add combustion delay parameter

data/scenarios/Testing/1355-combustion.yaml

@@ -21,6 +21,7 @@ solution: |
   ignite forward;
   turn right;
   move; move; move;
+  ignite left;
   turn right;
   move;
   ignite left;
@@ -75,6 +76,18 @@ entities:
       duration: [8, 8]
       product: null
     properties: [known, pickable, combustible]
+  - name: slowfuse
+    display:
+      attr: silver
+      char: '~'
+    description:
+      - Reliably combustible, but burns more slowly
+    combustion:
+      ignition: 20
+      duration: [64, 64]
+      delay: 63
+      product: null
+    properties: [known, pickable, combustible]
   - name: dynamite
     display:
       attr: red
@@ -103,6 +116,7 @@ world:
     'b': [grass, board]
     'i': [grass, cotton]
     'F': [grass, fuse]
+    'f': [grass, slowfuse]
     'd': [grass, dynamite, judge]
     '.': [grass]
   upperleft: [0, 0]
@@ -123,11 +137,11 @@ world:
     ......iiiiiiii........F...F...F...F..
     iiiiiiiiiiiiiii..Ω.FFFF...FFFFF...d..
     ......iiiiiiii.......................
-    iiiiiiiiiiiii.....qqqqqqqqqqqqqqqq...
-    ......iiiiii......qqqqqqqqqqqqqqqq...
-    iiiiiiiiiii.......qqqqqqqqqqqqqqqq...
-    ..................qqqqqqqqqqqqqqqq...
-    ..................qqqqqqqqqqqqqqqq...
-    ..................qqqqqqqqqqqqqqqq...
-    ..................qqqqqqqqqqqqqqqq...
+    iiiiiiiiiiiii..f..qqqqqqqqqqqqqqqq...
+    ......iiiiii...f..qqqqqqqqqqqqqqqq...
+    iiiiiiiiiii....f..qqqqqqqqqqqqqqqq...
+    ...............f..qqqqqqqqqqqqqqqq...
+    ..ffff...ffff..f..qqqqqqqqqqqqqqqq...
+    ..f..f...f..f..f..qqqqqqqqqqqqqqqq...
+    ..f..fffff..ffff..qqqqqqqqqqqqqqqq...
     ..................qqqqqqqqqqqqqqqq...

data/schema/combustion.json

@@ -9,18 +9,23 @@
         "ignition": {
             "default": 0.5,
             "type": "number",
-            "description": "Rate of ignition by a neighbor, per tick."
+            "description": "Rate of ignition by a neighbor.  This is the rate parameter of a Poisson distribution, i.e. the expected number of times per tick that a combusting neighbor would tend to ignite this entity.  Typically a number between 0 and 1, but it can be any nonnegative real number (default: 0.5)."
         },
         "duration": {
             "type": "array",
             "default": [100, 200],
             "$ref": "range.json",
             "description": "For combustible entities, a 2-tuple of integers specifying the minimum and maximum amount of time that the combustion shall persist."
         },
+        "delay": {
+            "type": "number",
+            "default": 0.0,
+            "description": "Warmup delay, i.e. the number of ticks combustion must persist until this entity will potentially start igniting its neighbors (default: 0)."
+        },
         "product": {
             "default": "ash",
             "type": ["string", "null"],
-            "description": "What entity, if any, is left over after combustion"
+            "description": "What entity, if any, is left over after combustion."
         }
     }
 }

src/swarm-engine/Swarm/Game/Step/Combustion.hs

@@ -67,7 +67,11 @@ igniteCommand c d = do
   let selfCombustibility = (e ^. entityCombustion) ? defaultCombustibility
   createdAt <- getNow
   combustionDurationRand <- addCombustionBot e selfCombustibility createdAt loc
-  forM_ (getNeighborLocs loc) $ igniteNeighbor createdAt combustionDurationRand
+  let warmup = delay selfCombustibility
+  let neighborAffectDuration = max 0 (combustionDurationRand - warmup)
+  when (neighborAffectDuration > 0) $
+    forM_ (getNeighborLocs loc) $
+      igniteNeighbor createdAt warmup neighborAffectDuration
  where
   verb = "ignite"
   verbed = "ignited"
@@ -117,7 +121,7 @@ addCombustionBot inputEntity combustibility ts loc = do
       ts
   return combustionDurationRand
  where
-  Combustibility _ durationRange maybeCombustionProduct = combustibility
+  Combustibility _ durationRange _ maybeCombustionProduct = combustibility
 
 -- | A system program for a "combustion robot", to burn an entity
 --   after it is ignited.
@@ -141,7 +145,7 @@ addCombustionBot inputEntity combustibility ts loc = do
 --    cells. This would avoid polluting the logic of the currently burning cell
 --    with logic to manage probabilities of combustion propagation.
 combustionProgram :: Integer -> Combustibility -> TSyntax
-combustionProgram combustionDuration (Combustibility _ _ maybeCombustionProduct) =
+combustionProgram combustionDuration (Combustibility _ _ _ maybeCombustionProduct) =
   [tmQ|
     wait $int:combustionDuration;
     if ($int:invQuantity > 0) {
@@ -156,18 +160,25 @@ combustionProgram combustionDuration (Combustibility _ _ maybeCombustionProduct)
     Nothing -> (0, "")
     Just p -> (1, p)
 
--- | We treat the 'ignition' field in the 'Combustibility' record
--- as a /rate/ in a Poisson distribution.
--- Ignition of neighbors depends on that particular neighbor entity's
--- combustion /rate/, but also on the duration
--- that the current entity will burn.
+-- | Possibly ignite a neighbor of a source entity that is combusting.
+--   @creationTime@ is the time the source entity began to combust.
+--   @warmup@ is the number of ticks of delay that the source entity
+--   needs to burn before it will start affecting its neighbors;
+--   @sourceDuration@ is the number of ticks that it will potentially
+--   affect its neighbors.
+--
+--   We treat the 'ignition' field in the 'Combustibility' record as a
+--   /rate/ in a Poisson distribution.  Ignition of neighbors depends
+--   on that particular neighbor entity's combustion /rate/, but also
+--   on the @sourceDuration@ time that the current entity will burn.
 igniteNeighbor ::
   Has (State GameState) sig m =>
   TimeSpec ->
   Integer ->
+  Integer ->
   Cosmic Location ->
   m ()
-igniteNeighbor creationTime sourceDuration loc = do
+igniteNeighbor creationTime warmup sourceDuration loc = do
   maybeEnt <- entityAt loc
   forM_ maybeEnt igniteEntity
  where
@@ -177,7 +188,8 @@ igniteNeighbor creationTime sourceDuration loc = do
       when (probabilityOfIgnition >= threshold) $ do
         ignitionDelayRand <- uniform (0, 1)
         let ignitionDelay =
-              floor
+              (warmup +)
+                . floor
                 . min (fromIntegral sourceDuration)
                 . negate
                 $ log ignitionDelayRand / rate

src/swarm-scenario/Swarm/Game/Entity.hs

@@ -243,19 +243,30 @@ data Combustibility = Combustibility
   --   See <https://math.stackexchange.com/a/1243629>.
   , duration :: (Integer, Integer)
   -- ^ min and max tick counts for combustion to persist
+  , delay :: Integer
+  -- ^ Delay until this entity may start igniting its neighbors.
   , product :: Maybe EntityName
   -- ^ what entity, if any, is left over after combustion
   }
-  deriving (Eq, Ord, Show, Read, Generic, Hashable, FromJSON, ToJSON)
+  deriving (Eq, Ord, Show, Read, Generic, Hashable, ToJSON)
+
+instance FromJSON Combustibility where
+  parseJSON = withObject "Combustibility" $ \v -> do
+    ignition <- v .: "ignition"
+    duration <- v .: "duration"
+    delay <- v .:? "delay" .!= 0
+    product <- v .: "product"
+    pure Combustibility {..}
 
 -- | The default combustion specification for a combustible entity
 --   with no combustion specification:
 --
 --   * ignition rate 0.5
 --   * duration (100, 200)
+--   * delay of 0
 --   * product @ash@
 defaultCombustibility :: Combustibility
-defaultCombustibility = Combustibility 0.5 (100, 200) (Just "ash")
+defaultCombustibility = Combustibility 0.5 (100, 200) 0 (Just "ash")
 
 ------------------------------------------------------------
 -- Entity