beta 2009.05.28 11:23

7 files changed, 960 insertions, 49 deletions

diff --git a/metapost/context/base/metafun.mp b/metapost/context/base/metafun.mp
index b828b8b9e..00011c8be 100644
--- a/metapost/context/base/metafun.mp
+++ b/metapost/context/base/metafun.mp
@@ -49,6 +49,8 @@ input mp-figs.mp ;
 
 input mp-mlib.mp ;
 
+if known context_mlib : input mp-chem.mp ; fi ; % only when mkiv
+
 %     mp-form.mp ;
 input mp-grid.mp ;
 input mp-func.mp ;
diff --git a/metapost/context/base/mp-chem.mp b/metapost/context/base/mp-chem.mp
new file mode 100644
index 000000000..1a5be8416
--- /dev/null
+++ b/metapost/context/base/mp-chem.mp
@@ -0,0 +1,729 @@
+%D \module
+%D   [       file=mp-chem.mp,
+%D        version=2009.05.13,
+%D          title=\CONTEXT\ \METAPOST\ graphics,
+%D       subtitle=chemicals,
+%D         author=Hans Hagen,
+%D           date=\currentdate,
+%D      copyright=\PRAGMA]
+%C
+%C This module is part of the \CONTEXT\ macro||package and is
+%C therefore copyrighted by \PRAGMA. See licen-en.pdf for
+%C details.
+
+%D This module in incomplete and experimental.
+
+% either consistent setting or not
+
+if known chem_reset : endinput ; fi ;
+
+numeric
+    chem_width, chem_radical_min, chem_radical_max, chem_text_max, chem_circle_radius,
+    chem_rotation, chem_adjacent, chem_stack, chem_substituent, chem_direction, chem_setting_scale,
+    chem_setting_offset, chem_text_offset, chem_picture_offset, chem_center_offset, chem_substituent_offset,
+    chem_setting_l, chem_setting_r, chem_setting_t, chem_setting_b ;
+
+boolean
+    chem_setting_axis,
+    chem_setting_fixedwidth, chem_setting_fixedheight,
+    chem_doing_pb, chem_text_trace ;
+
+path
+    chem_setting_bbox ;
+
+pair
+    chem_shift,
+    chem_adjacent_p, chem_substituent_p, chem_direction_p, chem_move_p ;
+
+numeric
+    chem_width[], chem_angle[], chem_start[], chem_initialrot[], chem_initialmov[] ;
+
+pair
+    chem_stack_d[],
+    chem_b_zero[], chem_n_zero[],
+    chem_r_max[], chem_r_min[],
+    chem_r_zero[], chem_mr_zero[], chem_pr_zero[], chem_crz_zero[],
+    chem_rt_zero[], chem_rtt_zero[], chem_rbt_zero[],
+    chem_mid_zero[] ;
+
+path
+    chem_b_path[], chem_bx_path[], chem_eb_path[], chem_sr_path[], chem_br_path[],
+    chem_sb_path[], chem_msb_path[], chem_psb_path[],
+    chem_s_path[], chem_ss_path[], chem_mss_path[], chem_pss_path[],
+    chem_e_path[], chem_sd_path[], chem_bb_path[], chem_oe_path[],
+    chem_ddt_path[], chem_ddb_path[], chem_ldt_path[], chem_ldb_path[], chem_rdt_path[], chem_rdb_path[],
+    chem_dbl_path[], chem_dbr_path[],
+    chem_ad_path[], chem_au_path[],
+    chem_r_path[], chem_rl_path[], chem_rr_path[],
+    chem_rb_path[], chem_prb_path[], chem_mrb_path[],
+    chem_srl_path[], chem_srr_path[],
+    chem_msr_path[], chem_psr_path[],
+    chem_mr_path[], chem_pr_path[],
+    chem_c_path[], chem_cc_path[],
+    chem_midt_path[], chem_midb_path[], chem_midst_path[], chem_midsb_path[] ;
+
+chem_setting_scale      :=  1 ;
+chem_base_width         := 40pt ;
+chem_text_offset        :=  3pt ;
+chem_center_offset      :=  6pt ;
+chem_picture_offset     := 10pt ;
+chem_substituent_offset := 10pt ;
+chem_radical_min        :=  1.25 ;
+chem_radical_max        :=  1.50 ;
+chem_text_min           :=  0.75 ;
+chem_text_max           :=  1.75 ;
+chem_circle_radius      :=  0.80 ;
+chem_rotation           :=  1 ;
+chem_adjacent           :=  0 ;
+chem_substituent        :=  0 ;
+chem_direction          :=  0 ;
+chem_stack_n            :=  0 ;
+chem_doing_pb           :=  false ;
+chem_shift              := origin ;
+chem_dot_factor         := 4 ;
+chem_text_trace         := false ;
+
+vardef chem_start_structure(expr n, l, r, t, b, scale, axis, fixedwidth, fixedheight, offset) =
+    chem_setting_axis := axis ;
+    chem_setting_l := l * scale ;
+    chem_setting_r := r * scale ;
+    chem_setting_t := t * scale ;
+    chem_setting_b := b * scale ;
+    chem_setting_fixedwidth := fixedwidth ;
+    chem_setting_fixedheight := fixedheight ;
+    chem_setting_offset := offset ;
+    if scale <> chem_setting_scale :
+        chem_setting_scale := scale ;
+        chem_init_all ;
+    fi ;
+    chem_rotation    := 1 ;
+    chem_adjacent    := 0 ;
+    chem_substituent := 0 ;
+    chem_direction   := 0 ;
+    chem_stack_n     := 0 ;
+    chem_doing_pb    := false ;
+    chem_shift       := origin ;
+enddef ;
+
+def chem_stop_structure =
+    currentpicture := currentpicture shifted - chem_shift ;
+    % axis here
+    if chem_setting_fixedwidth :
+        chem_setting_l := - xpart llcorner currentpicture ;
+        chem_setting_r :=   xpart urcorner currentpicture ;
+    fi ;
+    if chem_setting_fixedheight :
+        chem_setting_t :=   ypart urcorner currentpicture ;
+        chem_setting_b := - ypart llcorner currentpicture ;
+    fi ;
+    chem_setting_bbox :=
+        (-chem_setting_l,-chem_setting_b) -- ( chem_setting_r,-chem_setting_b) --
+        ( chem_setting_r, chem_setting_t) -- (-chem_setting_l, chem_setting_t) -- cycle ;
+    % maybe put it behind the picture
+    if chem_setting_axis :
+        save stp ; stp := chem_base_width/ 2 * chem_setting_scale ;
+        save siz ; siz := chem_base_width/10 * chem_setting_scale ;
+        draw (-chem_setting_l,0) -- (chem_setting_r,0) withcolor blue ;
+        draw (0,-chem_setting_b) -- (0,chem_setting_t) withcolor blue ;
+        for i = 0 step  stp until  chem_setting_r : draw (i,-siz) -- (i,siz) withcolor blue ; endfor ;
+        for i = 0 step -stp until -chem_setting_l : draw (i,-siz) -- (i,siz) withcolor blue ; endfor ;
+        for i = 0 step  stp until  chem_setting_t : draw (-siz,i) -- (siz,i) withcolor blue ; endfor ;
+        for i = 0 step -stp until -chem_setting_b : draw (-siz,i) -- (siz,i) withcolor blue ; endfor ;
+        draw chem_setting_bbox withcolor blue ;
+    fi ;
+    setbounds currentpicture to chem_setting_bbox ;
+enddef ;
+
+def chem_start_component =
+enddef ;
+def chem_stop_component =
+enddef ;
+
+def chem_pb =
+% draw boundingbox currentpicture withpen pencircle scaled 1mm withcolor blue ;
+% draw origin withpen pencircle scaled 2mm withcolor blue ;
+    chem_doing_pb := true ;
+enddef ;
+def chem_pe =
+% draw boundingbox currentpicture withpen pencircle scaled .5mm withcolor red ;
+% draw origin withpen pencircle scaled 1mm withcolor red ;
+    currentpicture := currentpicture shifted - chem_shift ;
+% draw origin withpen pencircle scaled .5mm withcolor green ;
+    chem_shift := origin ;
+    chem_doing_pb := false ;
+enddef ;
+
+vardef chem_do (expr p) =
+    if chem_doing_pb :
+        chem_doing_pb := false ;
+%         save pp ; pair pp ; pp := point 1 of ((origin -- p) enlonged chem_picture_offset) ;
+%         currentpicture := currentpicture shifted - pp ;
+%         chem_shift := chem_shift - center pp ;
+        currentpicture := currentpicture shifted - p ;
+        chem_shift := chem_shift - p ;
+        origin %  nullpicture
+    else :
+        p
+    fi
+enddef ;
+
+vardef chem_b (expr n, f, t, r, c) =
+    chem_draw (n, chem_b_path[n], f, t, r, c)  ;
+enddef ;
+vardef chem_sb (expr n, f, t, r, c) =
+    chem_draw (n, chem_sb_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_s (expr n, f, t, r, c) =
+    chem_draw (n, chem_s_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_ss (expr n, f, t, r, c) =
+    chem_draw (n, chem_ss_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_mid (expr n, r, c) =
+    chem_draw_fixed (n, chem_midt_path[n], r, c) ;
+    chem_draw_fixed (n, chem_midb_path[n], r, c) ;
+enddef ;
+vardef chem_mids (expr n, r, c) =
+    chem_draw_fixed (n, chem_midst_path[n], r, c) ;
+    chem_draw_fixed (n, chem_midsb_path[n], r, c) ;
+enddef ;
+vardef chem_mss (expr n, f, t, r, c) =
+    chem_draw (n, chem_mss_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_pss (expr n, f, t, r, c) =
+    chem_draw (n, chem_pss_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_msb (expr n, f, t, r, c) =
+    chem_draw (n, chem_msb_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_psb (expr n, f, t, r, c) =
+    chem_draw (n, chem_psb_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_eb  (expr n, f, t, r, c) =
+    chem_draw (n, chem_eb_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_db (expr n, f, t, r, c) =
+    if n = 1 :
+        chem_draw (n, chem_msb_path [n], f, t, r, c) ;
+        chem_draw (n, chem_psb_path [n], f, t, r, c) ;
+    else :
+        chem_draw (n, chem_dbl_path  [n], f, t, r, c) ;
+        chem_draw (n, chem_dbr_path  [n], f, t, r, c) ;
+    fi ;
+enddef ;
+vardef chem_er (expr n, f, t, r, c) =
+    chem_draw (n, chem_rl_path[n], f, t, r, c) ;
+    chem_draw (n, chem_rr_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_dr (expr n, f, t, r, c) =
+    chem_draw (n, chem_srl_path[n], f, t, r, c) ;
+    chem_draw (n, chem_srr_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_ad (expr n, f, t, r, c) =
+    chem_draw_arrow(n, chem_ad_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_au (expr n, f, t, r, c) =
+    chem_draw_arrow(n, chem_au_path[n], f, t, r, c)
+enddef ;
+vardef chem_r (expr n, f, t, r, c) =
+    if n < 0 :
+        chem_draw_vertical (n, chem_r_path[n], f, t, r, c) ;
+    else :
+        chem_draw (n, chem_r_path[n], f, t, r, c) ;
+    fi ;
+enddef ;
+vardef chem_rd (expr n, f, t, r, c) =
+    chem_dashed_normal (n, chem_r_path[n], f, t, r, c)
+enddef ;
+vardef chem_mrd (expr n, f, t, r, c) =
+    chem_dashed_normal (n, chem_mr_path[n], f, t, r, c)
+enddef ;
+vardef chem_prd (expr n, f, t, r, c) =
+    chem_dashed_normal (n, chem_pr_path[n], f, t, r, c)
+enddef ;
+vardef chem_br (expr n, f, t, r, c) =
+    chem_fill (n, chem_br_path[n], f, t, r, c )
+enddef ;
+vardef chem_rb (expr n, f, t, r, c) =
+    chem_fill (n, chem_rb_path[n], f, t, r, c)
+enddef ;
+vardef chem_mrb (expr n, f, t, r, c) =
+    chem_fill (n, chem_mrb_path[n], f, t, r, c)
+enddef ;
+vardef chem_prb (expr n, f, t, r, c) =
+    chem_fill (n, chem_prb_path[n], f, t, r, c)
+enddef ;
+vardef chem_mr (expr n, f, t, r, c) =
+    if n < 0 :
+        chem_draw_vertical(n, chem_mr_path[n], f, t, r, c)
+    else :
+        chem_draw (n, chem_mr_path[n], f, t, r, c)
+    fi
+enddef ;
+vardef chem_pr (expr n, f, t, r, c) =
+    if n < 0 :
+        chem_draw_vertical(n, chem_pr_path[n], f, t, r, c)
+    else :
+        chem_draw (n, chem_pr_path[n], f, t, r, c)
+    fi
+enddef ;
+vardef chem_sr (expr n, f, t, r, c) =
+    chem_draw (n, chem_sr_path[n], f, t, r, c)
+enddef ;
+vardef chem_msr (expr n, f, t, r, c) =
+    chem_draw (n, chem_msr_path[n], f, t, r, c)
+enddef ;
+vardef chem_psr (expr n, f, t, r, c) =
+    chem_draw (n, chem_psr_path[n], f, t, r, c)
+enddef ;
+vardef chem_c (expr n, f, t, r, c) =
+    chem_draw (n, chem_c_path[n], f, t, r, c)
+enddef ;
+vardef chem_cc (expr n, f, t, r, c) =
+    chem_draw (n, chem_cc_path[n], f, f, r, c)
+enddef ;
+vardef chem_cd (expr n, f, t, r, c) =
+    chem_dashed_connected (n, chem_c_path[n], f, t, r, c)
+enddef ;
+vardef chem_ccd (expr n, f, t, r, c) =
+    chem_dashed_normal (n, chem_cc_path[n], f, f, r, c)
+enddef ;
+vardef chem_rn  (expr n, i, t) =
+    chem_rt (n,i,t) ;
+enddef ;
+vardef chem_rtn (expr n, i, t) =
+    chem_rtt(n,i,t) ;
+enddef ;
+vardef chem_rbn (expr n, i, t) =
+    chem_rbt(n,i,t) ;
+enddef ;
+vardef chem_tb (expr n, f, t, r, c) = % one
+    chem_draw (n, chem_msb_path[n], f, t, r, c) ;
+    chem_draw (n, chem_sb_path [n], f, t, r, c) ;
+    chem_draw (n, chem_psb_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_ep (expr n, f, t, r, c) = % one
+    chem_draw (n, chem_e_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_es (expr n, f, t, r, c) = % one
+    chem_draw_dot (n, center chem_e_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_ed (expr n, f, t, r, c) = % one
+    chem_draw_dot (n, point 0 of chem_e_path[n], f, t, r, c) ;
+    chem_draw_dot (n, point 1 of chem_e_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_et (expr n, f, t, r, c) = % one
+    chem_draw_dot (n, point 0 of chem_e_path[n], f, t, r, c) ;
+    chem_draw_dot (n, center     chem_e_path[n], f, t, r, c) ;
+    chem_draw_dot (n, point 1 of chem_e_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_sd (expr n, f, t, r, c) = % one
+    chem_draw (n, chem_ddt_path[n], f, t, r, c) ;
+    chem_draw (n, chem_ddb_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_rdd (expr n, f, t, r, c) = % one
+    chem_draw (n, chem_ldt_path[n], f, t, r, c) ;
+    chem_draw (n, chem_ldb_path[n], f, t, r, c) ;
+    chem_draw (n, chem_psb_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_ldd (expr n, f, t, r, c) = % one
+    chem_draw (n, chem_msb_path[n], f, t, r, c) ;
+    chem_draw (n, chem_rdt_path[n], f, t, r, c) ;
+    chem_draw (n, chem_rdb_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_hb (expr n, f, t, r, c) = % one
+    chem_draw_dot (n, point 0 of chem_sb_path[n], f, t, r, c) ;
+    chem_draw_dot (n, center     chem_sb_path[n], f, t, r, c) ;
+    chem_draw_dot (n, point 1 of chem_sb_path[n], f, t, r, c) ;
+enddef ;
+vardef chem_bb (expr n, f, t, r, c) = % one
+    if n < 0 :
+        chem_fill (n, chem_bb_path[n], 1, 1, r, c) ;
+        chem_b (n, f, t, r, c) ;
+    else :
+        chem_fill (n, chem_bb_path[n], f, t, r, c) ;
+    fi ;
+enddef ;
+vardef chem_oe (expr n, f, t, r, c) = % one
+    chem_draw (n, chem_oe_path[n], f, t, r, c) ;
+enddef ;
+
+vardef chem_z_zero@#(text t) =
+    chem_text@#(t, chem_do(origin)) ;
+enddef ;
+vardef chem_cz_zero@#(text t) =
+    chem_text@#(t, chem_do(origin)) ;
+enddef ;
+vardef chem_z@#(expr n, p) (text t) =
+    if p = 0 :
+        chem_text@#(t, chem_do(origin)) ;
+    else :
+        chem_text@#(t, chem_do(chem_b_zero[n] rotated chem_ang(n,p))) ;
+    fi ;
+enddef ;
+vardef chem_cz@#(expr n, p) (text t) =
+    if n = 1 :
+        chem_c_text(t, chem_do(chem_crz_zero[n] rotated chem_ang(n,p))) ;
+    else :
+        chem_text@#(t, chem_do(chem_b_zero[n] rotated chem_ang(n,p))) ;
+    fi ;
+enddef ;
+vardef chem_midz@#(expr n, p) (text t) =
+    chem_text@#(t, chem_do(chem_mid_zero[n] rotated chem_ang(n,p))) ;
+enddef ;
+vardef chem_rz@#(expr n, p) (text t) =
+    if n < 0 :
+        % quite special
+        chem_text@#(t, chem_do(chem_r_zero[n] shifted (chem_b_zero[n] rotated chem_ang(n,p)))) ;
+    else :
+        chem_text@#(t, chem_do(chem_r_zero[n] rotated chem_ang(n,p))) ;
+    fi ;
+enddef ;
+vardef chem_crz@#(expr n, p) (text tx) =
+    chem_text(tx, chem_do(chem_crz_zero[n] rotated chem_ang(n,p))) ;
+enddef ;
+vardef chem_mrz@#(expr n, p) (text t) =
+    if n < 0 :
+        % quite special
+        chem_text@#(t, chem_do(chem_mr_zero[n] shifted (chem_b_zero[n] rotated chem_ang(n,p)))) ;
+    else :
+        chem_text@#(t, chem_do(chem_mr_zero[n] rotated chem_ang(n,p))) ;
+    fi ;
+enddef ;
+vardef chem_prz@#(expr n, p) (text t) =
+    if n < 0 :
+        % quite special
+        chem_text@#(t, chem_do(chem_pr_zero[n] shifted (chem_b_zero[n] rotated chem_ang(n,p)))) ;
+    else :
+        chem_text@#(t, chem_do(chem_pr_zero[n] rotated chem_ang(n,p))) ;
+    fi ;
+enddef ;
+vardef chem_rt@#(expr n, p) (text t) =
+    chem_text@#(t, chem_do(chem_rt_zero[n] rotated chem_ang(n,p))) ;
+enddef ;
+vardef chem_rtt@#(expr n, p) (text t) =
+    chem_text@#(t, chem_do(chem_rtt_zero[n] rotated chem_ang(n,p))) ;
+enddef ;
+vardef chem_rbt@#(expr n, p) (text t) =
+    chem_text@#(t, chem_do(chem_rbt_zero[n] rotated chem_ang(n,p))) ;
+enddef ;
+vardef chem_zt@#(expr n, p) (text t) =
+    if n = 1 :
+        chem_text@#(t, chem_do(chem_rt_zero[n] rotated chem_ang(n,p))) ;
+    else :
+        chem_text@#(t, chem_do(chem_n_zero[n] rotated chem_ang(n,p))) ;
+    fi ;
+enddef ;
+vardef chem_zn@#(expr n, p) (text t) =
+    if n = 1 :
+        chem_text@#(t, chem_do(chem_rt_zero[n] rotated chem_ang(n,p))) ;
+    else :
+        chem_text@#(t, chem_do(chem_n_zero[n] rotated chem_ang(n,p))) ;
+    fi ;
+enddef ;
+vardef chem_zbt@#(expr n, p) (text t) =
+    chem_text@#(t, chem_do(chem_rtt_zero[n] rotated chem_ang(n,p))) ;
+enddef ;
+vardef chem_zbn@#(expr n, p) (text t) =
+    chem_text@#(t, chem_do(chem_rtt_zero[n] rotated chem_ang(n,p))) ;
+enddef ;
+vardef chem_ztt@#(expr n, p) (text t) =
+    chem_text@#(t, chem_do(chem_rbt_zero[n] rotated chem_ang(n,p))) ;
+enddef ;
+vardef chem_ztn@#(expr n, p) (text t) =
+    chem_text@#(t, chem_do(chem_rbt_zero[n] rotated chem_ang(n,p))) ;
+enddef ;
+
+vardef chem_symbol(expr t) =
+    draw textext(t) ;
+enddef ;
+
+vardef chem_text@#(expr txt, z) = % adapted copy of thelabel@
+    save p ; picture p ;
+    p := textext(txt) ;
+    p := p
+        if (labtype@# >= 10) : shifted (0,ypart center p) fi
+        shifted (z + chem_text_offset*laboff@# - (labxf@#*lrcorner p + labyf@#*ulcorner p + (1-labxf@#-labyf@#)*llcorner p)) ;
+    if chem_text_trace :
+        draw z             withpen pencircle scaled 2pt withcolor red ;
+        draw boundingbox p withpen pencircle scaled 1pt withcolor red ;
+    fi ;
+    draw p
+enddef ;
+
+vardef chem_c_text(expr txt, z) = % adapted copy of thelabel@
+    save p ; picture p ; p := textext(txt) ;
+    save b ; path b ; b := (boundingbox p) shifted z ;
+    save a ; pair a ; a := (origin--z) intersection_point b ;
+    if intersection_found :
+        draw p shifted (z enlonged arclength(a -- center b)) ;
+    else :
+        draw p shifted z ;
+    fi
+%     draw b withcolor green ;
+%     draw a withcolor red ;
+enddef ;
+
+vardef chem_ang (expr n, d) =
+    ((-1 * (d-1) * chem_angle[n]) + (-chem_rotation+1) * 90 + chem_start[n]) % no ;
+enddef ;
+vardef chem_rot (expr n, d) =
+    chem_rotation := d ;
+enddef ;
+vardef chem_adj (expr n, d) =
+    chem_adjacent := d ;
+enddef ;
+vardef chem_sub (expr n, d) =
+    chem_substituent := d ;
+enddef ;
+vardef chem_dir (expr n, d) =
+    if n = 1 :
+        chem_direction_p := (origin - 2*center(chem_b_path[n] rotated chem_ang(n,d+1))) ;
+        currentpicture := currentpicture shifted chem_direction_p ;
+        chem_shift := chem_shift + chem_direction_p ;
+    fi ;
+enddef ;
+vardef chem_mov (expr n, d) =
+    if d = 0 :
+        currentpicture := currentpicture shifted - chem_shift ;
+        chem_shift := origin ;
+    else :
+        chem_move_p := (origin - 2*center(chem_b_path[n] rotated chem_ang(n,d+chem_initialmov[n]))) ;
+        currentpicture := currentpicture shifted chem_move_p ;
+        chem_shift := chem_shift + chem_move_p ;
+    fi ;
+enddef ;
+vardef chem_off (expr n, d) =
+    if (d = 1) or (d = 2) or (d = 8) :     % positive
+        currentpicture := currentpicture shifted (-chem_setting_offset,0) ;
+        chem_shift := chem_shift + (-chem_setting_offset,0)
+    elseif (d = 4) or (d = 5) or (d = 6) : % negative
+        currentpicture := currentpicture shifted ( chem_setting_offset,0) ;
+        chem_shift := chem_shift + ( chem_setting_offset,0)
+    fi ;
+enddef ;
+
+vardef chem_set(expr n, m) =
+    if chem_adjacent > 0 :
+        chem_adjacent_d := xpart chem_b_zero[n] + xpart chem_b_zero[m] ;
+        if     chem_adjacent = 1 : chem_adjacent_p := (-chem_adjacent_d, 0) ;
+        elseif chem_adjacent = 2 : chem_adjacent_p := (0, -chem_adjacent_d) ;
+        elseif chem_adjacent = 3 : chem_adjacent_p := ( chem_adjacent_d, 0) ;
+        elseif chem_adjacent = 4 : chem_adjacent_p := (0,  chem_adjacent_d) ;
+        else                     : chem_adjacent_p := origin ;
+        fi ;
+        currentpicture := currentpicture shifted chem_adjacent_p ;
+        chem_shift := chem_shift + chem_adjacent_p ;
+        chem_adjacent := 0 ;
+    fi ;
+    if chem_substituent > 0 :
+        if m = 1 :
+            chem_substituent_d := xpart chem_crz_zero[n] + chem_substituent_offset ;
+        else :
+            chem_substituent_d := xpart chem_crz_zero[n] +  xpart chem_b_zero[m] ;
+        fi ;
+        if     chem_substituent = 1 : chem_substituent_p := (-chem_substituent_d, 0) ; % - ?
+        elseif chem_substituent = 2 : chem_substituent_p := (0,  chem_substituent_d) ;
+        elseif chem_substituent = 3 : chem_substituent_p := ( chem_substituent_d, 0) ;
+        elseif chem_substituent = 4 : chem_substituent_p := (0, -chem_substituent_d) ;
+        else                        : chem_substituent_p := origin ;
+        fi ;
+        currentpicture := currentpicture shifted chem_substituent_p ;
+        chem_shift := chem_shift + chem_substituent_p ;
+        chem_substituent := 0 ;
+    fi ;
+    chem_rotation := chem_initialrot[m] ;
+enddef ;
+
+vardef chem_draw (expr n, path_fragment, from_point, to_point, linewidth, linecolor) =
+    for i:=from_point upto to_point:
+        draw (path_fragment rotated chem_ang(n,i)) withpen pencircle scaled linewidth withcolor linecolor ;
+    endfor ;
+enddef ;
+vardef chem_fill (expr n, path_fragment, from_point, to_point, linewidth, linecolor) =
+    for i:=from_point upto to_point:
+        fill (path_fragment rotated chem_ang(n,i)) withpen pencircle scaled 0 withcolor linecolor ;
+    endfor ;
+enddef ;
+
+vardef chem_dashed_normal (expr n, path_fragment, from_point, to_point, linewidth, linecolor) =
+    for i:=from_point upto to_point:
+        draw (path_fragment rotated chem_ang(n,i)) withpen pencircle scaled linewidth withcolor linecolor dashed evenly ;
+    endfor ;
+enddef ;
+vardef chem_dashed_connected (expr n, path_fragment, from_point, to_point, linewidth, linecolor) =
+    draw for i:=from_point upto to_point:
+        (path_fragment rotated chem_ang(n,i)) if i < to_point : -- fi
+    endfor withpen pencircle scaled linewidth withcolor linecolor dashed evenly ;
+enddef ;
+vardef chem_draw_dot (expr n, path_fragment, from_point, to_point, linewidth, linecolor) =
+    for i:=from_point upto to_point:
+        draw (path_fragment rotated chem_ang(n,i)) withpen pencircle scaled (chem_dot_factor*linewidth) withcolor linecolor ;
+    endfor ;
+enddef ;
+vardef chem_draw_fixed (expr n, path_fragment, linewidth, linecolor) =
+    draw (path_fragment rotated chem_ang(n,1)) withpen pencircle scaled linewidth withcolor linecolor ;
+enddef ;
+vardef chem_draw_arrow (expr n, path_fragment, from_point, to_point, linewidth, linecolor) =
+    for i:=from_point upto to_point:
+        drawarrow (path_fragment rotated chem_ang(n,i)) withpen pencircle scaled linewidth withcolor linecolor ;
+    endfor ;
+enddef ;
+vardef chem_draw_vertical (expr n, path_fragment, from_point, to_point, linewidth, linecolor) =
+    % quite special
+    for i:=from_point upto to_point:
+        draw (path_fragment shifted (chem_b_zero[n] rotated chem_ang(n,i))) withpen pencircle scaled linewidth withcolor linecolor ;
+    endfor ;
+enddef ;
+
+picture chem_stack_p[] ;
+pair chem_stack_shift[] ;
+
+vardef chem_save =
+    chem_stack_n := chem_stack_n + 1 ;
+    chem_stack_p[chem_stack_n] := currentpicture ;
+    chem_stack_shift[chem_stack_n] := chem_shift ;
+    chem_shift := origin ;
+% chem_adjacent := 0 ;
+% chem_substituent := 0 ;
+% chem_rotation := 1 ;
+    currentpicture := nullpicture ;
+enddef ;
+vardef chem_restore =
+    if chem_stack_n > 0 :
+        currentpicture := currentpicture shifted - chem_shift ;
+        addto chem_stack_p[chem_stack_n] also currentpicture ;
+        currentpicture := chem_stack_p[chem_stack_n] ;
+        chem_stack_p[chem_stack_n] := nullpicture ;
+        chem_shift := chem_stack_shift[chem_stack_n] ;
+        chem_stack_n := chem_stack_n - 1 ;
+    fi ;
+enddef ;
+
+def chem_init_some(expr n, ratio, angle, start, initialrot, initialmov)  =
+    chem_width     [n] := ratio * chem_base_width * chem_setting_scale ;
+    chem_angle     [n] := angle ;
+    chem_start     [n] := start ;
+    chem_initialrot[n] := initialrot ;
+    chem_initialmov[n] := initialmov ;
+    chem_b_zero    [n] := (chem_width[n],0) rotated (angle/2) ;
+    chem_n_zero    [n] := (chem_text_min*chem_width[n],0) rotated (angle/2) ;
+    chem_r_max     [n] := chem_radical_max*chem_b_zero[n] ;
+    chem_r_path    [n] := chem_b_zero[n] -- chem_r_max[n] ;
+    chem_mr_path   [n] := chem_r_path [n] rotatedaround(chem_b_zero[n], (180-angle)/2) ;
+    chem_pr_path   [n] := chem_r_path [n] rotatedaround(chem_b_zero[n],-(180-angle)/2) ;
+    chem_r_zero    [n] := point 1 of chem_r_path [n] ;
+    chem_mr_zero   [n] := point 1 of chem_mr_path[n] ;
+    chem_pr_zero   [n] := point 1 of chem_pr_path[n] ;
+    chem_crz_zero  [n] := point 1 of (chem_r_path[n] enlonged chem_center_offset) ;
+    chem_au_path   [n] := subpath (0.2,0.8) of (chem_r_max[n] -- (chem_r_max[n] rotated angle)) ;
+    chem_ad_path   [n] := reverse(chem_au_path[n]) ;
+    chem_rt_zero   [n] := (((chem_radical_max+chem_radical_min)/2)*chem_width[n],0) rotated (angle/2) ;
+    chem_rtt_zero  [n] := chem_rt_zero[n] rotated + 10 ;
+    chem_rbt_zero  [n] := chem_rt_zero[n] rotated - 10 ;
+    chem_b_path    [n] := reverse(chem_b_zero[n] -- (chem_b_zero[n] rotated -angle)) ;
+    chem_bx_path   [n] := reverse(chem_b_zero[n] -- (chem_b_zero[n] rotated -angle)) ; % ?
+    chem_sb_path   [n] := subpath (0.25,0.75) of chem_b_path[n] ;
+    chem_s_path    [n] := point 0 of chem_b_path[n] -- point 0 of (chem_b_path[n] rotated (2angle)) ;
+    chem_ss_path   [n] := subpath (0.25,0.75) of (chem_s_path[n]) ;
+    chem_pss_path  [n] := subpath (0.00,0.75) of (chem_s_path[n]) ;
+    chem_mss_path  [n] := subpath (0.25,1.00) of (chem_s_path[n]) ;
+    chem_mid_zero  [n] := origin shifted (-.25chem_width[n],0) ;
+    chem_midst_path[n] := chem_mid_zero[n] -- (chem_width[n],0) rotated ( angle + angle/2) ;
+    chem_midsb_path[n] := chem_mid_zero[n] -- (chem_width[n],0) rotated (-angle - angle/2) ;
+    chem_midt_path [n] := subpath (0.25,1.00) of chem_midst_path [n] ;
+    chem_midb_path [n] := subpath (0.25,1.00) of chem_midsb_path [n] ;
+    chem_msb_path  [n] := subpath (0.00,0.75) of chem_b_path[n] ;
+    chem_psb_path  [n] := subpath (0.25,1.00) of chem_b_path[n] ;
+    chem_dbl_path  [n] := chem_sb_path[n] shifted - (0.05[origin,center chem_sb_path[n]]) ; % parallel
+    chem_dbr_path  [n] := chem_sb_path[n] shifted + (0.05[origin,center chem_sb_path[n]]) ;
+    chem_eb_path   [n] := chem_sb_path[n] shifted - (0.25[origin,center chem_sb_path[n]]) ;
+    chem_sr_path   [n] := chem_radical_min*chem_b_zero[n] -- chem_r_max[n] ;
+    chem_rl_path   [n] := chem_r_path[n]  paralleled  (chem_base_width/20) ;
+    chem_rr_path   [n] := chem_r_path[n]  paralleled -(chem_base_width/20) ;
+    chem_srl_path  [n] := chem_sr_path[n] paralleled  (chem_base_width/20)  ;
+    chem_srr_path  [n] := chem_sr_path[n] paralleled -(chem_base_width/20)  ;
+    chem_br_path   [n] := point 1 of chem_sb_path[n] --
+        point 0 of chem_sb_path[n] rotatedaround(point 1 of chem_sb_path[n], -4) --
+        point 0 of chem_sb_path[n] rotatedaround(point 1 of chem_sb_path[n],  4) -- cycle ;
+    chem_rb_path   [n] := chem_b_zero[n] -- chem_r_max[n] rotated -2 -- chem_r_max[n] -- chem_r_max[n] rotated 2 --  cycle ;
+    chem_mrb_path  [n] := chem_rb_path[n] rotatedaround(chem_b_zero[n], (180-angle)/2) ;
+    chem_prb_path  [n] := chem_rb_path[n] rotatedaround(chem_b_zero[n],-(180-angle)/2) ;
+    chem_msr_path  [n] := chem_sr_path[n] rotatedaround(chem_b_zero[n], (180-angle)/2) ;
+    chem_psr_path  [n] := chem_sr_path[n] rotatedaround(chem_b_zero[n],-(180-angle)/2) ;
+    % not yet ok:
+    chem_c_path    [n] := subpath (30/45, -30/45) of (fullcircle            scaled (1.25*chem_circle_radius*chem_width[n]));
+    chem_cc_path   [n] := subpath (30/45,8-30/45) of (fullcircle rotated 90 scaled (1.25*chem_circle_radius*chem_width[n]));
+enddef ;
+
+def chem_init_three      = chem_init_some(3,30/52  ,120,-60,1,2) ; enddef ; % 60
+def chem_init_four       = chem_init_some(4,30/42.5, 90,  0,1,0) ; enddef ; % 45
+def chem_init_five       = chem_init_some(5,30/35  , 72,  0,1,0) ; enddef ; % 36
+def chem_init_six        = chem_init_some(6, 1     , 60,  0,1,0) ; enddef ; % 30
+def chem_init_eight      = chem_init_some(8,30/22.5, 45,  0,1,0) ; enddef ; % 22.5
+
+% bb R -R R Z -RZ +RZ
+
+def chem_init_some_front(expr n, ratio, angle, start, initialrot, initialmov) =
+    chem_init_some(n, ratio, angle, start, initialrot, initialmov) ;
+    chem_bb_path [n] := chem_b_path[n] rotated -angle -- chem_b_path[n] -- chem_b_path[n] rotated angle --
+                       (reverse(chem_b_path[n] shortened (chem_base_width/20))) paralleled (chem_base_width/20) --
+                        cycle ;
+    chem_r_max   [n] := chem_radical_max*chem_b_zero[n] ;
+    chem_mr_path [n] := origin -- origin shifted (0,-.25chem_base_width) ;
+    chem_pr_path [n] := origin -- origin shifted (0, .25*chem_base_width) ;
+    chem_r_path  [n] := point 1 of chem_mr_path[n] -- point 1 of chem_pr_path[n] ;
+    chem_mr_zero [n] := point 1 of chem_mr_path[n] ;
+    chem_pr_zero [n] := point 1 of chem_pr_path[n] ;
+enddef ;
+
+def chem_init_five_front = chem_init_some_front(-5,30/35,72,0,2,0) ; enddef ; % 36
+def chem_init_six_front  = chem_init_some_front(-6, 1   ,60,0,2,0) ; enddef ; % 30
+
+def chem_init_one =
+    chem_width     [1] := .75 * chem_base_width * chem_setting_scale ;
+    chem_angle     [1] := 45 ;
+    chem_start     [1] := 0 ;
+    chem_initialrot[1] := 1 ;
+    chem_initialmov[1] := 1 ;
+    chem_b_zero    [1] := (1.75*chem_width[1],0) ;
+    chem_r_min     [1] := chem_radical_min*chem_b_zero[1] ;
+    chem_r_max     [1] := chem_radical_max*chem_b_zero[1] ;
+    chem_r_path    [1] := (.5*chem_width[1],0) -- (1.25*chem_width[1],0) ;
+    chem_r_zero    [1] := point 1 of chem_r_path [1] ;
+    chem_b_path    [1] := chem_r_path[1] rotated + (chem_angle[1]) ; % used for move here
+    chem_b_zero    [1] := chem_r_zero[1] ;
+    chem_crz_zero  [1] := chem_r_zero[1] enlonged chem_center_offset ;
+    chem_e_path    [1] := (.5*chem_width[1],-.25*chem_width[1]) -- (.5*chem_width[1],.25*chem_width[1]) ;
+    chem_sb_path   [1] := chem_r_path [1] ;
+    chem_msb_path  [1] := chem_r_path [1] shifted (0,-.1chem_width[1]) ;
+    chem_psb_path  [1] := chem_r_path [1] shifted (0, .1chem_width[1]) ;
+    chem_ddt_path  [1] := subpath(0,.4) of chem_r_path [1] ;
+    chem_ddb_path  [1] := subpath(.6,1) of chem_r_path [1] ;
+    chem_ldt_path  [1] := chem_ddt_path [1] shifted (0,-.1chem_width[1]) ; % parallel
+    chem_ldb_path  [1] := chem_ddb_path [1] shifted (0,-.1chem_width[1]) ;
+    chem_rdt_path  [1] := chem_ddt_path [1] shifted (0, .1chem_width[1]) ;
+    chem_rdb_path  [1] := chem_ddb_path [1] shifted (0, .1chem_width[1]) ;
+    chem_bb_path   [1] := point 0 of chem_r_path[1] --
+        point 1 of chem_r_path[1] rotatedaround(point 0 of chem_r_path[1], -4) --
+        point 1 of chem_r_path[1] rotatedaround(point 0 of chem_r_path[1],  4) -- cycle ;
+    chem_oe_path   [1] := ((-20,0)--(10,0){up}..(20,10)..(30,0)..(40,-10)..(50.0,0)..(60,10)..(70,0)..(80,-10)..{up}(90,0)--(120,0))
+        xsized (.75*chem_width[1]) shifted point 0 of chem_r_path[1] ;
+    chem_rt_zero   [1] := point .5 of chem_r_path[1] ;
+    chem_rtt_zero  [1] := chem_rt_zero[1] rotated + (chem_angle[1]/2) ;
+    chem_rbt_zero  [1] := chem_rt_zero[1] rotated - (chem_angle[1]/2) ;
+enddef ;
+
+def chem_init_all =
+    chem_init_one ;
+    chem_init_three ;
+    chem_init_four ;
+    chem_init_five ;
+    chem_init_six ;
+    chem_init_eight ;
+    chem_init_five_front ;
+    chem_init_six_front ;
+enddef ;
+
+chem_init_all ;
+
diff --git a/metapost/context/base/mp-core.mp b/metapost/context/base/mp-core.mp
index 0bf19b8a5..6720fe90d 100644
--- a/metapost/context/base/mp-core.mp
+++ b/metapost/context/base/mp-core.mp
@@ -346,6 +346,8 @@ boolean force_multi_par_chain  ; force_multi_par_chain  := true  ;
 boolean one_piece_multi_par    ; one_piece_multi_par    := false ;
 boolean check_multi_par_chain  ; check_multi_par_chain  := true  ; % extra page check
 
+boolean multi_column_first_page_hack; multi_column_first_page_hack := false ;
+
 def simplify_multi_pars = % boundingbox ipv shape als optie
   for i := 1 upto nofmultipars :
     multipars[i] := boundingbox multipars[i] ;
@@ -428,8 +430,6 @@ def prepare_multi_pars (expr fn,fx,fy,fw,fh,fd,
 
   numeric multi_par_pages ; multi_par_pages := nxy[tpos]-nxy[fpos]+1 ;
 
-  ii := 0 ; nn := NOfTextAreas+1 ; nofmultipars := 0 ;
-
   vardef snapped_multi_pos (expr p) =
     if snap_multi_par_tops :
       if abs(ypart p - ypart ulcorner multipar) < par_line_height :
@@ -502,7 +502,7 @@ def prepare_multi_pars (expr fn,fx,fy,fw,fh,fd,
 
   vardef left_top_hang (expr same_area) =
 
-par_hang_after := ra + estimated_par_lines(py-fy) ;
+    par_hang_after := ra + estimated_par_lines(py-fy) ;
 
     if (par_hang_indent>0) and (par_hang_after<0) and obey_multi_par_hang :
       pair _ul_ ; _ul_ := (xpart ulcorner multipar, ypart snapped_multi_pos(ulxy[fpos]));
@@ -525,7 +525,7 @@ par_hang_after := ra + estimated_par_lines(py-fy) ;
 
   vardef right_top_hang (expr same_area) =
 
-par_hang_after := ra + estimated_par_lines(py-fy) ;
+    par_hang_after := ra + estimated_par_lines(py-fy) ;
 
     if (par_hang_indent<0) and (par_hang_after<0) and obey_multi_par_hang :
       pair _ur_ ; _ur_ := (xpart urcorner multipar, ypart snapped_multi_pos(urxy[fpos])) ;
@@ -552,17 +552,15 @@ par_hang_after := ra + estimated_par_lines(py-fy) ;
       pair _ul_ ; _ul_ := ulcorner multipar ;
       pair _pa_ ; _pa_ := _ul_ shifted (0,par_hang_after*par_line_height) ;
       _pa_ := (xpart _pa_,max(ypart _pa_,ypart llcorner multipar)) ;
-
-if t :
-  _pa_ := (xpart _pa_,max(ypart _pa_,ypart llxy[tpos]));
-fi ;
-if abs(ypart _pa_-ypart llxy[tpos])<par_line_height :
-  _pa_ := (xpart _pa_,ypart llxy[tpos]);
-fi ;
-if abs(ypart _pa_-ypart llcorner multipar)<par_line_height :
-  _pa_ := (xpart _pa_,ypart llcorner multipar);
-fi ;
-
+      if t :
+        _pa_ := (xpart _pa_,max(ypart _pa_,ypart llxy[tpos]));
+      fi ;
+      if abs(ypart _pa_-ypart llxy[tpos])<par_line_height :
+        _pa_ := (xpart _pa_,ypart llxy[tpos]);
+      fi ;
+      if abs(ypart _pa_-ypart llcorner multipar)<par_line_height :
+        _pa_ := (xpart _pa_,ypart llcorner multipar);
+      fi ;
       (xpart _ul_, ypart _pa_) --
       (xpart _ul_ + par_hang_indent, ypart _pa_) --
       (xpart _ul_ + par_hang_indent, ypart _ul_)
@@ -571,18 +569,15 @@ fi ;
     fi
   enddef ;
 
-
   vardef x_right_top_hang (expr i, t) =
     par_hang_after := min(0,ra + estimated_multi_par_height(i,t)) ;
     if (par_hang_indent<0) and (par_hang_after<0) :
       pair _ur_ ; _ur_ := urcorner multipar ;
       pair _pa_ ; _pa_ := _ur_ shifted (0,par_hang_after*par_line_height) ;
       _pa_ := (xpart _pa_,max(ypart _pa_,ypart lrcorner multipar)) ;
-if t :
-  _pa_ := (xpart _pa_,max(ypart _pa_,ypart snapped_multi_pos(urxy[tpos]))) ;
-fi ;
-
-
+      if t :
+        _pa_ := (xpart _pa_,max(ypart _pa_,ypart snapped_multi_pos(urxy[tpos]))) ;
+      fi ;
       (xpart _ur_ + par_hang_indent, ypart _ur_) --
       (xpart _ur_ + par_hang_indent, ypart _pa_) --
       (xpart _ur_, ypart _pa_)
@@ -681,6 +676,8 @@ fi ;
 
   % first loop
 
+  ii := 0 ; nn := NOfTextAreas+1 ; nofmultipars := 0 ;
+
   if enable_multi_par_fallback  and
      (nxy[fpos]=RealPageNumber) and
      (nxy[tpos]=RealPageNumber) and not
@@ -876,7 +873,7 @@ fi ;
           x_left_top_hang(i,true) --
           x_right_top_hang(i,true) --
           x_right_bottom_hang(i,true) --
-snapped_multi_pos(ulxy[tpos]) --
+          snapped_multi_pos(ulxy[tpos]) --
           llxy[tpos] --
           x_left_bottom_hang(i,true) --
           cycle ;
@@ -887,7 +884,7 @@ snapped_multi_pos(ulxy[tpos]) --
           ulcorner multipar --
           urcorner multipar --
           (xpart lrcorner multipar, ypart urxy[tpos]) --
-snapped_multi_pos(ulxy[tpos]) --
+          snapped_multi_pos(ulxy[tpos]) --
           llxy[tpos] --
           (xpart llcorner multipar, ypart llxy[tpos]) --
           cycle ;
@@ -896,45 +893,50 @@ snapped_multi_pos(ulxy[tpos]) --
 
       save_multipar (i,3,multipar) ;
 
-    else :
+    elseif multi_column_first_page_hack and ((nxy[fpos]=RealPageNumber) and (nxy[tpos]>=RealPageNumber) and (NOfTextColumns>1)) :
 
-      % handled later
+      save_multipar (i,2,multipar) ;
 
+    else :
+      % handled later
     fi ;
 
   endfor ;
 
   % second loop
 
-if force_multi_par_chain or (ii > 1) :
+  if force_multi_par_chain or (ii > 1) :
 
-  for i=ii+1 upto nn-1 :
+    for i=ii+1 upto nn-1 :
 
-    % rest of chain / todo : hang
+      % rest of chain / todo : hang
 
+% hm, the second+ column in column sets now gets lost in a NOfTextColumns
 
-if (not check_multi_par_chain) or ((nxy[fpos]<RealPageNumber) and (nxy[tpos]>RealPageNumber)) :
+    if (not check_multi_par_chain) or
+       ((nxy[fpos]<RealPageNumber) and (nxy[tpos]>RealPageNumber))
+       :
 
-    multipar := set_multipar(i) ;
+        multipar := set_multipar(i) ;
 
-    if obey_multi_par_hang and obey_multi_par_more :
+        if obey_multi_par_hang and obey_multi_par_more :
 
-      multipar :=
-        x_left_top_hang(i,false) --
-        x_right_top_hang(i,false) --
-        x_right_bottom_hang(i,false) --
-        x_left_bottom_hang(i,false) --
-        cycle ;
+          multipar :=
+            x_left_top_hang(i,false) --
+            x_right_top_hang(i,false) --
+            x_right_bottom_hang(i,false) --
+            x_left_bottom_hang(i,false) --
+            cycle ;
 
-    fi ;
+        fi ;
 
-    save_multipar(i,2,multipar) ;
+        save_multipar(i,2,multipar) ;
 
-fi ;
+      fi ;
 
-  endfor ;
+    endfor ;
 
-fi ;
+  fi ;
 
   % end of normal/fallback
 
@@ -1375,3 +1377,42 @@ enddef ;
 endinput ;
 
 end
+
+% for Jelle Huisman
+%
+% \setupcolors[state=start]
+% \dontcomplain
+% \definecolumnset[example][n=3,distance=5mm]
+% \startMPextensions
+%     multi_column_first_page_hack := true ;
+% \stopMPextensions
+% \startuseMPgraphic{mpos:par:trick}
+%     for i=1 upto nofmultipars-1 : draw (rightboundary multipars[i]) shifted (2.5mm, 0) ; endfor ;
+% \stopuseMPgraphic
+% \definetextbackground[test][mp=mpos:par:trick,method=mpos:par:columnset]
+% \starttext
+% \definecolumnsetspan[chapter][n=3]
+% \startcolumnset[example]
+% \startcolumnsetspan[chapter]
+% \chapter{Chapter One}
+% \stopcolumnsetspan
+% \starttextbackground[test] \dorecurse {3}{\input knuth } \stoptextbackground
+% \stopcolumnset
+% \startcolumnset[example]
+% \startcolumnsetspan[chapter]
+% \chapter{Chapter One}
+% \stopcolumnsetspan
+% \starttextbackground[test] \dorecurse {10}{\input knuth } \stoptextbackground
+% \stopcolumnset
+% \stoptext
+%
+% fast variant:
+%
+% \startuseMPgraphic{whatever}
+%     for i=1 upto NOfTextColumns-1 :
+%         draw (rightboundary TextColumns[i]) shifted (2.5mm,0) shifted -\MPxy\textanchor ;
+%     endfor ;
+%     setbounds currentpicture to OverlayBox ;
+% \stopuseMPgraphic
+% \defineoverlay[whatever][\useMPgraphic{whatever}]
+% \setupbackgrounds[text][background=whatever]
diff --git a/metapost/context/base/mp-mlib.mp b/metapost/context/base/mp-mlib.mp
index 134cd12a3..893222473 100644
--- a/metapost/context/base/mp-mlib.mp
+++ b/metapost/context/base/mp-mlib.mp
@@ -30,7 +30,9 @@ extra_endfig   := ";addto currentpicture also _tt_p_; " & extra_endfig; % was dr
 extra_beginfig := extra_beginfig & "resettextexts;";
 
 vardef rawtextext(expr str) =
-    if _trial_run_ :
+    if str = "" :
+        nullpicture
+    elseif _trial_run_ :
         image (
             _tt_n_ := _tt_n_ + 1 ;
             _tt_p_ := image (
@@ -51,6 +53,8 @@ vardef rawtextext(expr str) =
     fi
 enddef ;
 
+% not ok yet
+
 pair laboff.d, laboff.dlft, laboff.drt ; % new positional suffixes
 pair laboff.origin, laboff.raw         ; % graph mess
 
@@ -67,10 +71,66 @@ labtype.origin :=  0 ; labtype.raw  :=  0 ;
 laboff.origin = (infinity,infinity) ; labxf.origin := 0 ; labyf.origin := 0 ;
 laboff.raw    = (infinity,infinity) ; labxf.raw    := 0 ; labyf.raw    := 0 ;
 
+pair laboff.l   ; laboff.l  = laboff.lft  ;
+pair laboff.r   ; laboff.r  = laboff.rt   ;
+pair laboff.b   ; laboff.b  = laboff.bot  ;
+pair laboff.t   ; laboff.t  = laboff.top  ;
+pair laboff.l_t ; laboff.l_t = laboff.ulft ;
+pair laboff.r_t ; laboff.r_t = laboff.urt  ;
+pair laboff.l_b ; laboff.l_b = laboff.llft ;
+pair laboff.r_b ; laboff.r_b = laboff.lrt  ;
+pair laboff.t_l ; laboff.t_l = laboff.ulft ;
+pair laboff.t_r ; laboff.t_r = laboff.urt  ;
+pair laboff.b_l ; laboff.b_l = laboff.llft ;
+pair laboff.b_r ; laboff.b_r = laboff.lrt  ;
+
+labxf.l   ; labxf.l  = labxf.lft  ;
+labxf.r   ; labxf.r  = labxf.rt   ;
+labxf.b   ; labxf.b  = labxf.bot  ;
+labxf.t   ; labxf.t  = labxf.top  ;
+labxf.l_t ; labxf.l_t = labxf.ulft ;
+labxf.r_t ; labxf.r_t = labxf.urt  ;
+labxf.l_b ; labxf.l_b = labxf.llft ;
+labxf.r_b ; labxf.r_b = labxf.lrt  ;
+labxf.t_l ; labxf.t_l = labxf.ulft ;
+labxf.t_r ; labxf.t_r = labxf.urt  ;
+labxf.b_l ; labxf.b_l = labxf.llft ;
+labxf.b_r ; labxf.b_r = labxf.lrt  ;
+
+labyf.l   ; labyf.l  = labyf.lft  ;
+labyf.r   ; labyf.r  = labyf.rt   ;
+labyf.b   ; labyf.b  = labyf.bot  ;
+labyf.t   ; labyf.t  = labyf.top  ;
+labyf.l_t ; labyf.l_t = labyf.ulft ;
+labyf.r_t ; labyf.r_t = labyf.urt  ;
+labyf.l_b ; labyf.l_b = labyf.llft ;
+labyf.r_b ; labyf.r_b = labyf.lrt  ;
+labyf.t_l ; labyf.t_l = labyf.ulft ;
+labyf.t_r ; labyf.t_r = labyf.urt  ;
+labyf.b_l ; labyf.b_l = labyf.llft ;
+labyf.b_r ; labyf.b_r = labyf.lrt  ;
+
+labtype.l   ; labtype.l   = labtype.lft  ;
+labtype.r   ; labtype.r   = labtype.rt   ;
+labtype.b   ; labtype.b   = labtype.bot  ;
+labtype.t   ; labtype.t   = labtype.top  ;
+labtype.l_t ; labtype.l_t = labtype.ulft ;
+labtype.r_t ; labtype.r_t = labtype.urt  ;
+labtype.l_b ; labtype.l_b = labtype.llft ;
+labtype.r_b ; labtype.r_b = labtype.lrt  ;
+labtype.t_l ; labtype.t_l = labtype.ulft ;
+labtype.t_r ; labtype.t_r = labtype.urt  ;
+labtype.b_l ; labtype.b_l = labtype.llft ;
+labtype.b_r ; labtype.b_r = labtype.lrt  ;
+
 vardef thetextext@#(expr p,z) = % adapted copy of thelabel@
-    p
-        if (labtype@# >= 10) : shifted (0,ypart center p) fi
-        shifted (z + labeloffset*laboff@# - (labxf@#*lrcorner p + labyf@#*ulcorner p + (1-labxf@#-labyf@#)*llcorner p))
+    if string p :
+        thetextext@#(rawtextext(p),z)
+    else :
+        p
+            if (labtype@# >= 10) : shifted (0,ypart center p) fi
+            shifted (z + labeloffset*laboff@# - (labxf@#*lrcorner p + labyf@#*ulcorner p + (1-labxf@#-labyf@#)*llcorner p))
+    fi
 enddef;
 
 vardef textext@#(expr txt) =
@@ -82,6 +142,28 @@ vardef textext@#(expr txt) =
     fi
 enddef ;
 
+% \starttext
+%   \startMPpage
+%     numeric value ; value = 123 ;
+%     label.lft(decimal value,origin) ;
+%     draw "oeps" infont defaultfont ;
+%   \stopMPpage
+% \stoptext
+
+vardef thelabel@#(expr s, z) =
+    save p ; picture p ;
+    if picture s :
+        p = s ;
+    else :
+        p = textext("\definedfont[" & defaultfont & "]" & s) scaled defaultscale ;
+    fi ;
+    p shifted (z + labeloffset*laboff@# - (labxf@#*lrcorner p + labyf@#*ulcorner p + (1-labxf@#-labyf@#)*llcorner p))
+enddef;
+
+primarydef str infont name = % very naughty !
+    textext("\definedfont[" & name & "]" & str)
+enddef ;
+
 def circular_shade (expr p, n, ca, cb) =
     begingroup ;
         save ab, r ; pair ab ; numeric r ;
diff --git a/metapost/context/base/mp-page.mp b/metapost/context/base/mp-page.mp
index e3750b55b..71ca12aa0 100644
--- a/metapost/context/base/mp-page.mp
+++ b/metapost/context/base/mp-page.mp
@@ -444,4 +444,4 @@ def Enlarged (expr p, d) =
    ulEnlarged (p,d) -- cycle)
 enddef ;
 
-endinput ;
\ No newline at end of file
+endinput ;
diff --git a/metapost/context/base/mp-text.mp b/metapost/context/base/mp-text.mp
index c1f9c80e9..292b79b4f 100644
--- a/metapost/context/base/mp-text.mp
+++ b/metapost/context/base/mp-text.mp
@@ -86,8 +86,9 @@ string laboff_l  ; laboff_l  := ".lft"  ;
 string laboff_r  ; laboff_r  := ".rt"   ;
 string laboff_b  ; laboff_b  := ".bot"  ;
 string laboff_t  ; laboff_t  := ".top"  ;
+
 string laboff_lt ; laboff_lt := ".ulft" ;
-string laboff_rt ; laboff_rt := ".urt"  ;
+string laboff_rt ; laboff_rt := ".urt"  ; % bugged, conflict with r
 string laboff_lb ; laboff_lb := ".llft" ;
 string laboff_rb ; laboff_rb := ".lrt"  ;
 string laboff_tl ; laboff_tl := ".ulft" ;
diff --git a/metapost/context/base/mp-tool.mp b/metapost/context/base/mp-tool.mp
index ccec2f3c8..817f237b0 100644
--- a/metapost/context/base/mp-tool.mp
+++ b/metapost/context/base/mp-tool.mp
@@ -828,6 +828,15 @@ primarydef p crossed d =
    center p shifted ( 0,+d) -- ulcorner p -- cycle)
 enddef ;
 
+%D Also handy (math ladders):
+
+vardef laddered expr p =
+    point 0 of p
+    for i=1 upto length(p) :
+        -- (xpart (point i of p), ypart (point (i-1) of p)) -- (point i of p)
+    endfor
+enddef ;
+
 %D Saves typing:
 
 % vardef bottomboundary primary p = (llcorner p -- lrcorner p) enddef ;
@@ -975,6 +984,10 @@ enddef ;
 %  endgroup
 %enddef ;
 
+primarydef p paralleled d =
+    p shifted if d < 0 : - fi ((point abs(d) on (p rotatedaround(point 0 of p,90))) - point 0 of p)
+enddef ;
+
 vardef punked primary p =
   (point 0 of p for i=1 upto length(p)-1 : -- point i of p endfor
    if cycle p : -- cycle else : -- point length(p) of p fi)
@@ -1746,12 +1759,55 @@ def condition primary b = if b : "true" else : "false" fi enddef ;
 
 primarydef p stretched s =
   begingroup
-% save pp ; path pp ; pp := p scaled s ;
   save pp ; path pp ; pp := p xyscaled s ;
   (pp shifted ((point 0 of p) - (point 0 of pp)))
   endgroup
 enddef ;
 
+% primarydef p enlonged len =
+%     begingroup
+%     save al ; al := arclength(p) ;
+%     if al > 0 :
+%         if pair p :
+%             point 1 of ((origin -- p) stretched ((al+len)/al))
+%         else :
+%             p stretched ((al+len)/al)
+%         fi
+%     else :
+%         p
+%     fi
+%     endgroup
+% enddef ;
+
+primarydef p enlonged len =
+    begingroup
+    if pair p :
+        save q ; path q ; q := origin -- p ;
+        save al ; al := arclength(q) ;
+        if al > 0 :
+            point 1 of (q stretched ((al+len)/al))
+        else :
+            p
+        fi
+    else :
+        save al ; al := arclength(p) ;
+        if al > 0 :
+            p stretched ((al+len)/al)
+        else :
+            p
+        fi
+    fi
+    endgroup
+enddef ;
+
+% path p ; p := (0,0) -- (10cm,5cm) ;
+% drawarrow p withcolor red ;
+% drawarrow p shortened 1cm withcolor green ;
+
+primarydef p shortened d =
+    reverse ( ( reverse (p enlonged -d) ) enlonged -d )
+enddef ;
+
 % yes or no, untested -)
 
 def xshifted expr dx = shifted(dx,0) enddef ;