message: add ability to input a custom fb scale factor
diff: @@ -581,6 +581,13 @@ namespace ospray {
  if (ImGui::MenuItem("2.00x")) renderResolutionScale = 2.0f;
  if (ImGui::MenuItem("4.00x")) renderResolutionScale = 4.0f;
  + ImGui::Separator();
  +
  + if (ImGui::BeginMenu("custom")) {
  + ImGui::InputFloat("x##fb_scaling", &renderResolutionScale);
  + ImGui::EndMenu();
  + }
  +
  if (scale != renderResolutionScale)
  reshape(windowSize);
  