tikz-pgf
I'm pretty new to Tikz. How can I draw the below graph in Tikz?
I will break up my questions into small pieces.
Any help is much appreciated!
The cloud and the cylinder are in the shape libraries. See Sections 48.3 and 48.4 of the TikZ 2.10 manual.
The document collection shape you'll have to put together yourself, though. You can super-impose rectangles and then a tape shape on top of that.
Not a timely reply, but in case it's helpful to posterity, the code below uses fewer ePiX internals:
The strategy is to plot the surface first, then to overlay the vectors manually; vec_field() draws individual arrows, draw_surface() does the overlaying. The scene is manually chopped into three blocks to fine-tune the hidden object removal (see comments).
The vector field is specified by my_F(), and may be changed as needed. The return value should be a periodic, pair-valued function of u and v.
Andy
/* -*-ePiX-*- */
#include "epix.h"
using namespace ePiX;
const double MAX(2); // outside radius of torus
const int N1(40); // longitudes
const int N2(20); // latitudes
const double r0(0.95); // minor radius
const double R0(MAX - r0); // major radius
domain dom(P(0, 0), P(360, 360), mesh(N1, N2), mesh(3*N1, 3*N2));
// torus parametrization
P Phi(double u, double v)
{
double rad(R0 + r0*Cos(v));
return P(rad*Cos(u), rad*Sin(u), r0*Sin(v));
}
// vector field to plot (in plane coordinates)
P my_F(double u, double v)
{
P loc(Phi(u, v));
double x(loc.x1()), y(loc.x2()), z(loc.x3());
return 0.05*P((x - y)*(x + y), 2*x*y); // adjust as desired
}
// auxiliary mappings
// partial derivatives (manually computed)
P Phi_u(double u, double v)
{
double rad(R0 + r0*Cos(v));
return P(-rad*Sin(u), rad*Cos(u), 0);
}
P Phi_v(double u, double v)
{
return P(-r0*Cos(u)*Sin(v), -r0*Sin(u)*Sin(v), r0*Cos(v));
}
// draw vector if surface element faces camera
const double du(360/N1);
const double dv(360/N2);
void vec_field(double u, double v)
{
double u1(u + 0.5*du), v1(v + 0.5*dv); // middle of mesh element
P loc(Phi(u1, v1)),
Xu(Phi_u(u1, v1)), Xv(Phi_v(u1, v1)), dir(Xu*Xv); // cross product
if (0 < ((camera.viewpt() - loc)|dir))
{
P tmp(my_F(u1, v1)), // vector field in coordinates
vec(tmp.x1()*Xu + tmp.x2()*Xv); // field in R^3
dart(loc, loc + vec);
}
}
// will chop scene manually; group repeated drawing commands
void draw_surface()
{
pen(White(), 0);
surface(Phi, dom, -1); // cull back-facing elements
plain(Black());
for (int i = 0; i < 2*N1; ++i)
for (int j = 0; j < 2*N2; ++j)
vec_field(0.5*i*du, 0.5*j*dv);
}
int main()
{
picture(P(-3, -2.5),P(3, 2.5), "12x10cm");
begin();
degrees();
camera.at(sph(10, 80, 30));
P O(0, 0, 0), // origin
back(-MAX, -MAX, -MAX); // back corner
// axes and labels
arrow(back, back + (2*MAX + 1)*E_1);
label(back + (2*MAX + 1)*E_1, P(-4, 0), "$x$", l);
arrow(back, back + (2*MAX + 1)*E_2);
label(back + (2*MAX + 1)*E_2, P(0, -4), "$y$", b);
arrow(back, back + (2*MAX + 1)*E_3);
label(back + (2*MAX + 1)*E_3, P(0, 4), "$z$", t);
label_mask(White());
axis aX(P(-MAX, MAX, -MAX), P( MAX, MAX, -MAX), 2*MAX, P(0, -4), b);
axis aY(P( MAX, -MAX, -MAX), P( MAX, MAX - 1, -MAX), 2*MAX - 1, P(-2, 0), l);
axis aZ(P(-MAX, MAX, -MAX + 1), P(-MAX, MAX, MAX), 2*MAX - 1, P(0, -2), br);
aX.draw_labels();
aY.draw_labels();
aZ.draw_labels();
// background grids
black(0.5);
grid(P(-MAX, -MAX, -MAX), P(MAX, MAX, -MAX), 2*MAX, 2*MAX);
grid(P(-MAX, -MAX, -MAX), P(MAX, -MAX, MAX), 2*MAX, 2*MAX);
grid(P(-MAX, -MAX, -MAX), P(-MAX, MAX, MAX), 2*MAX, 2*MAX);
black();
fill(White());
// manually chop the scene
clip_face(O, -E_3); // bottom half
draw_surface();
clip_restore();
clip_face(O, E_3); // top back quarter
clip_face(O, -E_2);
draw_surface();
clip_restore();
clip_face(O, E_3); // top front quarter
clip_face(O, E_2);
draw_surface();
clip_restore();
tikz_format();
end();
}
Best Answer
This is too complicated for a comment. It is based on Gregor Perčič's solution.
First, you can simplify drawing rectangles. Second, using a scope you can move a group of objects around using the shift key, and create a node (more or less) using the local bounding box key.