Some pain in the as face behavering problems

pcmoor

Hi

extrude the section up and down, intersect with model, clean up, fixed. it can auto-fold

the section must be close to, but not exactly in same plane

Philip

pbacot

I thought you were talking about two situations. The edges do lie on the face of the closed shape, but that shape is not lying in the rectangular face. If you use Tools /Sandbox /Drape the shape will be made to lie on the face and act correctly.

gilles

I took a look at your model:

#1 The shape does not lay on the surface
#2 when you move the shape to the surface (+- 18,4mm) you will see the shape is not coplanar with the surface.

newnoob

The tip with extruding the shape, intersect it and cleaning up has fixed the problem.

But I am still unhapy because I dont get why SU does what it does and I'd like to understand.

@unknownuser said:

I took a look at your model:

#1 The shape does not lay on the surface
#2 when you move the shape to the surface (+- 18,4mm) you will see the shape is not coplanar with the surface.

I belive you that the shape is not coplanar with the surface but I do not understand it.

Because shouldn't it be coplanar with the surface (rectangle) when SU tell me "On Face" ?

the only other option is that the shape itself is not coplanar, but It sems as it would be, but maybe there is some tiny glitch with it, is there an option to indicate if the shape is planar?

... I was actually thinking that the circumstance that the shape is filled, indicates that it is planar, because if it would not be planar it would not be filled.

gilles

I think it is about SU tolerance, it seems to make some round up. When it happens you may get mad.

mitcorb

Hi:
This has occasionally happened in my modeling. When you get the cue "on face" and you click, a slight movement of your mouse hand will drift it off the cue, while the camera is still focused on the larger plane.
Actually, the curved part of your shape appears to be below the target plane and the other end seems to be above the plane. Your shape is so close to the larger plane that the highlighting shows through your shape and gives the impression that it is coplanar.
Since you have found a solution, this comment is just academic.

If your geometry has to be exact, then the extrude intersect procedure will produce a section slightly different in shape and area than if it were already coplanar and intersected. Again, this is a moot point.

Box

Because you geometry is quite large the small inaccuracies are less obvious.

newnoob

THX for all the comments.

@unknownuser said:

Hi:
This has occasionally happened in my modeling. When you get the cue "on face" and you click, a slight movement of your mouse hand will drift it off the cue, while the camera is still focused on the larger plane.
Actually, the curved part of your shape appears to be below the target plane and the other end seems to be above the plane. Your shape is so close to the larger plane that the highlighting shows through your shape and gives the impression that it is coplanar.
Since you have found a solution, this comment is just academic.

No it's not - I think you make some interesting points here.

@unknownuser said:

If your geometry has to be exact, then the extrude intersect procedure will produce a section slightly different in shape and area than if it were already coplanar and intersected. Again, this is a moot point.

Yea, when I was thinking about the extrude/intersect-fix-methode or the drape- methode I relized that the outcome will be actually different shape.

So when something has to be totally exact that is not really the way to go.

mitcorb

It really comes down to taking care, and checking your actions by getting used to orbiting for a better view or repositioning to ensure a correct snap. Sort of like developing a tolerance for tolerances in the program. Continued use will help develop your sense of what to expect.

mac1

newnoob;
What you are showing is typical of folks assuming they are doing things correctly and in fact that is not the case. If you are really interested in understanding the issue then you should post your OP model .

There are several suggestion to help you;
First and foremost learn and use the SU inference engine;

Secondly draw a ground plane and draw your shape on that to make sure it is planar;

Thirdly do the same for the rect and make sure to use inference in both cases. If you do not clicking of the mouse can cause very small inadvertent movement which can cause problems;
Forth set units precision( this is display ) to max, use the text tool and check the vertex x,y,z. This is not 100% but since SU uses 32 bit float ( 24 bit significant precision( 23 explicitly stored), sign bit 1, exponent this may show an issue whereas lesser display precision will not.
Note, when you click on the rect face and the face shows in your shape you know your model is wrong.