tough dragon
I want to draw an arrow between 2 content nodes, such that the arrow just touches the edges of the 2 nodes.
The TikZ equivalent is:
\node[draw] (A) at (0,0) {A};
\node[draw] (B) at (1,0) {B};
\draw[->] (A) -- (B);
My CeTZ code:
import draw: *
set-style(mark: (size: .05))
content(name: "A", (0,0), trect[A])
content(name: "B", (1,0), trect[B])
line("A", "B", mark: (end: ">"))
What I get:
What I want:
night lake
you can use anchors like this
flat bane
we don't use the nodes concept, everything is an "element". Referencing elements by name in coordinates picks a default anchor, here its center
night lake
?render
#import "@preview/cetz:0.1.1"
#let trect = rect
#cetz.canvas({
import cetz.draw: *
// set-style(mark: (size: .05))
content(name: "A", (0,0), trect[A])
content(name: "B", (2,0), trect[B])
line("A.right", "B.left", mark: (end: ">"))
})
delicate hamletBOT
?render
```rs
#import "@preview/cetz:0.1.1"
#let trect = rect
#cetz.canvas({
...
flat bane
you can use "left" and "right" anchor names as shown lol
night lake
dunno how to fix the ever so slight overlap of the arrow mark
flat bane
theres a pr for ithttps://github.com/johannes-wolf/cetz/pull/164
night lake
ah epic
tough dragon
Nice thank you!
But then for circles, is there a way to have nice arrows if we use the corner anchors? Like what is done in TikZ if we simply do \draw[->] (A) -- (B);
?render
#import "@preview/cetz:0.1.1"
#let tcircle = circle
#cetz.canvas({
import cetz.draw: *
content(name: "A", (0,0), tcircle[A])
content(name: "B", (2,1), tcircle[B])
line("A.top-right", "B.bottom-left", mark: (end: ">"))
})
flat bane
do you mean the arrow should be touching the circles?
if so no, at least not with the circles as content
tough dragon
Yes this is what I mean. I understand from what you say that it may be possible using the "circle" of cetz, but I don't think it is possible to have text inside, is it?
flat bane
you could place content on top of the circle
night lake
?render
#import "@preview/cetz:0.1.1"
#cetz.canvas({
import cetz.draw: *
circle(name: "A", (0,0), radius: 0.5)
circle(name: "B", (3,2), radius: 0.5)
content("A.center", [A])
content("B.center", [B])
line("A.top-right", "B.bottom-left", mark: (end: ">"))
})
night lake
even then they dont touch when using the top-* or bottom-* anchors, ig anchors use a bounding box then?
tough dragon
you could place content on top of the circle
Yes but we wouldn't have the dynamically-sized circle/rect depending on the text content
high glacier
The circle anchors are currently the bounding box of the circle. Don't know if this is by design or will be fixed, but for now, just use a relative coordinate to set the points of the line:
?render ```
#import "@preview/cetz:0.1.1"
#cetz.canvas({
import cetz.draw: *
circle(name: "A", (0,0), radius: 0.5)
circle(name: "B", (3,2), radius: 0.5)
content("A.center", [A])
content("B.center", [B])
line(
(rel:(45deg, .5), to:"A"),
(rel:(225deg, .5), to:"B"), mark: (end: ">"))
})
viral patrol
No no no… there is a better way of doing that (see the tree gallery example):
line((a: a, number: .6, abs: true, b: b), (a: b, number: .6, abs: true, b: a), mark: (end: ">", start: ">"))
The .6 is the radius of the circle. abs: true makes .6 get interpreted as an absolute distance (vs. the shorthand relative distance syntax).
?render
#import "@preview/cetz:0.1.1"
#cetz.canvas({
import cetz.draw: *
circle(name: "A", (0,0), radius: 0.5)
circle(name: "B", (3,2), radius: 0.5)
content("A.center", [A])
content("B.center", [B])
line((a: "A", number: .5, abs: true, b: "B"), (a: "B", number: .5, abs: true, b: "A"), mark: (end: ">", start: ">"))
})
high glacier
No no no… there is a better way of doing that (see the tree gallery example):
``...
Definitively looks better, but the "top-left" and "bottom-right" anchors of a circle would be at a 45 degree angle on the circle, wouldn't they?
viral patrol
Yes, they should be 🙂
viral patrol
I opened a PR for this.
tough dragon
Thank you everyone, but again, I am not sure these techniques would handle well long or multi-line text. I would like a solution that is content-agnostic. As of right now, the TikZ way to do it is simpler to me:
\node[draw, circle] (A) at (0,0) {arbitrary text};
\node[draw, circle, align=center] (B) at (3,2) {arbitrary\\text};
\draw[->] (A) -- (B);
?render
#import "@preview/cetz:0.1.1"
#cetz.canvas({
import cetz.draw: *
circle(name: "A", (0,0), radius: 0.5)
circle(name: "B", (3,2), radius: 0.5)
content("A.center", [arbitrary text])
content("B.center", [arbitrary\ text])
line((a: "A", number: .5, abs: true, b: "B"), (a: "B", number: .5, abs: true, b: "A"), mark: (end: ">"))
})
delicate hamletBOT
?render
```
#import "@preview/cetz:0.1.1"
#cetz.canvas({
import cetz.draw: *
...
tough dragon
Ok so apparently, using frame: "circle" on a content element, I can have the "best" of both worlds, however I still find it a bit ugly. It would be nice to have an arrow that follows the line passing through the center of both circles.
?render
#import "@preview/cetz:0.1.1"
#cetz.canvas({
import cetz.draw: *
content((0,0), [arbitrary text], name: "A", frame: "circle")
content((3,2), [arbitrary\ text], name: "B", frame: "circle")
line("A.top-right", "B.bottom-left", mark: (end: ">"))
})
viral patrol
A somewhat better looking version you can get with the current cetz:
?render ```
#import "@preview/cetz:0.1.1"
#cetz.canvas({
import cetz.draw: *
place-anchors(name: "A", {
content((0,0), [arbitrary text], frame: "circle")
}, (pos: .15, name: ">"))
place-anchors(name: "B", {
content((3,2), [arbitrary\ text], frame: "circle")
}, (pos: .65, name: ">"))
line("A.>", "B.>", mark: (end: ">"))
})
Trying to display your code (I don't have access to a computer right now)
?render
#import "@preview/cetz:0.1.1"
#cetz.canvas({
import cetz.draw: *
place-anchors(name: "A", {
content((0,0), [arbitrary text], frame: "circle")
}, (pos: .15, name: ">"))
place-anchors(name: "B", {
content((3,2), [arbitrary\ text], frame: "circle")
}, (pos: .65, name: ">"))
line("A.>","B.>", mark: (end: ">"))
})
An error occurred:
communicating with worker
Caused by:
io error: failed to fill whole buffer
Ok I cannot render the code on Discord but on typst.app it works well
However every time you have to specifiy the position of the anchor on the circle, which I don't find optimal.
I think that it is a bit of a shame that line("A", "B", mark: (end: ">")) does not yield the same result as the TikZ examples I gave. Would the CetZ developers accept a PR that redefines the behaviour of line("A", "B", mark: (end: ">")) to match that of TikZ, i.e., it draws an arrow that touches the edges of the 2 circles and that follows the line passing through the centers?
If some people still want to get the old behaviour of the arrow going from one center to the other, they can still do line("A.center", "B.center", mark: (end: ">")), so everyone is happy
tough dragon
Hum, looking at the code, it might be difficult to extend it to support what I want. https://github.com/johannes-wolf/cetz/blob/779ebf8b4bb49d87ddc9ee536e5aed427e4ca59c/src/draw.typ#L375
A line takes two coordinates, however if these coordinates are given as names (eg. "A", "B"...), these coordinates are resolved before passing to the line() function, so it poses a problem if you want to draw an arrow that just touches the edges of circle A and B, because it would require the resolution to be done inside the line function (to compute the coordinates depending on the circles' radius and the angle of the line), am I correct?
viral patrol
I am the author of cetz (+ @flat bane), and yes, this is currently not very easy to implement. Cetz does not really know of nodes but only anchors. You would have to save nodes by their name (which is easy) and then find the intersection between a nodes shape and the shape of the arrow (also not hard). The functions for path intersection exist. Current way cetz interprets node names is by resolving them to their default anchor.
I have no time right now to implement it, but I am happy to accept a PR.
Although I am not sure if the tikz syntax (using node names) is the best way to do it in cetz, as it introduces a lot of special paths. (Does this work for all elements in tikz? Like for rectangles?)
An easy way would be implementing it as a function, i.e. connect(a, b, ..style), that connects two paths using a straight line.
tough dragon
Although I am not sure if the tikz syntax (using node names) is the best way to ...
Thanks for your input, indeed this syntax works for every kind of node in TikZ, I will try to make a new function like you said (connect maybe) and show it to you if it works 😉
viral patrol
Thanks for your input, indeed this syntax works for every kind of node in TikZ, ...
With this fix https://github.com/johannes-wolf/cetz/pull/219/files#diff-5c624d18b26eaec8282b6f1e683fe06e423c454904657daf11eb3f306e88e7f7R70 it is easy to get the intersection of content (with frame) and a line. The link points to an example.
In the current version of cetz, there is a bug regarding intersections(..) with content.
tough dragon
That's nice, it does nearly all the work. Do you know when it will be merged?
viral patrol
It is merged… but I am not sure when to release a new cetz version.
Or are you using a local installation?
tough dragon
Ok so here is the connect() function that I made and that does what I want. This function connects 2 nodes, node_a and node_b, by an arrow that follows the line between the 2 node centers, but that just touches the edges of the 2 nodes.
#let connect(node_a, node_b) = {
import draw: *
let name_a = node_a.at(0).name
let name_b = node_b.at(0).name
let name_intersections_set = name_a + "-" + name_b + "--intersections"
intersections(name: name_intersections_set, {
node_a
node_b
line(name_a, name_b, stroke: none)
})
line(name_intersections + ".0", name_intersections + ".1", mark: (end: ">"))
}
Example:
#let test = canvas({
import draw: *
let a = content((0, 0), [Das ist\ ein Text!], frame: "circle", name: "a")
let b = content((3, 2), [Hallo!], frame: "circle", name: "b")
connect(a, b)
})
tough dragon
With this fix https://github.com/johannes-wolf/cetz/pull/219/files#diff-5c624d18...
Note that this function relies on the above bugfix for the intersections() function, which is not yet published in a cetz release.
I will try to see how this new feature could be integrated in the current CeTZ codebase, but I'm afraid to do a PR that goes against the design principles of the library. In my head, this feature could be integrated to the existing line() function, but currently, the connect() function takes in parameters nodes and not strings (for node/anchor names). But having a line() function that takes both nodes and strings in parameters would result in ugly code IMHO. However, I don't know how to do otherwise, because we have to pass the nodes (and not the names) to the intersections() function. I would be happy to learn how to retrieve the node based on its name if we do not have access to the context.
On another note, it's funny to observe that both TikZ and CeTZ were made by German guys
supple fiber
No no no… there is a better way of doing that (see the tree gallery example):
``...
Can't you reuse this method?
?render
#import "@preview/cetz:0.1.1"
#cetz.canvas({
import cetz.draw: *
content((0,0), [arbitrary text], name: "A", frame: "circle")
content((3,2), [arbitrary\ text], name: "B", frame: "circle")
line((a: "A", number: .5, abs: true, b: "B"), (a: "B", number: .5, abs: true, b: "A"), mark: (end: ">", start: ">"))
})
