Implement dice and percent as global lua functions

Intended to simplify many of the math.random calls currently in use, and
make them more semantic and thus more readable.

The dice function d() takes either a two-argument form which is the same
as in the C source (number of dice, faces per die) or a one-argument
form that rolls a single die.

The percent(N) function returns true N% of the time.

diff --git a/dat/nhlib.lua b/dat/nhlib.lua
index fb35acd1c5eae2b7ea5105391a2c339b3427a622..983542b5b388ff0833b4bdcda27133bcde1a0c4b 100644 (file)
--- a/dat/nhlib.lua
+++ b/dat/nhlib.lua
@@ -21,3 +21,23 @@ end
 
 align = { "law", "neutral", "chaos" };
 shuffle(align);
+
+-- d(2,6) = 2d6
+-- d(20) = 1d20 (single argument = implicit 1 die)
+function d(dice, faces)
+   if (faces == nil) then
+      -- 1-arg form: argument "dice" is actually the number of faces
+      return math.random(1, dice)
+   else
+      local sum = 0
+      for i=1,dice do
+         sum = sum + math.random(1, faces)
+      end
+      return sum
+   end
+end
+
+-- percent(20) returns true 20% of the time
+function percent(threshold)
+   return math.random(0,99) < threshold
+end