2015-03-09 19:29:00

4 files changed, 45 insertions, 24 deletions

diff --git a/metapost/context/base/mp-chem.mpiv b/metapost/context/base/mp-chem.mpiv
index a316a1a30..7ca40bbea 100644
--- a/metapost/context/base/mp-chem.mpiv
+++ b/metapost/context/base/mp-chem.mpiv
@@ -11,7 +11,8 @@
 %C therefore copyrighted by \PRAGMA. See licen-en.pdf for
 %C details.
 
-%D This module is incomplete and experimental.
+%D This module is incomplete and experimental. Okay, it's not that bad but we do need
+%D some disclaimer.
 
 % either consistent setting or not
 
@@ -300,7 +301,6 @@ enddef ;
 
 chem_init_all ; % WHY does this not work unless defined and then called?
 
-
 % Like most often in ConTeXt, we will trap but then silently ignore mistaken use,
 % unless of course the error be too harmful...
 
@@ -529,6 +529,17 @@ vardef chem_set (suffix $) =
     % This is a fairly complicated optimization and ajustement. It took some
     % thinking to get right, so beware!
 
+    % And then even more time fixing a bug of a rotation +- half the symmetry
+    % angle of a structure depending on the scale and/or the font size
+    % (through chem_b_length).
+
+    % first save the symmetry angle of the structure (as in chem_rot):
+    chem_num0 := if chem_stacked[$] : 3 else : 0 fi ;
+    chem_num9 := if chem_tetra[$] : 360 else :
+                 abs(angle(point 0+chem_num0 of chem_b_path[$]) -
+                     angle(point 1+chem_num0 of chem_b_path[$]))
+                 fi ;
+
     if (chem_adjacent<>0) and chem_star[P] and chem_star[$] :
         % nop
         chem_adjacent := 0 ;
@@ -581,7 +592,8 @@ vardef chem_set (suffix $) =
                           -((point (chem_adjacent-1) of chem_b_path[P]) chem_transformed(P)) ;
         fi
         % adjust the bond angles
-        chem_rotation := (chem_rotation + angle(chem_pair1)-angle(chem_pair3)) mod 360 ;
+        chem_num4 := (angle(chem_pair1)-angle(chem_pair3)) zmod chem_num9 ;
+        chem_rotation := chem_rotation + chem_num4 ;
         if not chem_star[$] :
             chem_pair4 :=
                 if chem_star[P] :
@@ -666,7 +678,8 @@ vardef chem_set (suffix $) =
                 fi
             endfor
             if not chem_front[$] : % adjust rotation
-                chem_rotation := (chem_rotation + angle(chem_pair1)-angle(chem_pair3)) mod 360 ;
+                chem_num4 := angle(chem_pair1)-angle(chem_pair3) ;
+                chem_rotation := (chem_rotation + chem_num4) mod 360 ;
             fi ;
             chem_t := identity chem_transformed($) ;
             chem_pair4 := (point chem_num3 of chem_b_path[$]) transformed chem_t ;
@@ -674,6 +687,9 @@ vardef chem_set (suffix $) =
                 currentpicture := currentpicture shifted chem_pair4 ;
                 chem_origin    := chem_origin    shifted chem_pair4 ;
             fi
+            if not chem_front[$] : % adjust rotation
+                chem_rotation := chem_rotation zmod chem_num9 ;
+            fi
         fi
         chem_substituent := 0 ;
     fi ;
@@ -1571,9 +1587,9 @@ vardef chem_rot (suffix $) (expr d, s) = % ROT
             chem_rotation := 0
         else :
             chem_num0 := if chem_stacked[$] : 3 else : 0 fi ;
-            chem_num1 := .5(angle(point d+chem_num0 of chem_b_path[$]) -
+            chem_num1 := .5(angle(point d+chem_num0   of chem_b_path[$]) -
                             angle(point d+chem_num0-1 of chem_b_path[$])) ;
-            chem_rotation := (chem_rotation + s*chem_num1) mod 360 ;
+            chem_rotation := (chem_rotation + s*chem_num1) zmod 360 ;
         fi
     fi
 enddef ;
@@ -1584,7 +1600,7 @@ vardef chem_mir (suffix $) (expr d, s)  = % MIR
     if not chem_front[$] :
         if d=0 : % inversion
             if chem_mirror=origin :
-                chem_rotation := (chem_rotation + 180*s) mod 360 ;
+                chem_rotation := (chem_rotation + 180*s) zmod 360 ;
             else :
                 chem_mirror := chem_mirror rotated 90 ;
             fi
@@ -1600,7 +1616,7 @@ vardef chem_mir (suffix $) (expr d, s)  = % MIR
                     chem_num0 := -360 - chem_num0 ;
                 fi
                 chem_num0 := chem_num0 * s ;
-                chem_rotation := (chem_rotation + 2chem_num0) mod 360 ;
+                chem_rotation := (chem_rotation + 2chem_num0) zmod 360 ;
                 chem_mirror := origin ;
             fi
         fi
diff --git a/metapost/context/base/mp-mlib.mpiv b/metapost/context/base/mp-mlib.mpiv
index 1140673ab..907c0c4b7 100644
--- a/metapost/context/base/mp-mlib.mpiv
+++ b/metapost/context/base/mp-mlib.mpiv
@@ -390,11 +390,11 @@ string mfun_prescript_separator ; mfun_prescript_separator := char(13) ;
 % Shades
 
 % for while we had this:
-%
-% newinternal shadefactor  ; shadefactor  := 1 ;
-% pair        shadeoffset  ; shadeoffset  := origin ;
-% boolean     trace_shades ; trace_shades := false ;
-%
+
+newinternal shadefactor  ; shadefactor  := 1 ;      % currently obsolete
+pair        shadeoffset  ; shadeoffset  := origin ; % currently obsolete
+boolean     trace_shades ; trace_shades := false ;  % still there
+
 % def withlinearshading (expr a, b) =
 %     withprescript "sh_type=linear"
 %     withprescript "sh_domain=0 1"
@@ -523,8 +523,8 @@ def withcircularshade (expr a, b, ra, rb, ca, cb) =
     withprescript "sh_factor=1"
     withprescript "sh_color_a="  & colordecimals ca
     withprescript "sh_color_b="  & colordecimals cb
-    withprescript "sh_center_a=" & ddecimal (a shifted shadeoffset)
-    withprescript "sh_center_b=" & ddecimal (b shifted shadeoffset)
+    withprescript "sh_center_a=" & ddecimal a % (a shifted shadeoffset)
+    withprescript "sh_center_b=" & ddecimal b % (b shifted shadeoffset)
     withprescript "sh_radius_a=" & decimal ra
     withprescript "sh_radius_b=" & decimal rb
 enddef ;
@@ -535,8 +535,8 @@ def withlinearshade (expr a, b, ca, cb) =
     withprescript "sh_factor=1"
     withprescript "sh_color_a="  & colordecimals ca
     withprescript "sh_color_b="  & colordecimals cb
-    withprescript "sh_center_a=" & ddecimal (a shifted shadeoffset)
-    withprescript "sh_center_b=" & ddecimal (b shifted shadeoffset)
+    withprescript "sh_center_a=" & ddecimal a % (a shifted shadeoffset)
+    withprescript "sh_center_b=" & ddecimal b % (b shifted shadeoffset)
 enddef ;
 
 % replaced (obsolete):
@@ -595,8 +595,8 @@ vardef define_circular_shade (expr a, b, ra, rb, ca, cb) =
     & mfun_prescript_separator & "sh_factor=1"
     & mfun_prescript_separator & "sh_color_a="  & colordecimals ca
     & mfun_prescript_separator & "sh_color_b="  & colordecimals cb
-    & mfun_prescript_separator & "sh_center_a=" & ddecimal (a shifted shadeoffset)
-    & mfun_prescript_separator & "sh_center_b=" & ddecimal (b shifted shadeoffset)
+    & mfun_prescript_separator & "sh_center_a=" & ddecimal a % (a shifted shadeoffset)
+    & mfun_prescript_separator & "sh_center_b=" & ddecimal b % (b shifted shadeoffset)
     & mfun_prescript_separator & "sh_radius_a=" & decimal ra
     & mfun_prescript_separator & "sh_radius_b=" & decimal rb
     ;
@@ -610,8 +610,8 @@ vardef define_linear_shade (expr a, b, ca, cb) =
     & mfun_prescript_separator & "sh_factor=1"
     & mfun_prescript_separator & "sh_color_a=" & colordecimals ca
     & mfun_prescript_separator & "sh_color_b=" & colordecimals cb
-    & mfun_prescript_separator & "sh_center_a=" & ddecimal (a shifted shadeoffset)
-    & mfun_prescript_separator & "sh_center_b=" & ddecimal (b shifted shadeoffset)
+    & mfun_prescript_separator & "sh_center_a=" & ddecimal a % (a shifted shadeoffset)
+    & mfun_prescript_separator & "sh_center_b=" & ddecimal b % (b shifted shadeoffset)
     ;
     mfun_defined_cs
 enddef ;
diff --git a/metapost/context/base/mp-tool.mpii b/metapost/context/base/mp-tool.mpii
index 62bd122f5..a5bb345a1 100644
--- a/metapost/context/base/mp-tool.mpii
+++ b/metapost/context/base/mp-tool.mpii
@@ -1407,7 +1407,7 @@ primarydef pct along pat = % also negative
 enddef ;
 
 primarydef len on pat = % no outer ( ) .. somehow fails
-    (arctime if len>0 : len else : (arclength(pat)+len) fi of pat) of pat
+    (arctime if len>=0 : len else : (arclength(pat)+len) fi of pat) of pat
 enddef ;
 
 % this cuts of a piece from both ends
diff --git a/metapost/context/base/mp-tool.mpiv b/metapost/context/base/mp-tool.mpiv
index dda8e84a1..30c3f0f50 100644
--- a/metapost/context/base/mp-tool.mpiv
+++ b/metapost/context/base/mp-tool.mpiv
@@ -368,6 +368,11 @@ vardef asinh  primary x = ln(x+(x++1))     enddef ;
 vardef sinh   primary x = save xx ; xx = exp x ; (xx-1/xx)/2 enddef ;
 vardef cosh   primary x = save xx ; xx = exp x ; (xx+1/xx)/2 enddef ;
 
+%D Like mod, but useful for anglesl it returns (-.5d,+.5d] and is used
+%D in for instance mp-chem.
+
+primarydef a zmod b = (-((b/2 - a) mod b) + b/2) enddef ;
+
 %D Sometimes this is handy:
 
 def undashed =
@@ -1364,7 +1369,7 @@ primarydef pct along pat = % also negative
 enddef ;
 
 primarydef len on pat = % no outer ( ) .. somehow fails
-    (arctime if len>0 : len else : (arclength(pat)+len) fi of pat) of pat
+    (arctime if len>=0 : len else : (arclength(pat)+len) fi of pat) of pat
 enddef ;
 
 % this cuts of a piece from both ends
@@ -2315,7 +2320,7 @@ enddef ;
 %D Handy:
 
 def break =
-    exitif true fi ;
+    exitif true ; % fi
 enddef ;
 
 %D New too: