message: avoid clearing the framebuffer when only tonemapping parameters have been changed
diff: @@ -160,7 +160,20 @@ namespace ospray {
  void Renderer::postCommit(RenderContext &ctx)
  {
  - if (lastModified() > frameMTime || childrenLastModified() > frameMTime) {
  + bool modified = lastModified() > frameMTime;
  + if (!modified) {
  + for (const auto& c : children()) {
  + // ignore changes to the frame buffer/tone mapper
  + if (c.second->lastModified() > frameMTime
  + || (c.second->childrenLastModified() > frameMTime && c.first != "frameBuffer"))
  + {
  + modified = true;
  + break;
  + }
  + }
  + }
  +
  + if (modified) {
  ospFrameBufferClear(
  (OSPFrameBuffer)child("frameBuffer").valueAs<OSPObject>(),
  OSP_FB_COLOR | OSP_FB_ACCUM
  