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+// Three-dimensional graphing routines
+
+private import math;
+import graph;
+import three;
+
+triple zero3(real) {return O;}
+
+typedef triple direction3(real);
+direction3 Dir(triple dir) {return new triple(real) {return dir;};}
+
+ticklocate ticklocate(real a, real b, autoscaleT S=defaultS,
+ real tickmin=-infinity, real tickmax=infinity,
+ real time(real)=null, direction3 dir)
+{
+ if((valuetime) time == null) time=linear(S.T(),a,b);
+ ticklocate locate;
+ locate.a=a;
+ locate.b=b;
+ locate.S=S.copy();
+ if(finite(tickmin)) locate.S.tickMin=tickmin;
+ if(finite(tickmax)) locate.S.tickMax=tickmax;
+ locate.time=time;
+ locate.dir=zero;
+ locate.dir3=dir;
+ return locate;
+}
+
+private struct locateT {
+ real t; // tick location time
+ triple V; // tick location in frame coordinates
+ triple pathdir; // path direction in frame coordinates
+ triple dir; // tick direction in frame coordinates
+
+ void dir(transform3 T, path3 g, ticklocate locate, real t) {
+ pathdir=unit(shiftless(T)*dir(g,t));
+ triple Dir=locate.dir3(t);
+ dir=unit(Dir);
+ }
+ // Locate the desired position of a tick along a path.
+ void calc(transform3 T, path3 g, ticklocate locate, real val) {
+ t=locate.time(val);
+ V=T*point(g,t);
+ dir(T,g,locate,t);
+ }
+}
+
+void drawtick(picture pic, transform3 T, path3 g, path3 g2,
+ ticklocate locate, real val, real Size, int sign, pen p,
+ bool extend)
+{
+ locateT locate1,locate2;
+ locate1.calc(T,g,locate,val);
+ path3 G;
+ if(extend && size(g2) > 0) {
+ locate2.calc(T,g2,locate,val);
+ G=locate1.V--locate2.V;
+ } else
+ G=(sign == 0) ?
+ locate1.V-Size*locate1.dir--locate1.V+Size*locate1.dir :
+ locate1.V--locate1.V+Size*sign*locate1.dir;
+ draw(pic,G,p,name="tick");
+}
+
+triple ticklabelshift(triple align, pen p=currentpen)
+{
+ return 0.25*unit(align)*labelmargin(p);
+}
+
+// Signature of routines that draw labelled paths with ticks and tick labels.
+typedef void ticks3(picture, transform3, Label, path3, path3, pen,
+ arrowbar3, margin3, ticklocate, int[], bool opposite=false,
+ bool primary=true);
+
+// Label a tick on a frame.
+void labeltick(picture pic, transform3 T, path3 g,
+ ticklocate locate, real val, int sign, real Size,
+ ticklabel ticklabel, Label F, real norm=0)
+{
+ locateT locate1;
+ locate1.calc(T,g,locate,val);
+ triple align=F.align.dir3;
+ if(align == O) align=sign*locate1.dir;
+
+ triple shift=align*labelmargin(F.p);
+ if(dot(align,sign*locate1.dir) >= 0)
+ shift=sign*(Size)*locate1.dir;
+
+ real label;
+ if(locate.S.scale.logarithmic)
+ label=locate.S.scale.Tinv(val);
+ else {
+ label=val;
+ if(abs(label) < zerotickfuzz*norm) label=0;
+ // Fix epsilon errors at +/-1e-4
+ // default format changes to scientific notation here
+ if(abs(abs(label)-1e-4) < epsilon) label=sgn(label)*1e-4;
+ }
+
+ string s=ticklabel(label);
+ triple v=locate1.V+shift;
+ if(s != "")
+ label(pic,F.defaulttransform3 ? baseline(s,baselinetemplate) : F.T3*s,v,
+ align,F.p);
+}
+
+// Add axis label L to frame f.
+void labelaxis(picture pic, transform3 T, Label L, path3 g,
+ ticklocate locate=null, int sign=1, bool ticklabels=false)
+{
+ triple m=pic.min(identity4);
+ triple M=pic.max(identity4);
+ triple align=L.align.dir3;
+ Label L=L.copy();
+
+ pic.add(new void(frame f, transform3 T, picture pic2, projection P) {
+ path3 g=T*g;
+ real t=relative(L,g);
+ triple v=point(g,t);
+ picture F;
+ if(L.align.dir3 == O)
+ align=unit(invert(L.align.dir,v,P))*abs(L.align.dir);
+
+ if(ticklabels && locate != null && piecewisestraight(g)) {
+ locateT locate1;
+ locate1.dir(T,g,locate,t);
+ triple pathdir=locate1.pathdir;
+
+ triple perp=cross(pathdir,P.normal);
+ if(align == O)
+ align=unit(sgn(dot(sign*locate1.dir,perp))*perp);
+ path[] g=project(box(T*m,T*M),P);
+ pair z=project(v,P);
+ pair Ppathdir=project(v+pathdir,P)-z;
+ pair Perp=unit(I*Ppathdir);
+ real angle=degrees(Ppathdir,warn=false);
+ transform S=rotate(-angle,z);
+ path[] G=S*g;
+ pair Palign=project(v+align,P)-z;
+ pair Align=rotate(-angle)*dot(Palign,Perp)*Perp;
+ pair offset=unit(Palign)*
+ abs((Align.y >= 0 ? max(G).y : (Align.y < 0 ? min(G).y : 0))-z.y);
+ triple normal=cross(pathdir,align);
+ if(normal != O) v=invert(z+offset,normal,v,P);
+ }
+
+ label(F,L,v);
+ add(f,F.fit3(identity4,pic2,P));
+ },exact=false);
+
+ path3[] G=path3(texpath(L,bbox=true));
+ if(G.length > 0) {
+ G=L.align.is3D ? align(G,O,align,L.p) : L.T3*G;
+ triple v=point(g,relative(L,g));
+ pic.addBox(v,v,min(G),max(G));
+ }
+}
+
+// Tick construction routine for a user-specified array of tick values.
+ticks3 Ticks3(int sign, Label F="", ticklabel ticklabel=null,
+ bool beginlabel=true, bool endlabel=true,
+ real[] Ticks=new real[], real[] ticks=new real[], int N=1,
+ bool begin=true, bool end=true,
+ real Size=0, real size=0, bool extend=false,
+ pen pTick=nullpen, pen ptick=nullpen)
+{
+ return new void(picture pic, transform3 t, Label L, path3 g, path3 g2, pen p,
+ arrowbar3 arrow, margin3 margin, ticklocate locate,
+ int[] divisor, bool opposite, bool primary) {
+ // Use local copy of context variables:
+ int Sign=opposite ? -1 : 1;
+ int sign=Sign*sign;
+ pen pTick=pTick;
+ pen ptick=ptick;
+ ticklabel ticklabel=ticklabel;
+
+ real Size=Size;
+ real size=size;
+ if(Size == 0) Size=Ticksize;
+ if(size == 0) size=ticksize;
+
+ Label L=L.copy();
+ Label F=F.copy();
+ L.p(p);
+ F.p(p);
+ if(pTick == nullpen) pTick=p;
+ if(ptick == nullpen) ptick=pTick;
+
+ bool ticklabels=false;
+ path3 G=t*g;
+ path3 G2=t*g2;
+
+ scalefcn T;
+
+ real a,b;
+ if(locate.S.scale.logarithmic) {
+ a=locate.S.postscale.Tinv(locate.a);
+ b=locate.S.postscale.Tinv(locate.b);
+ T=locate.S.scale.T;
+ } else {
+ a=locate.S.Tinv(locate.a);
+ b=locate.S.Tinv(locate.b);
+ T=identity;
+ }
+
+ if(a > b) {real temp=a; a=b; b=temp;}
+
+ real norm=max(abs(a),abs(b));
+
+ string format=autoformat(F.s,norm...Ticks);
+ if(F.s == "%") F.s="";
+ if(ticklabel == null) {
+ if(locate.S.scale.logarithmic) {
+ int base=round(locate.S.scale.Tinv(1));
+ ticklabel=format == "%" ? Format("") : DefaultLogFormat(base);
+ } else ticklabel=Format(format);
+ }
+
+ bool labelaxis=L.s != "" && primary;
+
+ begingroup3(pic,"axis");
+
+ if(primary) draw(pic,margin(G,p).g,p,arrow);
+ else draw(pic,G,p);
+
+ for(int i=(begin ? 0 : 1); i < (end ? Ticks.length : Ticks.length-1); ++i) {
+ real val=T(Ticks[i]);
+ if(val >= a && val <= b)
+ drawtick(pic,t,g,g2,locate,val,Size,sign,pTick,extend);
+ }
+ for(int i=0; i < ticks.length; ++i) {
+ real val=T(ticks[i]);
+ if(val >= a && val <= b)
+ drawtick(pic,t,g,g2,locate,val,size,sign,ptick,extend);
+ }
+
+ if(N == 0) N=1;
+ if(Size > 0 && primary) {
+ for(int i=(beginlabel ? 0 : 1);
+ i < (endlabel ? Ticks.length : Ticks.length-1); i += N) {
+ real val=T(Ticks[i]);
+ if(val >= a && val <= b) {
+ ticklabels=true;
+ labeltick(pic,t,g,locate,val,Sign,Size,ticklabel,F,norm);
+ }
+ }
+ }
+ if(labelaxis)
+ labelaxis(pic,t,L,G,locate,Sign,ticklabels);
+
+ endgroup3(pic);
+ };
+}
+
+// Automatic tick construction routine.
+ticks3 Ticks3(int sign, Label F="", ticklabel ticklabel=null,
+ bool beginlabel=true, bool endlabel=true,
+ int N, int n=0, real Step=0, real step=0,
+ bool begin=true, bool end=true, tickmodifier modify=None,
+ real Size=0, real size=0, bool extend=false,
+ pen pTick=nullpen, pen ptick=nullpen)
+{
+ return new void(picture pic, transform3 T, Label L,
+ path3 g, path3 g2, pen p,
+ arrowbar3 arrow, margin3 margin=NoMargin3, ticklocate locate,
+ int[] divisor, bool opposite, bool primary) {
+ path3 G=T*g;
+ real limit=Step == 0 ? axiscoverage*arclength(G) : 0;
+ tickvalues values=modify(generateticks(sign,F,ticklabel,N,n,Step,step,
+ Size,size,identity(),1,
+ project(G,currentprojection),
+ limit,p,locate,divisor,
+ opposite));
+ Ticks3(sign,F,ticklabel,beginlabel,endlabel,values.major,values.minor,
+ values.N,begin,end,Size,size,extend,pTick,ptick)
+ (pic,T,L,g,g2,p,arrow,margin,locate,divisor,opposite,primary);
+ };
+}
+
+ticks3 NoTicks3()
+{
+ return new void(picture pic, transform3 T, Label L, path3 g,
+ path3, pen p, arrowbar3 arrow, margin3 margin,
+ ticklocate, int[], bool opposite, bool primary) {
+ path3 G=T*g;
+ if(primary) draw(pic,margin(G,p).g,p,arrow,margin);
+ else draw(pic,G,p);
+ if(L.s != "" && primary) {
+ Label L=L.copy();
+ L.p(p);
+ labelaxis(pic,T,L,G,opposite ? -1 : 1);
+ }
+ };
+}
+
+ticks3 InTicks(Label format="", ticklabel ticklabel=null,
+ bool beginlabel=true, bool endlabel=true,
+ int N=0, int n=0, real Step=0, real step=0,
+ bool begin=true, bool end=true, tickmodifier modify=None,
+ real Size=0, real size=0, bool extend=false,
+ pen pTick=nullpen, pen ptick=nullpen)
+{
+ return Ticks3(-1,format,ticklabel,beginlabel,endlabel,N,n,Step,step,
+ begin,end,modify,Size,size,extend,pTick,ptick);
+}
+
+ticks3 OutTicks(Label format="", ticklabel ticklabel=null,
+ bool beginlabel=true, bool endlabel=true,
+ int N=0, int n=0, real Step=0, real step=0,
+ bool begin=true, bool end=true, tickmodifier modify=None,
+ real Size=0, real size=0, bool extend=false,
+ pen pTick=nullpen, pen ptick=nullpen)
+{
+ return Ticks3(1,format,ticklabel,beginlabel,endlabel,N,n,Step,step,
+ begin,end,modify,Size,size,extend,pTick,ptick);
+}
+
+ticks3 InOutTicks(Label format="", ticklabel ticklabel=null,
+ bool beginlabel=true, bool endlabel=true,
+ int N=0, int n=0, real Step=0, real step=0,
+ bool begin=true, bool end=true, tickmodifier modify=None,
+ real Size=0, real size=0, bool extend=false,
+ pen pTick=nullpen, pen ptick=nullpen)
+{
+ return Ticks3(0,format,ticklabel,beginlabel,endlabel,N,n,Step,step,
+ begin,end,modify,Size,size,extend,pTick,ptick);
+}
+
+ticks3 InTicks(Label format="", ticklabel ticklabel=null,
+ bool beginlabel=true, bool endlabel=true,
+ real[] Ticks, real[] ticks=new real[],
+ real Size=0, real size=0, bool extend=false,
+ pen pTick=nullpen, pen ptick=nullpen)
+{
+ return Ticks3(-1,format,ticklabel,beginlabel,endlabel,
+ Ticks,ticks,Size,size,extend,pTick,ptick);
+}
+
+ticks3 OutTicks(Label format="", ticklabel ticklabel=null,
+ bool beginlabel=true, bool endlabel=true,
+ real[] Ticks, real[] ticks=new real[],
+ real Size=0, real size=0, bool extend=false,
+ pen pTick=nullpen, pen ptick=nullpen)
+{
+ return Ticks3(1,format,ticklabel,beginlabel,endlabel,
+ Ticks,ticks,Size,size,extend,pTick,ptick);
+}
+
+ticks3 InOutTicks(Label format="", ticklabel ticklabel=null,
+ bool beginlabel=true, bool endlabel=true,
+ real[] Ticks, real[] ticks=new real[],
+ real Size=0, real size=0, bool extend=false,
+ pen pTick=nullpen, pen ptick=nullpen)
+{
+ return Ticks3(0,format,ticklabel,beginlabel,endlabel,
+ Ticks,ticks,Size,size,extend,pTick,ptick);
+}
+
+ticks3 NoTicks3=NoTicks3(),
+InTicks=InTicks(),
+OutTicks=OutTicks(),
+InOutTicks=InOutTicks();
+
+triple tickMin3(picture pic)
+{
+ return minbound(pic.userMin(),(pic.scale.x.tickMin,pic.scale.y.tickMin,
+ pic.scale.z.tickMin));
+}
+
+triple tickMax3(picture pic)
+{
+ return maxbound(pic.userMax(),(pic.scale.x.tickMax,pic.scale.y.tickMax,
+ pic.scale.z.tickMax));
+}
+
+axis Bounds(int type=Both, int type2=Both, triple align=O, bool extend=false)
+{
+ return new void(picture pic, axisT axis) {
+ axis.type=type;
+ axis.type2=type2;
+ axis.position=0.5;
+ axis.align=align;
+ axis.extend=extend;
+ };
+}
+
+axis YZEquals(real y, real z, triple align=O, bool extend=false)
+{
+ return new void(picture pic, axisT axis) {
+ axis.type=Value;
+ axis.type2=Value;
+ axis.value=pic.scale.y.T(y);
+ axis.value2=pic.scale.z.T(z);
+ axis.position=1;
+ axis.align=align;
+ axis.extend=extend;
+ };
+}
+
+axis XZEquals(real x, real z, triple align=O, bool extend=false)
+{
+ return new void(picture pic, axisT axis) {
+ axis.type=Value;
+ axis.type2=Value;
+ axis.value=pic.scale.x.T(x);
+ axis.value2=pic.scale.z.T(z);
+ axis.position=1;
+ axis.align=align;
+ axis.extend=extend;
+ };
+}
+
+axis XYEquals(real x, real y, triple align=O, bool extend=false)
+{
+ return new void(picture pic, axisT axis) {
+ axis.type=Value;
+ axis.type2=Value;
+ axis.value=pic.scale.x.T(x);
+ axis.value2=pic.scale.y.T(y);
+ axis.position=1;
+ axis.align=align;
+ axis.extend=extend;
+ };
+}
+
+axis YZZero(triple align=O, bool extend=false)
+{
+ return new void(picture pic, axisT axis) {
+ axis.type=Value;
+ axis.type2=Value;
+ axis.value=pic.scale.y.T(pic.scale.y.scale.logarithmic ? 1 : 0);
+ axis.value2=pic.scale.z.T(pic.scale.z.scale.logarithmic ? 1 : 0);
+ axis.position=1;
+ axis.align=align;
+ axis.extend=extend;
+ };
+}
+
+axis XZZero(triple align=O, bool extend=false)
+{
+ return new void(picture pic, axisT axis) {
+ axis.type=Value;
+ axis.type2=Value;
+ axis.value=pic.scale.x.T(pic.scale.x.scale.logarithmic ? 1 : 0);
+ axis.value2=pic.scale.z.T(pic.scale.z.scale.logarithmic ? 1 : 0);
+ axis.position=1;
+ axis.align=align;
+ axis.extend=extend;
+ };
+}
+
+axis XYZero(triple align=O, bool extend=false)
+{
+ return new void(picture pic, axisT axis) {
+ axis.type=Value;
+ axis.type2=Value;
+ axis.value=pic.scale.x.T(pic.scale.x.scale.logarithmic ? 1 : 0);
+ axis.value2=pic.scale.y.T(pic.scale.y.scale.logarithmic ? 1 : 0);
+ axis.position=1;
+ axis.align=align;
+ axis.extend=extend;
+ };
+}
+
+axis
+Bounds=Bounds(),
+YZZero=YZZero(),
+XZZero=XZZero(),
+XYZero=XYZero();
+
+// Draw a general three-dimensional axis.
+void axis(picture pic=currentpicture, Label L="", path3 g, path3 g2=nullpath3,
+ pen p=currentpen, ticks3 ticks, ticklocate locate,
+ arrowbar3 arrow=None, margin3 margin=NoMargin3,
+ int[] divisor=new int[], bool above=false, bool opposite=false)
+{
+ Label L=L.copy();
+ real t=reltime(g,0.5);
+ if(L.defaultposition) L.position(t);
+ divisor=copy(divisor);
+ locate=locate.copy();
+
+ pic.add(new void (picture f, transform3 t, transform3 T, triple, triple) {
+ picture d;
+ ticks(d,t,L,g,g2,p,arrow,margin,locate,divisor,opposite,true);
+ add(f,t*T*inverse(t)*d);
+ },above=above);
+
+ addPath(pic,g,p);
+
+ if(L.s != "") {
+ frame f;
+ Label L0=L.copy();
+ L0.position(0);
+ add(f,L0);
+ triple pos=point(g,L.relative()*length(g));
+ pic.addBox(pos,pos,min3(f),max3(f));
+ }
+}
+
+real xtrans(transform3 t, real x)
+{
+ return (t*(x,0,0)).x;
+}
+
+real ytrans(transform3 t, real y)
+{
+ return (t*(0,y,0)).y;
+}
+
+real ztrans(transform3 t, real z)
+{
+ return (t*(0,0,z)).z;
+}
+
+private triple defaultdir(triple X, triple Y, triple Z, bool opposite=false,
+ projection P) {
+ triple u=cross(P.normal,Z);
+ return abs(dot(u,X)) > abs(dot(u,Y)) ? -X : (opposite ? Y : -Y);
+}
+
+// An internal routine to draw an x axis at a particular y value.
+void xaxis3At(picture pic=currentpicture, Label L="", axis axis,
+ real xmin=-infinity, real xmax=infinity, pen p=currentpen,
+ ticks3 ticks=NoTicks3,
+ arrowbar3 arrow=None, margin3 margin=NoMargin3, bool above=true,
+ bool opposite=false, bool opposite2=false, bool primary=true)
+{
+ int type=axis.type;
+ int type2=axis.type2;
+ triple dir=axis.align.dir3 == O ?
+ defaultdir(Y,Z,X,opposite^opposite2,currentprojection) : axis.align.dir3;
+ Label L=L.copy();
+ if(L.align.dir3 == O && L.align.dir == 0) L.align(opposite ? -dir : dir);
+
+ real y=axis.value;
+ real z=axis.value2;
+ real y2,z2;
+ int[] divisor=copy(axis.xdivisor);
+
+ pic.add(new void(picture f, transform3 t, transform3 T, triple lb,
+ triple rt) {
+ transform3 tinv=inverse(t);
+ triple a=xmin == -infinity ? tinv*(lb.x-min3(p).x,ytrans(t,y),
+ ztrans(t,z)) : (xmin,y,z);
+ triple b=xmax == infinity ? tinv*(rt.x-max3(p).x,ytrans(t,y),
+ ztrans(t,z)) : (xmax,y,z);
+ real y0;
+ real z0;
+ if(abs(dir.y) < abs(dir.z)) {
+ y0=y;
+ z0=z2;
+ } else {
+ y0=y2;
+ z0=z;
+ }
+
+ triple a2=xmin == -infinity ? tinv*(lb.x-min3(p).x,ytrans(t,y0),
+ ztrans(t,z0)) : (xmin,y0,z0);
+ triple b2=xmax == infinity ? tinv*(rt.x-max3(p).x,ytrans(t,y0),
+ ztrans(t,z0)) : (xmax,y0,z0);
+
+ if(xmin == -infinity || xmax == infinity) {
+ bounds mx=autoscale(a.x,b.x,pic.scale.x.scale);
+ pic.scale.x.tickMin=mx.min;
+ pic.scale.x.tickMax=mx.max;
+ divisor=mx.divisor;
+ }
+
+ triple fuzz=X*epsilon*max(abs(a.x),abs(b.x));
+ a -= fuzz;
+ b += fuzz;
+
+ picture d;
+ ticks(d,t,L,a--b,finite(y0) && finite(z0) ? a2--b2 : nullpath3,
+ p,arrow,margin,
+ ticklocate(a.x,b.x,pic.scale.x,Dir(dir)),divisor,
+ opposite,primary);
+ add(f,t*T*tinv*d);
+ },above=above);
+
+ void bounds() {
+ if(type == Min)
+ y=pic.scale.y.automin() ? tickMin3(pic).y : pic.userMin().y;
+ else if(type == Max)
+ y=pic.scale.y.automax() ? tickMax3(pic).y : pic.userMax().y;
+ else if(type == Both) {
+ y2=pic.scale.y.automax() ? tickMax3(pic).y : pic.userMax().y;
+ y=opposite ? y2 :
+ (pic.scale.y.automin() ? tickMin3(pic).y : pic.userMin().y);
+ }
+
+ if(type2 == Min)
+ z=pic.scale.z.automin() ? tickMin3(pic).z : pic.userMin().z;
+ else if(type2 == Max)
+ z=pic.scale.z.automax() ? tickMax3(pic).z : pic.userMax().z;
+ else if(type2 == Both) {
+ z2=pic.scale.z.automax() ? tickMax3(pic).z : pic.userMax().z;
+ z=opposite2 ? z2 :
+ (pic.scale.z.automin() ? tickMin3(pic).z : pic.userMin().z);
+ }
+
+ real Xmin=finite(xmin) ? xmin : pic.userMin().x;
+ real Xmax=finite(xmax) ? xmax : pic.userMax().x;
+
+ triple a=(Xmin,y,z);
+ triple b=(Xmax,y,z);
+ triple a2=(Xmin,y2,z2);
+ triple b2=(Xmax,y2,z2);
+
+ if(finite(a)) {
+ pic.addPoint(a,min3(p));
+ pic.addPoint(a,max3(p));
+ }
+
+ if(finite(b)) {
+ pic.addPoint(b,min3(p));
+ pic.addPoint(b,max3(p));
+ }
+
+ if(finite(a) && finite(b)) {
+ picture d;
+ ticks(d,pic.scaling3(warn=false),L,
+ (a.x,0,0)--(b.x,0,0),(a2.x,0,0)--(b2.x,0,0),p,arrow,margin,
+ ticklocate(a.x,b.x,pic.scale.x,Dir(dir)),divisor,
+ opposite,primary);
+ frame f;
+ if(L.s != "") {
+ Label L0=L.copy();
+ L0.position(0);
+ add(f,L0);
+ }
+ triple pos=a+L.relative()*(b-a);
+ triple m=min3(d);
+ triple M=max3(d);
+ pic.addBox(pos,pos,(min3(f).x,m.y,m.z),(max3(f).x,m.y,m.z));
+ }
+ }
+
+ // Process any queued y and z axes bound calculation requests.
+ for(int i=0; i < pic.scale.y.bound.length; ++i)
+ pic.scale.y.bound[i]();
+ for(int i=0; i < pic.scale.z.bound.length; ++i)
+ pic.scale.z.bound[i]();
+
+ pic.scale.y.bound.delete();
+ pic.scale.z.bound.delete();
+
+ bounds();
+
+ // Request another x bounds calculation before final picture scaling.
+ pic.scale.x.bound.push(bounds);
+}
+
+// An internal routine to draw an x axis at a particular y value.
+void yaxis3At(picture pic=currentpicture, Label L="", axis axis,
+ real ymin=-infinity, real ymax=infinity, pen p=currentpen,
+ ticks3 ticks=NoTicks3,
+ arrowbar3 arrow=None, margin3 margin=NoMargin3, bool above=true,
+ bool opposite=false, bool opposite2=false, bool primary=true)
+{
+ int type=axis.type;
+ int type2=axis.type2;
+ triple dir=axis.align.dir3 == O ?
+ defaultdir(X,Z,Y,opposite^opposite2,currentprojection) : axis.align.dir3;
+ Label L=L.copy();
+ if(L.align.dir3 == O && L.align.dir == 0) L.align(opposite ? -dir : dir);
+
+ real x=axis.value;
+ real z=axis.value2;
+ real x2,z2;
+ int[] divisor=copy(axis.ydivisor);
+
+ pic.add(new void(picture f, transform3 t, transform3 T, triple lb,
+ triple rt) {
+ transform3 tinv=inverse(t);
+ triple a=ymin == -infinity ? tinv*(xtrans(t,x),lb.y-min3(p).y,
+ ztrans(t,z)) : (x,ymin,z);
+ triple b=ymax == infinity ? tinv*(xtrans(t,x),rt.y-max3(p).y,
+ ztrans(t,z)) : (x,ymax,z);
+ real x0;
+ real z0;
+ if(abs(dir.x) < abs(dir.z)) {
+ x0=x;
+ z0=z2;
+ } else {
+ x0=x2;
+ z0=z;
+ }
+
+ triple a2=ymin == -infinity ? tinv*(xtrans(t,x0),lb.y-min3(p).y,
+ ztrans(t,z0)) : (x0,ymin,z0);
+ triple b2=ymax == infinity ? tinv*(xtrans(t,x0),rt.y-max3(p).y,
+ ztrans(t,z0)) : (x0,ymax,z0);
+
+ if(ymin == -infinity || ymax == infinity) {
+ bounds my=autoscale(a.y,b.y,pic.scale.y.scale);
+ pic.scale.y.tickMin=my.min;
+ pic.scale.y.tickMax=my.max;
+ divisor=my.divisor;
+ }
+
+ triple fuzz=Y*epsilon*max(abs(a.y),abs(b.y));
+ a -= fuzz;
+ b += fuzz;
+
+ picture d;
+ ticks(d,t,L,a--b,finite(x0) && finite(z0) ? a2--b2 : nullpath3,
+ p,arrow,margin,
+ ticklocate(a.y,b.y,pic.scale.y,Dir(dir)),divisor,
+ opposite,primary);
+ add(f,t*T*tinv*d);
+ },above=above);
+
+ void bounds() {
+ if(type == Min)
+ x=pic.scale.x.automin() ? tickMin3(pic).x : pic.userMin().x;
+ else if(type == Max)
+ x=pic.scale.x.automax() ? tickMax3(pic).x : pic.userMax().x;
+ else if(type == Both) {
+ x2=pic.scale.x.automax() ? tickMax3(pic).x : pic.userMax().x;
+ x=opposite ? x2 :
+ (pic.scale.x.automin() ? tickMin3(pic).x : pic.userMin().x);
+ }
+
+ if(type2 == Min)
+ z=pic.scale.z.automin() ? tickMin3(pic).z : pic.userMin().z;
+ else if(type2 == Max)
+ z=pic.scale.z.automax() ? tickMax3(pic).z : pic.userMax().z;
+ else if(type2 == Both) {
+ z2=pic.scale.z.automax() ? tickMax3(pic).z : pic.userMax().z;
+ z=opposite2 ? z2 :
+ (pic.scale.z.automin() ? tickMin3(pic).z : pic.userMin().z);
+ }
+
+ real Ymin=finite(ymin) ? ymin : pic.userMin().y;
+ real Ymax=finite(ymax) ? ymax : pic.userMax().y;
+
+ triple a=(x,Ymin,z);
+ triple b=(x,Ymax,z);
+ triple a2=(x2,Ymin,z2);
+ triple b2=(x2,Ymax,z2);
+
+ if(finite(a)) {
+ pic.addPoint(a,min3(p));
+ pic.addPoint(a,max3(p));
+ }
+
+ if(finite(b)) {
+ pic.addPoint(b,min3(p));
+ pic.addPoint(b,max3(p));
+ }
+
+ if(finite(a) && finite(b)) {
+ picture d;
+ ticks(d,pic.scaling3(warn=false),L,
+ (0,a.y,0)--(0,b.y,0),(0,a2.y,0)--(0,a2.y,0),p,arrow,margin,
+ ticklocate(a.y,b.y,pic.scale.y,Dir(dir)),divisor,
+ opposite,primary);
+ frame f;
+ if(L.s != "") {
+ Label L0=L.copy();
+ L0.position(0);
+ add(f,L0);
+ }
+ triple pos=a+L.relative()*(b-a);
+ triple m=min3(d);
+ triple M=max3(d);
+ pic.addBox(pos,pos,(m.x,min3(f).y,m.z),(m.x,max3(f).y,m.z));
+ }
+ }
+
+ // Process any queued x and z axis bound calculation requests.
+ for(int i=0; i < pic.scale.x.bound.length; ++i)
+ pic.scale.x.bound[i]();
+ for(int i=0; i < pic.scale.z.bound.length; ++i)
+ pic.scale.z.bound[i]();
+
+ pic.scale.x.bound.delete();
+ pic.scale.z.bound.delete();
+
+ bounds();
+
+ // Request another y bounds calculation before final picture scaling.
+ pic.scale.y.bound.push(bounds);
+}
+
+// An internal routine to draw an x axis at a particular y value.
+void zaxis3At(picture pic=currentpicture, Label L="", axis axis,
+ real zmin=-infinity, real zmax=infinity, pen p=currentpen,
+ ticks3 ticks=NoTicks3,
+ arrowbar3 arrow=None, margin3 margin=NoMargin3, bool above=true,
+ bool opposite=false, bool opposite2=false, bool primary=true)
+{
+ int type=axis.type;
+ int type2=axis.type2;
+ triple dir=axis.align.dir3 == O ?
+ defaultdir(X,Y,Z,opposite^opposite2,currentprojection) : axis.align.dir3;
+ Label L=L.copy();
+ if(L.align.dir3 == O && L.align.dir == 0) L.align(opposite ? -dir : dir);
+
+ real x=axis.value;
+ real y=axis.value2;
+ real x2,y2;
+ int[] divisor=copy(axis.zdivisor);
+
+ pic.add(new void(picture f, transform3 t, transform3 T, triple lb,
+ triple rt) {
+ transform3 tinv=inverse(t);
+ triple a=zmin == -infinity ? tinv*(xtrans(t,x),ytrans(t,y),
+ lb.z-min3(p).z) : (x,y,zmin);
+ triple b=zmax == infinity ? tinv*(xtrans(t,x),ytrans(t,y),
+ rt.z-max3(p).z) : (x,y,zmax);
+ real x0;
+ real y0;
+ if(abs(dir.x) < abs(dir.y)) {
+ x0=x;
+ y0=y2;
+ } else {
+ x0=x2;
+ y0=y;
+ }
+
+ triple a2=zmin == -infinity ? tinv*(xtrans(t,x0),ytrans(t,y0),
+ lb.z-min3(p).z) : (x0,y0,zmin);
+ triple b2=zmax == infinity ? tinv*(xtrans(t,x0),ytrans(t,y0),
+ rt.z-max3(p).z) : (x0,y0,zmax);
+
+ if(zmin == -infinity || zmax == infinity) {
+ bounds mz=autoscale(a.z,b.z,pic.scale.z.scale);
+ pic.scale.z.tickMin=mz.min;
+ pic.scale.z.tickMax=mz.max;
+ divisor=mz.divisor;
+ }
+
+ triple fuzz=Z*epsilon*max(abs(a.z),abs(b.z));
+ a -= fuzz;
+ b += fuzz;
+
+ picture d;
+ ticks(d,t,L,a--b,finite(x0) && finite(y0) ? a2--b2 : nullpath3,
+ p,arrow,margin,
+ ticklocate(a.z,b.z,pic.scale.z,Dir(dir)),divisor,
+ opposite,primary);
+ add(f,t*T*tinv*d);
+ },above=above);
+
+ void bounds() {
+ if(type == Min)
+ x=pic.scale.x.automin() ? tickMin3(pic).x : pic.userMin().x;
+ else if(type == Max)
+ x=pic.scale.x.automax() ? tickMax3(pic).x : pic.userMax().x;
+ else if(type == Both) {
+ x2=pic.scale.x.automax() ? tickMax3(pic).x : pic.userMax().x;
+ x=opposite ? x2 :
+ (pic.scale.x.automin() ? tickMin3(pic).x : pic.userMin().x);
+ }
+
+ if(type2 == Min)
+ y=pic.scale.y.automin() ? tickMin3(pic).y : pic.userMin().y;
+ else if(type2 == Max)
+ y=pic.scale.y.automax() ? tickMax3(pic).y : pic.userMax().y;
+ else if(type2 == Both) {
+ y2=pic.scale.y.automax() ? tickMax3(pic).y : pic.userMax().y;
+ y=opposite2 ? y2 :
+ (pic.scale.y.automin() ? tickMin3(pic).y : pic.userMin().y);
+ }
+
+ real Zmin=finite(zmin) ? zmin : pic.userMin().z;
+ real Zmax=finite(zmax) ? zmax : pic.userMax().z;
+
+ triple a=(x,y,Zmin);
+ triple b=(x,y,Zmax);
+ triple a2=(x2,y2,Zmin);
+ triple b2=(x2,y2,Zmax);
+
+ if(finite(a)) {
+ pic.addPoint(a,min3(p));
+ pic.addPoint(a,max3(p));
+ }
+
+ if(finite(b)) {
+ pic.addPoint(b,min3(p));
+ pic.addPoint(b,max3(p));
+ }
+
+ if(finite(a) && finite(b)) {
+ picture d;
+ ticks(d,pic.scaling3(warn=false),L,
+ (0,0,a.z)--(0,0,b.z),(0,0,a2.z)--(0,0,a2.z),p,arrow,margin,
+ ticklocate(a.z,b.z,pic.scale.z,Dir(dir)),divisor,
+ opposite,primary);
+ frame f;
+ if(L.s != "") {
+ Label L0=L.copy();
+ L0.position(0);
+ add(f,L0);
+ }
+ triple pos=a+L.relative()*(b-a);
+ triple m=min3(d);
+ triple M=max3(d);
+ pic.addBox(pos,pos,(m.x,m.y,min3(f).z),(m.x,m.y,max3(f).z));
+ }
+ }
+
+ // Process any queued x and y axes bound calculation requests.
+ for(int i=0; i < pic.scale.x.bound.length; ++i)
+ pic.scale.x.bound[i]();
+ for(int i=0; i < pic.scale.y.bound.length; ++i)
+ pic.scale.y.bound[i]();
+
+ pic.scale.x.bound.delete();
+ pic.scale.y.bound.delete();
+
+ bounds();
+
+ // Request another z bounds calculation before final picture scaling.
+ pic.scale.z.bound.push(bounds);
+}
+
+// Internal routine to autoscale the user limits of a picture.
+void autoscale3(picture pic=currentpicture, axis axis)
+{
+ bool set=pic.scale.set;
+ autoscale(pic,axis);
+
+ if(!set) {
+ bounds mz;
+ if(pic.userSetz()) {
+ mz=autoscale(pic.userMin().z,pic.userMax().z,pic.scale.z.scale);
+ if(pic.scale.z.scale.logarithmic &&
+ floor(pic.userMin().z) == floor(pic.userMax().z)) {
+ if(pic.scale.z.automin())
+ pic.userMinz(floor(pic.userMin().z));
+ if(pic.scale.z.automax())
+ pic.userMaxz(ceil(pic.userMax().z));
+ }
+ } else {mz.min=mz.max=0; pic.scale.set=false;}
+
+ pic.scale.z.tickMin=mz.min;
+ pic.scale.z.tickMax=mz.max;
+ axis.zdivisor=mz.divisor;
+ }
+}
+
+// Draw an x axis in three dimensions.
+void xaxis3(picture pic=currentpicture, Label L="", axis axis=YZZero,
+ real xmin=-infinity, real xmax=infinity, pen p=currentpen,
+ ticks3 ticks=NoTicks3,
+ arrowbar3 arrow=None, margin3 margin=NoMargin3, bool above=false)
+{
+ if(xmin > xmax) return;
+
+ if(pic.scale.x.automin && xmin > -infinity) pic.scale.x.automin=false;
+ if(pic.scale.x.automax && xmax < infinity) pic.scale.x.automax=false;
+
+ if(!pic.scale.set) {
+ axis(pic,axis);
+ autoscale3(pic,axis);
+ }
+
+ bool newticks=false;
+
+ if(xmin != -infinity) {
+ xmin=pic.scale.x.T(xmin);
+ newticks=true;
+ }
+
+ if(xmax != infinity) {
+ xmax=pic.scale.x.T(xmax);
+ newticks=true;
+ }
+
+ if(newticks && pic.userSetx() && ticks != NoTicks3) {
+ if(xmin == -infinity) xmin=pic.userMin().x;
+ if(xmax == infinity) xmax=pic.userMax().x;
+ bounds mx=autoscale(xmin,xmax,pic.scale.x.scale);
+ pic.scale.x.tickMin=mx.min;
+ pic.scale.x.tickMax=mx.max;
+ axis.xdivisor=mx.divisor;
+ }
+
+ axis(pic,axis);
+
+ if(xmin == -infinity && !axis.extend) {
+ if(pic.scale.set)
+ xmin=pic.scale.x.automin() ? pic.scale.x.tickMin :
+ max(pic.scale.x.tickMin,pic.userMin().x);
+ else xmin=pic.userMin().x;
+ }
+
+ if(xmax == infinity && !axis.extend) {
+ if(pic.scale.set)
+ xmax=pic.scale.x.automax() ? pic.scale.x.tickMax :
+ min(pic.scale.x.tickMax,pic.userMax().x);
+ else xmax=pic.userMax().x;
+ }
+
+ if(L.defaultposition) {
+ L=L.copy();
+ L.position(axis.position);
+ }
+
+ bool back=false;
+ if(axis.type == Both) {
+ triple v=currentprojection.normal;
+ back=dot((0,pic.userMax().y-pic.userMin().y,0),v)*sgn(v.z) > 0;
+ }
+
+ xaxis3At(pic,L,axis,xmin,xmax,p,ticks,arrow,margin,above,false,false,!back);
+ if(axis.type == Both)
+ xaxis3At(pic,L,axis,xmin,xmax,p,ticks,arrow,margin,above,true,false,back);
+ if(axis.type2 == Both) {
+ xaxis3At(pic,L,axis,xmin,xmax,p,ticks,arrow,margin,above,false,true,false);
+ if(axis.type == Both)
+ xaxis3At(pic,L,axis,xmin,xmax,p,ticks,arrow,margin,above,true,true,false);
+ }
+}
+
+// Draw a y axis in three dimensions.
+void yaxis3(picture pic=currentpicture, Label L="", axis axis=XZZero,
+ real ymin=-infinity, real ymax=infinity, pen p=currentpen,
+ ticks3 ticks=NoTicks3,
+ arrowbar3 arrow=None, margin3 margin=NoMargin3, bool above=false)
+{
+ if(ymin > ymax) return;
+
+ if(pic.scale.y.automin && ymin > -infinity) pic.scale.y.automin=false;
+ if(pic.scale.y.automax && ymax < infinity) pic.scale.y.automax=false;
+
+ if(!pic.scale.set) {
+ axis(pic,axis);
+ autoscale3(pic,axis);
+ }
+
+ bool newticks=false;
+
+ if(ymin != -infinity) {
+ ymin=pic.scale.y.T(ymin);
+ newticks=true;
+ }
+
+ if(ymax != infinity) {
+ ymax=pic.scale.y.T(ymax);
+ newticks=true;
+ }
+
+ if(newticks && pic.userSety() && ticks != NoTicks3) {
+ if(ymin == -infinity) ymin=pic.userMin().y;
+ if(ymax == infinity) ymax=pic.userMax().y;
+ bounds my=autoscale(ymin,ymax,pic.scale.y.scale);
+ pic.scale.y.tickMin=my.min;
+ pic.scale.y.tickMax=my.max;
+ axis.ydivisor=my.divisor;
+ }
+
+ axis(pic,axis);
+
+ if(ymin == -infinity && !axis.extend) {
+ if(pic.scale.set)
+ ymin=pic.scale.y.automin() ? pic.scale.y.tickMin :
+ max(pic.scale.y.tickMin,pic.userMin().y);
+ else ymin=pic.userMin().y;
+ }
+
+
+ if(ymax == infinity && !axis.extend) {
+ if(pic.scale.set)
+ ymax=pic.scale.y.automax() ? pic.scale.y.tickMax :
+ min(pic.scale.y.tickMax,pic.userMax().y);
+ else ymax=pic.userMax().y;
+ }
+
+ if(L.defaultposition) {
+ L=L.copy();
+ L.position(axis.position);
+ }
+
+ bool back=false;
+ if(axis.type == Both) {
+ triple v=currentprojection.normal;
+ back=dot((pic.userMax().x-pic.userMin().x,0,0),v)*sgn(v.z) > 0;
+ }
+
+ yaxis3At(pic,L,axis,ymin,ymax,p,ticks,arrow,margin,above,false,false,!back);
+
+ if(axis.type == Both)
+ yaxis3At(pic,L,axis,ymin,ymax,p,ticks,arrow,margin,above,true,false,back);
+ if(axis.type2 == Both) {
+ yaxis3At(pic,L,axis,ymin,ymax,p,ticks,arrow,margin,above,false,true,false);
+ if(axis.type == Both)
+ yaxis3At(pic,L,axis,ymin,ymax,p,ticks,arrow,margin,above,true,true,false);
+ }
+}
+// Draw a z axis in three dimensions.
+void zaxis3(picture pic=currentpicture, Label L="", axis axis=XYZero,
+ real zmin=-infinity, real zmax=infinity, pen p=currentpen,
+ ticks3 ticks=NoTicks3,
+ arrowbar3 arrow=None, margin3 margin=NoMargin3, bool above=false)
+{
+ if(zmin > zmax) return;
+
+ if(pic.scale.z.automin && zmin > -infinity) pic.scale.z.automin=false;
+ if(pic.scale.z.automax && zmax < infinity) pic.scale.z.automax=false;
+
+ if(!pic.scale.set) {
+ axis(pic,axis);
+ autoscale3(pic,axis);
+ }
+
+ bool newticks=false;
+
+ if(zmin != -infinity) {
+ zmin=pic.scale.z.T(zmin);
+ newticks=true;
+ }
+
+ if(zmax != infinity) {
+ zmax=pic.scale.z.T(zmax);
+ newticks=true;
+ }
+
+ if(newticks && pic.userSetz() && ticks != NoTicks3) {
+ if(zmin == -infinity) zmin=pic.userMin().z;
+ if(zmax == infinity) zmax=pic.userMax().z;
+ bounds mz=autoscale(zmin,zmax,pic.scale.z.scale);
+ pic.scale.z.tickMin=mz.min;
+ pic.scale.z.tickMax=mz.max;
+ axis.zdivisor=mz.divisor;
+ }
+
+ axis(pic,axis);
+
+ if(zmin == -infinity && !axis.extend) {
+ if(pic.scale.set)
+ zmin=pic.scale.z.automin() ? pic.scale.z.tickMin :
+ max(pic.scale.z.tickMin,pic.userMin().z);
+ else zmin=pic.userMin().z;
+ }
+
+ if(zmax == infinity && !axis.extend) {
+ if(pic.scale.set)
+ zmax=pic.scale.z.automax() ? pic.scale.z.tickMax :
+ min(pic.scale.z.tickMax,pic.userMax().z);
+ else zmax=pic.userMax().z;
+ }
+
+ if(L.defaultposition) {
+ L=L.copy();
+ L.position(axis.position);
+ }
+
+ bool back=false;
+ if(axis.type == Both) {
+ triple v=currentprojection.vector();
+ back=dot((pic.userMax().x-pic.userMin().x,0,0),v)*sgn(v.y) > 0;
+ }
+
+ zaxis3At(pic,L,axis,zmin,zmax,p,ticks,arrow,margin,above,false,false,!back);
+ if(axis.type == Both)
+ zaxis3At(pic,L,axis,zmin,zmax,p,ticks,arrow,margin,above,true,false,back);
+ if(axis.type2 == Both) {
+ zaxis3At(pic,L,axis,zmin,zmax,p,ticks,arrow,margin,above,false,true,false);
+ if(axis.type == Both)
+ zaxis3At(pic,L,axis,zmin,zmax,p,ticks,arrow,margin,above,true,true,false);
+ }
+}
+
+// Set the z limits of a picture.
+void zlimits(picture pic=currentpicture, real min=-infinity, real max=infinity,
+ bool crop=NoCrop)
+{
+ if(min > max) return;
+
+ pic.scale.z.automin=min <= -infinity;
+ pic.scale.z.automax=max >= infinity;
+
+ bounds mz;
+ if(pic.scale.z.automin() || pic.scale.z.automax())
+ mz=autoscale(pic.userMin().z,pic.userMax().z,pic.scale.z.scale);
+
+ if(pic.scale.z.automin) {
+ if(pic.scale.z.automin()) pic.userMinz(mz.min);
+ } else pic.userMinz(min(pic.scale.z.T(min),pic.scale.z.T(max)));
+
+ if(pic.scale.z.automax) {
+ if(pic.scale.z.automax()) pic.userMaxz(mz.max);
+ } else pic.userMaxz(max(pic.scale.z.T(min),pic.scale.z.T(max)));
+}
+
+// Restrict the x, y, and z limits to box(min,max).
+void limits(picture pic=currentpicture, triple min, triple max)
+{
+ xlimits(pic,min.x,max.x);
+ ylimits(pic,min.y,max.y);
+ zlimits(pic,min.z,max.z);
+}
+
+// Draw x, y and z axes.
+void axes3(picture pic=currentpicture,
+ Label xlabel="", Label ylabel="", Label zlabel="",
+ triple min=(-infinity,-infinity,-infinity),
+ triple max=(infinity,infinity,infinity),
+ pen p=currentpen, arrowbar3 arrow=None, margin3 margin=NoMargin3)
+{
+ xaxis3(pic,xlabel,min.x,max.x,p,arrow,margin);
+ yaxis3(pic,ylabel,min.y,max.y,p,arrow,margin);
+ zaxis3(pic,zlabel,min.z,max.z,p,arrow,margin);
+}
+
+triple Scale(picture pic=currentpicture, triple v)
+{
+ return (pic.scale.x.T(v.x),pic.scale.y.T(v.y),pic.scale.z.T(v.z));
+}
+
+real ScaleZ(picture pic=currentpicture, real z)
+{
+ return pic.scale.z.T(z);
+}
+
+// Draw a tick of length size at triple v in direction dir using pen p.
+void tick(picture pic=currentpicture, triple v, triple dir, real size=Ticksize,
+ pen p=currentpen)
+{
+ triple v=Scale(pic,v);
+ pic.add(new void (picture f, transform3 t) {
+ triple tv=t*v;
+ draw(f,tv--tv+unit(dir)*size,p);
+ });
+ pic.addPoint(v,p);
+ pic.addPoint(v,unit(dir)*size,p);
+}
+
+void xtick(picture pic=currentpicture, triple v, triple dir=Y,
+ real size=Ticksize, pen p=currentpen)
+{
+ tick(pic,v,dir,size,p);
+}
+
+void xtick3(picture pic=currentpicture, real x, triple dir=Y,
+ real size=Ticksize, pen p=currentpen)
+{
+ tick(pic,(x,pic.scale.y.scale.logarithmic ? 1 : 0,
+ pic.scale.z.scale.logarithmic ? 1 : 0),dir,size,p);
+}
+
+void ytick(picture pic=currentpicture, triple v, triple dir=X,
+ real size=Ticksize, pen p=currentpen)
+{
+ tick(pic,v,dir,size,p);
+}
+
+void ytick3(picture pic=currentpicture, real y, triple dir=X,
+ real size=Ticksize, pen p=currentpen)
+{
+ tick(pic,(pic.scale.x.scale.logarithmic ? 1 : 0,y,
+ pic.scale.z.scale.logarithmic ? 1 : 0),dir,size,p);
+}
+
+void ztick(picture pic=currentpicture, triple v, triple dir=X,
+ real size=Ticksize, pen p=currentpen)
+{
+ xtick(pic,v,dir,size,p);
+}
+
+void ztick3(picture pic=currentpicture, real z, triple dir=X,
+ real size=Ticksize, pen p=currentpen)
+{
+ xtick(pic,(pic.scale.x.scale.logarithmic ? 1 : 0,
+ pic.scale.y.scale.logarithmic ? 1 : 0,z),dir,size,p);
+}
+
+void tick(picture pic=currentpicture, Label L, real value, triple v,
+ triple dir, string format="", real size=Ticksize, pen p=currentpen)
+{
+ Label L=L.copy();
+ L.align(L.align,-dir);
+ if(shift(L.T3)*O == O)
+ L.T3=shift(dot(dir,L.align.dir3) > 0 ? dir*size :
+ ticklabelshift(L.align.dir3,p))*L.T3;
+ L.p(p);
+ if(L.s == "") L.s=format(format == "" ? defaultformat : format,value);
+ L.s=baseline(L.s,baselinetemplate);
+ label(pic,L,Scale(pic,v));
+ tick(pic,v,dir,size,p);
+}
+
+void xtick(picture pic=currentpicture, Label L, triple v, triple dir=Y,
+ string format="", real size=Ticksize, pen p=currentpen)
+{
+ tick(pic,L,v.x,v,dir,format,size,p);
+}
+
+void xtick3(picture pic=currentpicture, Label L, real x, triple dir=Y,
+ string format="", real size=Ticksize, pen p=currentpen)
+{
+ xtick(pic,L,(x,pic.scale.y.scale.logarithmic ? 1 : 0,
+ pic.scale.z.scale.logarithmic ? 1 : 0),dir,size,p);
+}
+
+void ytick(picture pic=currentpicture, Label L, triple v, triple dir=X,
+ string format="", real size=Ticksize, pen p=currentpen)
+{
+ tick(pic,L,v.y,v,dir,format,size,p);
+}
+
+void ytick3(picture pic=currentpicture, Label L, real y, triple dir=X,
+ string format="", real size=Ticksize, pen p=currentpen)
+{
+ xtick(pic,L,(pic.scale.x.scale.logarithmic ? 1 : 0,y,
+ pic.scale.z.scale.logarithmic ? 1 : 0),dir,format,size,p);
+}
+
+void ztick(picture pic=currentpicture, Label L, triple v, triple dir=X,
+ string format="", real size=Ticksize, pen p=currentpen)
+{
+ tick(pic,L,v.z,v,dir,format,size,p);
+}
+
+void ztick3(picture pic=currentpicture, Label L, real z, triple dir=X,
+ string format="", real size=Ticksize, pen p=currentpen)
+{
+ xtick(pic,L,(pic.scale.x.scale.logarithmic ? 1 : 0,
+ pic.scale.z.scale.logarithmic ? 1 : 0,z),dir,format,size,p);
+}
+
+private void label(picture pic, Label L, triple v, real x, align align,
+ string format, pen p)
+{
+ Label L=L.copy();
+ L.align(align);
+ L.p(p);
+ if(shift(L.T3)*O == O)
+ L.T3=shift(ticklabelshift(L.align.dir3,L.p))*L.T3;
+ if(L.s == "") L.s=format(format == "" ? defaultformat : format,x);
+ L.s=baseline(L.s,baselinetemplate);
+ label(pic,L,v);
+}
+
+void labelx(picture pic=currentpicture, Label L="", triple v,
+ align align=-Y, string format="", pen p=currentpen)
+{
+ label(pic,L,Scale(pic,v),v.x,align,format,p);
+}
+
+void labelx3(picture pic=currentpicture, Label L="", real x,
+ align align=-Y, string format="", pen p=currentpen)
+{
+ labelx(pic,L,(x,pic.scale.y.scale.logarithmic ? 1 : 0,
+ pic.scale.z.scale.logarithmic ? 1 : 0),align,format,p);
+}
+
+void labely(picture pic=currentpicture, Label L="", triple v,
+ align align=-X, string format="", pen p=currentpen)
+{
+ label(pic,L,Scale(pic,v),v.y,align,format,p);
+}
+
+void labely3(picture pic=currentpicture, Label L="", real y,
+ align align=-X, string format="", pen p=currentpen)
+{
+ labely(pic,L,(pic.scale.x.scale.logarithmic ? 1 : 0,y,
+ pic.scale.z.scale.logarithmic ? 1 : 0),align,format,p);
+}
+
+void labelz(picture pic=currentpicture, Label L="", triple v,
+ align align=-X, string format="", pen p=currentpen)
+{
+ label(pic,L,Scale(pic,v),v.z,align,format,p);
+}
+
+void labelz3(picture pic=currentpicture, Label L="", real z,
+ align align=-X, string format="", pen p=currentpen)
+{
+ labelz(pic,L,(pic.scale.x.scale.logarithmic ? 1 : 0,
+ pic.scale.y.scale.logarithmic ? 1 : 0,z),align,format,p);
+}
+
+typedef guide3 graph(triple F(real), real, real, int);
+typedef guide3[] multigraph(triple F(real), real, real, int);
+
+graph graph(interpolate3 join)
+{
+ return new guide3(triple f(real), real a, real b, int n) {
+ real width=b-a;
+ return n == 0 ? join(f(a)) :
+ join(...sequence(new guide3(int i) {return f(a+(i/n)*width);},n+1));
+ };
+}
+
+multigraph graph(interpolate3 join, bool3 cond(real))
+{
+ return new guide3[](triple f(real), real a, real b, int n) {
+ real width=b-a;
+ if(n == 0) return new guide3[] {join(cond(a) ? f(a) : nullpath3)};
+ guide3[] G;
+ guide3[] g;
+ for(int i=0; i < n+1; ++i) {
+ real t=a+(i/n)*width;
+ bool3 b=cond(t);
+ if(b)
+ g.push(f(t));
+ else {
+ if(g.length > 0) {
+ G.push(join(...g));
+ g=new guide3[] {};
+ }
+ if(b == default)
+ g.push(f(t));
+ }
+ }
+ if(g.length > 0)
+ G.push(join(...g));
+ return G;
+ };
+}
+
+guide3 Straight(... guide3[])=operator --;
+guide3 Spline(... guide3[])=operator ..;
+
+guide3 graph(picture pic=currentpicture, real x(real), real y(real),
+ real z(real), real a, real b, int n=ngraph,
+ interpolate3 join=operator --)
+{
+ return graph(join)(new triple(real t) {return Scale(pic,(x(t),y(t),z(t)));},
+ a,b,n);
+}
+
+guide3[] graph(picture pic=currentpicture, real x(real), real y(real),
+ real z(real), real a, real b, int n=ngraph,
+ bool3 cond(real), interpolate3 join=operator --)
+{
+ return graph(join,cond)(new triple(real t) {
+ return Scale(pic,(x(t),y(t),z(t)));
+ },a,b,n);
+}
+
+guide3 graph(picture pic=currentpicture, triple v(real), real a, real b,
+ int n=ngraph, interpolate3 join=operator --)
+{
+ return graph(join)(new triple(real t) {return Scale(pic,v(t));},a,b,n);
+}
+
+guide3[] graph(picture pic=currentpicture, triple v(real), real a, real b,
+ int n=ngraph, bool3 cond(real), interpolate3 join=operator --)
+{
+ return graph(join,cond)(new triple(real t) {
+ return Scale(pic,v(t));
+ },a,b,n);
+}
+
+guide3 graph(picture pic=currentpicture, triple[] v,
+ interpolate3 join=operator --)
+{
+ int i=0;
+ return graph(join)(new triple(real) {
+ triple w=Scale(pic,v[i]);
+ ++i;
+ return w;
+ },0,0,v.length-1);
+}
+
+guide3[] graph(picture pic=currentpicture, triple[] v, bool3[] cond,
+ interpolate3 join=operator --)
+{
+ int n=v.length;
+ int i=0;
+ triple w;
+ checkconditionlength(cond.length,n);
+ bool3 condition(real) {
+ bool b=cond[i];
+ if(b) w=Scale(pic,v[i]);
+ ++i;
+ return b;
+ }
+ return graph(join,condition)(new triple(real) {return w;},0,0,n-1);
+}
+
+guide3 graph(picture pic=currentpicture, real[] x, real[] y, real[] z,
+ interpolate3 join=operator --)
+{
+ int n=x.length;
+ checklengths(n,y.length);
+ checklengths(n,z.length);
+ int i=0;
+ return graph(join)(new triple(real) {
+ triple w=Scale(pic,(x[i],y[i],z[i]));
+ ++i;
+ return w;
+ },0,0,n-1);
+}
+
+guide3[] graph(picture pic=currentpicture, real[] x, real[] y, real[] z,
+ bool3[] cond, interpolate3 join=operator --)
+{
+ int n=x.length;
+ checklengths(n,y.length);
+ checklengths(n,z.length);
+ int i=0;
+ triple w;
+ checkconditionlength(cond.length,n);
+ bool3 condition(real) {
+ bool3 b=cond[i];
+ if(b != false) w=Scale(pic,(x[i],y[i],z[i]));
+ ++i;
+ return b;
+ }
+ return graph(join,condition)(new triple(real) {return w;},0,0,n-1);
+}
+
+// The graph of a function along a path.
+guide3 graph(triple F(path, real), path p, int n=1,
+ interpolate3 join=operator --)
+{
+ guide3 g=join(...sequence(new guide3(int i) {
+ return F(p,i/n);
+ },n*length(p)));
+ return cyclic(p) ? join(g,cycle) : join(g,F(p,length(p)));
+}
+
+guide3 graph(triple F(pair), path p, int n=1, interpolate3 join=operator --)
+{
+ return graph(new triple(path p, real position)
+ {return F(point(p,position));},p,n,join);
+}
+
+guide3 graph(picture pic=currentpicture, real f(pair), path p, int n=1,
+ interpolate3 join=operator --)
+{
+ return graph(new triple(pair z) {return Scale(pic,(z.x,z.y,f(z)));},p,n,
+ join);
+}
+
+guide3 graph(real f(pair), path p, int n=1, real T(pair),
+ interpolate3 join=operator --)
+{
+ return graph(new triple(pair z) {pair w=T(z); return (w.x,w.y,f(w));},p,n,
+ join);
+}
+
+// Connect points in v into segments corresponding to consecutive true elements
+// of b using interpolation operator join.
+path3[] segment(triple[] v, bool[] cond, interpolate3 join=operator --)
+{
+ checkconditionlength(cond.length,v.length);
+ int[][] segment=segment(cond);
+ return sequence(new path3(int i) {return join(...v[segment[i]]);},
+ segment.length);
+}
+
+bool uperiodic(triple[][] a) {
+ int n=a.length;
+ if(n == 0) return false;
+ int m=a[0].length;
+ triple[] a0=a[0];
+ triple[] a1=a[n-1];
+ real epsilon=sqrtEpsilon*norm(a);
+ for(int j=0; j < m; ++j)
+ if(abs(a0[j]-a1[j]) > epsilon) return false;
+ return true;
+}
+bool vperiodic(triple[][] a) {
+ int n=a.length;
+ if(n == 0) return false;
+ int m=a[0].length-1;
+ real epsilon=sqrtEpsilon*norm(a);
+ for(int i=0; i < n; ++i)
+ if(abs(a[i][0]-a[i][m]) > epsilon) return false;
+ return true;
+}
+
+// return the surface described by a matrix f
+surface surface(triple[][] f, bool[][] cond={})
+{
+ if(!rectangular(f)) abort("matrix is not rectangular");
+
+ int nx=f.length-1;
+ int ny=nx > 0 ? f[0].length-1 : 0;
+
+ bool all=cond.length == 0;
+
+ int count;
+ if(all)
+ count=nx*ny;
+ else {
+ count=0;
+ for(int i=0; i < nx; ++i) {
+ bool[] condi=cond[i];
+ bool[] condp=cond[i+1];
+ for(int j=0; j < ny; ++j)
+ if(condi[j] && condi[j+1] && condp[j] && condp[j+1]) ++count;
+ }
+ }
+
+ surface s=surface(count);
+ s.index=new int[nx][ny];
+ int k=-1;
+ for(int i=0; i < nx; ++i) {
+ bool[] condi,condp;
+ if(!all) {
+ condi=cond[i];
+ condp=cond[i+1];
+ }
+ triple[] fi=f[i];
+ triple[] fp=f[i+1];
+ int[] indexi=s.index[i];
+ for(int j=0; j < ny; ++j) {
+ if(all || (condi[j] && condi[j+1] && condp[j] && condp[j+1]))
+ s.s[++k]=patch(new triple[] {fi[j],fp[j],fp[j+1],fi[j+1]});
+ indexi[j]=k;
+ }
+ }
+
+ if(count == nx*ny) {
+ if(uperiodic(f)) s.ucyclic(true);
+ if(vperiodic(f)) s.vcyclic(true);
+ }
+
+ return s;
+}
+
+surface bispline(real[][] z, real[][] p, real[][] q, real[][] r,
+ real[] x, real[] y, bool[][] cond={})
+{ // z[i][j] is the value at (x[i],y[j])
+ // p and q are the first derivatives with respect to x and y, respectively
+ // r is the second derivative ddu/dxdy
+ int n=x.length-1;
+ int m=y.length-1;
+
+ bool all=cond.length == 0;
+
+ int count;
+ if(all)
+ count=n*m;
+ else {
+ count=0;
+ for(int i=0; i < n; ++i) {
+ bool[] condi=cond[i];
+ for(int j=0; j < m; ++j)
+ if(condi[j]) ++count;
+ }
+ }
+
+ surface s=surface(count);
+ s.index=new int[n][m];
+ int k=0;
+ for(int i=0; i < n; ++i) {
+ int ip=i+1;
+ real xi=x[i];
+ real xp=x[ip];
+ real x1=interp(xi,xp,1/3);
+ real x2=interp(xi,xp,2/3);
+ real hx=x1-xi;
+ real[] zi=z[i];
+ real[] zp=z[ip];
+ real[] ri=r[i];
+ real[] rp=r[ip];
+ real[] pi=p[i];
+ real[] pp=p[ip];
+ real[] qi=q[i];
+ real[] qp=q[ip];
+ int[] indexi=s.index[i];
+ bool[] condi=all ? null : cond[i];
+ for(int j=0; j < m; ++j) {
+ if(all || condi[j]) {
+ real yj=y[j];
+ int jp=j+1;
+ real yp=y[jp];
+ real y1=interp(yj,yp,1/3);
+ real y2=interp(yj,yp,2/3);
+ real hy=y1-yj;
+ real hxy=hx*hy;
+ real zij=zi[j];
+ real zip=zi[jp];
+ real zpj=zp[j];
+ real zpp=zp[jp];
+ real pij=hx*pi[j];
+ real ppj=hx*pp[j];
+ real qip=hy*qi[jp];
+ real qpp=hy*qp[jp];
+ real zippip=zip+hx*pi[jp];
+ real zppmppp=zpp-hx*pp[jp];
+ real zijqij=zij+hy*qi[j];
+ real zpjqpj=zpj+hy*qp[j];
+
+ s.s[k]=patch(new triple[][] {
+ {(xi,yj,zij),(xi,y1,zijqij),(xi,y2,zip-qip),(xi,yp,zip)},
+ {(x1,yj,zij+pij),(x1,y1,zijqij+pij+hxy*ri[j]),
+ (x1,y2,zippip-qip-hxy*ri[jp]),(x1,yp,zippip)},
+ {(x2,yj,zpj-ppj),(x2,y1,zpjqpj-ppj-hxy*rp[j]),
+ (x2,y2,zppmppp-qpp+hxy*rp[jp]),(x2,yp,zppmppp)},
+ {(xp,yj,zpj),(xp,y1,zpjqpj),(xp,y2,zpp-qpp),(xp,yp,zpp)}},copy=false);
+ indexi[j]=k;
+ ++k;
+ }
+ }
+ }
+
+ return s;
+}
+
+// return the surface described by a real matrix f, interpolated with
+// xsplinetype and ysplinetype.
+surface surface(real[][] f, real[] x, real[] y,
+ splinetype xsplinetype=null, splinetype ysplinetype=xsplinetype,
+ bool[][] cond={})
+{
+ real epsilon=sqrtEpsilon*norm(y);
+ if(xsplinetype == null)
+ xsplinetype=(abs(x[0]-x[x.length-1]) <= epsilon) ? periodic : notaknot;
+ if(ysplinetype == null)
+ ysplinetype=(abs(y[0]-y[y.length-1]) <= epsilon) ? periodic : notaknot;
+ int n=x.length; int m=y.length;
+ real[][] ft=transpose(f);
+ real[][] tp=new real[m][];
+ for(int j=0; j < m; ++j)
+ tp[j]=xsplinetype(x,ft[j]);
+ real[][] q=new real[n][];
+ for(int i=0; i < n; ++i)
+ q[i]=ysplinetype(y,f[i]);
+ real[][] qt=transpose(q);
+ real[] d1=xsplinetype(x,qt[0]);
+ real[] d2=xsplinetype(x,qt[m-1]);
+ real[][] r=new real[n][];
+ real[][] p=transpose(tp);
+ for(int i=0; i < n; ++i)
+ r[i]=clamped(d1[i],d2[i])(y,p[i]);
+ surface s=bispline(f,p,q,r,x,y,cond);
+ if(xsplinetype == periodic) s.ucyclic(true);
+ if(ysplinetype == periodic) s.vcyclic(true);
+ return s;
+}
+
+// return the surface described by a real matrix f, interpolated with
+// xsplinetype and ysplinetype.
+surface surface(real[][] f, pair a, pair b, splinetype xsplinetype,
+ splinetype ysplinetype=xsplinetype, bool[][] cond={})
+{
+ if(!rectangular(f)) abort("matrix is not rectangular");
+
+ int nx=f.length-1;
+ int ny=nx > 0 ? f[0].length-1 : 0;
+
+ if(nx == 0 || ny == 0) return nullsurface;
+
+ real[] x=uniform(a.x,b.x,nx);
+ real[] y=uniform(a.y,b.y,ny);
+ return surface(f,x,y,xsplinetype,ysplinetype,cond);
+}
+
+// return the surface described by a real matrix f, interpolated linearly.
+surface surface(real[][] f, pair a, pair b, bool[][] cond={})
+{
+ if(!rectangular(f)) abort("matrix is not rectangular");
+
+ int nx=f.length-1;
+ int ny=nx > 0 ? f[0].length-1 : 0;
+
+ if(nx == 0 || ny == 0) return nullsurface;
+
+ bool all=cond.length == 0;
+
+ triple[][] v=new triple[nx+1][ny+1];
+ for(int i=0; i <= nx; ++i) {
+ real x=interp(a.x,b.x,i/nx);
+ bool[] condi=all ? null : cond[i];
+ triple[] vi=v[i];
+ real[] fi=f[i];
+ for(int j=0; j <= ny; ++j)
+ if(all || condi[j])
+ vi[j]=(x,interp(a.y,b.y,j/ny),fi[j]);
+ }
+ return surface(v,cond);
+}
+
+// return the surface described by a parametric function f over box(a,b),
+// interpolated linearly.
+surface surface(triple f(pair z), pair a, pair b, int nu=nmesh, int nv=nu,
+ bool cond(pair z)=null)
+{
+ if(nu <= 0 || nv <= 0) return nullsurface;
+
+ bool[][] active;
+ bool all=cond == null;
+ if(!all) active=new bool[nu+1][nv+1];
+
+ real du=1/nu;
+ real dv=1/nv;
+ pair Idv=(0,dv);
+ pair dz=(du,dv);
+
+ triple[][] v=new triple[nu+1][nv+1];
+
+ for(int i=0; i <= nu; ++i) {
+ real x=interp(a.x,b.x,i*du);
+ bool[] activei=all ? null : active[i];
+ triple[] vi=v[i];
+ for(int j=0; j <= nv; ++j) {
+ pair z=(x,interp(a.y,b.y,j*dv));
+ if(all || (activei[j]=cond(z))) vi[j]=f(z);
+ }
+ }
+ return surface(v,active);
+}
+
+// return the surface described by a parametric function f over box(a,b),
+// interpolated with usplinetype and vsplinetype.
+surface surface(triple f(pair z), pair a, pair b, int nu=nmesh, int nv=nu,
+ splinetype[] usplinetype, splinetype[] vsplinetype=Spline,
+ bool cond(pair z)=null)
+{
+ return surface(f,uniform(a.x,b.x,nu),uniform(a.y,b.y,nv),
+ usplinetype,vsplinetype,cond);
+}
+
+// return the surface described by a real function f over box(a,b),
+// interpolated linearly.
+surface surface(real f(pair z), pair a, pair b, int nx=nmesh, int ny=nx,
+ bool cond(pair z)=null)
+{
+ return surface(new triple(pair z) {return (z.x,z.y,f(z));},a,b,nx,ny,cond);
+}
+
+// return the surface described by a real function f over box(a,b),
+// interpolated with xsplinetype and ysplinetype.
+surface surface(real f(pair z), pair a, pair b, int nx=nmesh, int ny=nx,
+ splinetype xsplinetype, splinetype ysplinetype=xsplinetype,
+ bool cond(pair z)=null)
+{
+ bool[][] active;
+ bool all=cond == null;
+ if(!all) active=new bool[nx+1][ny+1];
+
+ real dx=1/nx;
+ real dy=1/ny;
+ pair Idy=(0,dy);
+ pair dz=(dx,dy);
+
+ real[][] F=new real[nx+1][ny+1];
+ real[] x=uniform(a.x,b.x,nx);
+ real[] y=uniform(a.y,b.y,ny);
+ for(int i=0; i <= nx; ++i) {
+ bool[] activei=all ? null : active[i];
+ real[] Fi=F[i];
+ real x=x[i];
+ for(int j=0; j <= ny; ++j) {
+ pair z=(x,y[j]);
+ Fi[j]=f(z);
+ if(!all) activei[j]=cond(z);
+ }
+ }
+ return surface(F,x,y,xsplinetype,ysplinetype,active);
+}
+
+guide3[][] lift(real f(real x, real y), guide[][] g,
+ interpolate3 join=operator --)
+{
+ guide3[][] G=new guide3[g.length][];
+ for(int cnt=0; cnt < g.length; ++cnt) {
+ guide[] gcnt=g[cnt];
+ guide3[] Gcnt=new guide3[gcnt.length];
+ for(int i=0; i < gcnt.length; ++i) {
+ guide gcnti=gcnt[i];
+ guide3 Gcnti=join(...sequence(new guide3(int j) {
+ pair z=point(gcnti,j);
+ return (z.x,z.y,f(z.x,z.y));
+ },size(gcnti)));
+ if(cyclic(gcnti)) Gcnti=Gcnti..cycle;
+ Gcnt[i]=Gcnti;
+ }
+ G[cnt]=Gcnt;
+ }
+ return G;
+}
+
+guide3[][] lift(real f(pair z), guide[][] g, interpolate3 join=operator --)
+{
+ return lift(new real(real x, real y) {return f((x,y));},g,join);
+}
+
+void draw(picture pic=currentpicture, Label[] L=new Label[],
+ guide3[][] g, pen[] p, light light=currentlight, string name="",
+ render render=defaultrender,
+ interaction interaction=LabelInteraction())
+{
+ pen thin=is3D() ? thin() : defaultpen;
+ if(g.length > 1)
+ begingroup3(pic,name == "" ? "contours" : name,render);
+ for(int cnt=0; cnt < g.length; ++cnt) {
+ guide3[] gcnt=g[cnt];
+ pen pcnt=thin+p[cnt];
+ for(int i=0; i < gcnt.length; ++i)
+ draw(pic,gcnt[i],pcnt,light,name);
+ if(L.length > 0) {
+ Label Lcnt=L[cnt];
+ for(int i=0; i < gcnt.length; ++i) {
+ if(Lcnt.s != "" && size(gcnt[i]) > 1)
+ label(pic,Lcnt,gcnt[i],pcnt,name,interaction);
+ }
+ }
+ }
+ if(g.length > 1)
+ endgroup3(pic);
+}
+
+void draw(picture pic=currentpicture, Label[] L=new Label[],
+ guide3[][] g, pen p=currentpen, light light=currentlight,
+ string name="", render render=defaultrender,
+ interaction interaction=LabelInteraction())
+{
+ draw(pic,L,g,sequence(new pen(int) {return p;},g.length),light,name,
+ render,interaction);
+}
+
+real maxlength(triple f(pair z), pair a, pair b, int nu, int nv)
+{
+ return min(abs(f((b.x,a.y))-f(a))/nu,abs(f((a.x,b.y))-f(a))/nv);
+}
+
+// return a vector field on a parametric surface f over box(a,b).
+picture vectorfield(path3 vector(pair v), triple f(pair z), pair a, pair b,
+ int nu=nmesh, int nv=nu, bool truesize=false,
+ real maxlength=truesize ? 0 : maxlength(f,a,b,nu,nv),
+ bool cond(pair z)=null, pen p=currentpen,
+ arrowbar3 arrow=Arrow3, margin3 margin=PenMargin3,
+ string name="", render render=defaultrender)
+{
+ picture pic;
+ real du=1/nu;
+ real dv=1/nv;
+ bool all=cond == null;
+ real scale;
+
+ if(maxlength > 0) {
+ real size(pair z) {
+ path3 g=vector(z);
+ return abs(point(g,size(g)-1)-point(g,0));
+ }
+ real max=size((0,0));
+ for(int i=0; i <= nu; ++i) {
+ real x=interp(a.x,b.x,i*du);
+ for(int j=0; j <= nv; ++j)
+ max=max(max,size((x,interp(a.y,b.y,j*dv))));
+ }
+ scale=max > 0 ? maxlength/max : 1;
+ } else scale=1;
+
+ begingroup3(pic,name == "" ? "vectorfield" : name,render);
+ for(int i=0; i <= nu; ++i) {
+ real x=interp(a.x,b.x,i*du);
+ for(int j=0; j <= nv; ++j) {
+ pair z=(x,interp(a.y,b.y,j*dv));
+ if(all || cond(z)) {
+ path3 g=scale3(scale)*vector(z);
+ string name="vector";
+ if(truesize) {
+ picture opic;
+ draw(opic,g,p,arrow,margin,name,render);
+ add(pic,opic,f(z));
+ } else
+ draw(pic,shift(f(z))*g,p,arrow,margin,name,render);
+ }
+ }
+ }
+ endgroup3(pic);
+ return pic;
+}
+
+triple polar(real r, real theta, real phi)
+{
+ return r*expi(theta,phi);
+}
+
+guide3 polargraph(real r(real,real), real theta(real), real phi(real),
+ int n=ngraph, interpolate3 join=operator --)
+{
+ return graph(join)(new triple(real t) {
+ return polar(r(theta(t),phi(t)),theta(t),phi(t));
+ },0,1,n);
+}
+
+// True arc
+path3 Arc(triple c, triple v1, triple v2, triple normal=O, bool direction=CCW,
+ int n=nCircle)
+{
+ v1 -= c;
+ real r=abs(v1);
+ v1=unit(v1);
+ v2=unit(v2-c);
+
+ if(normal == O) {
+ normal=cross(v1,v2);
+ if(normal == O) abort("explicit normal required for these endpoints");
+ }
+
+ transform3 T=align(unit(normal));
+ transform3 Tinv=transpose(T);
+ v1=Tinv*v1;
+ v2=Tinv*v2;
+
+ real fuzz=sqrtEpsilon*max(abs(v1),abs(v2));
+ if(abs(v1.z) > fuzz || abs(v2.z) > fuzz)
+ abort("invalid normal vector");
+
+ real phi1=radians(longitude(v1,warn=false));
+ real phi2=radians(longitude(v2,warn=false));
+ if(direction) {
+ if(phi1 >= phi2) phi1 -= 2pi;
+ } else if(phi2 >= phi1) phi2 -= 2pi;
+
+ static real piby2=pi/2;
+ return shift(c)*T*polargraph(new real(real theta, real phi) {return r;},
+ new real(real t) {return piby2;},
+ new real(real t) {return interp(phi1,phi2,t);},
+ n,operator ..);
+}
+
+path3 Arc(triple c, real r, real theta1, real phi1, real theta2, real phi2,
+ triple normal=O, bool direction, int n=nCircle)
+{
+ return Arc(c,c+r*dir(theta1,phi1),c+r*dir(theta2,phi2),normal,direction,n);
+}
+
+path3 Arc(triple c, real r, real theta1, real phi1, real theta2, real phi2,
+ triple normal=O, int n=nCircle)
+{
+ return Arc(c,r,theta1,phi1,theta2,phi2,normal,
+ theta2 > theta1 || (theta2 == theta1 && phi2 >= phi1) ? CCW : CW,
+ n);
+}
+
+// True circle
+path3 Circle(triple c, real r, triple normal=Z, int n=nCircle)
+{
+ static real piby2=pi/2;
+ return shift(c)*align(unit(normal))*
+ polargraph(new real(real theta, real phi) {return r;},
+ new real(real t) {return piby2;},
+ new real(real t) {return interp(0,2pi,t);},n,operator ..);
+
+}