(Bug) Affinty Designer circles (ellipse tool) are distorted

[Hachi2024]

(Request 1) Please fix this bug as soon as possible.

(Request 2) Enable the zoom factor to be set numerically.

(Request 3) I would like it to be possible to set the zoom rate to a maximum of approximately 87 million percent at once. However, a question I have always had is that when the zoom rate is set to the maximum, the entire screen goes completely dark, which is difficult to use. Please improve this so that the figures can be seen.

 

Affinty Designer ver2.5.5(Latest release version)

iMac M3 late2023

macOS 14.7(23H124): The latest 15.1 has not yet been installed.

This bug can be reproduced.

It also occurs in new documents.

I can upload a document that shows the problem.

 

hardware acceleration (in Preferences > Performance): attached Figure A below

 

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(a) (Bug) The circumference of the circle is distorted (when viewed at about 50000% zoom)

 

I noticed this bug when I was using Affinty Designer to see if I could do an accurate mathematical construction.

Draw a circle (200mm diameter) using the elliptical tool.

If you draw a line (radius) from the centre to a length (100mm) equal to the radius and rotate it, it is of course accurate in the directions 0°, 90°, 180° and 270°. The edge of the radius line coincides with the centre of the circumference.

 

However, at angles such as the 45° direction, it was noticed that the circumference was clearly shifted inwards or outwards. The radius is lengthening or shortening.

For example, calculate the exact coordinates of a point on the circumference in the 45° direction and draw a point there. This will clearly show that the circumference is distorted.

 

A line that is the same length (100mm) from the centre as the radius is of course accurate in length when the line is rotated.

 

From the above, it can be confirmed that the circumference of the circle created by the Ellipse tool is distorted.

 

Instead of distorting only outwards, the radius lengthens, shortens and lengthens again within a 90° range, as shown in the reproduction below. It appears to be a low-level algorithm that averages by distorting outwards and inwards.

 

However, this is hardly a circle.

 

It is clearly visible when zoomed by about 5,000%. It is normal to zoom in this much, so if the image appears distorted at this level of zoom, it cannot be used for construction. 

As the drawing of circles is fundamental, being inaccurate is unacceptable.

 

I have been using Affinty Designer for over eight years now and believed that the circles were drawn accurately. 

Since Serif claims 'zoom one million(!) percent and beyond', it must be guaranteed that a perfect circle will still have an accurate circumference as a perfect circle even when zoomed in to that level.

 

(b) Reproduction method

The easiest way to reproduce this (see below) is to zoom the bottom point of the circle (180° direction) and rotate the radius line +180° as well. The circle is then rotated (counterclockwise) by 1° between +0° and +90°.

Comparison at about 50000% zoom:

+0° : Zero distortion.

+1°〜+17°(local maximum)〜+30°: Circumference is distorted outwards(Radius longer than 100mm)。

+31° : Almost zero distortion.

+32°〜+45°(local minimum)〜+58° : Circumference is distorted inwards(Radius shorter than 100mm).

+59° : Almost zero distortion.

+60°〜+74°(local maximum)〜+89°: Circumference is distorted outwards(Radius longer than 100mm).

+90° : Zero distortion.

 

(1/8) At a rotation angle of 0° of the circle, the distortion is zero (Figure1)

(2) Slight distortion even at +1° rotation, but clearly at +2°(Figure2)

(3) Radius local maximum at +17° rotation (Figure3)

(4) Distortion returns to almost zero after +31° rotation (Figure4)

(5) Radius local minimum at +45° rotation (Figure5)

(6) Distortion returns to almost zero after +59° rotation (Figure6)

(7) Radius local maximum at +74° rotation (Figure7)

(8/8) +90° rotation returns the distortion to zero (Figure8)

 

a document that shows the problem

circles_distorted.afdesign

 

[MEB]

Hi @Hachi2024,
Welcome to Affinity Forums
1. Affinity apps use cubic Bézier curve approximations to draw circles and ellipses, so there is always a small margin of error, which we consider acceptable for a vector illustration program. The issue is known to the developers, and there is an internal request to improve this to support true circles (which I’ve now bumped but, perhaps a CAD application might be better suited for the type of work you're doing? Why do you need such a high level of precision, could you provide a bit of context?

2. You can set the zoom level in the context toolbar (first control) when the Zoom tool is selected.

3. Not sure why it goes black. Will check with development.
For feature requests please, create a new thread in the Feedback for the Affinity V2 Suite of Products section of the Forums which is the thread dev follows for suggestions/improvements.

Thank you for your feedback.

[Hachi2024]

Hi MEB,

Thanks.

 

I saw that it was tagged "APL-1294" and knew that this was a known issue.

I found out there that the perfect circle asset file was released in 2021. I installed this and tried it, and indeed, at about 50000% zoom, it can be seen as a perfect circle. For the time being I will use this.

 

   https://forum.affinity.serif.com/index.php?/topic/150167-rotation-invariant-perfect-circle/

 

It is not practical to start using a CAD application from scratch, apart from the familiar Affinity Designer.

 

The answer to the question "Why do you need such a high level of precision?”,

is because I am now examining a mathematical construction problem.

I do not use Affinity Designer just for mathematical construction.

One use should be at a level where it can also be used for mathematical construction.

When you advertise zoom one million(!) percent and beyond, then the approximation of the circle should be perfect within that zoom range.

 

One other request.

I have set the number of decimal part to 6. When I select a coordinate or angle value and press the up or down arrow key, the value changes by one, which is both convenient and inconvenient. It is not user-friendly.

 

What we really need is, for example, in the case of a value like 10.123456, to press the up arrow key to get 10.123457. When we want to make subtle adjustments, it will be great if we can set the value at the left of the cursor position to +1. Improve it as such.

Edited November 9, 2024 by Hachi2024