# I need free drawing software for 2D designs

Discussion in 'Computer Science & Culture' started by Billy T, Mar 12, 2012.

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1. ### Billy TUse Sugar Cane Alcohol car FuelValued Senior Member

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I downloaded Google´s free 3D SketchUp8, and it seems to be fantastic, but would take months of learning to use. My needs are for a simple to use, free 2D program that I can use to make line segments and arcs of curves. I spent several hours trying to find one. Any suggestions?

The ideal program would use an XY coordinate system and to draw a line segment; I would just imput the (x,y) of the start and finish points. For arc I would also just give the two end points, and some simple indication of the radius of curvature OR better still would be a third point on the arc the circle passes thru. Normally it would be a point on the perpendicular line bisecting the line between those two points as that would let me easily specify the diameter of the arc´s circle also.

I.e. I happen to know that (C/2)^2 = (D-x)x where C is the length of the cord between the arc´s two end points and x is the displacement of that "third point" from the cord, and D is the diameter of the circle of the cord.

Think even the old MS Paint program might serve my needs, but could not find a free download of it. I would rather have a program with more mathematical inputs like I mentioned above for arcs & line segments. (Give xy coordinates, not try to drag a pointer, as my design will need to be mathematically exact so the various parts will fit perfectly together.)

Google´s SketchUp does, on quick inspection, seem to use coordinate inputs, so if no one can help me find what I want, I plan to suggest they offer a 2D only simple version of sketchUp for people like me who only want to make simple 2D designs in a coordinate grid, not skyscrapers you can virtually walk thru.

BTW, if you are young, needing money, I bet you could earn some if you did become good with SketchUp8. I think it allows you to make a 3D building in detail and then insert it into Google Earth, as if it really existed there. I.e. your paying customer could virtually look out of the 7th floor window of the virtual building you made for him to see if the near by real building blocked his view of the sea, etc. In a decade or so, we will have trouble knowing what is real and what is virtual in the "real world." Too bad virtual food will not feed the hungry.

Last edited by a moderator: Mar 12, 2012

3. ### przyksquishyValued Senior Member

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Some I know of that might fit the bill: Dia, Inkscape, xfig, Gimp.

If you don't mind writing code and having the image generated by a compiler: Metapost. There's also PGF/TikZ if you're using LaTeX. These two systems will certainly let you use formulae.

5. ### Billy TUse Sugar Cane Alcohol car FuelValued Senior Member

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Thanks. Which do you recommend and do you know the download link? - (I am terrible at searching - I use my vast memory instead.)

I don´t do LaTex, but several times I have been tempted to learn instead of writing out "pi" and "square root of (xxx)" etc.

PS I´m still open to suggestions from others or your ideas as to which of PRZYK´s best serves my "math inputs" (xy coordinate specifications) desires for making lines and arcs.

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7. ### Crunchy CatF-in' *meow* baby!!!Valued Senior Member

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Paint.NET may have what you are looking for.

8. ### przyksquishyValued Senior Member

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The best way to get this software depends on the operating system you're using. If you're using Linux or Mac OS X with a Linux or BSD-like software repository (Homebrew, Fink, MacPorts, Gentoo Prefix) then they're probably available from the repository. For Windows, as usual you go to the project's website and download the installer.

Dia is available here: https://live.gnome.org/Dia
Inkscape is available here: http://inkscape.org/

These both have Windows versions, so in both cases just follow the download links for them. Xfig and GIMP don't have standalone Windows versions available, but for reference here's their project homepages anyway. I expect the difficulty is that they both depend on the X Window system. They may be available for Windows via Cygwin though.

Xfig: http://www.xfig.org/
GIMP: http://www.gimp.org/

Of these, GIMP is a general purpose image manipulation program. Dia, Inkscape, and Xfig are more intended for scientific and technical diagrams. I've used Dia and know it has features like "snap to grid" that are useful for this (as well as being generally easy and intuitive to learn and use). I imagine the others do to. I know colleagues who use Inkscape for their diagrams. These are all graphical ("point and click") utilities and I don't know if any of them will let you input coordinates or formulae, but they're all hands down better for scientific and technical diagrams than MS Paint.

If you're relying on heavy use of coordinates and formulae then your best options might be the likes of MetaPost or PGF/TikZ. Probably the best way to get either of these is as part of a TeX distribution (eg. MiKTeX for Windows). MetaPost is a standalone program that you can use independently of TeX: you feed it a source file in text form that describes the diagram you want, and it outputs a PostScript file with your image in it (which you can then convert to other formats if PostScript isn't what you want). PGF/TikZ is similar but the code is typed directly into a TeX document. If you like the look of it though you can still use PGF/TikZ to generate isolated images in a roundabout way, by putting the code in an otherwise empty LaTeX document and using the LaTeX Preview package to isolate it. I'm pretty sure these and other similar source-based diagram generators will let you generate curves via formulae.

As I said MetaPost and PGF/TikZ are best obtained as part of a TeX distribution, but their homepages are still useful for documentation:

MetaPost: http://www.tug.org/metapost.html
PGF/TikZ: http://sourceforge.net/projects/pgf/

MetaPost's Wikipedia page is a quick way to get a code example and a few screenshots.

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10. ### Billy TUse Sugar Cane Alcohol car FuelValued Senior Member

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Thanks to all. Spidergoat´s is a 3D program. I only need 2D. Also I will only be using line segments (two end points input I hope) and arc of circles (two end points and distance of third point, or its coordinates, on perpendicular bi-sector of that chord, I hope).

"snap to grid" would destroy the exact mathematical fit of the complex parts I would draw. I would not input any formulae into the program, but would "pre-compute" outside of the program the coordinates of the "third point" of the arcs (with the simple equation I gave in prior post)

przyk: Are any of your suggestions for 2 D only or with "z-axis" sticking straight out of the paper, so easy to ignore? My operating system is XP, professional.

Last edited by a moderator: Mar 12, 2012
11. ### spidergoatLiddle' Dick TaterValued Senior Member

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Virtually all 3D programs support 2D tools for drawing. You can also turn off the snap to grid. I haven't actually used wings3D for making stuff, but it is free. Also Rhino has a free trial period with I think 20 saves allowed without a license.

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13. ### Billy TUse Sugar Cane Alcohol car FuelValued Senior Member

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My interest / bias for 2D only is related to the time required to learn how to use.

I only spent 30 minutes or so looking at SketchUp8 after download of it but guessed it would take me a month to learn how to draw my first line segment or arc in the xy plane. That you think it is "easy" impresses me.

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15. ### Billy TUse Sugar Cane Alcohol car FuelValued Senior Member

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I looked briefly at their web page. This made me want to look more when I have time:

"... DoubleCAD XT is a full-powered 2D CAD application — one that you already know how to use — and is free with none of the usual limitations:

We're not constraining printing, saving, file sizes... we're not including untimely time-outs... we're not even constraining the software license — our free DoubleCAD XT can be used for unlimited personal and commercial use. ..."

Thanks for this suggestion. You use AutoCad and they claim to be quite like it. In AutoCad, can you make a line segment by giving (x,y) coordinates of two end points for it? If yes, how do you make an arc? Also with the two end coordinates and some other fact telling center of circle location? OR a third point on the arc?

I will only use straight line segments and parts circle for arcs (no ellipses, etc) as want pieces to be cheap to make with standard machine tools. (Probably only a milling machine with rotating table on the bed holding the piece being cut. If I still had access to the small shop I used as a graduate student, I could make it myself. At least from those days, I know what adds cost and what is cheap to do.)

Last edited by a moderator: Mar 13, 2012
16. ### spidergoatLiddle' Dick TaterValued Senior Member

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Send me your requirements, and I'll do it for you.

17. ### Pincho PaxtonBannedBanned

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Well Autocad is used for making milling drawings, you can make arcs and everything else, you can add trigonometry to the angles. So the link I posted should be similar. You can use the centre of a circle to create arcs, you can probably click on a line also to create arcs (it has been 16 years since I used it). I'm sure it must come with a manual.

Last edited: Mar 13, 2012
18. ### przyksquishyValued Senior Member

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They're all 2D applications.

19. ### Billy TUse Sugar Cane Alcohol car FuelValued Senior Member

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Thanks, but I need to consider minor variations in the shape before selecting final design. Also I may seek patent protection - probably a design pattent.

I "invented" a "flat tank" for compressed gas fuel, but found engineers at Thycole Corp had same basic idea and it was already well protected by pattents in several countries. I think I now have a cheaper way to make it via extrusions that fit together. Their tank has complex machining required, I think.

20. ### spidergoatLiddle' Dick TaterValued Senior Member

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Sounds interesting.

21. ### NasorValued Senior Member

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Remember, a design patent will only protect *non-functional* aspects of the design...

22. ### PandaemoniValued Senior Member

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If your tank design is functionally better than theirs, I agree that a design patent may not be what you want. Thycole could take your design, make it look cosmetically different, and there would be little you could do.

Also remember that competing patents (unless they were drafted poorly) probably cover more than just the invention as they have manufactured it, but a variations on the same general idea. If you idea for the redesigned tank is sufficiently novel to qualify for its own utility patent, it might still be allowed, but expect Thycole to oppose it. It also sounds like you may need to get a license of their patented work to use your tank (though your tank may have uses independent of their patents).

23. ### Billy TUse Sugar Cane Alcohol car FuelValued Senior Member

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To Pandaemoni & Nasor:

Thanks. Yes, I need to learn just how much protection is possible with a "design patent." Clearly it is useless if a minor modification gets around it. My current hope is that it can cover a general shape and fit together concept, even if many minor changes in the dimensions or details are made. -Sort of a "Topological design patent" if that is possible, not one specific set of dimensions.

In some ways it is more for the fun of creation than the hope for profit that motivates me. I have more than enough money but it would be nice (I think, but am not sure) to leave more to my heirs. (Not sure - as inherting too much can be very destructive of what I consider to be the productive life they should lead. - I never paid a dime for my education, so am treating Cornell as one of my heirs.)

If I were a big corporation with staff of patent lawyers, I might go head to head with Thycole because my "flat tank" is significantly different from theirs, and better, I think. They have some serious abrupt stress direction changes that I avoid so think I can hold gas at higher pressure with same volume and weight of tank.

When I worked at APL/JHU, in the space Department, I had a very minor role in the invention of an inplantable, rechargeable pacemaker (which was later sold by MedTronics). There is an amazing overlap in the requirements for it and space craft as both need: light weight, small, high reliability circuits with great manufacturing quality control, remote command of operations, to resist unusual enviroment that is trying to destroy item, high energy efficiency, and a few other considerations.

The patent APL got was only a design patent - basically on the shape of the case! but there was some importance to that as the RF energy it was weekly recharged with had to pass thru the case. Later, compact batteries and much lower energy requirement in electronics improved so much that the battery powered pacer would last several years and recharge was dropped.

When the truth is told, the doctors wanted the fees they got every few years for the minor abdominal surgery* needed to replace the battery and did not like that the rechargeable system would have 98% probablility of outliving the patient with no more surgery required. BTW, when a pacer did fail, 99.9% of the time it was the cable, which flexes with every beat of the heart.

The US has a profit based medical system, not one where doctors are on salary, and it shows up as more than double the medical costs with about 2 to 3 years lower life expectancy than the European systems. (No insurance companies taking a profit cut and government buying huge volumes of drugs with competitive bids instead of individual drug store chains buying are also significant reasons why the cost is less than half.)

* Pacers are implanted in the abdome with only a cable going up to the heart.

Last edited by a moderator: Mar 16, 2012