From: Kevin Wixson <kevin@wi...>  20050608 17:52:05

Inkscape Artists, I'm giving a presentation on Inkscape at my local LUG on the 21st, and I need some really outstanding examples of work done in Inkscape so I can really wow them. I've looked at the Wiki page and will be linking to some of the work I found there, but I really need some more examples I can actually put in my OOo Impress presentation, which will subsequently be published on the LUG's web site. I'm interested in receiving examples of your best work of any variety, short bio information (with hyperlink, if applicable), and copyright licensing details, so that I can use them as I've described. Please send to examples@... . Also, I would sincerely appreciate an SVG drawing of the Bezier curve mathematical formula. It's for use in the same, but may have other applications as well. Thank you very much. Kevin Wixson 
From: <mental@ry...>  20050608 18:11:18

Quoting Kevin Wixson <kevin@...>: > Also, I would sincerely appreciate an SVG drawing of the Bezier > curve mathematical formula. It's for use in the same, but may have > other applications as well. Could you elaborate on what you need? There are several different ways of expressing it. What aspects do you want the illustration to highlight? mental 
From: Kevin Wixson <kevin@wi...>  20050608 20:53:22

mental@... wrote: >Quoting Kevin Wixson <kevin@...>: > > > >>Also, I would sincerely appreciate an SVG drawing of the Bezier >>curve mathematical formula. It's for use in the same, but may have >>other applications as well. >> >> > >Could you elaborate on what you need? There are several different >ways of expressing it. What aspects do you want the illustration >to highlight? > >mental > > Well, I'd like to show a representational sample of material with everything from simple icons to elaborate, near photo realistic illustrations. I would like to demonstrate the breadth of utility of the application as well as the possible complexity of illustrations created with Inkscape. So, there will be some icons shown, some clipart (from openclipart.org), some abstract "wallpaper" gradient laden kind of stuff, some "cartoon" quality drawings, and hopefully some fully developed artistic compositions of representational art. The presentation should show a sampling of the many various purposes to which people put Inkscape to use. It's the last one that I think I might come up short on, so I'm probably most especially interested in complete, nonabstract, illustrations that seem like something you'd see up in an art gallery. Thanks for your interest and help. PS.. Some people have also asked for clarification about the drawing of the Bezier curve formula I'm requesting. What I'm actually interested in is the representation I saw when my college instructor drew it on the board. It had a big Greek symbol in it with vector symbols (the arrows) and bits above and below and I'm not sure what all else, but it's something that isn't done with the normal ASCII characters in a row. I don't precisely know what it's made up of or how to describe it or else I certainly would have made it by myself. But since I don't know how, I'm asking for help. Kevin 
From: <mental@ry...>  20050608 22:16:49

Quoting Kevin Wixson <kevin@...>: > PS.. Some people have also asked for clarification about the > drawing of the Bezier curve formula I'm requesting. What I'm > actually interested in is the representation I saw when my > college instructor drew it on the board. It had a big Greek > symbol in it with vector symbols (the arrows) and bits above > and below and I'm not sure what all else, but it's something > that isn't done with the normal ASCII characters in a row. > I don't precisely know what it's made up of or how to describe > it or else I certainly would have made it by myself. But since > I don't know how, I'm asking for help. Hmm. I'm not sure how to depict this. If you have something handy to render TeX, this TeX fragment will render the general form of the parametric bezier curve function: B(t) =3D \sum_{k=3D0}^N {P_k}{N! \over k!(N  k)!}{t^k}(1  t)^{Nk} N is one less than the number of control points; the control points are named P_0 through P_N, and t is the position along the curve (ranging from 0.0 through 1.0). That's the ultrageneric form, though. In Inkscape, we pretty much only deal with cubic beziers (four control points), which means N=3D3. With N=3D3, the above simplifies to: B(t) =3D {P_0}(1  t)^3 + {P_1}3{t}(1  t)^2 + {P_2}3{t^2}(1  t) + {P_3}{t^3} In practical graphics programming, this is often reformulated as a simple cubic equation with appropriate coefficients: \begin{matrix} B(t) & =3D & {C_2}t^3 + {C_1}t^2 + {C_0}t + P_0 \mbox{ where} \\ \quad C_0 & =3D & 3(P_1  P_0) \\ \quad C_1 & =3D & 3(P_2  P_1)  C_0 \\ \quad C_2 & =3D & P_3  P_0  C_0  C_1 \end{matrix} (mathheads will have to forgive my clumsy TeX; this is not my field) This last one isn't as sexy looking, but it's what we actually use, more or less. The first and last of the four control points correspond to path nodes, and the second and third correspond to control handles. Multinode curves actually just place these cubic curves endtoend so they share starting and ending points. You may also be interested in De Casteljau's algorithm, which is what makes Beziers so convenient for computers to work with. It also looks cool when illustrated graphically. (De Casteljau basically just means that you can pick an arbitrary t  0.5 is typical  and subdivide the bezier at that point to produce two smaller, flatter curves of the same degree which fit together to make the original curve. Do this enough times and you can just draw the flattish beziers as straight line segments. Very easy way for computers to draw them. The algorithm has other handy uses too.) (Actually, you can see De Casteljau in action by selecting two adjacent nodes in Inkscape and hitting the "insert node" button repeatedly to subdivide. It's the algorithm used to find those subdivisions.) I probably won't have time to do up SVG versions of these myself, so if someone else wants to take a stab at it, they're welcome to do so... mental 
From: <ted@go...>  20050608 18:19:08

On Wed, 8 Jun 2005, Kevin Wixson wrote: > I'm giving a presentation on Inkscape at my local LUG on the 21st, and I > need some really outstanding examples of work done in Inkscape so I can > really wow them. I've looked at the Wiki page and will be linking to > some of the work I found there, but I really need some more examples I > can actually put in my OOo Impress presentation, which will subsequently > be published on the LUG's web site. Well, it's not art, but you're welcome to use any elements of presentations that I've done on/with Inkscape. (I keep meaning to get them in CVS, I will someday) Anway, the most recent is here: http://gould.cx/ted/presentations/scale/ http://gould.cx/ted/presentations/scale/inkscapescalepres.tar.gz Here is the math that I use to describe Bezier Curves: http://gould.cx/ted/presentations/asu/index.php?slide=13 Though, I find the pictures before that help people alot more. I just include the math because otherwise someone asks, and it is nearly impossible to explain without a slide. I go over it quickly though. Ted 