Town Growth Mechanics - Revision history

Hazzard: /* Town growth speed */

2020-01-10T22:48:05Z

‎Town growth speed

Hazzard: /* Town growth speed */ 1/12 probability citation

2020-01-10T22:11:59Z

‎Town growth speed: 1/12 probability citation

Hazzard: /* Town growth speed */

2020-01-10T22:04:26Z

‎Town growth speed

Hazzard: /* Town growth speed */ update recent cargo days

2020-01-10T22:03:19Z

‎Town growth speed: update recent cargo days

Hazzard: Hazzard moved page User:Mfb/Towns to Town Growth Mechanics: Make a proper page

2020-01-10T20:04:47Z

Hazzard moved page User:Mfb/Towns to Town Growth Mechanics: Make a proper page

Hazzard: /* Town growth speed */ add town growth scale

2020-01-10T20:03:42Z

‎Town growth speed: add town growth scale

Hazzard: /* Town growth speed */

2020-01-10T19:57:13Z

‎Town growth speed

Hazzard at 22:29, 9 January 2020

2020-01-09T22:29:31Z

Hazzard at 22:27, 9 January 2020

2020-01-09T22:27:33Z

Hazzard: /* Application to town building */ typo fix

2020-01-09T19:45:14Z

‎Application to town building: typo fix

@@ Line 61: / Line 61: @@
 *First, the game checks whether town can grow at all. If town growth is not funded and the town needs water, food or whatever (and has population>90 for subarctic, population>60 for subtropic), it does not grow at all. If town growth is funded, these checks are ignored and the town always grows.
 *Active stations can influence town growth: A station is counted if it is within region 0 of the town and the last loading or unloading process of any type is at most 20 [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3356-L3370] * 185 [https://github.com/OpenTTD/OpenTTD/blob/2fd871e2af5cb9e239628843fbd40499ee43406a/src/date_type.h#L32] = 3700 ticks, or 50 days ago. Up to 5 different stations are counted, everything above that is useless.
-*If no station is present and growth is not funded, there is only a 1/12 probability that the town grows at all [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3450]. (It's not clear to me how often this is re-rolled)
+*If no station is present and growth is not funded, there is only a 1/12 probability that the town grows at all [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3450]. The random chance is calculated at the start of each month.
 If the towns grows, "the number of times towns are processed before a new building is built" (comment in the code) is then looked up in of two arrays, where smaller numbers indicate faster growth: [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3372-L3399]

@@ Line 61: / Line 61: @@
 *First, the game checks whether town can grow at all. If town growth is not funded and the town needs water, food or whatever (and has population>90 for subarctic, population>60 for subtropic), it does not grow at all. If town growth is funded, these checks are ignored and the town always grows.
 *Active stations can influence town growth: A station is counted if it is within region 0 of the town and the last loading or unloading process of any type is at most 20 [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3356-L3370] * 185 [https://github.com/OpenTTD/OpenTTD/blob/2fd871e2af5cb9e239628843fbd40499ee43406a/src/date_type.h#L32] = 3700 ticks, or 50 days ago. Up to 5 different stations are counted, everything above that is useless.
-*If no station is present and growth is not funded, there is a 11/12 probability that the town does not grow at all.
+*If no station is present and growth is not funded, there is only a 1/12 probability that the town grows at all [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3450]. (It's not clear to me how often this is re-rolled)
 If the towns grows, "the number of times towns are processed before a new building is built" (comment in the code) is then looked up in of two arrays, where smaller numbers indicate faster growth: [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3372-L3399]

@@ Line 60: / Line 60: @@
 *First, the game checks whether town can grow at all. If town growth is not funded and the town needs water, food or whatever (and has population>90 for subarctic, population>60 for subtropic), it does not grow at all. If town growth is funded, these checks are ignored and the town always grows.
-*Active stations can influence town growth: A station is counted if it is within region 0 of the town and the last loading or unloading process of any type is at most 20 [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3356-L3370] * 185 [https://github.com/OpenTTD/OpenTTD/blob/2fd871e2af5cb9e239628843fbd40499ee43406a/src/date_type.h#L32] = 3700 ticks, or 50 days ago.
+*Active stations can influence town growth: A station is counted if it is within region 0 of the town and the last loading or unloading process of any type is at most 20 [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3356-L3370] * 185 [https://github.com/OpenTTD/OpenTTD/blob/2fd871e2af5cb9e239628843fbd40499ee43406a/src/date_type.h#L32] = 3700 ticks, or 50 days ago. Up to 5 different stations are counted, everything above that is useless.
-−
 Up to 5 different stations are counted, everything above that is useless.
 *If no station is present and growth is not funded, there is a 11/12 probability that the town does not grow at all.
-The following is based on this function: [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3372-L3399]
+If the towns grows, "the number of times towns are processed before a new building is built" (comment in the code) is then looked up in of two arrays, where smaller numbers indicate faster growth: [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3372-L3399]
-−
 If the towns grows, "the number of times towns are processed before a new building is built" (comment in the code) is then looked up in of two arrays, where smaller numbers indicate faster growth:
 *With funded growth: { 120, 120, 120, 100, 80, 60 } with { 0, 1, 2, 3, 4, 5 } stations. This means that the first two stations are pointless (120->120) and 5 stations double town growth (only 60 units instead of 120)
-*Without funded growth: { 320, 420, 300, 220, 160, 100 } with { 0, 1, 2, 3, 4, 5 } stations. The value for 0 stations (320) is smaller than the value with 1 station (420), but without any stations we get this growth only in 1/12 of the cases. Therefore, the first station is very important for town growth, and additional stations can speed up growth by an additional factor of 4 (1->5 stations). 5 stations without funding are just a bit better than no stations with funding - if the town does not allow to build stations, simply fund growth.
+*Without funded growth: { 320, 420, 300, 220, 160, 100 } with { 0, 1, 2, 3, 4, 5 } stations. The value for 0 stations (320) is smaller than the value with 1 station (420), but without any stations we get this growth only in 1/12 of the cases.
 This number is then divided by 2^i where i refers to the settings of town growth rate:

@@ Line 60: / Line 60: @@
 *First, the game checks whether town can grow at all. If town growth is not funded and the town needs water, food or whatever (and has population>90 for subarctic, population>60 for subtropic), it does not grow at all. If town growth is funded, these checks are ignored and the town always grows.
-*Active stations can influence town growth: A station is counted if it is within region 0 of the town and the last loading or unloading process of any type is at most 20 (days?) ago. Up to 5 different stations are counted, everything above that is useless.
+*Active stations can influence town growth: A station is counted if it is within region 0 of the town and the last loading or unloading process of any type is at most 20 [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3356-L3370] * 185 [https://github.com/OpenTTD/OpenTTD/blob/2fd871e2af5cb9e239628843fbd40499ee43406a/src/date_type.h#L32] = 3700 ticks, or 50 days ago.
 *If no station is present and growth is not funded, there is a 11/12 probability that the town does not grow at all.

@@ Line 81: / Line 81: @@
 Again, the result is rounded down.
+This is approximately the number of days between town growth. The actual number of days is about 5% less, since a day is 74 ticks but a town growth cycle is 70 ticks. [https://github.com/OpenTTD/OpenTTD/blob/5c10c426fe2a7722daa0d66dbaed2a0887f69891/src/town.h#L299][https://github.com/OpenTTD/OpenTTD/blob/2fd871e2af5cb9e239628843fbd40499ee43406a/src/date_type.h#L37]
-[I think that the result is equal to the number of days between town growth, but I did not check the scale yet.]
 ==House number and town size==

← Older revision	Revision as of 20:04, 10 January 2020
(No difference)

← Older revision		Revision as of 19:57, 10 January 2020
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	*If no station is present and growth is not funded, there is a 11/12 probability that the town does not grow at all.		*If no station is present and growth is not funded, there is a 11/12 probability that the town does not grow at all.

		+	The following is based on this function: [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L3372-L3399]

	If the towns grows, "the number of times towns are processed before a new building is built" (comment in the code) is then looked up in of two arrays, where smaller numbers indicate faster growth:		If the towns grows, "the number of times towns are processed before a new building is built" (comment in the code) is then looked up in of two arrays, where smaller numbers indicate faster growth:

@@ Line 9: / Line 9: @@
 The algorithm to build new houses works like this:
-) First, calculate how many times the town tries to build a house (which I will call N):
+) First, calculate how many times the town tries to build a house (which I will call N): [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L1524-L1540]
 * If the town is founded with "2x2 grid" or "3x3 grid" as road layout, N = 10 + housenumber*1/9
 * If the town is founded with "better roads", N = 10 + housenumber*2/9

@@ Line 19: / Line 19: @@
 ) now, begin at the city center (usually the road under the town sign, or a road next to it)
 * If there is no road or if there is another, unconnected road, build a road (if allowed by game settings) and always stop the function
-* If not, choose a random direction. If the current tile has a road connection in this direction, do nothing. Otherwise, if the neighbor tile in this direction is empty, build a house there and stop the function. There are more checks involved (e.g. "is the tile in water?"), but they are not important here. If towns are allowed to build roads and have a grid layout, no house will be built at tiles reserved for roads.
+* If not, choose a random direction. If the current tile has a road connection in this direction, do nothing. Otherwise, if the neighbor tile in this direction is empty, build a house there and stop the function. There are more checks involved (e.g. "is the tile in water?"), but they are not important here. If towns are allowed to build roads and have a grid layout, no house will be built at tiles reserved for roads. [https://github.com/OpenTTD/OpenTTD/blob/39e6247bec6b958b11c6ab58430a4197eb1deb6a/src/town_cmd.cpp#L2307-L2335]
 ** Starting in version 1.6, choices that are trivially dead ends are ignored. [https://github.com/OpenTTD/OpenTTD/commit/915aad7603d33dadc47b335ed6369e94da625933#diff-7cb08cdaf3c712e038974cf3b954fa43]

@@ Line 94: / Line 94: @@
 ==Application to town building==
+[[File:Deadend.jpg|thumb|right|A dead end towards east]]
 * Avoid dead ends in populated areas. The town growth algorithm might run into them and stop without building a house. A dead end somewhere outside does not matter - as long as there are no houses, the town does not use this road anyway at the moment.
-* A single road tile with an open end may count as a dead end. The town might follow it, try to build a road (and fail) and stop. [[File:Deadend.jpg|thumb|right|A dead end towards east]]. This was adjusted in 1.6 [https://github.com/OpenTTD/OpenTTD/commit/915aad7603d33dadc47b335ed6369e94da625933#diff-7cb08cdaf3c712e038974cf3b954fa43].
+* A single road tile with an open end may count as a dead end. The town might follow it, try to build a road (and fail) and stop. This was adjusted in 1.6 [https://github.com/OpenTTD/OpenTTD/commit/915aad7603d33dadc47b335ed6369e94da625933#diff-7cb08cdaf3c712e038974cf3b954fa43].
 * Avoid having too many road junctions. Every junction is a place where the town might change its search direction, reducing the effective range where it searches for empty spots to build new houses.
 * Use growth tunnels/bridges if your road layout near the city center is so complex that the outer parts get too few houses. However, let them end within region 3 (roads with trees) until this area is filled with houses.