message: add ability to toggle frame buffer accumulation in scene graph
diff: @@ -51,6 +51,7 @@ namespace ospray {
  NodeFlags::gui_slider).setMinMax(1.f, 64.f);
  createChild("useSRGB", "bool", true);
  + createChild("useAccumBuffer", "bool", true);
  createChild("useVarianceBuffer", "bool", true);
  createFB();
  @@ -62,6 +63,7 @@ namespace ospray {
  if (lastModified() >= lastCommitted()
  || child("size").lastModified() >= lastCommitted()
  || child("displayWall").lastModified() >= lastCommitted()
  + || child("useAccumBuffer").lastModified() >= lastCommitted()
  || child("useVarianceBuffer").lastModified() >= lastCommitted()
  || child("useSRGB").lastModified() >= lastCommitted()
  || child("toneMapping").lastModified() >= lastCommitted())
  @@ -159,14 +161,15 @@ namespace ospray {
  auto format = useSRGB ? OSP_FB_SRGBA : OSP_FB_RGBA8;
  + auto useAccum = child("useAccumBuffer").valueAs<bool>();
  auto useVariance = child("useVarianceBuffer").valueAs<bool>();
  ospFrameBuffer = ospNewFrameBuffer((osp::vec2i&)fbsize,
  (displayWallStream=="")
  ? format
  : OSP_FB_NONE,
  - OSP_FB_COLOR | OSP_FB_ACCUM |
  + OSP_FB_COLOR |
  + (useAccum ? OSP_FB_ACCUM : 0) |
  (useVariance ? OSP_FB_VARIANCE : 0));
  - clearAccum();
  setValue(ospFrameBuffer);
  }
  