<URL: http://bugs.freeciv.org/Ticket/Display.html?id=15947 >
Better fix this if 2.1 is ever to be released I suppose...
The problem was in the function below, in 2.08 there was no T_UNKNOWN
check. I assume every tile is T_UNKNOWN when the map generator is
generating a map causing it to make no rivers.
--------common/map.c----------
bool is_water_adjacent_to_tile(const struct tile *ptile)
{
if (ptile->terrain != T_UNKNOWN
...
-----------------------------
So I fixed fill_island_rivers(..) as best I could with my rusty
programming skills.
### Fixes / Removals
* if ((i * 3 > k * 2 --- don't know what that was trying to do, seems
to be cut and pasted from the terrain placing code.
* not_placed(ptile) --- doesn't seem to do anything, another copy from
terrain placing code, there is already a check if the tile belongs to
the current island's isleindex.
* Didn't have a check if the tile it's evaluating already has a river.
This could cause it place a river twice in one tile, reducing the amount
by around 30% on average. Possibly all the way down to 1 tile worst case
when it placed a mouth that had nowhere to grow, given the 0.5% chance
of creating a second river.
*2.08 hex topology island river generation used to create river loops.
### Improvements
* River mouths can now only be surrounded by 2 ocean tiles, only 1 of
which is cardinal. This gets rid of the hideous corner / peninsular 2 or
3 mouthed river outlets. Makes it look more natural too, especially
when they start from an inlet or landlocked lake. Also ensures ~90% of
the time there are 2 directions the river can go from the mouth, pushing
the river further inland and usually making it more than 1 tile long.
* Increased the amount of river tiles generated by 75% for the island
generator. I figure rivers will be more important now the capital gets
corruption and a 75% production bonus under despotism. High production
tiles that still produce trade are best in this situation.
Also in gen1 most inland tiles are mountains / hills, it's a lot harder
to irrigate inland gen3 islands with random terrain placement.
I really wish rivers were still a pregame option instead of having to
turn the world into swamp and jungle.
* Increased the rivers aversion to ocean, and reduced it's windiness and
tendency to fork. This makes it go further inland and windy forking
rivers ain't as useful for unit movement / irrigation.
* Changed all the cardinal / percent - TRUE's & FALSE's into constants
so the code is more readable. Just picked the m_ prefix out of thin air
for map.h . Should I of used #DEFINES or just commented every line like
the generator1 river function instead ?.
* Split some checks into helper functions making the code more readable.
### Problems
* Doesn't generate proper rivers for the hex2t tileset. Although that
tileset doesn't create proper coastlines either and uses a different hex
layout to isophex so I'll assume my code isn't at fault.
--- Yautja
Index: common/map.h
===================================================================
--- common/map.h (revision 12345)
+++ common/map.h (working copy)
@@ -80,6 +80,11 @@
TF_HEX = 8
};
+static const bool m_adjacent = FALSE;
+static const bool m_cardinal = TRUE;
+static const bool m_number = FALSE;
+static const bool m_percent = TRUE;
+
#define MAP_IS_ISOMETRIC (topo_has_flag(TF_ISO) || topo_has_flag(TF_HEX))
#define CURRENT_TOPOLOGY (map.topology_id)
Index: server/generator/mapgen.c
===================================================================
--- server/generator/mapgen.c (revision 12345)
+++ server/generator/mapgen.c (working copy)
@@ -1470,6 +1470,35 @@
}
/**************************************************************************
+ returns true if ptile is suitable for a river mouth
+**************************************************************************/
+static bool island_river_mouth_suitability( struct tile *ptile )
+{
+ return(count_ocean_near_tile(ptile, m_cardinal, m_number) == 1
+ && count_ocean_near_tile(ptile, m_adjacent, m_percent) <= 35
+ && count_special_near_tile(ptile,
+ m_adjacent, m_number, S_RIVER) == 0);
+}
+
+
+/**************************************************************************
+ returns true if river cardinal and tile is suitable for extending it
+**************************************************************************/
+static bool island_river_suitability( struct tile *ptile )
+{
+ return((count_special_near_tile(ptile, m_cardinal, m_number, S_RIVER) == 1
+ && count_ocean_near_tile(ptile, m_cardinal, m_number) == 0)
+ && count_ocean_near_tile(ptile, m_adjacent, m_percent) < 20
+ && count_special_near_tile(ptile,
+ m_adjacent, m_percent, S_RIVER) < 35
+ /* helps with straightness, ocean avoidance and reduces forking */
+ && ((count_special_near_tile(ptile,
+ m_adjacent, m_percent, S_RIVER) +
+ count_ocean_near_tile(ptile, m_adjacent, m_percent) * 2)
+ < myrand(25) + 25));
+}
+
+/**************************************************************************
fill an island with rivers
**************************************************************************/
static void fill_island_rivers(int coast, long int *bucket,
@@ -1485,30 +1514,25 @@
i = *bucket / capac;
i++;
*bucket -= i * capac;
-
+
+ /* generate 75% more rivers than generator 1 */
+ i = (i * 175) / 100;
+
k = i;
- failsafe = i * (pstate->s - pstate->n) * (pstate->e - pstate->w);
+ failsafe = i * (pstate->s - pstate->n) * (pstate->e - pstate->w) * 5;
if (failsafe < 0) {
failsafe = -failsafe;
}
-
+
while (i > 0 && (failsafe--) > 0) {
struct tile *ptile = get_random_map_position_from_state(pstate);
if (tile_get_continent(ptile) == pstate->isleindex
- && not_placed(ptile)) {
-
- /* the first condition helps make terrain more contiguous,
- the second lets it avoid the coast: */
- if ((i * 3 > k * 2
- || count_special_near_tile(ptile, FALSE, TRUE, S_RIVER) > 0
- || myrand(100) < 50)
- && (!is_cardinally_adj_to_ocean(ptile) || myrand(100) < coast)) {
- if (is_water_adjacent_to_tile(ptile)
- && count_ocean_near_tile(ptile, FALSE, TRUE) < 50
- && count_special_near_tile(ptile, FALSE, TRUE, S_RIVER) < 35) {
- tile_set_special(ptile, S_RIVER);
- i--;
- }
+ && !tile_has_special(ptile, S_RIVER)) {
+ if ((island_river_mouth_suitability( ptile )
+ && (myrand(100) < coast || i == k ))
+ || island_river_suitability( ptile )) {
+ tile_set_special(ptile, S_RIVER);
+ i--;
}
}
}
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