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john77m

Scale by percent/Affinity Designer

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Hi john77m,

Welcome to Affinity Forums :)

[EDITED] You can use math operations inside input fields, so for example if you want to change the width of an object to half you can replace the existing value with *=50% in the Transform panel. [EDITED]. For information about the expressions you can use in the input fields check the menu Help ▸  Affinity Designer Help ▸ Workspace ▸ More ▸ Expressions for field input.

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… you can add *50% after the existing value in the Transform panel or  replace the existing value with *=50%. Both notations will work.

 

Yes, both work, but they are not the same. The first one results in wrong/inaccurate results in too many cases!

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Hi Oval,

Can you post a sample file/example where it fails using the first notation and works with the second please?

Thanks.

 

LOL. john77m is not an advanced user of Affinity Designer. If you simplify things, bridges can collapse. You know that the numbers in the fields don’t represent/show the exact dimensions in many cases.

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Yes, both work, but they are not the same. The first one results in wrong/inaccurate results in too many cases!

 

 

In particular because john77m is not an advanced user he would be very happy to know where expressions fail  :)

But not only him, I'm curious too as other members of the community for sure... Which are these cases?

 

I wasn't able to find a bug related...


The white dog, making tools for artists, illustrators and doodlers

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LOL. john77m is not an advanced user of Affinity Designer. If you simplify things, bridges can collapse. You know that the numbers in the fields don’t represent/show the exact dimensions in many cases.

 

 

Oval,

That's not an inaccuracy bug. The application is simply rounding the values if there isn't enough decimal places to represent the whole result.

You can change the number of decimal places used for different units in Affinity Preferences, User Interface section.

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I wasn't able to find a bug related...

 

Who said, it is a bug? You just get different results. Think about that: π is not 3.141592653589793

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Oval,

That's not an inaccuracy bug. The application is simply rounding the values if there isn't enough decimal places to represent the whole result.

You can change the number of decimal places used for different units in Affinity Preferences, User Interface section.

That was not said. But don’t advise beginners, both results are the same in all cases, if you don’t tell them in which cases both results in the same dimensions. You only can get six places, which is not the precision of the real dimensions of the objects.

 

Adding “*50% after the existing value in the Transform panel” should not be used/advise, if you don’t know that the field shows the exact value.

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Oval,

Internally the application uses more than six decimal places to perform calculations, however for practical reasons the max number of values displayed in the fields are six.

This in not uncommon, other applications do the same. This is also an illustration/design application not a CAD software. What are you doing with it that requires such a high number of decimal places?

If you need such level of precision maybe you should consider a CAD application instead?

 

I can't explain/detail every single related feature when a user poses a question about something for obvious reasons. The accuracy/precision of the input fields was not in question here - just how to use percentages to scale objects.

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Oval,

Internally the application uses more than six decimal places to perform calculations, however for practical reasons the max number of values displayed in the fields are six.

This in not uncommon, other applications do the same. This is also an illustration/design application not a CAD software. What are you doing with it that requires such a high number of decimal places?

If you need such level of precision maybe you should consider a CAD application instead?

 

I can't explain/detail every single related feature when a user poses a question about something for obvious reasons. The accuracy/precision of the input fields was not in question here - just how to use percentages to scale objects.

 

Hey, a very good strategy to ask questions … 

 

Did you tell him that both result in different dimensions in most cases? No.

 

Have you asked john77m before, with how many decimal places he works? No. Perhaps with one.

 

Why do you need an example? You know that both are mathematically different.

 

Why do you ask me questions about my needs? It is about john77m’s needs.

 

You know that not only CAD needs precision. If he needs to duplicate his object many times for a watch design or just to align with x*2, your precision could be not enough. Perhaps he is a type(face) designer, not an illustrator, … have you asked?

 

Imprecise numbers (in the fields / in the context toolbar with only one correct decimal place) are still not indicated.

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Who said, it is a bug? You just get different results. Think about that: π is not 3.141592653589793

 

The discussion is moving to Georg's proof here... :P

Ok clear!   ;)


The white dog, making tools for artists, illustrators and doodlers

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Oval,

You are right. The first notation only works correctly if the number of decimal places set in Preferences is high enough to avoid rounding.

I'm checking this with the dev team. I didn't understood your first post correctly. Please accept my apologies and thanks for the heads up.

 

Thanks, perhaps an indicator will prevent some people to run into problems in future.

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@Oval

 

You know that the numbers in the fields don’t represent/show the exact dimensions in many cases.

 

I'm not sure what you mean by "in many cases".  Quite simply, floating point double precision far exceeds anything a user would want to see.  The process of making most geometry will mean that most numbers displayed will be rounded to some degree.  Even numbers that look whole might have a very small fractional part that we truncate/round.  Do you need to see the 0.000001 of the real number?  Probably not.

 

I get the impression you are seeing this as a bug, as opposed to an intentional feature.  No app is going to give you this sort of precision when dealing in text entry.  I think we've covered this subject on about 10 threads now!

 

So, we offer two approaches to formula entry - direct input where the text is interpreted directly (so subject to the rounding that was applied when turning the number into text), and relative formula that operate on the internally held precise value. It depends on the operator used and the content of the text field when you hit enter.  Since this feature requires some degree of knowledge, it's reasonable to expect people to read the help file to get the low down on how this works and how precision is affected.

 

Read the help, and all should be clear.


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@ Ben

 

I get the impression you are seeing this as a bug, …

 

No, never. Just said both methods can result in different dimensions. Like john77m, many users are not watchmakers. An easy example: If they illustrate they do it without knowing the exact dimensions. If advised to use both “notations” as equal [see the unedited version of #2] they can get in trouble when they just add *50% after the existing value, group it with some other objects, do it again and again … and then backwards with 200%, … and they wonder: Does not fit any more!

 

HTH

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