Is there a way to stretch a block while limiting the angle it can stretch by?

[benMEG52]

This is quite complicated to explain, but I’m trying to create a dynamic block for a flat cone. I want it to stretch at the top and bottom, but while keeping the sides of the cone at less than 22.5 degrees each though.

I’ve attached a DWG that hopefully clarifies things. The magenta lines are the area that the sides of the cone (all in white) need to stay within while being stretched in a straight line.

[Marlon-CV]

@benMEG52 , I downloaded the dwg but there is no block.

Are you needing help creating from scratch or do you have one I can have a look at?

[j.palmeL29YX · Accepted solution]

Something as shown in the attached attempt? 

[benMEG52]

That looks exactly like it, thanks! 🙂

How did you do the parameters? It looks like you used constraints, which I'm not at all familiar with.

Also, can you change it so it has 2 grips on both vertical constraints, and for the grip on the horizontal constraint to stay with the line when stretching it?

[benMEG52]

Yeah, it's just linework actually.

Jurgen Palme looks to have sorted it though 🙂

[j.palmeL29YX]

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@benMEG52 wrote:

How did you do the parameters?

... constraints, which I'm not at all familiar with.

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I'll try to explain in a video. 

If you have further questions ... I am here  😉 

[j.palmeL29YX]

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@benMEG52 wrote:

Can you change it ... for the grip on the horizontal constraint to stay with the line when stretching it?

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Not possible while the height is too small. This behavior is caused by the solution principle. As long as the user chooses a height (per grip or type a value in the properties window) which results in an angle smaller than 22.5° the grip IS assigned to the vertical line. If the users drags the grip in the "not allowed" range, the formula of d4 ensures that the geometry doesn't follow this demand. 

[j.palmeL29YX]

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@benMEG52 wrote:

Also, can you change it so it has 2 grips on both vertical constraints, 

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It is possible, but IMO not to suggest - the grip (the end of the dragged line) dosn't (and can not) follow the mouse movement. 

If you do it nevertheless don't forgot to modify the formula. Instead of d1 and d2 you must type d1/2 and d2/2 ...

[benMEG52]

OK, I'll just use it as is.

Thanks again!

[benMEG52]

If I want to add linework to a block, is there a simple way to have it controlled with the previously set up constraints? With parameters, it's easy to add or remove lines from a selection set, but there doesn't seem to be a way to do this with constraints.

For example, if I add 2 green lines as shown on the attached block, the horizontal or vertical constraints only seem to control the green lines OR the cone shaped polyline, not both.

on the attached block

[j.palmeL29YX]

If you add new geometry, then of course appropriate constraints must also be added to get the intended result. 

Unfortunately I do not understand what you want to get: what should happen when you change which value? Which dimensions do you want to change, and how should the block look after that? Can you please show us with some sketches?

[j.palmeL29YX]

Could it be (just a guess) that you need the green lines as a visual reference geometry for when you will reach the 22.5° limit when dragging the grips? 

[benMEG52]

What I'm trying to do is create a ductwork transformation block, eg for use when transforming ductwork from 300mm down to 200mm ductwork, but which can't go larger than a 22.5 degree angle. The first block you did works fine for that, but I also want to have a rectangular to circular duct transformation, which needs the inner lines from the block I shared earlier today. These lines should stretch horizontally to stay touching the midpoint of the left hand vertical line (controlled by the R2 constraint in your block) and vertically to stay touching the endpoints of the right hand vertical line (controlled by the R1 constraint).

I've also attached a demo block in case the above isn't clear

[j.palmeL29YX]

Based on my first suggestion above (Post #3) it is easy to solve. 

Your last block in Demo1.dwg includes Dynamic Parameters and Actions. Mixing dynamic parameters/actions with constraints usually just causes problems and is not to suggest. But without constraints I see no way to realize the "22,5° limitation". 

[benMEG52]

Hi, I'm trying to create a duct transformation similar to the one above, but with only one angled side.

I've gone through all the steps in the video you posted, but can't get it to limit the angle to 22.5 degrees. What am I doing wrong?

[benG6WHW]

Still trying to get it to work...