.
diff: @@ -574,7 +574,7 @@ bool loadMesh(Mesh& mesh, const char* path)
  }
  else
  {
  - mesh = generatePlane(1000);
  + mesh = generatePlane(200);
  printf("# tessellated plane: %d vertices, %d triangles\n", int(mesh.vertices.size()), int(mesh.indices.size() / 3));
  }
  @@ -635,7 +635,9 @@ int main(int argc, char** argv)
  }
  else
  {
  - if (argc > 2 && strcmp(argv[1], "-d") == 0)
  + if (strcmp(argv[1], "-d") == 0)
  + {
  + if (argc > 2)
  {
  for (int i = 2; i < argc; ++i)
  {
  @@ -643,6 +645,11 @@ int main(int argc, char** argv)
  }
  }
  else
  + {
  + processDev(0);
  + }
  + }
  + else
  {
  for (int i = 1; i < argc; ++i)
  {
  