Industry - production change cb on consruction (patch)

[andythenorth]

It would be useful to be able to run the production change cb when an industry is constructed.
- set / randomise initial production
- convenient and sensible place to initialise local storage (can return 'no change' as the cb result)

Wondering if it would be acceptable to:
- define a bit on cb flags (prop 22),
- if bit set, call IndustryMonthlyLoop() from DoCreateNewIndustry()

[EDIT - that was a silly approach, sensible patch in next post.]

This is same way colour / cargo callbacks are called, and avoids duplicating IndustryMonthlyLoop, but I don't know if it's sane.

I favour this approach because it solves the problem, won't break existing newgrfs, involves very little new code, and won't require many (if any) changes in renum/nml.

industry_cmd.cpp, lines around 2681, 1656

[andythenorth]

Patch adds callback 15F, called on industry construction.
(Patch updated to address various issues, also adding cb to newgrf debug, also fix comments)

Return 4-128 to set production level (prod_level).

Patch for nml to add cb 15F.

Version of FIRS where Arable Farm uses cb 15F.

cb_15f.patch

(2.91 KiB) Downloaded 178 times

nml_cb_15f.patch

(590 Bytes) Downloaded 136 times

firs-r2752M.zip

(341.12 KiB) Downloaded 126 times

-- Possible extension --
Authors using production cb for primary production (or other purposes) might want to set 'previous month production' accurately using their production algorithm. Values for last_month_production[0] and last_month_production[1] could be optionally set by cb 15F. Pass absolute values for these in registers 0x100 and 0x101?

EDIT - irc discussion suggested that authors using production cb for production can still set initial prod_level via cb 15F to adjust the value of 'previous month production' to one suiting the industry.

[andythenorth]

Added to OpenTTD in r24186 (thanks frosch)

Also thanks to the others who helped