fix: plow rotation on headland

#3413

#3413 (comment)

scripts/Course.lua

@@ -445,6 +445,22 @@ function Course:isOnHeadland(ix, n, boundaryId)
     end
 end
 
+---@param ix number
+---@return boolean|nil true if ix is on a clockwise headland (around the field, or around an island). False if
+--- it is on a counterclockwise headland, and nil, if is is not on a headland.
+function Course:isOnClockwiseHeadland(ix)
+    local boundaryId = self.waypoints[ix].attributes:getBoundaryId()
+    if boundaryId == nil then
+        return nil
+    end
+    if CourseGenerator.isHeadland(boundaryId) then
+        return self.headlandClockwise
+    elseif CourseGenerator.isIslandHeadland(boundaryId) then
+        return self.islandHeadlandClockwise
+    end
+    return nil
+end
+
 function Course:isHeadlandTransition(ix)
     return self.waypoints[ix]:isHeadlandTransition()
 end

scripts/ai/AIDriveStrategyPlowCourse.lua

@@ -155,8 +155,9 @@ function AIDriveStrategyPlowCourse:rotatePlows()
     local ix = self.ppc:getCurrentWaypointIx()
     local plowShouldBeOnTheLeft
     if self.course:isOnHeadland(ix) then
-        plowShouldBeOnTheLeft = self.course:isLeftSideWorked(ix)
-        self:debug('On a headland, plow should be on the left %s', tostring(plowShouldBeOnTheLeft))
+        local clockwise = self.course:isOnClockwiseHeadland(ix)
+        plowShouldBeOnTheLeft = not clockwise
+        self:debug('On a headland (clockwise %s), plow should be on the left %s', tostring(clockwise), tostring(plowShouldBeOnTheLeft))
     else
         local isNextTurnLeft = self.course:isNextTurnLeft(ix)
         if isNextTurnLeft == nil then

scripts/courseGenerator/CourseGenerator.lua

@@ -56,6 +56,18 @@ CourseGenerator.cDefaultHeadlandOverlapPercentage = 5
 CourseGenerator.debugPoints = {}
 CourseGenerator.debugPolylines = {}
 
+---@param boundaryId string boundary ID from the waypoint attributes
+---@return boolean true if this boundary ID is associated with a headland around the field
+function CourseGenerator.isHeadland(boundaryId)
+    return string.sub(boundaryId, 1) == CourseGenerator.Headland.boundaryIdPrefix
+end
+
+---@param boundaryId string boundary ID from the waypoint attributes
+---@return boolean true if this boundary ID is associated with a headland around an island
+function CourseGenerator.isIslandHeadland(boundaryId)
+    return string.sub(boundaryId, 1) == CourseGenerator.IslandHeadland.boundaryIdPrefix
+end
+
 --- Return true when running in the game
 -- used by file and log functions to determine how exactly to do things,
 -- for example, io.flush is not available from within the game.

scripts/courseGenerator/Headland.lua

@@ -1,5 +1,8 @@
 local Headland = CpObject()
 
+--- Headlands around the field will always have a boundary ID starting with 'F' (for field)
+Headland.boundaryIdPrefix = 'F'
+
 --- Create a headland from a base polygon. The headland is a new polygon, offset by width, that is, inside
 --- of the base polygon.
 ---
@@ -251,7 +254,7 @@ end
 --- A short ID to identify the boundary this headland is based on when serializing/deserializing. By default, this
 --- is the field boundary.
 function Headland:getBoundaryId()
-   return 'F'
+   return Headland.boundaryIdPrefix
 end
 
 function Headland:__tostring()
@@ -265,6 +268,9 @@ CourseGenerator.Headland = Headland
 ---@class IslandHeadland
 local IslandHeadland = CpObject(CourseGenerator.Headland)
 
+--- Headlands around the field will always have a boundary ID starting with 'I' (for island)
+IslandHeadland.boundaryIdPrefix = 'I'
+
 --- Create an island headland around a base polygon. The headland is a new polygon, offset by width, that is, outside
 --- of the base polygon.
 ---
@@ -305,7 +311,7 @@ end
 
 --- A short ID in the form I<island ID> to identify the boundary this headland is based on when serializing/deserializing
 function IslandHeadland:getBoundaryId()
-    return 'I' .. self.island:getId()
+    return IslandHeadland.boundaryIdPrefix .. self.island:getId()
 end
 
 function IslandHeadland:__tostring()