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Am I the only one who finds it unusual that the rotate angle in the transform palette work counterclockwise? - i.e. 15° is counterclockwise, (-15°) is clockwise?  Is that "left handed coordinate system" related thing (y axis goes down) or something trig-related? 

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6 hours ago, AndyQ said:

Am I the only one who finds it unusual that the rotate angle in the transform palette work counterclockwise? - i.e. 15° is counterclockwise, (-15°) is clockwise?  Is that "left handed coordinate system" related thing (y axis goes down) or something trig-related? 

This is due to the definition of a Cartesian coordinate system. See here: https://en.wikipedia.org/wiki/Angle#Positive_and_negative_angles

It's a convention.

d.


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5 hours ago, dominik said:

This is due to the definition of a Cartesian coordinate system. See here: https://en.wikipedia.org/wiki/Angle#Positive_and_negative_angles

 

However, that article says:

Quote

With positive angles representing rotations toward the positive y-axis and negative angles representing rotations toward the negative y-axis.

Since our positive y-axis goes down, that would require that a positive rotation be clockwise, not counter-clockwise.


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47 minutes ago, walt.farrell said:

Since our positive y-axis goes down

Hi @walt.farrell,

an interesting thought. With 'our positive y-axis' you refer to the y-axis in the Affinity products?
If so this has a certain logic to it. But I assume this is something only a representative from Serif can explain how the decision was made.

I learned at school that positive angles point counterclockwise. That's why I never wondered about AD's behaviour.

d.


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31 minutes ago, dominik said:

With 'our positive y-axis' you refer to the y-axis in the Affinity products?

Yes.


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1 hour ago, walt.farrell said:

However, that article says:

Quote

With positive angles representing rotations toward the positive y-axis and negative angles representing rotations toward the negative y-axis.

It seems to me that there’s room for improvement in the wording of that article! The positive direction of the y-axis is the part above the x-axis, and the positive side of the y-axis is the part to the right of the y-axis.


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32 minutes ago, Alfred said:

It seems to me that there’s room for improvement in the wording of that article! The positive direction of the y-axis is the part above the x-axis, and the positive side of the y-axis is the part to the right of the y-axis.

Perhaps, but I don't see how that would help our current discussion. In any case, it's a wiki, and anyone who has registered with the site can edit a page unless it's locked, so feel free :)

 


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10 hours ago, dominik said:

This is due to the definition of a Cartesian coordinate system. See here: https://en.wikipedia.org/wiki/Angle#Positive_and_negative_angles it's a convention. d.

Sweet.  It does also say that bearing angles are measured as positive in a clockwise direction, which would explain my association of clockwise with "positive". I've just done a quick flick through a bunch of other applications, from vector to VFX to 3D apps and there's a mix of approaches. What's weird is that I never really thought of this before - I must be subconsciously adapting to different application approaches many times during a working day - the apps I use most are Photoshop (positive clockwise), 3DS MAX (positive clockwise), Illustrator (anticlockwise), CorelDraw (anticlockwise), After Effects (clockwise), InDesign (anticlockwise) and HitFilm (clockwise). Also checked were Blender (anticlockwise),  Fusion (anticlockwise) and Powerpoint (clockwise). I got tired of opening/testing applications after that little set, although I could go on. It's interesting to see Adobe using different conventions amongst its programs - counterclockwise for the "paper-based" idioms of AI and ID, but clockwise for the "screen-based" programs like PS and AE. 

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Since our positive y-axis goes down, that would require that a positive rotation be clockwise, not counter-clockwise.

And it does in SVG, and therefore in Inkscape. But I'm not saying it should in Affinity Designer. Because unfortunately, Descartes's grave was desecrated by the graphics industry long ago. So everything's just a scattered mess anyway.

Go try and tell your trig or calc professor (or your HP graphing calculator) that the Y axis origin should be at the top of something called a "page," and therefore vertical values should increase downward. But that's what has happened to vector-based graphics programs; something that is by definition math-coordinate driven.

The root problem is, Affinity Designer should be an illustration program first and foremost, and a proper Cartesian coordinate system is what should be used in all such programs. But that's not Serif's fault. That ship sailed with FreeHand. (It was actually merely run aground by if-you-can't-beat-'em-just-buy-and-discontinue-'em Adobe.) And somewhere around that time, Adobe also flipped the Y axis in Illustrator to assuage uninformed demand from users who don't know Descartes from Adam, and it and everything that imitates it drives me freakin' nuts.

Related: Even before inverting Y, Illustrator's single Artboard was always inexplicably created at the center of the program's limited pasteboard. And it still is, and that's one reason why its page handling was (and still is) far more cumbersome than it should be. FreeHand's initial default page was properly created at the lower left;  in other words, at the origin of its proper Cartesian coordinate system. So added pages proceeded sensibly without, in effect, wanting to waste half or three-quarters of its limited pasteboard.

A vector based drawing program (or CAD program) should, by default, have its X ruler at the bottom of the screen, not at the top, and positive Y values should increase upward. But if Serif had done that, there would be a firestorm from users who now think Y values increase downward, just because they do in a web page—and Adobe Illustrator.

It's too late for this issue. But please, for everything else going forward, let's just forget Adobe Illustrator so that vector-based drawing can actually move forward.

For example: If vector-based drawing ever does get out of its Adobe-esque doily drawing doldrums, one thing we might find of interest is the feature that has long existed in Canvas for directly plotting curves by formulae and function. Guess what kind of coordinate system that feature uses.

JET

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1 hour ago, JET_Affinity said:

Go try and tell your trig or calc professor (or your HP graphing calculator) that the Y axis origin should be at the top of something called a "page," and therefore vertical values should increase downward

Personally, I think that this concept stems from the times of terminals and their printers (Unix, DOS), where movement in the X axis (from left to right) is not a problem (natural shift of the carriage), but movement in the Y axis is possible only from top to bottom (line feed).

This is also the basis for char/pixel addressing in the PC.
https://whatis.techtarget.com/definition/x-and-y-coordinates


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17 hours ago, Pšenda said:

Personally, I think that this concept stems from the times of terminals and their printers (Unix, DOS), where movement in the X axis (from left to right) is not a problem (natural shift of the carriage), but movement in the Y axis is possible only from top to bottom (line feed)

They also had vector displays on computers in the early days, with no such limitation (CRTs but with lines drawn by a beam moving from coordinate to coordinate).  These were still around in the 80's (some video arcade games used them). Other vector devices, like plotters, also have a long history. I think the first vector graphic program I used was "Y-up"; Zenographics Mirage, on DEC VAX systems (ported to early PC's in the mid-80's). I think you're right about screen coordinates being based on the raster scanning order of CRT's, but I still find it annoying  -  especially as someone who draws lots of graphs where I'm plotting Y-up on a Y-down page....(which means arsing around if you're doing this programmatically )

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On ‎9‎/‎28‎/‎2019 at 2:10 PM, AndyQ said:

It's interesting to see Adobe using different conventions amongst its programs…

But not really surprising, given that many of Adobe's graphics apps (including Photoshop) were acquired.

One of the advantages of the Affinity platform is that all three of its "legs" (raster, vector, assembly) seem to have been conceived and are being developed together as a cohesive platform, not as a mere marketing bundle of separately-developed (or acquired) programs. The "integration" (something Adobe has always loved to banter about) is deeper than mere interface window dressing.

Which is why I tend to "weep and moan" whenever I hear users demand conforming to the "mean ol' levee" of Adobe Illustrator, the interface of which is more twisted than the Mississippi. There are straighter (and more elegantly integrated) paths to the needed functionality, if we can just afford the dev team time to consider them, and offer our input (which the dev team seems refreshingly open to) with some appreciative civility. (Alluding to other threads, not this one.)

JET

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On 9/28/2019 at 8:15 AM, walt.farrell said:
Quote

With positive angles representing rotations toward the positive y-axis and negative angles representing rotations toward the negative y-axis.

Since our positive y-axis goes down, that would require that a positive rotation be clockwise, not counter-clockwise.

Actually, it would be clockwise when on the right side of the axis and counterclockwise when on the left side of the axis, would it not?

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4 minutes ago, fde101 said:

Actually, it would be clockwise when on the right side of the axis and counterclockwise when on the left side of the axis, would it not?

Good point.


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8 hours ago, JET_Affinity said:

Which is why I tend to "weep and moan" whenever I hear users demand conforming to the "mean ol' levee" of Adobe Illustrator, the interface of which is more twisted than the Mississippi. There are straighter (and more elegantly integrated) paths to the needed functionality, if we can just afford the dev team time to consider them, and offer our input (which the dev team seems refreshingly open to) with some appreciative civility. (Alluding to other threads, not this one.)

JET

I certainly don't want designer to be like Illustrator, at least not at the basic vector editing capabilities. I've always liked Corel's vector editing (and selection techniques) a lot better than AI's, but can't stand other elements of the interface. Both camps seem stubborn in their approach to not learn from either each other or others. I do think Designer can learn from some of Adobes interface management system - like saving workspaces, being able to dock tools etc. Since I have no choice but to use Adobe apps it does make it easier that  Affinity uses many similar conventions, the panning/zooming shortcut compatibility makes it easy to move between the two camps, whereas if I pick up Corel after not using it for six months I have a mental breakdown trying to remember the basics. Designer isn't far off being able to do all I need, but all three of the applications I've mentioned have their strengths and weaknesses. Certainly Affinity wins hands-down for value and even if I'm not going to use the products a lot I'll be buying any upgrades and continuing to learn more about 'em.

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Standard rotation convention is that a positive rotation rotates away from the primary axis towards the secondary axis (conventionally X towards Y) - so a 90 degree rotation will take you from the X axis to the Y axis.  This understanding becomes more relevant as you add more axes.

 

Clockwise/anticlockwise are all dependant on the handedness (is that a real word?) of the coordinate system and the method of projection to the visualisation plane.

 

It is true that we are not representing the rotation correctly in Affinity.  Our logical axis (as the user perceives) points right (X) and down (Y), yet our positive rotation behaves as though our Y is up.  This is something that may well get addressed in the not too distant future (no promises on time).  It crept in due to the different behaviours expected from different people when dealing exclusively with either vector or raster content.


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23 hours ago, Ben said:

It is true that we are not representing the rotation correctly in Affinity.  Our logical axis (as the user perceives) points right (X) and down (Y), yet our positive rotation behaves as though our Y is up.  This is something that may well get addressed in the not too distant future (no promises on time).  It crept in due to the different behaviours expected from different people when dealing exclusively with either vector or raster content.

Fair enough, this isn't really a problem at all, I just brought it up out of interest and am surprised at how much discussion it's gotten. I certainly wouldn't call it any sort of priority! - as I mentioned in an earlier post, I checked a bunch of applications and they're all over the place in regards to how they deal with rotation. Cheers!

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