I hope I can articulate this properly. How does the isometric system work under the hood in Affinity Designer? Coming from Illustrator I noticed the power of the isometric system in Affinity with the plane system. When I was designing a basic isometric cube I noticed that fitting each side of the cube to its corresponding plane keeps the dimensions of each side of the cube a perfect 1:1 ratio even in isometric perspective. Affinity Designer Isometric Design

But when working in Illustrator and I make each side of the cube fit its corresponding plane the dimensions are not equalIllustrator Isometric Design Dimensions

Even when I do the SSR method in Affinity the resulting objects still keep their 1:1 ratio. So I am just curious to know how the inner workings of the isometric system work within Affinity.

2 Answers 2


This is essentially a free action for a programmer, just a question of how to build the gui for it. What you actually do is make a skeved cooridate system (transformation matrix)

Illustrator has a damaged way to handle transformation matrices. Mostly because Adobe likes to make sure they dont exist to users. As it happens adobe ignores skew of all matrices when displaying values. Presumably because this is confusing to users to have nonorthogonal bases. The data is there it just dont want to tell you this.

This is even true in affinity in general. Would have been much much better if they had just taken the playbook from DCC apps and actually showing the transforms as actual dataobjects (and while they are at it make tangent just points with filters). But as it stands all 2D editors choose to hide a very useful technical property, although inkscape atlrast lets you acess the raw values. If they would then you wouldnt need to womder about this when you make other axonometric transforms that arent isometric, like ones for isometric shadows.

PS: I supose it was a good idea in late 1980's. But stuff has become way more technical since then and today users would benefit from raw data access. Especially since they will see it in webdev anyway.

PPS: it takes about 20 lines of code to change a tool like illustrator or affinity to actually support 3D coordinates. A thousand to add z sorting add clipping so the fact that affinity can not do true rotatabe isometrics is a decission


Illustrator gives the size only as apparent height and width. Illustrator doesn't care nor know that your drawing can present objects in 3D space. Illustrator knows only one plane (=the artboard).

Illustrator knows 3D only in a certain case: 3D effects can hold one object at a time in 3D space and that happens just when the effect is adjusted. Before and after it the object is a planar shape on the artboard.

Affinity D creates for you three different grids which are the rectangular grids on XY,XZ and YZ planes projected onto your artboard plane. You have no actual 3D depth, but drawing along those projected girds can create fake parallel 2D projections of 3D objects. All parallel planes are projected equally to your artboard because there's no perspective, so it's enough to have only the projected grids available on the artboard.

Actually one projected rectangular grid would be enough for drawing in isometric projection, but Affinity D gives to you all three for convenience. They all are needed if the projection is other than isometric. You see the grid of the current "working plane".

If you change the projection the already drawn parts do not adapt, they are only flat objects on your artboard.

Affinity D calculates the dimensions of the drawn objects as real 3D dimensions and shows the selection boxes as SkewedScaledRotated rectangles instead of the usual horizontal boxes. To make it happen you must have the selector tool option "Cycle Selection Boxes" =ON.

The Transform panel shows the straight on the face dimensions of the drawn object. There's also the rotation and skew angles which would transform the straight on the face rectangle to be seen on the drawing plane.

enter image description here

BTW. Option "Cycle Selection Boxes" is harmfully switched OFF as soon as you change the working plane.

  • Is the “cycle selection boxes available on the iPad version of Affinity? And I have to say that I really like the plane system in Affinity. Although I sure hope affinity can fix the isometric graph zoom alignment issue. I have been designing all my isometric stuff in Illustrator for the past few years. Which app would you say has the more precise isometric system? Jan 21, 2021 at 1:44
  • @IsionIndustries Neither is more accurate. Anyway consider working in a 3D CAD program instead it makes it much much faster. (CAD because CAD programs work on vector data not polygon data)
    – joojaa
    Jan 21, 2021 at 8:12
  • @IsionIndustries I use only Windows. iPad version is a redesign, it can be somehow more streamlined. Or harmfully limited - no knowledge here. What alignment problems you have had? One problem in isometric projection: Converting a straight on the face shape to a working plane or backwards needs scaling. You must use irrational numbers sqrt(2) and sqrt(3). Inputting them as too short decimal numbers creates inaccuracy, part will not fit together. If you draw everything with a single grid everything fits, no matter is the grid exact or not. Pixel dimensions and irrational numbers = impossibility
    – user82991
    Jan 21, 2021 at 9:04
  • The alignment issues are related to how the iPad version of Affinity Designer renders the grid in the background at different zoom levels, apparently its a bug. But my OCD is killer because I always have to make sure everything is precisely aligned. And what do you mean "converting a straight on the face shape"? Jan 21, 2021 at 14:50
  • Draw a shape which is on your artboard and presents just that same shape on that artboard without being a projection of something else. Then it's straight on the face. SSR'ed rectangles can be pure rectangles seen in another way than straight on the face. Or as well they can be SSR'ed rectangles seen straight on the face.
    – user82991
    Jan 21, 2021 at 15:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.