[Freeciv-Dev] (PR#20668) Patch: add tech_cost_style=3

["(Eddie Anderson)" <saywhat@xxxxxxxxxxxx>]

<URL: http://bugs.freeciv.org/Ticket/Display.html?id=20668 >

   This is a patch (for trunk 12312) which adds a new
tech_cost_style - number 3.  It does *not* change the default
tech_cost_style; that remains 1. 

   The new tech_cost_style=3 implements the formula:
cost of a tech = (1 + num_parents) * baseresearchcost 

   It produces tech costs which are all integer multiples of
baseresearchcost.  I like it and use it.  I hope you will add it to
freeciv as an option. 

   In addition to the code, I added comments describing
tech_cost_style=3 and made minor corrections to comments regarding
other tech_cost_styles.  Based on what I saw, tech_cost_style=3 used
to signify "tech costs are defined in the ruleset"; tech_cost_style=2
now serves that purpose. 

   I also rewrote the comments describing tech_cost_style=0 (CivI /
II compatible) in two different ways (once in game.ruleset and once
in tech.c).  I hope you like at least one of them. 

   This is my first patch using SVN.  As such, it is partly a test
to see if I've got the procedure right. 

   I've used this code for several weeks (on 2.1.0.b2 and later on
trunk) without any problems.  I also tested with tech_cost_style
set to 0 and 1 and didn't see any problems there.  I didn't know how
to do a meaningful test of tech_cost_style=2; AFAIK I don't have a
ruleset that contains predefined tech costs. 

   I also ran autogames (using the default of tech_cost_style=1).
Not surprisingly, the savegames were identical with and without the
patch. 

   I hope this patch meets with your approval. 

 -Eddie 


Index: server/ruleset.c
===================================================================
--- server/ruleset.c    (revision 12312)
+++ server/ruleset.c    (working copy)
@@ -2655,7 +2655,7 @@
 
   game.info.tech_cost_style =
       secfile_lookup_int(&file, "civstyle.tech_cost_style");
-  if (game.info.tech_cost_style < 0 || game.info.tech_cost_style > 2) {
+  if (game.info.tech_cost_style < 0 || game.info.tech_cost_style > 3) {
     freelog(LOG_ERROR, "Bad value %i for tech_cost_style. Using 0.",
            game.info.tech_cost_style);
     game.info.tech_cost_style = 0;
Index: data/default/techs.ruleset
===================================================================
--- data/default/techs.ruleset  (revision 12312)
+++ data/default/techs.ruleset  (working copy)
@@ -32,7 +32,7 @@
 ; helptext     = optional help text string (set units ruleset for examples)
 ; bonus_message = text seen when a player is the first to 
 ;                 discover an bonus tech.
-; cost         = if tech_cost_style is set to 3, this field is read for
+; cost         = if tech_cost_style is set to 2, this field is read for
 ;                information on how much a tech costs
 ;
 ; Special values for req1 and req2 are "None" (first section below) 
Index: data/default/game.ruleset
===================================================================
--- data/default/game.ruleset   (revision 12312)
+++ data/default/game.ruleset   (working copy)
@@ -34,7 +34,7 @@
 ; Barbarian leader ransom in gold
 ransom_gold      = 100
 
-; Base research cost for tech styles 1 & 2
+; Base research cost (used by tech_cost_styles 0, 1, & 3)
 base_tech_cost   = 20
 
 ; City center minimum outputs
@@ -75,13 +75,20 @@
 granary_food_inc       = 10
 
 ; Method of calculating technology costs
-;   0 - Civ (I|II) style. Every new tech add researchcost to cost of next tech.
+;   0 - Civ (I|II) style.  The Nth tech that you research costs 
+;       (N * baseresearchcost).  E.g. if baseresearchcost = 20, then the
+;         1st tech costs 20, 2nd tech costs 40, 15th tech costs 300, etc.
 ;   1 - Cost of technology is 
-;         MAX((1+parents) * (researchcost/2) * sqrt(1+parents), researchcost)
-;       where num_parents == number of requirement for tech, counted 
+;         MAX((1+num_parents) * (researchcost/2) * sqrt(1+num_parents), 
+;          researchcost)
+;       where num_parents == number of requirements for the tech, counted 
 ;       recursively.
-;   2 - Cost are read from tech.ruleset. Missing costs are generated by
+;   2 - Costs are read from techs.ruleset. Missing costs are generated by
 ;       style 1.
+;   3 - Cost of technology is 
+;         (1+num_parents) * researchcost
+;       where num_parents == number of requirements for the tech, counted 
+;       recursively.
 tech_cost_style = 1
 
 ; Technology leak from other civilizations
===================================================================
Index: common/tech.c
===================================================================
--- common/tech.c       (revision 12312)
+++ common/tech.c       (working copy)
@@ -35,9 +35,10 @@
    server/ruleset.c (for the server)
    client/packhand.c (for the client) */
 
-/* Precalculated costs according to techcost style 1.  These do not include
- * the sciencebox multiplier. */
+/* Precalculated costs according to techcost style 1 or 3.  These do not 
+ * include the sciencebox multiplier. */
 static double techcoststyle1[A_LAST];
+static double techcoststyle3[A_LAST];
 
 static const char *flag_names[] = {
   "Bonus_Tech", "Bridge", "Railroad", "Fortress",
@@ -392,12 +393,19 @@
   from game.info.tech_cost_style and game.info.tech_leakage.
 
   tech_cost_style:
-  0 - Civ (I|II) style. Every new tech adds N to the cost of the next tech.
-  1 - Cost of technology is 
-        (1 + parents) * 10 * sqrt(1 + parents)
-      where num_parents == number of requirement for tech (recursive).
-  2 - Cost are read from tech.ruleset. Missing costs are generated by
+  0 - Civ (I|II) style. Every new tech costs baseresearchcost more than 
+      the cost of the preceding tech.  So the Nth tech that you research 
+      costs (N * baseresearchcost).   It doesn't matter if a tech is high
+      or low on the tech tree.  All that matters is that it is the Nth 
+      tech that *you* are researching.
+  1 - Cost of a technology is 
+        (1 + num_parents) * (baseresearchcost/2) * sqrt(1 + num_parents)
+      where num_parents == number of prerequisites for that tech (recursive).
+  2 - Costs are read from techs.ruleset. Missing costs are generated by
       style 1.
+  3 - Cost of a technology is 
+        (1 + num_parents) * baseresearchcost
+      where num_parents == number of prerequisites for that tech (recursive).
 
   tech_leakage:
   0 - No reduction of the technology cost.
@@ -452,6 +460,9 @@
   case 2:
     base_cost = advances[tech].preset_cost;
     break;
+  case 3:
+    base_cost = techcoststyle3[tech];
+    break;
   default:
     die("Invalid tech_cost_style %d %d", game.info.tech_cost_style,
        tech_cost_style);
@@ -608,6 +619,7 @@
     const double cost = base * reqs * sqrt(reqs);
 
     techcoststyle1[tech] = MAX(cost, game.info.base_tech_cost);
+    techcoststyle3[tech] = (reqs - 1) * game.info.base_tech_cost;
   } tech_type_iterate_end;
 }
 
@@ -693,13 +705,12 @@
 **************************************************************************/
 bool techs_have_fixed_costs()
 {
-  return ((game.info.tech_cost_style == 1
-          || game.info.tech_cost_style == 2)
+  return (game.info.tech_cost_style != 0
          && game.info.tech_leakage == 0);
 }
 
 /****************************************************************************
-  Inialize tech structures.
+  Initialize tech structures.
 ****************************************************************************/
 void techs_init(void)
 {