Clipping plane's inherent construction plane - bug?

Hello,

it seems to me that a clipping plane should have a defined construction plane direction consistent for all clipping planes.

When I create a new Clipping Plane the inherent direction of the clipping plane object is xy-plane along the axis and z opposite direction to the small arrows at the end of the lines.

Like this.

Unfortunately, at least in this file, I have clipping planes that have the construction plane of the object oriented in other directions. Meaning that when you pick it up using Cplane/Object, you get unexpected results.

You see two clipping planes. East have the object cplane correctly oriented. But the South clipping plane which was constructed by rotating the East one 90 degrees, have the same cplane orientation as the East.

This can’t possibly be the intention. Something must be wrong here:

(Images are from Rhino 9, but I just assume that it is the same in Rhino 8.)

/Erik

Hej Erik -
I’m having a hard time understanding the issue here.

What does “picking up” mean? What is using Cplane/Object?

Is this a Gumball problem?
-wim

Better explanation:

I draw a elongated box and pick it:

When I pick it I see the gumball is oriented with X pointing right.

I rotate the box around the Z-axis clockwise. Deselect it and then select it again.

The gumball is oriented the same way as before the rotation.

If I use Cplane _Object

image

and pick the box:

(This has nothing to do with the gumball, it’s just there to show what I’m talking about.)

The orientation of the cplane / gumball is oriented after the “inherent” object cplane. As far as I understand every piece of geometry has it’s own “internal” cplane. (Is it possible to forcibly change this internal position/rotation somehow?)

Now to me the Clipping Plane is NOT a normal geometrical object. And it should not be treated as one. I know that you disagree, but one day I hope it will dawn on you, that it is not. (Manipulating it as a geometrical object is fine in many ways, but it is also extremely annoying and complex. Discussion about this elsewhere.)

So I create a Clipping Plane (I returned to the World Cplane)

And I use Cplane _Object to pick the ClippingPlanes “internal” Cplane, I get this:

You can see that the x-axis points to the right.

Now, at least for an architect, it makes sense that the clipping plane z-axis goes as it does in the clipping plane. Because when you draw “in section” you want to draw in the XY-plane.

To me it does not make sense that clipping plane would have different “internal” cplanes. But apparently they have. Which makes lift hard when you draw “in section” and you try to orient the drawing cplane by picking the ClippingPlane marker using Cplane _Object … and it turns out that the z-axis is along the section line arrow line …

This is to me is a bug. Or a misconception of sorts.

This Clipping Plane. If I pick up the “internal” Cplane (Cplane Object) of it will orient like this:

It’s perpendicular to the square. It should be oriented like this:

In this saved view I would like to be able to orient my cplane so that I can draw “in section” in this view. Meaning that it should draw exactly where the clippingplane section is.

Now what happens if I pick up that ClippingPlane’s “internal” cplane?

You see the thin line in the middle of the square symbol. That is the grid/cplane oriented the wrong way.

Well … that was a long explanation. Maybe you have thought about these things in a different way. But to me this is the natural way of handling these things. To me it is extremely weird that the clipping plane symbol can have internal orientations that are different (eg z not perpendicular to the square symbol).


When using the new markup tool this becomes a nightmare. The annotation stuff end up everywhere depending on where you happen to draw etc. I would be more than happy to share my screen and show the nightmare in front of me.


Thanks for you time

/Erik

@wim @erik6 Erik’s problem appears to be caused by unexpected behavior when Cplanes are created from a clipping plane widget.

When a Cplane is created from a clipping plane using Cplane with the Object option the Cplane is oriented with the clipping plane widget the first time a Cplane is created from the clipping plane. If the Cplane is rotated then any subsequent use of Cplane with the Object option creates a new Cplane the origin moved to the new center of the clipping plane widget but the new Cplane does not orient with the clipping plane widget. Rather it uses the orientation from the first time Cplane with the Object option was used with that clipping plane widget. This includes instances when a clipping plane is copied from an existing clipping plane and rotated. This behavior appears to have started in Rhino 8.

I started a new, more succint thread specifically about this unexpected behavior.

@erik6 Until the bug is fixed you can either create all clipping planes separately (not copy and move an existing clipping plane); or create cplanes directly and save them as named cplanes and then create clipping planes on the named cplanes.

Sure, this is not a serious issue. It can be worked around. It’s just irritating.

Looking forward to the fix.

Who is in charge of the Clipping Plane feature? Rajaa ?

/Erik