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Jolyon  
#1 Posted : Sunday, February 04, 2018 4:49:11 PM(UTC)
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Somebody put me out of my misery please

My question is about associativity and why when I iterate (ie. even to change the nature of a defining spline minutely), I must delete my surfaces and solids, 'remove links' and rebuild my object from the driving curves.

In order to illustrate this, I have made a very simple model - we can call it the 'butter dish lid' (attached)

It uses a series of intersecting surfaces, which I trim back to one-another and stitch into a solid

(The method is exactly the same as I use to create enormously complex free form shapes, which I can then feature with holes, bosses, and rad blends and then shell)

So the problem ... I expect to be able to utilise 'associativity' in my 'drive curves' to affect the surfaces, in turn modifying the surface intersects (and of course trims), thus in turn redefining the perimeter of the 'butter dish lid'. (... Ultimately this would naturally update a 'stitched solid', several feature holes perhaps, some bosses and then rad blends and ultimately the shell, let's say).

Should just work, right !?

Model is attached - You'll see that if you adjust one or more of the splines (in the plan view), the surfaces will update - as will their intersections to one another ... Great !

One more note - I have not put a cover surface on the bottom of the butter dish lid, so you'll be unable to stitch it into a solid until you do. This may be where the problem lies.

If you do add the necessary cover surface - (and go back to the top view) - you will see that you can no longer adjust the driving spines and have the driven surfaces and intersects recalculate. (A given spline point will just nonchalantly return to where they were before you tried to move it).

Further, if you stitch your 6 surfaces into a solid - you will then encounter error dialogs (and the adjustment will fail as before)

At this point, in a live project, knowing I must adjust a driving spline, I would normally dump the surfs / solids and remove all links before rebuilding - but this simply CANNOT be right. I waste days rebuilding and rebuilding and rebuilding.

So what am I doing wrong ?

Help Meeee !


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UGMENTALCASE  
#2 Posted : Monday, February 05, 2018 4:22:55 AM(UTC)
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Somebody else mentioned a similar thing, once they have done a series of features down the line, they struggle to high hell to edit past ones. I've noticed that I've had to add a new curve in (on my projects) and use the replace curve, and cross my fingers.

I have noticed a similar thing when you join curves together. Say if you sketch a pin (to do a revolve on) and think to join the curves, you then want to modify the length of a part of those joined curves, you can't. It's impossible. When you select the curve, with deep select, you don't get the option too. I think you might be seeing a similar thing. Once certain functions are used, there's no way back :-)
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Jolyon  
#3 Posted : Monday, February 05, 2018 5:11:00 AM(UTC)
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OK - even simpler example

(The more an example of a fail can be distilled - the easier it is for the dev teem to fix, right ?)

Here is a square polygon with a cover surface

It's split by a surface (which is extruded from spline A)

(Hide half of the split cover)

Then extrude a surface (call it B) from the split edge of the remaining half of the cover

Associativity DOES NOT EXIST between spline A and extrude B

This is fundamental !
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NeuTechFLA  
#4 Posted : Monday, February 05, 2018 5:41:49 AM(UTC)
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And...(hoping the video will make it through)

Nope....too large. I will try again with a different compression.

Edited by user Monday, February 05, 2018 5:43:15 AM(UTC)  | Reason: Not specified

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NeuTechFLA  
#5 Posted : Monday, February 05, 2018 5:54:11 AM(UTC)
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I have it on mine. I used the surface to split the other surface, not the curve. Grab the interior point and move it laterally. You will see the surface split moves too.

Edited by user Monday, February 05, 2018 5:55:28 AM(UTC)  | Reason: Not specified

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Jolyon  
#6 Posted : Monday, February 05, 2018 6:06:22 AM(UTC)
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Your model seems to work - great !!

- but you have unresolved links that won't go away

That doesn't explain why my case doesn't : (
NeuTechFLA  
#7 Posted : Monday, February 05, 2018 6:13:32 AM(UTC)
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Originally Posted by: Jolyon Go to Quoted Post
Your model seems to work - great !!

- but you have unresolved links that won't go away

That doesn't explain why my case doesn't : (


I cannot seem to get my mind wrapped around the concept of unresolved links in Shark. I resolve them before I save but other than that, clueless.

And yes, I still have not helped you in any way. I will try one fresh here and see if I get the same result.
Jolyon  
#8 Posted : Monday, February 05, 2018 6:20:09 AM(UTC)
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(Sorry Dean - I'm getting myself confused now)

... your example does NOT work

You cannot drive an extrusion (blue) from that surface intersect

(moving a point on the driving spline tries to move the surface intersection but fails because of the extrude - which does not update)

Edited by user Monday, February 05, 2018 6:22:06 AM(UTC)  | Reason: Not specified

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NeuTechFLA  
#9 Posted : Monday, February 05, 2018 6:38:33 AM(UTC)
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Try this one.

Still has "unresolved links" after a change. But the more that I think of it, this is nothing more than a Creo, Catia or SolidWorks regen. Just in Shark it's an explicit thing.

The trick I found on this one was I could not extrude the blue surface from the split edge. I needed to add an surface intersect to get the curve at the split and used that as the drive curve for the blue. I layered the items.

There is a spline driving the large surface. Modify that one and the splits/blue surface go along for the ride.

Edited by user Monday, February 05, 2018 6:40:37 AM(UTC)  | Reason: Not specified

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Jolyon  
#10 Posted : Monday, February 05, 2018 6:59:43 AM(UTC)
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OK - Good thinking Dean !

So -

To summarise, you can't drive geometry from a 'split surface' (intersection), but you can drive it from a 'surface to surface intersect'

Reason that raises my hackles in an associative history modeller like this is ... if you can't build associative geometry from a surface split intersection - then why does it let you build geometry there at all ?

It's bad logic (and it means that for each such instance, I must both split AND intersect the surface ... argh

Jol
NeuTechFLA  
#11 Posted : Monday, February 05, 2018 7:09:41 AM(UTC)
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It appears so, Shark needs an explicit "something" to reference when driving an extrude. I am in the middle of working a funky shaped "butter lid" as well. I have the shape modifiable with the same technique just used. But, now I am seeing that to have a solid that will accept a draft feature, the technique will need to get a bit more complex. Ahhhhh, the work-arounds, my friend....the CadLand entry fee.

I will upload it when it's ready.
Jolyon  
#12 Posted : Monday, February 05, 2018 7:33:11 AM(UTC)
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>>Shark needs an explicit "something" to reference when driving an extrude

Shark needs an explicit 'intersection' to reference when driving an extrude, cover surface pro anything at all

SO - why does Shark allow the selection of 'split' surface edges in the creation of downstream extrudes, cover surfaces etc ... if it cannot honour their associativity ?

Not right !

Grumpy Jol
Jolyon  
#13 Posted : Monday, February 05, 2018 7:41:51 AM(UTC)
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OK - going back to the 'butter dish lid' - I can now get it to update a stitched solid

- thank you Dean, I needed a different perspective

(Unfortunately, on updating a driving spline - I then had issues with 'unresolved links' - but edit>resolve links did fix it - woohoo !)
NeuTechFLA  
#14 Posted : Monday, February 05, 2018 7:51:59 AM(UTC)
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Originally Posted by: Jolyon Go to Quoted Post
OK - going back to the 'butter dish lid' - I can now get it to update a stitched solid

- thank you Dean, I needed a different perspective

(Unfortunately, on updating a driving spline - I then had issues with 'unresolved links' - but edit>resolve links did fix it - woohoo !)


Sorry...couldn't help myself.

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Jolyon  
#15 Posted : Monday, February 05, 2018 7:52:34 AM(UTC)
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every time I update a driving spline, I get this nonsense

thankfully if I edit>resolve links, it goes away

.. but can't it check for integrity when it rebuilds it ?
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NeuTechFLA  
#16 Posted : Monday, February 05, 2018 7:56:01 AM(UTC)
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It really should.... That makes for a very long day.

And why doesn't the Thicken Solid have a option to draft? If it did my modifiable butter dish would be complete. Also, the Draft Face feature does not seems to like to use curves as the neutral/start element.

Edited by user Monday, February 05, 2018 8:04:20 AM(UTC)  | Reason: Not specified

Jolyon  
#17 Posted : Monday, February 05, 2018 8:06:03 AM(UTC)
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I accidentally rear ended a car at a stop light on my way to work this morning. A "little person" climbed out of the car and came over to me. I said "Are you OK?". He said, "Well, I'm not happy." I said, "Well, which one are you?"
NeuTechFLA  
#18 Posted : Monday, February 05, 2018 8:08:07 AM(UTC)
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Brilliant!

I have to get to my real job. But a few observations:

Intersected curves seem to be associative in themselves. The yellow curves in the attached model are resultants of surface intersections. The magenta curves drive the fore-aft surfaces and the red curve drives the large face. Move the knots around and you will see the face move.

Anything that comes afterward seems to be independent whether that "anything" was tagged to the intersected curves or not. This is where constraints might come in handy. I.E. locking two vertices together with a parent/child relationship.

If the Thicken had an option to add draft angle within the feature itself, the part would be complete/modifiable and solid.

Edited by user Monday, February 05, 2018 8:41:18 AM(UTC)  | Reason: Not specified

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Jolyon  
#19 Posted : Monday, February 05, 2018 10:03:55 AM(UTC)
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Here's my take on son of 'Butter Dish Lid'

It's a shelled solid

You should be able to adjust the driving splines and have the solid regenerate

Notes: unsubtle moves will result in no-regenerate (unsurprisingly)

... any regen will cause 'unresolved link disease' ... but this may be resolved by edit>resolve links

What a ball ache to get this to work - thanks to Dean for the 'intersect surfaces' work-around !

So Tim ... listening ?

1. - 'Surface Split' edges ARE usable as drive curves for downstream extrudes etc ... BUT they need to maintain ASSOCIATIVITY

... Tim & co ... is this possible ??

2. - On regenerating, a part must check itself for UNRESOLVED LINKS and FIX ITSELF (if possible).

Can we do this ?

Thanks !!

Jol
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Jolyon  
#20 Posted : Monday, February 05, 2018 10:05:57 AM(UTC)
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If we had a STEP-THOUGH history, we could just play a part (like a movie) ... and see how it was made !!
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