Free diagramming tool

denori · Post by **denori** » January 2nd, 2010, 4:15 pm

Hi Chris,

My apologies for the problems with the ODB last year. There were server issues.

You can now upload to the ODB.

origamimasterjared · January 2nd, 2010, 9:42 pm

oyster wrote:how can we draw in a accurate way with inkscape in the following cases?
1. angular bisector
2. divide a line into N parts. this line can be not the paper border, not a vertical or horizontal line, so the grid does not help very much
3. to snap on arbitrary line endpoint

This is how I do angle bisectors. It's not Inkscape-specific (I don't use Inkscape), but based on geometric construction.

For dividing a line in n equal parts you can make an n x n grid or just n+1 equally spaced lines that extend along the line:

Your third question is Inkscape-specific, so someone else will have to help you with that. I use Freehand, but these should work universally. Hope that helps!

Jonnycakes · Post by **Jonnycakes** » January 3rd, 2010, 12:01 am

Inkscape doesn't have a built in angle bisector function, unfortunately. There is a counter at the bottom of the screen that shows what angle the line you are drawing is, but if that is not accurate enough, use Jared's method.

Inkscape can divide a line into parts by adding nodes, as long as it is a binary (power of 2) division. Select the "nodes" tool (N) and select the endpoints of the line segment you want to bisect. Then use the "add nodes" tool (insert) to add nodes to the segment.

To snap to an arbitrary line endpoint, use Inkscape's snapping feature. Go to "File>Document Properties" (Ctrl+Shift+D) and go to the snapping tab. In .46 you can operate everything from there. In version .47 things changed, and all snapping operations are done from the toolbar at the top of your screen. I am a little shaky about the snapping functions in .47, but selecting "snap to objects" and "snap to cusp nodes" will enable snapping to an arbitrary line endpoint. The snap function also handles snapping to paths, guides, path intersections (.47 only) and other things.

Good luck!

topsu · Post by **topsu** » January 3rd, 2010, 2:38 pm

All the 'basic' angles can be found by clicking file > inkscape preferences > steps , and then choosing the angle from the list found there, and pressing ctrl while drawing a line. Very easy to use, especially if the design mainly uses specific angles like 22.5 or 30.

EDIT: seems like that's not what you were asking exactly, but it's very useful.

oyster · Post by **oyster** » January 3rd, 2010, 5:00 pm

thank you everyone for give me hints for my inkscape question

I used hycad ( http://www.drawease.com/ ) before, which is a acad alike but small and cheap, however it can't export pdf, and the dxf/wmf from it is too bad

Jonnycakes · Post by **Jonnycakes** » January 3rd, 2010, 10:40 pm

topsu wrote:All the 'basic' angles can be found by clicking file > inkscape preferences > steps , and then choosing the angle from the list found there, and pressing ctrl while drawing a line. Very easy to use, especially if the design mainly uses specific angles like 22.5 or 30.

EDIT: seems like that's not what you were asking exactly, but it's very useful.

That is a very, very useful tool, but it only goes to increments of .5 degrees and often that doesn't quite work (11.25 degrees, etc.).

kehom · Post by **kehom** » January 4th, 2010, 2:46 am

Jonnycakes wrote:That is a very, very useful tool, but it only goes to increments of .5 degrees and often that doesn't quite work (11.25 degrees, etc.).

That's bizarre. I did rotate a diagonal line by exactly 11.25.
I just "Ctrl+Shift+M" (Object->Transform) then selected the "Rotate" tab and... well, the rest is self explanatory.

The only complain that I have with Inkscape is the way the Start/End/Middle markers and line patterns are displayed.

Jonnycakes · Post by **Jonnycakes** » January 4th, 2010, 10:20 pm

With the transform tool you can rotate lines by other angles, but what I mean is that with the basic angle snapping function (hold Ctrl as you draw a line) can only be set to multiples of .5 degrees.

kehom · Post by **kehom** » January 5th, 2010, 1:30 am

Ahh, ok, yes, that's right!
Well, in any way, you can change the grid size (Ctrl+Shift+D -> Grids tab -> set smaller X and Y spacing) and when you have a good zoom, you will have a different Grid Snapping angle, smaller than 0.5.

The angle snapping (Ctrl), well... I really don't know if there is any setting that makes better granularity.

ahudson · Post by **ahudson** » January 5th, 2010, 5:01 am

Using grid snapping to do angles won't work very well, I'm afraid-- a lot of angle bisectors (even simple ones like 22.5º) have an irrational slope, and won't ever hit any grid points. I find the most useful way is to zoom in and edit the nodes by hand, instead of relying on grid snapping. This also means you can fine-tune your lines to look better in context (sometimes you WANT certain points to be a little off, for example if you're trying to show that several layers meet at a point)

For angle bisectors I just eyeball it-- it's not perfect, but in most situations it's more than good enough.

kehom · Post by **kehom** » January 5th, 2010, 2:23 pm

I know grid snapping is not good enough. I use that just as a helper. But when I need different angles I do use the Transform tool, as I mentioned before.
For angle bisectors, I usually try to know the value of the angle in which I'm bisecting. After that, I just use the transform tool.
As for showing different layers, I do the distortion by creating more lines a little off from the ones in front. Those "in front layers" I usually try to do as perfect as possible. Of course, they are often off by some bits. But, hard to see on computer screen and even harder when printed!

The point here is: Inkscape is free and very powerful!

newbpcpfolder · Post by **newbpcpfolder** » August 24th, 2010, 3:36 pm

ahudson wrote:I've never seen anyone successfully use a raster graphics program to make good diagrams.

I've successfully diagrammed using MS-Paint, a raster editor program

Post by **origami_8** » August 24th, 2010, 8:27 pm

Paint is the worst imaginable program for diagramming, even MS Word is better not to speak about vector graphic programs.

newbpcpfolder · Post by **newbpcpfolder** » August 25th, 2010, 3:25 am

But Petr Stuchlý's Diagrams are all made in Paint.And 2 of them even got accepted into OUSA 09 and OUSA 10!

Post by **origami_8** » August 25th, 2010, 5:14 am

Of course you "can" draw diagrams with paint, it's just a hell lot more work than with a vector graphic program. In a vector graphic program deleting single lines or objects afterwards doesn't mean to painfully erase them pixel by pixel trying not to touch the other lines you've already drawn, just click on the object you want removed and hit "del" on your keyboard. There are tools to force lines on specific angles. You can copy and rearrange objects, cut them on lines and so on. Working with Freehand I usually start with a square object as my paper, fill in the folding lines, then cut the square along those lines and rearrange the individual parts as I need them, just as they would be arranged in a real piece of paper.This way it is easier to keep proportions as they are. You can choose from different line styles including dashed and dotted lines. Working with layers is very useful for Origami diagrams. It's as if you had all those elements as cut out objects on your table and could arrange them behind each other as you need them leaving some completely some only partly visible.
There are several more reasons why a vector graphic program is way better than a raster graphic program and paint especially has absolutely no tools to make diagramming easy. Just try out Inkscape and you will see the differences. You may also want to try diagramming in MS-Word if you have it, but it isn't thought as drawing software so especially in the newer versions you will encounter a lot of unnecessary mouse movements to get back to the drawing dialogues.