BLine tool bug

I just downloaded Synfig for Windows (from the download page). My impression was very good… until it started crashing.

Following the Flower Animation tutorial, I created a file. The next step is to edit the tangents for the BLine. I have not managed to move the tangents for all three points before Synfig crashes. The error is reproducible (savefile attached), but does not output any error information.

Do you know what the problem is?

EDIT: I started from step 1 in the tutorial, and BLine editing still causes Synfig to crash. Starting it from the command line, the error is usually “The application has requested the Runtime to terminate it in an unusual way…”
tut-anim.sifz (1.04 KB)

Hi, nikitakit
There are a few things you can do to help yourself and help us to fix that.

  1. First try to follow these instructions to increase the stability of synfigstudio if you didn’t do it already.
  2. To obtain some information from a crash you should run synfigstudio from a terminal (a MSDOS prompt). All the crash messages will be drop there (if any). You said that ran synfigstudio form the command line but that kind of message seems to be a windows message. Paste the terminal message here, not the windows pop up.
  3. Provide your Operating System version and your main hardware system information. I guess you’re under Windows Vista in a dual Core. It is just to confirm that you don’t have XP.

I’m not Windows user (linux here) and I’ve tested the provided file and edited the tangents without any problem. So I bet that it is a problem of stability of synfigstudio under windows than a file problem.


1)I did that just now. The file I posted works now… hopefully it was just a stability issue.
2)What I wrote was the error message. A complete copy-paste of my terminal can be found here (if you need it).
3)Nope. I’m using old XP right now (I’m on a public computer). Synfig version is 0.61.09

Is XP incompatible with Synfig? I’ll try it on Vista at home and see what happens.

Thanks for answering, and sorry I didn’t provide enough info.

I just finished the snowflake tutorial (despite the crashes)… It should mention that only exported parameters can be linked. (It took me a while to figure out why the Link option wasn’t available)

Is XP the one that is supposed to be more stable.

Please post here any other trouble you have.

I don’t see any difference in stability of Synfig between running on XP or Vista. I just XP on my day-to-day machine.


I’m sorry for send unverified information.

Ok, I’m back with another question.

This time, while experimenting, I tried liking a tangent of a BLine to one of the points. I expected one of the sides of my triangle to always be straight since the tangent points to another one of the points. Instead, I get a rather strange drawing that is somewhat larger than the original (the 2nd picture is zoomed out).

Does anyone know what exactly happens?

My steps were:

  1. Draw a BLine triangle
  2. Extend and split all tangents
  3. Drag tangent for one vertex on top of another vertex.
  4. Link the tangent and vertex.

Hmm… I haven’t tried it, but I suspect your problem is a relative one.

Tangents are given as offsets from the point they are attached to. i.e. a point at 0,0 with a horizontal tangent with handles at say (-10,0) and (10,0) will have the same tangent offsets as a horizontal tangent to a random point (43,56) - it’ll still be (-10,0) & (10,0), not (33,56) & (53,56).

You’d have to do some math to figure out what the offset would be in relation between the point whose tangent you were wanting to link, and the point you want to link it to.

I can’t tell from your picture, but I suspect you’ve linked the absolute location of the top triangle corner to the relative offset of the tangent.


I just used the selection (Normal) tool for linking. So that’s probably the problem… Though perhaps the UI should support absolute linking.

Yes, linking can be a little non-intuitive. Depending on the order you select the items, you can greatly affect the outcome (connecting point A to point B when you wanted to connect point B to point A for example).

Because of the way tangents are relative to their vertex, they are not easy to link to absolute vertex positions. In the attached file, I’ve converted the locations of vertex 2 & 3 into composite values, exported them, then calculated the position of the tangent of vertex 2 based on the relative locations of vertex 2 & 3. (Please don’t ask why the scale value is 3 to make it work - I suspect it’s something to do with the relation of units used internally to synfig, but my brain’s tired right now)

link.sifz (1.07 KB)

That scalar is 3 because Synfigstudio internally draws the ducks at 1/3 of the real length of the tangent. It is just a question of handling. If the tangent were drawn at full scale they would be much bigger and less readable for edition. Anyway the way the tangents are drawn would not affect the parameter value so if there is need to scale by 3 the tangent values it seems that there is a bug there (duck representation is affecting tangent parameter value what’s not good).

Good point. I hadn’t realized they were intentionally scaled by 3, but it makes sense when it doesn’t matter… I was just trying to line them up so they matched the desired effect.