[Therion] Scrap limits

[Martin Budaj]

Hi,

there is no change regarding the limits in Therion. If there is a real
need, following could be done:

- in the current version of MetaPost, it's possible to used "double"
arithmetic just by specifying a command line option, which practically
eliminates MetaPost limits

- instead of pdfTeX we could use LuaTeX to produce the PDFs. This
doubles the number of registers available from 32768 to 65536.
Registers are needed to reference the fragments of all
scraps/sections; you usually need up to 6 of them for a scrap. So you
would get maybe 12000 instead of 6000 scraps in one output file. It
would require some substantial work to support LuaTeX (there is e.g.
completely different font handling compared to PdfTeX).

And yes, the limit applies just to the data selected for export.

Martin


On Tue, Nov 28, 2017 at 9:44 PM, Benedikt Hallinger via Therion
<therion at speleo.sk> wrote:
> Maybe another question:
> Assume a large cave with thousands of scraps.
> When i make a thconfig file sourcing all that data, but using "select"
> statements i only select partial data,
> does the metapost limit apply to the whole dataset or just the scraps
> covered by the select command?
>
>
>
> Am 2017-11-28 22:19, schrieb Benedikt Hallinger via Therion:
>>
>> Hello Martin,
>> is the blow limit of 4096 scraps still valid in the current version?
>> Or is it already fixed so we can use more scraps?
>>
>>
>>
>>> On Tue, Dec 1, 2009 at 5:26 PM, Carl Magnuson <magnu213 at umn.edu>
>>> wrote:
>>>>
>>>> It looks like the solution is to issue the following metapost command:
>>>> warningcheck := 0;
>>>
>>>
>>> Indeed. The new limit will be 32768 and could not be increased further
>>> in Metapost itself.
>>>
>>> The solution would be modification of how therion manages metapost
>>> pictures (currently they are stored in files data.1 to data.4000, with
>>> files data.4001 to data.4095 reserved for pattern definitions). This
>>> numbering scheme could be modified to allow more file name prefixes
>>> and consequently theoretically unlimited number of scraps processed by
>>> metapost.
>>>
>>> On the other hand there is still pdfTeX limit which would not allow
>>> much more scraps. PdfTeX uses internal registers for scraps
>>> referencing (scrap data is included only once in pdf file and can be
>>> referenced on multiple pages). You could avoid pdftex limit by using
>>> SVG output (if SVG viewers would process large number of internal
>>> references).
>>>
>>> In the longer-term future (a few years) I would like to use metapost
>>> as a library instead of external metapost executable, which would
>>> solve the problems with temporary files (and other problems as well).
>>>
>>>> However adding it in a
>>>> code metapost
>>>> warningcheck := 0;
>>>> endcode
>>>> block seems to have no effect, mpost still fails on more then 4096
>>>> scraps.
>>>
>>>
>>> Therion currently inserts warningcheck:=1; before scraps without good
>>> reason, so it will be fixed soon.
>>>
>>> If the new warningcheck setting would work for you, I would prefer not
>>> to modify current file numbering scheme for metapost pictures and have
>>> it fixed later with implementation of metapost library.
>>>
>>> Martin
>>
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