----- Forwarded message from Hans Bezemer <hbeze...@kliksafe.nl> -----
Date: Fri, 14 Mar 2025 07:14:17 +0100 From: Hans Bezemer <hbeze...@kliksafe.nl> To: Norwid Behrnd <nbeh...@yahoo.com> Subject: Re: On bonds, arrows and space, was: Slight alteration to back bond of chem.pic Dear Norwid, Using your ChemDraw example document as a reference I've made up the following list of things that are needed to recreate your document using chem / chem.pic. 1. Bonds in noncyclic molecules This is mostly done by adding new bonds to chem.pic. Most of the bonds were created over the past weeks put need some refinement. 2. Bonds in cyclic molecules This is a bit more tricky because of the mechanism of how the rings are created. >From what I understand now, a ring is created in the chem script with all single bonds and extra bonds (double / triple) are added later if needed. I've managed to create a dashed double bond, so will move on from there. 3. Space and arrows To (more) easily create chemical equations using structural formulas it would be convenient to have various arrows available, along with the option to insert white space. Arrows and space can use the same mechanism as bonds, so I think something along the lines of: -> carrow right from <- carrow <=> carrow and so on. I've added a `c' to the word arrow (from `c'hem) to differentiate from the arrow command from pic. Drawing arcs for reaction mechanisms are fairly easy done by using pic directly, so I think there's no need for chem alternative for that. Is this list complete? I'll start with the noncyclic bonds, arrows and spaces first. On a side note: I use eqn when using formulas: .EQ gfont R 2HCl ~+~ 2Na ~\[->]~ NaCl ~+~ H sub 2 .EN Kind regards, Hans On Mon, Mar 10, 2025 at 03:31:01PM +0100, Norwid Behrnd wrote: > Dear Hans > > On Thu, 6 Mar 2025 08:34:13 +0100 > Hans Bezemer via GNU roff typesetting system discussion <groff@gnu.org> wrote: > > > Yes they are. Maybe a mere descriptive name would be more appropiate: > > - dashed for what's now called `racemic' > > - wdashed for what's now called 'back' (and leave back unaltered, see > > comment below) > > - rwdashed for what's now called 'rback' > > > > What would you prefer? > > To me, these names (proposal by March 6th) are better -- since easier to > recall -- than the ones initially proposed by March 4th. > > [> ...] > > > > Why a `back` and an > > > additional `rback`? > > > > Mere practical reasons: sometimes it is easier to start with the > > substituent: > > After more familiarization with groff chem on my side, this makes sense now. > > [> ...] > > > > > No, I just started tinkering with chem and chem.pic because I needed a > > wedged dashed bond. > > I think there's even a more simple solution, which gives the individual > > user the > > possibility to create his own bonds to his liking. > > > > Changing this line: > > if ($Words[0] =~ /^(double|triple|front|back)$/ && > > in chem into: > > if ($Words[0] =~ /^[a-z]/ && > > would give the opportunity to source your own bonds and leave chem.pic > > unaltered. > > I used this as a point of entry to add a new bond, dashed double (cf. attached > zip archive) dubbed here as `ddouble`. While preliminary, within the daisies, > it is somewhat functional. Within cycles (second example), the approach fails > -- my bad, likely because I don't yet understand fully the ring function. In > the MWE shared, this part of the source code still is in the original form. > > An other additional bond type could be a bold double bond (`bdouble`?), for > later, and maybe a few arrows and hooks -- for comparison, I add a .png (at > 300 > dpi resolution) and .pdf of ChemDraw using the ACS1996 style puts on the > paper. The implicit(?) unit of length in groff's chem is inch, isn't it? > > Kind regards, > > Norwid ----- End forwarded message -----
