Set highlight style on a GLB object is not changing the highlight

Jeff Foster
Thu, 10/23/2025 - 19:20

Forums:

I am using this code in the initviewer function to try to load the model and set the highlight style.

  // Create AIS context
  myContext = new AIS_InteractiveContext (myViewer);
  myContext->SetDisplayMode ((int )AIS_DisplayMode::AIS_Shaded, false);
    myContext->DefaultDrawer ()->SetFaceBoundaryDraw(true);
    myContext->DefaultDrawer ()->FaceBoundaryAspect()->SetColor(Quantity_NameOfColor::Quantity_NOC_BLACK);
    myContext->DefaultDrawer ()->FaceBoundaryAspect()->SetWidth(1.2);
    Handle(Prs3d_Drawer) highlightStyle = new Prs3d_Drawer();
    highlightStyle->SetColor(Quantity_NOC_CYAN);
    myContext->SetHighlightStyle(Prs3d_TypeOfHighlight_LocalDynamic, highlightStyle);
    myContext->SetHighlightStyle(Prs3d_TypeOfHighlight_LocalSelected, highlightStyle);
    myContext->SetHighlightStyle(Prs3d_TypeOfHighlight_Dynamic, highlightStyle);
    myContext->SetHighlightStyle(Prs3d_TypeOfHighlight_Selected, highlightStyle);

  myView = myViewer->CreateView();
  myView->TriedronDisplay (Aspect_TOTP_LEFT_LOWER, Quantity_NOC_WHITE, 0.20, V3d_ZBUFFER);

Any advice on how to set the highlight style for when a part is selected? Thanks

gkv311 n
Thu, 10/23/2025 - 21:19

What you expect/want to see and what you actually see? Any screenshots?

Jeff Foster
Fri, 10/24/2025 - 07:33

It doesn't appear to be setting the color of the highlight. With that code I would expect the highlight color to be a cyan color. What is see is a dark gray highlight color. See the attached photo with the bolt in the the red circle is the selected part of the model and it is just a slightly darker gray than the rest of the model. So I was trying to get the selection to stand out with this code.

Attachments:

23816.jpg

gkv311 n
Fri, 10/24/2025 - 08:19

On your screenshot it looks like your objects have highlight mode AIS_Shaded instead of default AIS_Wireframe, but this is not specified in the code snippet. How do you set it? If you doing something like AIS_Shape::SetHilightMode() then beware that this method creates a custom Prs3d_Drawer for highlighting of specific object, and fills it with default values - e.g. Quantity_NOC_GRAY80:

void PrsMgr_PresentableObject::SetHilightMode (const Standard_Integer theMode)
{
  if (myHilightDrawer.IsNull())
  {
    myHilightDrawer = new Prs3d_Drawer();
    myHilightDrawer->Link (myDrawer);
    myHilightDrawer->SetAutoTriangulation (Standard_False);
    myHilightDrawer->SetColor (Quantity_NOC_GRAY80);
    myHilightDrawer->SetZLayer(Graphic3d_ZLayerId_UNKNOWN);
  }
  if (myDynHilightDrawer.IsNull())
  {
    myDynHilightDrawer = new Prs3d_Drawer();
    myDynHilightDrawer->Link (myDrawer);
    myDynHilightDrawer->SetColor (Quantity_NOC_CYAN1);
    myDynHilightDrawer->SetAutoTriangulation (Standard_False);
    myDynHilightDrawer->SetZLayer(Graphic3d_ZLayerId_Top);
  }
  myHilightDrawer   ->SetDisplayMode (theMode);
  myDynHilightDrawer->SetDisplayMode (theMode);
}

If you want to change default highlight mode for all objects in AIS_InteractiveContext you might want to change Prs3d_Drawer::SetDisplayMode() of related style in it. -1 means to use active display mode of main presentation.

pload MODELING VISUALIZATION
box b 150 0 0 100 100 100
pcone c 100 0 100
vinit View1
vdisplay b c -dispMode 1
vaspects -faceBoundaryDraw 1 -faceBoundaryWidth 2 -faceBoundaryColor BLACK
vselprops selHighlight -color CYAN -dispMode -1

Extra notes:

    myContext->DefaultDrawer ()->FaceBoundaryAspect()->SetWidth(1.2);

using fractional line width is probably not a good idea - it will be either ignored or will produce extra aliasing/smashing effect on lines in most cases.

Default highlight style sets more properties than just a color, so that these lines will have more side effects on Viewer behavior than you might expect:

    Handle(Prs3d_Drawer) highlightStyle = new Prs3d_Drawer();
    highlightStyle->SetColor(Quantity_NOC_CYAN);
    myContext->SetHighlightStyle(Prs3d_TypeOfHighlight_LocalDynamic, highlightStyle);

Default style would also link to main presentation Prs3d_Drawer instance (so that there is no need to duplicate exactly same customizations) and configure different Z-Layers.

I would suggest to change existing drawers in context like:

myContext->HighlightStyle(Prs3d_TypeOfHighlight_Selected)->SetColor(Quantity_NOC_CYAN);
myContext->HighlightStyle(Prs3d_TypeOfHighlight_Selected)->SetDisplayMode(-1);

instead of assigning a new Prs3d_Drawer instance.

Attachments:

draw_sel_cyan.png