message: add prefix/suffix for interpolation automatically
  allows for every camera state saved as a keyframe to be used, instead of
  skipping the first/last states. still have some discontinuities in the
  middle of the path
diff: @@ -613,6 +613,18 @@ void MainWindow::buildUI()
  if (ImGui::ArrowButton("play", ImGuiDir_Right)) {
  animatingPath = !animatingPath;
  g_camPathAnimIndex = 1;
  + if (animatingPath) {
  + // create prefix and suffix interp states for catmull-rom
  + size_t last = g_camPath.size() - 1;
  + CameraState prefix = g_camPath[0].slerp(g_camPath[1], -.1f);
  + CameraState suffix =
  + g_camPath[last - 1].slerp(g_camPath[last - 2], 1.1f);
  + g_camPath.insert(g_camPath.begin(), prefix);
  + g_camPath.push_back(suffix);
  + } else {
  + g_camPath.pop_back();
  + g_camPath.erase(g_camPath.begin());
  + }
  }
  }
  for (int i = 0; i < g_camPath.size(); i++) {
  