Custom AIS_InteractiveObject: different presentation when hilighted

Gianluca Antoniacci
Tue, 03/16/2021 - 11:29

Forums:

Hello everyone,

I'm trying to inherit from AIS_InteractiveObject in order to create a new object (usinig OCC 7.3.0)

I've seen that, implementing properly the Compute() method I can build its presentation as desired (more or less).

Of course I will vary its aspect according to "theMode" parameter in case this is needed.

But one of my goals is also to have a possibly different representation of this interactive object when the mouse passes over it (dynamic hilight) and/or when the object is selected: of course, by changing the properties for drawer associated to selection/hilight mechanism is a way, but this doesn't change its aspect very much as, I guess, only color, thickness, material, transparency and so on will be affected. How will I, for instance, get my object to look like a box (its bounding box, for instance) instead of a sphere or a 3D wire? I thought that this can be achieved with a certain usage of Compute method, but I don't remember how...

Many thanks in advance

Gianluca

Kirill Gavrilov
Wed, 03/17/2021 - 17:38

The simplest way is using different Display Mode for main presentation and highlighting. For that you need redefining AIS_InteractiveObject::Compute() to handle different Display Modes and choose one for highlighting - see AIS_InteractiveObject::SetDisplayMode() and AIS_InteractiveObject::SetHilightMode().

This is how AIS_Shape behaves by default, when the main presentation is AIS_Shaded (1) and highlighting is AIS_Wireframe (0).

Gianluca Antoniacci
Thu, 03/18/2021 - 13:32

Hello Kirill,

many thanks for your answer.

As a matter of fact I was able to remember this approach and managed to gete a different representation for my object.

I still have many questions about this:

I understood that SetHilightMode() is now obsolete and that a HilightDrawer and a DynamicHilightDrawer are to be used instead. But if I set two drawer for my newly created object, the custom selection mechanism doesn't seem to work anymore. Am I doing something wrong or is just the confusion in my head (and lack of knowledge) the actual problem here?
Using a new drawer each time I'm entering the compute method (it seems to be corrupted if created once and for all within the constructor of my object) I managed to get a different representation when selecting/hilighting it: how can I force its color to be as desired? The shape is correct but the coloro is always cyan when hilighted and "almost wite" when selected. How come?
as you can see fromo the attached picture, both representations are shown: I expected them to be mutually exclusive...
Here is a snipped of my code (I'm using C# wrapper with OCC 7.3.0):

public override void Compute(PrsMgr_PresentationManager thePrsMgr, Prs3d_Presentation thePrs, int theMode)
{
thePrs.Clear();
if (theMode == 3)
{
for (int i = 0; i < _centers.Count; i++)
{
gp_Pnt curCenter = _centers[i];
double curRadius = _radii[i];
BRepPrimAPI_MakeSphere sphereMk = new BRepPrimAPI_MakeSphere(curCenter, curRadius);
StdPrs_ShadedShape.Add(thePrs, sphereMk.Shape(), Attributes());
}
}
else if (theMode == 0)
{
Prs3d_Drawer dynamicHilightDrawer = new Prs3d_Drawer();
dynamicHilightDrawer.SetColor(new Quantity.Quantity_Color(Quantity.Quantity_NameOfColor.Quantity_NOC_BLUE1));
Prs3d_LineAspect lineAspect = dynamicHilightDrawer.LineAspect();
lineAspect.SetAspect(new Graphic3d_AspectLine3d(new Quantity.Quantity_Color(Quantity.Quantity_NameOfColor.Quantity_NOC_BLUE1), Aspect.Aspect_TypeOfLine.Aspect_TOL_DASH, 3));
dynamicHilightDrawer.SetLineAspect(lineAspect);
for (int i = 0; i < _centers.Count; i++)
{

// for some reasons, here the list of gp_Pnt is not consisten any longer and I get a null exception!!!
//gp_Pnt curCenter = _centers[i];
gp_Pnt curCenter = new gp_Pnt(_xList[i], _yList[i], _zList[i]);
double curRadius = _radii[i];
Bnd.Bnd_Box bb = new Bnd.Bnd_Box();
bb.SetVoid();
double x = _xList[i];
double y = _yList[i];
double z = _zList[i];
bb.Update(x - curRadius, y - curRadius, z - curRadius, x + curRadius, y + curRadius, z + curRadius);
StdPrs_BndBox.Add(thePrs, bb, dynamicHilightDrawer);
}
}

Many thanks again

Gianluca

Attachments:

CustomSelection.jpg