Align by origin? Issues centering a triangle.

[_lmf_]

Hi all, I took a look around the forums but couldn't find my question answered. I'm new to affinity programs so apologies if this is an obvious fix.

I'm trying to align a triangle on the page so that it is visually centered. When I click "align middle", this is what happens [see picture attached]

As you can see, it's aligning the triangle by calculating the space above and below it, but because it's a triangle, this type of alignment looks unbalanced. I need to center this triangle by its origin (or center point) instead. That is, I want the center point of the triangle to match the center point of the page. Is this possible?

Curiously, the group of white shapes you see inside the green triangle is also roughly triangle shaped, and when I hit "align middle" for this group, it worked the way I wanted. Why does align middle work via the center point for this group, but not for the triangle?

Thanks.

[Wosven]

HI @_lmf_,

You're using a polygon. I'm not sure that's what you want, but if you convert it to curves, the center will be higher (not taking in account the sides of the polygon, but of the triangle), and centering it will be different.

Oups, I messed my tests... No tests after a lonnnng day for me 😂

Edited November 10, 2021 by Wosven
Not sure of my results at this hour!

[thomaso]

Hi @_lmf_,
welcome to the Affinity forums!

Like Wosven, I wonder about the bounding box of your green triangle, in particular the space below its bottom edge. When I adjust it vertically centered to the page then it looks as expected:

1 hour ago, _lmf_ said:

visually centered.

Note that some shapes, especially triangles, may have various "visual" center points. Affinity is using its center according to the bounding box (also in your screenshot, what makes it appear off the center). This geometrical center point may feel visually slightly too close to the top (because its surface is smaller in its upper half). Another center point would be its "physical emphasis" (that center point which would make it float evenly if the shape gets cut out and placed on a needle).

[_lmf_]

4 hours ago, Wosven said:

You're using a polygon. I'm not sure that's what you want

I'm not sure it is either, but that's the only way I've figured out how to draw a true equilateral triangle. The triangle tool doesn't seem to allow you to draw a true equilateral triangle, and even affinity's own guides tell you to use the polygon tool if you need a true equilateral triangle. This seems weird to me and is a bit of an annoyance. Is there some secret way to get an equilateral triangle with the actual triangle tool? I'd love to know it.

3 hours ago, thomaso said:

Like Wosven, I wonder about the bounding box of your green triangle, in particular the space below its bottom edge. When I adjust it vertically centered to the page then it looks as expected:

When I draw a triangle with the polygon tool (again, I'm only doing this because it's the only way I know if to get an equilateral triangle!), I always get that extra space underneath it in my bounding box. I'm assuming this is a side effect of using the polygon tool. I guess I'll just convert all my polygon triangles to curves to get them to align correctly.

[GarryP]

Because the Triangle Tool draws the shape to the boundaries of the rectangle it’s drawn in, it’s difficult to get to it draw an equilateral triangle without manual work, as you have found out.
However, you can use the Polygon Tool instead and give the shape three Sides, as you have said, but that has the problem of the shape being drawn inside an ellipse which is drawn within the rectangle boundary.
I think the only ‘fix’ is to convert the ‘polygon triangle’ to curves as you are already doing.

[thomaso]

7 hours ago, _lmf_ said:

When I draw a triangle with the polygon tool (again, I'm only doing this because it's the only way I know if to get an equilateral triangle!), I always get that extra space underneath it in my bounding box.

Ah, correct, I haven't considered this before. As a workaround you could use the option "Cycle Selection Box" which temporarily toggles an object's bounding box view (though it might not help if the triangle gets or was rotated).

[thomaso]

Unfortunately the Triangle Tool's Preset option does not allow to save a custom, equilateral triangle as new preset, this presets seem to respect the "Top point" position only but ignore the aspect ration of the bounding box, so the menu option is grayed out for any triangle which also has its top point at 50%.

Instead, saving in the Asset panel appears to be the way for faster access to an equilateral triangle shape object.

[R C-R]

Not only is the triangle tool unable to create an equilateral triangle, because the 'top point' position setting only goes from zero to 100%, it can't create triangles where one of its angles is obtuse (greater than 90°).

[thomaso]

1 hour ago, R C-R said:

the 'top point' position setting only goes from zero to 100%, it can't create triangles where one of its angles is obtuse (greater than 90°).

Wouldn't you adjust the triangle's height, instead or as workaround?

Nevertheless, according its editability and the center point issue the Triangle Tool limitation is similar to this for the two generic Call-Out Shapes where the aiming tail end position can only get positioned along 1 of its 4 bounding box edges and not around a corner. Also, its center point includes the tail, quite disturbing if the shape gets used as text frame for vertically aligned text, which both reduces its typical use as a speech bubble.

 

[R C-R]

Just now, thomaso said:

Wouldn't you adjust the triangle's height, instead or as workaround?

How would doing that create a triangle with a vertex that is greater than 90°? For example, like this:

[Old Bruce]

Think different.

[thomaso]

It's possible (> rotation) … but feels soon too cumbersome for use as generic object.

[David in Яuislip]

15 minutes ago, thomaso said:

Wouldn't you adjust the triangle's height,

yes

[R C-R]

2 hours ago, thomaso said:

Wouldn't you adjust the triangle's height, instead or as workaround?

You can do that but there is no way I can see to set any specific angle or without an extra step to set the triangle's bounding box rotation to 0°.

What I would like to see is a context toolbar option for the Triangle Tool to set the angles of the triangle directly, either instead of (preferred) or in addition to the Top point adjustment, which I think is of limited value. This would make it easy to create every kind of triangle, including equilateral ones, & would permit making more useful & diverse triangle presets.

[thomaso]

30 minutes ago, R C-R said:

there is no way I can see to set any specific angle or without an extra step to set the triangle's bounding box rotation to 0°.

What I would like to see is a context toolbar option for the Triangle Tool to set the angles

Correct. Indeed Affinity lacks in several features for construction, it is just no CAD application like for architecture and engineering. It may be useful to define a triangel by angles but also it can be desired to define by more than 1 length of its legs. Concerning 'set the triangle's bounding box rotation to 0°' I miss (as others, too) a "reset current as new base" option for all object transformations, in particular for scaling. This would also help in cases where a text frame got scaled unintended by its outer handle but noticed at a later moment only.

Note, if we get an option to create a triangle by angles (or lengths of its legs) then we actually would also expect measuring tools (which I guess have been requested already) and consequently labeling tools for measurements. So to improve construction features would be a major feature & coding package if it wants to satisfy a bunch of needs and use cases instead of just selectively certain options (which will cause user questions "why this but not that?"). To bring it back to our current reality: Before such improvements, I would expect the confusing subdivisions of the ruler to be fixed in an app update.  

[R C-R]

2 hours ago, thomaso said:

Note, if we get an option to create a triangle by angles (or lengths of its legs) then we actually would also expect measuring tools (which I guess have been requested already) and consequently labeling tools for measurements.

Why would we expect measuring tools? If the Triangle Tool just had more options on the context bar, like a toggle between setting side lengths or vertex angles (any 2 of the 3 of either would work) then that would go a long way in making it a highly capable triangle creation tool.

[_lmf_]

27 minutes ago, R C-R said:

Why would we expect measuring tools? If the Triangle Tool just had more options on the context bar, like a toggle between setting side lengths or vertex angles (any 2 of the 3 of either would work) then that would go a long way in making it a highly capable triangle creation tool.

I agree, I'm not sure why making different types of triangles is inherently related to construction and engineering. I needed my triangle for a simple, digital only logo. This was actually my first graphic design project in Affinity designer, and I already ran into the issue, so it's definitely not something only engineers would want.

2 hours ago, thomaso said:

Affinity...is just no CAD application like for architecture and engineering.

I don't need it to be, and I think that's out of it's scope anyway as a competitor to Adobe Illustrator. Although defining triangles by the angles would be slick, personally I'd be satisfied if the polygon tool triangles just had their bounding box issue fixed.

[thomaso]

9 minutes ago, R C-R said:

Why would we expect measuring tools?

Because "we" as community already do: https://forum.affinity.serif.com/index.php?/search/&q=measure tool&quick=1
Or: Why should improvements for the construction of geometric objects focus on triangles in particular? Possibly wouldn't be understood by "us"

Nevertheless, yes, it appears weird that among the various generic shape tools the equilateral triangles seem to be forgotten "by design". I'd expect this option at least via modifier key, maybe instead of the current square bounding box via shift key. Interesting that also neither the Arrow Shape Tool nor the 3 triangular stroke arrows offer the option for equilateral triangles. The arrow names sound rather coincidentally, arbitrary, maybe their triangles are too?

[lacerto]

On 11/11/2021 at 5:07 AM, _lmf_ said:

I'm assuming this is a side effect of using the polygon tool. I guess I'll just convert all my polygon triangles to curves to get them to align correctly.

The polygon tool draws all shapes within an ellipse, but the Alignment panel uses the actual bounding box of each instance of the polygon shape, and accordingly would not align a triangle by its rotation center. Because the rotation center by default stays at the center of the defining ellipse, the easiest method to center any polygon shape by its rotation center would be to temporarily set its Curve option to 100%, then center align, and then turn the curve setting back to the original (typically 0 %). 

Alternatively (in apps like CorelDRAW or VectorStyler), one could temporarily add the number of sides of the polygon to 4 to get a square that has its corners at the defining ellipse, then center align, and finally redefine the number of sides back to 3. Personally I find the way the app now behaves useful as the user can easily choose whether to align based on the actual bounding box of the shape, or by the bounding box of the underlying ellipse, and it is also useful to have the center of rotation by default stay at the spot defined by the ellipse (rather than being automatically changed according to the shape bounding box).

 

[thatGuy]

for the shape itself you can either

- use the polygon tool or

- use the triangle tool and create a triangle inside a square box, then multiply the height by sin(60) or

- use the star tool, 3 points and max. inner radius

depending on your overall goal any method has its advantage.

for the position you can use the point transform tool to snap the center of mass to your guides or spread center, regardless of the bounding box overlapping or not

[R C-R]

7 hours ago, Lagarto said:

The polygon tool draws all shapes within an ellipse, but the Alignment panel uses the actual bounding box of each instance of the polygon shape, and accordingly would not align a triangle by its rotation center.

What I would like is for the Triangle Tool to set the default rotation center to the intersection of the 3 lines that bisect the angles of the 3 vertices of the triangle, like this:

Without that & some way to set either the angles or lengths there doesn't seem to be much point in having a Triangle Tool, at least to me.

[thomaso]

21 minutes ago, R C-R said:

What I would like is for the Triangle Tool

You might also like this interactive graphic that illustrates the different points and axes of different triangles.

https://www.mathespass.at/klasse2/dreiecke_punkte.php

[R C-R]

9 minutes ago, thomaso said:

You might also like this interactive graphic that illustrates the different points and axes of different triangles.

If I understood German well enough I might like it but unfortunately I do not.

Anyway, I think if the Triangle Tool just set the default center point as in my example & permitted explicitly setting vertex angles on the Context toolbar, that would be enough.

[thomaso]

4 hours ago, thatGuy said:

for the shape itself you can either

… how does the formula *sin(…) transform exactly?

In what way does it influence the aspect ratio of a triangles bounding box?
It appears to turn a triangle with a squared box to an equilateral triangle. But what does it with any other?

[R C-R]

13 minutes ago, thomaso said:

… how does the formula *sin(…) transform exactly?

In what way does it influence the aspect ratio of a triangles bounding box?
It appears to turn a triangle with a squared box to an equilateral triangle. But what does it with any other?

Yes, it seems to work to make equilateral triangles only if the triangle's W & H dimensions are equal so its bounding box is square, and if the Top point is 50%. Otherwise it fails.

However, as long as the top point is 50%, what does work is setting H to w*sin(60).