increase magic power for low levels in E3 (instead of divide by 2 sometimes giving powers of < 1.0, cap it below at 1)

several spells have now had problems with powers lower than they were ever designed for, including shapeshift
also added a test and some framework for shapeshift spell (in E2).
https://bugs.eressea.de/view.php?id=1588

scripts/tests/e2/init.lua

@@ -2,3 +2,4 @@ require 'tests.e2.shiplanding'
 require 'tests.e2.e2features'
 require 'tests.e2.movement'
 require 'tests.e2.guard'
+require 'tests.e2.spells'

scripts/tests/e2/spells.lua

@@ -0,0 +1,28 @@
+require "lunit"
+
+module("tests.e2.spells", package.seeall, lunit.testcase)
+
+function setup()
+    eressea.free_game()
+    eressea.settings.set("nmr.removenewbie", "0")
+    eressea.settings.set("nmr.timeout", "0")
+    eressea.settings.set("NewbieImmunity", "0")
+    eressea.settings.set("rules.economy.food", "4")
+end
+
+function test_shapeshift()
+    local r = region.create(42, 0, "plain")
+    local f = faction.create("noreply@eressea.de", "demon", "de")
+    local u1 = unit.create(f, r, 1)
+    local u2 = unit.create(f, r, 1)
+    u1:clear_orders()
+    u1.magic = "gray"
+    u1:set_skill("magic", 2)
+    u1.aura = 1
+    u1:add_spell("shapeshift")
+    u1:add_order("ZAUBERE STUFE 1 Gestaltwandlung " .. itoa36(u2.id) .. " Goblin")
+    process_orders()
+    assert_equal(f.race, u2.race)
+    s = u2:show()
+    assert_equal("1 Goblin", string.sub(s, string.find(s, "1 Goblin")))
+end

src/battle.c

@@ -1868,7 +1868,7 @@ static void do_extra_spell(troop at, const att * a)
     else {
         int level = a->level;
         assert(a->level > 0);
-        cast_combatspell(at, sp, level, level * MagicPower());
+        cast_combatspell(at, sp, level, MagicPower((float)level));
     }
 }
 

src/bind_unit.c

@@ -20,6 +20,7 @@ without prior permission by the authors of Eressea.
 #include "alchemy.h"
 #include "bindings.h"
 #include "move.h"
+#include "reports.h"
 
 /*  attributes includes */
 #include <attributes/racename.h>
@@ -57,6 +58,17 @@ without prior permission by the authors of Eressea.
 #include <stdlib.h>
 #include <limits.h>
 
+static int tolua_bufunit(lua_State * L) {
+    char buf[8192];
+    unit *self = (unit *)tolua_tousertype(L, 1, 0);
+    int mode = (int)tolua_tonumber(L, 2, see_unit);
+    if (!self)  return 0;
+
+    bufunit(self->faction, self, 0, mode, buf, sizeof(buf));
+    tolua_pushstring(L, buf);
+    return 1;
+
+}
 static int tolua_unit_get_objects(lua_State * L)
 {
     unit *self = (unit *)tolua_tousertype(L, 1, 0);
@@ -533,7 +545,7 @@ static void unit_castspell(unit * u, const char *name, int level)
             }
             else {
                 castorder co;
-                create_castorder(&co, u, 0, sp, u->region, level, level * MagicPower(), 0, 0, 0);
+                create_castorder(&co, u, 0, sp, u->region, level, MagicPower((float)level), 0, 0, 0);
                 sp->cast(&co);
                 free_castorder(&co);
             }
@@ -1058,6 +1070,7 @@ void tolua_unit_open(lua_State * L)
 #ifdef BSON_ATTRIB
             tolua_variable(L, TOLUA_CAST "attribs", &tolua_unit_get_attribs, 0);
 #endif
+            tolua_function(L, TOLUA_CAST "show", &tolua_bufunit);
         }
         tolua_endmodule(L);
     }

src/magic.c

@@ -117,14 +117,17 @@ static float MagicRegeneration(void)
     return value;
 }
 
-float MagicPower(void)
+float MagicPower(float force)
 {
     static float value = -1.0;
+    if (force <= 0) {
+        return 0;
+    }
     if (value < 0) {
         const char *str = get_param(global.parameters, "magic.power");
         value = str ? (float)atof(str) : 1.0f;
     }
-    return value;
+    return _max(value * force, 1.0f);
 }
 
 static int a_readicastle(attrib * a, void *owner, struct storage *store)
@@ -1074,7 +1077,7 @@ spellpower(region * r, unit * u, const spell * sp, int cast_level, struct order
         }
     }
 
-    force = force * MagicPower();
+    force = MagicPower(force);
 
     return _max(force, 0);
 }

src/magic.h

@@ -360,7 +360,7 @@ extern "C" {
     extern void write_spells(struct quicklist *slist, struct storage *store);
     extern void read_spells(struct quicklist **slistp, magic_t mtype,
     struct storage *store);
-    extern float MagicPower(void);
+    float MagicPower(float force);
 
     extern struct spellbook * get_spellbook(const char * name);
     extern void free_spellbooks(void);