1import three; 2import math; 3texpreamble("\usepackage{bm}"); 4 5size(300,0); 6 7pen thickp=linewidth(0.5mm); 8real radius=0.8, lambda=37, aux=60; 9 10currentprojection=perspective(4,1,2); 11 12// Planes 13pen bg=gray(0.9)+opacity(0.5); 14draw(surface((1.2,0,0)--(1.2,0,1.2)--(0,0,1.2)--(0,0,0)--cycle),bg); 15draw(surface((0,1.2,0)--(0,1.2,1.2)--(0,0,1.2)--(0,0,0)--cycle),bg); 16draw(surface((1.2,0,0)--(1.2,1.2,0)--(0,1.2,0)--(0,0,0)--cycle),bg); 17 18real r=1.5; 19pen p=rgb(0,0.7,0); 20draw(Label("$x$",1),O--r*X,p,Arrow3); 21draw(Label("$y$",1),O--r*Y,p,Arrow3); 22draw(Label("$z$",1),O--r*Z,p,Arrow3); 23label("$\rm O$",(0,0,0),W); 24 25// Point Q 26triple pQ=radius*dir(lambda,aux); 27draw(O--radius*dir(90,aux),dashed); 28label("$\rm Q$",pQ,N+3*W); 29draw("$\lambda$",arc(O,0.15pQ,0.15*Z),N+0.3E); 30 31// Particle 32triple m=pQ-(0.26,-0.4,0.28); 33real width=5; 34dot("$m$",m,SE,linewidth(width)); 35draw("$\bm{\rho}$",(0,0,0)--m,Arrow3,PenMargin3(0,width)); 36draw("$\bm{r}$",pQ--m,Arrow3,PenMargin3(0,width)); 37 38// Spherical octant 39real r=sqrt(pQ.x^2+pQ.y^2); 40draw(arc((0,0,pQ.z),(r,0,pQ.z),(0,r,pQ.z)),dashed); 41draw(arc(O,radius*Z,radius*dir(90,aux)),dashed); 42draw(arc(O,radius*Z,radius*X),thickp); 43draw(arc(O,radius*Z,radius*Y),thickp); 44draw(arc(O,radius*X,radius*Y),thickp); 45 46// Moving axes 47triple i=dir(90+lambda,aux); 48triple k=unit(pQ); 49triple j=cross(k,i); 50 51draw(Label("$x$",1),pQ--pQ+0.2*i,2W,red,Arrow3); 52draw(Label("$y$",1),pQ--pQ+0.32*j,red,Arrow3); 53draw(Label("$z$",1),pQ--pQ+0.26*k,red,Arrow3); 54 55draw("$\bm{R}$",O--pQ,Arrow3,PenMargin3); 56draw("$\omega\bm{K}$",arc(0.9Z,0.2,90,-120,90,160,CW),1.2N,Arrow3); 57