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fairland: Compute resources by interpolating tables

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The functions mapping elevation to resources are piecewise linear.
Replace them by linear interpolation on data points defined in tables.
Tables are easier to tweak for deities than code.

The data points are a bit awkward because the functions they replace
are.  The next commit will tweak them to address that.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
This commit is contained in:
Markus Armbruster 2020-08-21 07:32:36 +02:00
parent 39ef156f00
commit 5b5e2cdfa8
1 changed files with 81 additions and 84 deletions
Download patch file Download diff file Expand all files Collapse all files

165
src/util/fairland.c
View file

@ -109,8 +109,8 @@
* 5. Set resources * 5. Set resources
* *
* Sector resources are simple functions of elevation. You can alter * Sector resources are simple functions of elevation. You can alter
* macros OIL_MAX, IRON_MIN, GOLD_MIN, FERT_MAX, and URAN_MIN to * iron_conf[], gold_conf[], fert_conf[], oil_conf[], and uran_conf[]
* customize them. * to customize them.
*/ */
#include <config.h> #include <config.h>
@ -129,31 +129,69 @@
#include "version.h" #include "version.h"
#include "xy.h" #include "xy.h"
/* The following five numbers refer to elevation under which (in the case of
fertility or oil) or over which (in the case of iron, gold, and uranium)
sectors with that elevation will contain that resource. Elevation ranges
from 0 to 100 */
/* raise FERT_MAX for more fertility */
#define FERT_MAX 56
/* raise OIL_MAX for more oil */
#define OIL_MAX 33
/* lower IRON_MIN for more iron */
#define IRON_MIN 22
/* lower GOLD_MIN for more gold */
#define GOLD_MIN 36
/* lower URAN_MIN for more uranium */
#define URAN_MIN 56
/* do not change these defines */ /* do not change these defines */
#define LANDMIN 1 /* plate altitude for normal land */ #define LANDMIN 1 /* plate altitude for normal land */
#define PLATMIN 36 /* plate altitude for plateau */ #define PLATMIN 36 /* plate altitude for plateau */
#define HIGHMIN 98 /* plate altitude for mountains */ #define HIGHMIN 98 /* plate altitude for mountains */
/*
* Resource configuration
* Resources are determined by elevation. The map from elevation to
* resource is defined as a linear interpolation of resource data
* points (elev, res) defined in the tables below. Elevations range
* from -127 to 127, and resource values from 0 to 100.
*/
struct resource_point {
int elev;
double res;
};
struct resource_point iron_conf[] = {
{ -127, 0 },
{ 21, 0 },
{ 84, 120.0 * 63 / 76 },
{ 85, 100 },
{ HIGHMIN - 1, 100 },
{ HIGHMIN , 0 },
{ 127, 0 } };
struct resource_point gold_conf[] = {
{ -127, 0 },
{ 35, 0 },
{ HIGHMIN - 1, 80 },
{ HIGHMIN, 80 },
{ 127, 85 } };
struct resource_point fert_conf[] = {
{ -127, 100 },
{ -59, 100 },
{ LANDMIN - 1, 41 },
{ LANDMIN, 100 },
{ 10, 100 },
{ 11, 120.0 * 45 / 55 },
{ 56, 0 },
{ 127, 0 } };
struct resource_point oil_conf[] = {
{ -127, 100 },
{ -49, 100 },
{ LANDMIN - 1, 2 },
{ LANDMIN, 100 },
{ 6, 100 },
{ 7, 120.0 * 27 / 33 },
{ 34, 0 },
{ 127, 0 } };
struct resource_point uran_conf[] = {
{ -127, 0 },
{ 55, 0 },
{ 90, 100 },
{ 97, 100 },
{ 98, 0 },
{ 127, 0 } };
static void qprint(const char * const fmt, ...) static void qprint(const char * const fmt, ...)
ATTRIBUTE((format (printf, 1, 2))); ATTRIBUTE((format (printf, 1, 2)));
@ -1360,77 +1398,36 @@ elev_to_sct_type(int elevation)
ADD THE RESOURCES ADD THE RESOURCES
****************************************************************************/ ****************************************************************************/
/*
* Map elevation @elev to a resource value according to @conf.
* This is a linear interpolation on the data points in @conf.
*/
static int static int
set_fert(int e) elev_to_resource(int elev, struct resource_point conf[])
{ {
int fert = 0; int i, elev1, elev2, delev;
if (e < LANDMIN) double res1, res2, dres;
fert = LANDMIN - e + 40;
else if (e < FERT_MAX)
fert = (120 * (FERT_MAX - e)) / (FERT_MAX - LANDMIN);
if (fert > 100)
fert = 100;
return fert;
}
static int for (i = 1; elev > conf[i].elev; i++) ;
set_oil(int e) assert(conf[i - 1].elev <= elev);
{
int oil = 0;
if (e < LANDMIN)
oil = (LANDMIN - e) * 2;
else if (e <= OIL_MAX)
oil = (120 * (OIL_MAX - e + 1)) / (OIL_MAX - LANDMIN + 1);
if (oil > 100)
oil = 100;
return oil;
}
static int elev1 = conf[i - 1].elev;
set_iron(int e) elev2 = conf[i].elev;
{ delev = elev2 - elev1;
int iron = 0; res1 = conf[i - 1].res;
if (e >= IRON_MIN && e < HIGHMIN) res2 = conf[i].res;
iron = (120 * (e - IRON_MIN + 1)) / (HIGHMIN - IRON_MIN); dres = res2 - res1;
if (iron > 100) return (int)(res1 + ((elev - elev1) * dres) / delev);
iron = 100;
return iron;
}
static int
set_gold(int e)
{
int gold = 0;
if (e >= GOLD_MIN) {
if (e < HIGHMIN)
gold = (80 * (e - GOLD_MIN + 1)) / (HIGHMIN - GOLD_MIN);
else
gold = 80 + 5 * (e - HIGHMIN) / (127 - HIGHMIN);
}
if (gold > 100)
gold = 100;
return gold;
}
static int
set_uran(int e)
{
int uran = 0;
if (e >= URAN_MIN && e < HIGHMIN)
uran = (120 * (e - URAN_MIN + 1)) / (HIGHMIN - URAN_MIN);
if (uran > 100)
uran = 100;
return uran;
} }
static void static void
add_resources(struct sctstr *sct) add_resources(struct sctstr *sct)
{ {
sct->sct_fertil = set_fert(sct->sct_elev); sct->sct_min = elev_to_resource(sct->sct_elev, iron_conf);
sct->sct_oil = set_oil(sct->sct_elev); sct->sct_gmin = elev_to_resource(sct->sct_elev, gold_conf);
sct->sct_min = set_iron(sct->sct_elev); sct->sct_fertil = elev_to_resource(sct->sct_elev, fert_conf);
sct->sct_gmin = set_gold(sct->sct_elev); sct->sct_oil = elev_to_resource(sct->sct_elev, oil_conf);
sct->sct_uran = set_uran(sct->sct_elev); sct->sct_uran = elev_to_resource(sct->sct_elev, uran_conf);
} }
/**************************************************************************** /****************************************************************************