Switch town growth rate and counter to actual game ticks #6763

ldpl · 2018-04-29T16:42:04Z

This is more of a groundwork type patch rather one doing something particularly useful. It's needed to be settled first as it changes inner workings of town growth and my other town patches are obviously affected by that. But to keep it simple I actually tried to make this patch change as little as possible and not focus on GS API or gameplay changes. Though some stuff still got fixed along the way.

There are three main reasons for this tick conversion

To allow towns to grow faster than 1 hous / 70 ticks
To allow more granularity of town growth speed where it matters (<30 days/house)
To make town growth more smooth and not affected by 70 tick steps or tick overflow.

So what it actually changes:

growth_rate and grow_counter now use actual game ticks instead of big town ticks (70 ticks). That makes effective range of growth speed 1-65100 ticks instead of 70-~2219980 (with step 70). So instead of 30000 days slowest growth speed is now 880 which is still plenty (and unreachable without GS as it only goes to about 400 normally).
Moves TOWN_GROWTH_RATE_CUSTOM to town flags. Just a nice thing to do as it frees one more bit for growth_rate and gets rid of &~TOWN_GROWTH_RATE_CUSTOM everywhere.
Fixes sligthly uneven growth of towns due to tick overflow issue (since 2**16 % 70 != 0 for some towns tick handlers were not called).
Fixes Incorrect town growth rate ticks to days conversion #5827 because, well, if in needs to be changed anyway why not do it right.
Makes days to ticks conversion in GS growth methods more precise. Had my doubts about this one, but technically it's just a bugfixing not API change since it just didn't do it right before. Having to emulate completely wrong old behaviour here seems even more weird to me.

What it does NOT change:

Does not significantly change normal town growth mechanics (without GS) including funding. In fact, except for a few minor things it should be tick-perfectly the same.
Does not really address Erroneous behavior of Get/SetGrowthRate GS methods #6378, as most of that code is still intact despite the tick switch.
Does not provide GS methods to fully take advantage of the new range to separate GS API stuff from this issue.
Still updates growth rate on monthly tick, so no Keep town growth rate in sync with house count #6397 for now.

LordAro · 2018-04-29T19:20:18Z

src/saveload/saveload.cpp

@@ -266,7 +266,7 @@
 *  196   27778   1.7.x
 *  197   27978   1.8.x
 */


add PR# to comment when bumping revision? Probably needs some discussion

git blame ftw? :)

git log -U0 -G "SAVEGAME_VERSION =" src/saveload/saveload.cpp
And get rid of this pointless comment altogether

Eh, loses a lot of otherwise easily findable history that way

You mean openttd version history? Yeah, will be a bit trickier to get, but saves from the need for someone to constantly update the comment. Like how the hell am I even supposed to know what's next OpenTTD version is going to be?

The important part here are the savegame versions of the stable branches.
The revisions are not important.

Please don't add the 1.8.x. That's wrong.

frosch123 · 2018-04-30T17:20:55Z

src/saveload/afterload.cpp

+				t->growth_rate = TownTicksToGameTicks(t->growth_rate & ~0x8000);
+			}
+			/* Offset t->grow_counter by t->index to emulate original behaviour of spreading tick calls. */
+			t->grow_counter = TownTicksToGameTicks(t->grow_counter) + ((uint32)_tick_counter + t->index) % TOWN_GROWTH_TICKS;


I would drop "_tick_counter" here.
It rather confuses than affects stuff.

frosch123 · 2018-04-30T17:21:23Z

src/town_cmd.cpp

-	t->growth_rate = 250;
+	/* Spread growth across ticks so even if there are many
+	 * similar towns they're unlikely to grow all at once */
+	t->grow_counter = ((uint32)_tick_counter + t->index) % TOWN_GROWTH_TICKS;


Again, I would drop "_tick_counter" here.
It rather confuses than affects stuff.

I actually don't like it from competitive CB perspective, but it makes sense since if you create a big map with a lot of towns many of them will have exact same growth_rate so will be growing in same tick which I assume can even be a bit laggy in some cases (haven't tested though). I was thinking of making default growth rate calculation to be smooth rather than jump in 50-house steps then it will probably be ok to remove this part but before that I'd leave it be.

@frosch123 or did you mean drop _tick_counter but leave t->index? Yeah, that would probably work.

Yes, leave t->index for the spreading of CPU resources.
But remove _tick_counter since it does not do anything.

ldpl · 2018-05-01T20:40:27Z

src/town_cmd.cpp

-				/* If growth failed wait TOWN_GROWTH_TICKS before retrying */
-				i = TOWN_GROWTH_TICKS - 1;
+				/* If growth failed wait a bit before retrying */
+				i = min(t->growth_rate, TOWN_GROWTH_TICKS - 1);


Also reduced retry time as it was growing in waves on fast speeds.

frosch123 · 2018-05-02T17:41:15Z

Please don't add the "1.8.x" to the savegame version. It won't be 1.8.x.

ldpl added 3 commits April 29, 2018 19:31

Change: Switch to game ticks when counting town growth

f52e34e

Change: Add comment for TownTicksToGameTicks function

e28773e

Fix: fix grow_counter overflow when town can't place a building

f6021ce

LordAro reviewed Apr 29, 2018

View reviewed changes

frosch123 requested changes Apr 30, 2018

View reviewed changes

Change: Reduce time for town to retry building houses on fast growth

73df5e5

ldpl commented May 1, 2018

View reviewed changes

ldpl added 2 commits May 2, 2018 20:47

Change: remove 1.8.x from savegame version comment

59a2749

Change: Add 1.8.x back to 197 savegame version

6acc114

frosch123 approved these changes May 2, 2018

View reviewed changes

frosch123 merged commit fef8b83 into OpenTTD:master May 2, 2018

ldpl deleted the towns/tick_growth branch July 14, 2020 08:25

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Switch town growth rate and counter to actual game ticks #6763

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Switch town growth rate and counter to actual game ticks #6763

Switch town growth rate and counter to actual game ticks #6763

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