in some applications, one wants to use ellipses as node shapes in figures, e.g., when in the literature on a subject typically uses ellipses to denote certain things in figures. The problems with normal ellipses is that they often waste a lot of space:
When a figure is already very wide, then the large "end caps" at the left and right ends of the ellipse can be very annoying, as they consume some space. It would be nice if there was another node shape type that is still round, but more space saving. With flatter end caps, an ellipse around some text can have some lower width:
The first of these ellipses is still a normal one, but the other ones are "morphed" a bit. They are still recognizable as ellipses, though (although they strictly speaking aren't).
The process of building custom node shapes for this is a bit over my head, especially since the math that would be involved for computing the correct boundaries for some node context is probably complicated to do in Tikz.
Here is the Python code that I used for constructing these examples: one can see that using an exponential function does the trick. But for using the node shape in practice, it's probably a bit more important to have the functionality of drawing such shapes in LaTeX itself.
#!/usr/bin/python
import math
def moreimpact(x,base):
if x<0:
return -math.pow(-x,base)
else:
return math.pow(x,base)
print "\\documentclass{article}"
print "\\usepackage{tikz}"
print "\\usetikzlibrary{shapes}"
print "\\begin{document}"
print "\\begin{tikzpicture}"
print "\\node[draw,shape=ellipse,inner sep=1pt] (f1) at (0,2) {This is a long text that leads to a very large ellipse};"
for j in xrange(0,4):
print "\\draw",
for i in xrange(0,360):
if i!=0:
print " -- ",
xpos = math.cos(i/180.0*math.pi)
ypos = math.sin(i/180.0*math.pi)
print "(%f,%f)" % (5*moreimpact(xpos,1.0-0.1*j),0.3*moreimpact(ypos,1.0-0.1*j)-j*1.2),
print " -- cycle;"
print "\\end{tikzpicture}"
print "\\end{document}"
Does anyone know how to define a new node shape for such a "compressed ellipse" or something similar in TikZ (optimally parametrized by what I called "impact" in the code above)? The answer is probably helpful for many people, as I think that this node shape is quite useful in situations in which there is little space for a figure (e.g., presentations), and rectangles or rectangles with rounded corners are already taken for denoting something different.
EDIT: Qrrbrbirlbel provided a link to a post about a "superellipse", which contains some code for a new TikZ node shape called "superellipse". This is precisely what has been asked for. It's just a pity that the size computation doesn't really work:
\node[shape=superellipse,superellipse parameter=3] at (2,3) {This is a long text that leads to a very large ellipse};
This can be worked around by adding negative spaces, but it's just a workaround.
rounded rectangleshape from theshapes.misclibrary (not exactly ellipses but it can be customized very detailed). Or the superellipse?inner xsepsetting, so rather than using negative spaces, you could do:\node[thick, shape=superellipse,superellipse parameter=3, inner xsep=-10mm] at (2,3) {This is a long text that leads to a very fitted node};