message: Definition of Progress and Cancel callback
diff: @@ -326,6 +326,15 @@ extern "C" {
  OSPRenderer,
  const uint32_t frameBufferChannels OSP_DEFAULT_VAL(=OSP_FB_COLOR));
  + /*! progress and cancel callback function type
  + progress is in (0..1]
  + returned "bool" value != 0 indicates ospRenderFrame should continue rendering
  + */
  + typedef int (*OSPProgressFunc)(void* userPtr, const float progress);
  +
  + /*! set callback for given Device to call when an error occurs*/
  + OSPRAY_INTERFACE void ospSetProgressFunc(OSPProgressFunc, void* userPtr);
  +
  //! create a new renderer of given type
  /*! return 'NULL' if that type is not known */
  OSPRAY_INTERFACE OSPRenderer ospNewRenderer(const char *type);
  