From 8ff18178b182a95e021dc361a4ee49a597ffbc57 Mon Sep 17 00:00:00 2001
From: justin <justin.g.kruger@gmail.com>
Date: Tue, 8 Mar 2022 23:19:14 +0000
Subject: [PATCH] Example use of fallback in placement room positions

---
 src/Dodge/PlacementSpot.hs |  5 +++++
 src/Dodge/Room/Tanks.hs    | 10 ++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/Dodge/PlacementSpot.hs b/src/Dodge/PlacementSpot.hs
index fcf12f295..3b5e9073d 100644
--- a/src/Dodge/PlacementSpot.hs
+++ b/src/Dodge/PlacementSpot.hs
@@ -37,6 +37,11 @@ unusedSpotAwayFromLink x = PSPos f (const id) Nothing
                 -> Just (PS p a,UsedSpot p a t)
         _       -> Nothing
 
+setFallback :: Placement -> Placement -> Placement
+setFallback fallback plmnt = plmnt
+    & plSpot . psFallback .~ Just fallback
+    & plIDCont %~ fmap (fmap $ setFallback fallback)
+
 unusedOffPathAwayFromLink :: Float -> PlacementSpot
 unusedOffPathAwayFromLink x = PSPos f (const id) Nothing
   where
diff --git a/src/Dodge/Room/Tanks.hs b/src/Dodge/Room/Tanks.hs
index 0ab55775d..1bd583af8 100644
--- a/src/Dodge/Room/Tanks.hs
+++ b/src/Dodge/Room/Tanks.hs
@@ -36,12 +36,14 @@ tanksRoom crs its = do
     thetank <- randomTank <&> plSpot .~ unusedOffPathAwayFromLink 50
     let room = roomRectAutoLinks w h
         nwestlnks = length $ filter ((OnEdge West `S.member`) . _rlType) $ _rmLinks room
+    girderPosOrder <- shuffle [1 .. nwestlnks - 2]
     let plmnts = 
-            --[ twoRoomPoss (isUnusedLinkType (OnEdge West)) (isUnusedLinkType (OnEdge East)) $ \ps1 ps2 ->
-            [ twoRoomPoss (isUnusedLinkType (FromSouth i)) (isUnusedLinkType (FromSouth i)) $ \ps1 ps2 ->
+            --ok, this has become complicated
+            foldr1 setFallback [ twoRoomPoss (isUnusedLinkType (FromSouth i)) 
+                (isUnusedLinkType (FromSouth i)) $ \ps1 ps2 ->
                 sps0 $ PutShape $ girderV 96 20 10 (_psPos ps1) (_psPos ps2) 
-                | i <- [1 .. nwestlnks - 2]]
-            ++ map (\it -> sps0 (PutFlIt it) & plSpot .~ anyUnusedSpot) its
+                | i <- girderPosOrder]
+            : map (\it -> sps0 (PutFlIt it) & plSpot .~ anyUnusedSpot) its
             ++ map (\cr -> sps0 (PutCrit cr) & plSpot .~ unusedSpotAwayFromLink 50) crs
             ++ replicate ntanks thetank
 --            , sps0 $ PutShape $ colorSH orange $ pipePP 2 (V3 50 50 25) (V3 50 120 25)