2016-12-02 10:19:00

2 files changed, 92 insertions, 30 deletions

diff --git a/metapost/context/base/mpiv/mp-node.mpiv b/metapost/context/base/mpiv/mp-node.mpiv
index e511ca20c..c7b0bcabe 100644
--- a/metapost/context/base/mpiv/mp-node.mpiv
+++ b/metapost/context/base/mpiv/mp-node.mpiv
@@ -18,14 +18,15 @@ if known context_node : endinput ; fi ;
 
 boolean context_node ; context_node := true ;
 
-% returns a picture
+% returns a pair suffix if the path is unknown
 
 vardef makenode@#(suffix p)(text t) =
     save i ; numeric i ;
     for a = t :
-        if not known i : % first argument is the index
+        if unknown i : % first argument is the index
             i = a ;
             if not picture p.pic[i] : picture p.pic[] ; fi
+            if not pair    p.pos[i] : pair    p.pos[] ; fi
                 %
                 % note that one needs to declare "path p[] ; picture p[]pic[] ;"
                 % before calling node() if one is to use a pseudo-array for p
@@ -45,11 +46,19 @@ vardef makenode@#(suffix p)(text t) =
             fi ;
         fi
     endfor
+    p.pos[i] if known p : := point i of p ; fi
 enddef ;
 
+% returns a picture
+
 vardef node@#(suffix p)(text t) =
-    makenode@#(p)(t) ;
+    if pair makenode@#(p)(t) :
+        % nop: gobble the function return.
+    fi
     for a = t :
+        if (unknown p) and (known p.pos[a]) :
+            makenodepath(p) ;
+        fi
         if known p.pic[a] :
             p.pic[a] if known p : shifted point a of p fi
         else :
@@ -65,8 +74,14 @@ vardef fromto@#(expr d)(suffix p)(expr f)(suffix q)(text s) =
     save r, t, l ;
     path r[] ; numeric t ; picture l ;
     for a = s :
-        if not known t :
+        if unknown t :
             t = a ;
+            if (unknown p) and (known p.pos[f]) :
+                makenodepath(p) ;
+            fi
+            if (unknown q) and (known q.pos[t]) :
+                makenodepath(q) ;
+            fi
             r0 = if ((not numeric d) and
                      (point f of p = point f of q) and
                      (point t of p = point t of q)) :
@@ -114,3 +129,46 @@ vardef fromto@#(expr d)(suffix p)(expr f)(suffix q)(text s) =
         r2
     fi
 enddef ;
+
+% returns pair: bounding point of the node picture
+
+vardef nodeboundingpoint@#(suffix p)(expr i) =
+    if known p.pic[i] :
+        boundingpoint@#(p.pic[i])
+    else :
+        origin
+    fi
+enddef ;
+
+% returns pair: scaled laboff direction 
+
+vardef relative@#(expr s) =
+    (mfun_laboff@# scaled s)
+enddef ;
+
+% returns pair: vector between nodes (+ optional scale)
+
+vardef betweennodes@#(suffix p)(expr f)(suffix q)(text s) =
+    save t ; numeric t ;
+    for a = s :
+        if unknown t :
+            t = a ;
+            nodeboundingpoint@#(q,t) + nodeboundingpoint@#(p,f)
+        else :
+            + relative@#(a)
+        fi
+    endfor
+enddef ;
+
+% build a path from the node positions.
+% Must be continuous in index starting at 0.
+
+vardef makenodepath(suffix p) =
+    if unknown p :
+        save i ; i = -1 ;
+        p = forever : exitif unknown p.pos[incr i] ;
+                 p.pos[i] --
+             endfor cycle ;
+    fi
+enddef ;
+
diff --git a/metapost/context/base/mpiv/mp-tool.mpiv b/metapost/context/base/mpiv/mp-tool.mpiv
index 68bc0a9c7..809384ef7 100644
--- a/metapost/context/base/mpiv/mp-tool.mpiv
+++ b/metapost/context/base/mpiv/mp-tool.mpiv
@@ -871,7 +871,7 @@ secondarydef p intersection_point q =
     begingroup
     save x_, y_ ;
     (x_,y_) = p intersectiontimes q ;
-    if x_<0 :
+    if x_ < 0 :
         intersection_found := false ;
         center p % origin
     else :
@@ -3262,25 +3262,21 @@ primarydef p crossingunder q =
             fi
         endfor
     elseif path p :
-        save n, m, t, a, b, c, r, h ;
+        save n, m, t, a, b, c, r, bcuttings, hold ;
         numeric n, m, t[] ;
-        path a, b, c, r, hold[] ;
+        path a, b, c, r, bcuttings, hold[] ;
         c := makepath(currentpen scaled crossingscale) ;
         r := if picture q : boundingbox fi q ;
         t[0] := n := m := 0 ;
         a := p ;
-save last ; numeric last ; last := infinity ;
-        forever : % find all intersections
+        % The cutbefore/cutafter using c below prevents endless loops!
+       %forever : % find all intersections
+        for i=1 upto 100 : % limit the number, until we can make this robust
             clearxy ; z = a intersectiontimes r ;
-exitif x = last ; % prevent loop
-last := x ;
-% maybe we need a threshold for x ;
-% message(decimal x & "+" & decimal m) ;
-            if (x < 0) and (m > 0) :
+            if x < 0 :
+                exitif m < 1 ;
                 a := hold[m] ; m := m - 1 ;
                 clearxy ; z = a intersectiontimes r ;
-            else :
-                exitif x < 0 ;
             fi
             (t[incr n], whatever) = p intersectiontimes point x of a ;
             if x = 0 :
@@ -3288,18 +3284,26 @@ last := x ;
             elseif x = length a :
                 a := a cutafter  c shifted point x of a ;
             else : % before or after?
-                b := subpath (0,x) of a cutafter  c shifted point x of a ;
+                b := subpath (0,x)        of a cutafter  c shifted point x of a ;
+                bcuttings := cuttings ;
                 a := subpath (x,length a) of a cutbefore c shifted point x of a ;
                 clearxy ; z = a intersectiontimes r ;
                 if x < 0 :
                     a := b ;
+                    cuttings := bcuttings ;
                 else :
-                    clearxy ; z = b intersectiontimes r ;
-                    if x >= 0 :
-                        hold[incr m] := b ;
+                    if length bcuttings > 0 :
+                        clearxy ; z = b intersectiontimes r ;
+                        if x >= 0 :
+                            hold[incr m] := b ;
+                        fi
                     fi
                 fi
             fi
+            if length cuttings = 0 :
+                exitif m < 1 ;
+                a := hold[m] ; m := m - 1 ;
+            fi
         endfor
 
         if n = 0 : % No crossings, we return the PATH
@@ -3316,6 +3320,16 @@ last := x ;
             for i=if cycle p: 2 else: 1 fi upto n :
                 % skip the first segment if cyclic
                 % as it gets repeated (fully) at the end.
+                if crossingoption > 0 :
+                    if crossingoption = 1 :
+                        addto pic doublepath c shifted point t[i] of p
+                        withpen currentpen withtransparency(1,.5) ;
+                    elseif crossingoption = 2 :
+                        addto pic also
+                        infotext (incr m,crossingscale/5)
+                        shifted point t[i] of p ;
+                    fi
+                fi
                 a := subpath (t[i-1],t[i]) of p
                     if i > 1 :
                         cutbefore (c shifted point t[i-1] of p)
@@ -3324,16 +3338,6 @@ last := x ;
                         cutafter  (c shifted point t[i]   of p)
                     fi ;
                 if (not picture q) or (a outsideof q) :
-                    if crossingoption > 0 :
-                        addto pic also infotext (
-                            if crossingoption = 1 :
-                                incr(m)
-                            elseif crossingoption = 2 :
-                                i if cycle p: -1 fi
-                            fi
-                            ,crossingscale/5)
-                        shifted point t[i] of p ;                        ;
-                    fi ;
                     addto pic doublepath a withpen currentpen ;
                 fi
             endfor