Manual Combine Unloader function & other small tweaks

[antler22]

This feature adds a "Call Grain Cart" button to manually-driven combines (i.e. combines that the player is driving themselves, not Courseplay-controlled). When activated, a nearby Courseplay-managed grain cart automatically:

1. Approaches the combine via pathfinding
2. Positions itself under the combine's unloading pipe
3. Follows the combine while it harvests (including through gentle curves and S-bends)
4. Leaves when the player closes the pipe (2-second debounce prevents false exits)
5. Automatically re-approaches if it loses position

The design goal is that the player only touches the button once — the grain cart handles everything until the pipe is closed.

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Files Changed

File	Status	Summary
scripts/ai/CpManualCombineProxy.lua	New	Proxy class mimicking AIDriveStrategyCombineCourse interface
scripts/specializations/CpAIFieldWorker.lua	Modified	Call Grain Cart button toggle and proxy lifecycle
scripts/specializations/CpAIWorker.lua	Modified	Disable button/keybind for forage harvesters
scripts/ai/strategies/AIDriveStrategyUnloadCombine.lua	Modified	Core unloader steering, off-track recovery, proximity fixes
scripts/ai/PurePursuitController.lua	Modified	Soft-recovery hook before hard CP shutdown
scripts/pathfinder/PathfinderUtil.lua	Modified	Defensive windrow filtering in hasFruit()
config/VehicleSettingsSetup.xml	Modified	Lower minimum for "Call Unloader At" setting

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1. New File: scripts/ai/CpManualCombineProxy.lua

A new class that implements the full AIDriveStrategyCombineCourse interface for manually-driven combines. This allows AIDriveStrategyUnloadCombine to interact with a manual combine using the same method calls it uses for CP-driven combines, without any nil checks or special-casing scattered through the unloader code.

Key design decisions

isManualProxy() → true
A marker method so the unloader strategy can identify a manual proxy without re-querying the vehicle. Used to gate manual-only behavior throughout AIDriveStrategyUnloadCombine.

getFillLevelPercentage() → 1
Always reports 100% full. The farmer is in full control — the grain cart must never leave because of a low fill level. The only valid exit condition is isUnloadFinished().

isUnloadFinished()
Requires the discharge to be continuously off for 2 seconds before returning true. This prevents a momentary swerve or brief pipe misalignment from prematurely ending the session. Once it returns true, the grain cart departs and the proxy re-summons it if the button is still active.

willWaitForUnloadToFinish()
3-second debounce before reporting the combine as "stopped." A GPS micro-correction or terrain hitch lasting less than 3 seconds is ignored. Without this, a brief stop would flip the grain cart from UNLOADING_MOVING_COMBINE to UNLOADING_STOPPED_COMBINE, triggering unnecessary state cycling.

registerUnloader(driver) / deregisterUnloader()
Uses a CpTemporaryObject with a 1-second TTL. The grain cart calls registerUnloader every frame while it has an active combine. When the cart releases (soft recovery or natural exit), the TTL expires and the proxy's callUnloaderWhenNeeded() can re-summon within ~2.5 seconds.

callUnloaderWhenNeeded()
Runs every 1500 ms. If no unloader is registered, searches active CP unloader vehicles via AIDriveStrategyUnloadCombine.isActiveCpCombineUnloader(), scores by fill level and distance, and calls strategy:call(self.vehicle, nil) on the best candidate. This is the mechanism that auto-resumes after soft recovery.

getFruitAtSides() → nil, nil
Forage harvesters crash calculateAutoAimPipeOffsetX() if this returns nil before checkFruit() has run. Returning nil, nil is safe for standard combines and avoids the crash for any chopper that might somehow reach this code path.

isTurning() → false
The unloader has special "wait during combine turn" logic that is inappropriate when the farmer is manually steering. Always returning false keeps the grain cart tracking the pipe rather than holding position at the headland.

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2. Modified: scripts/specializations/CpAIFieldWorker.lua

What was added

• cpIsCallGrainCartActive() — Returns true when spec.cpManualCombineProxy ~= nil.
• cpToggleCallGrainCart() — Creates a new CpManualCombineProxy (activate) or deletes the existing one (deactivate). Guards against activation when CP is already active on the combine.
• cpGetManualCombineProxy() — Returns the current proxy instance.
• onUpdate(dt) — Drives the proxy's update loop each tick (course refresh + unloader call cycle). Auto-deactivates the proxy if getIsCpActive() becomes true on the combine.

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3. Modified: scripts/specializations/CpAIWorker.lua

"Call Grain Cart" button disabled for forage harvesters

Forage harvesters (choppers) have an auto-aiming spout and behave very differently from grain combines. Calling a grain cart unloader on a chopper causes errors. The button and keybind are now hidden when the vehicle has pipeSpec.numAutoAimingStates > 0.

local isChopper = pipeSpec and (pipeSpec.numAutoAimingStates or 0) > 0
local showCallGrainCart = hasPipe and not isCpActive and not isChopper

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4. Modified: scripts/ai/strategies/AIDriveStrategyUnloadCombine.lua

This is the most significant set of changes. All modifications are backward-compatible with CP-driven combines — manual-only code is gated by combineStrategy:isManualProxy().

4a. setAIVehicle() — Extended PPC grace period

if self.ppc then
    self.ppc.offTrackGracePeriodMs = 20000
end

Unloaders track moving targets (combine position changes, rendezvous shifts, post-turn realignment). The default 10-second off-track grace period is too short for this use case. Extended to 20 seconds to give the pathfinder and steering more time to recover before any shutdown is considered.

4b. onOffTrackShutdown() — New soft-recovery method

function AIDriveStrategyUnloadCombine:onOffTrackShutdown()
    self:info('Soft recovery to IDLE instead of stopping CP.')
    self:startWaitingForSomethingToDo()
    return true  -- handled; PPC must NOT call stopCurrentAIJob
end

Called by the PPC (see section 5) when the off-track grace period expires. Transitions the grain cart to IDLE and releases the combine. The proxy's callUnloaderWhenNeeded() re-summons within ~2.5 seconds. The user never has to walk over to the grain cart to restart it manually.

This is safe for both manual and CP-driven combines: CP combines call unloader:call() again when they need service; the proxy does the same via its update loop.

4c. driveBesideCombine() — Direct steering goal for manual combines

The problem with course-based steering for manual combines:
AIDriveStrategyUnloadCombine normally steers by following a copy of the combine's fieldwork course offset to the pipe side. Manual combines have no fieldwork course — only a static placeholder is available. As the combine curves or S-bends, the grain cart drifts far from the stale placeholder, and the PPC cannot correct.

The solution — live goal point from the pipe reference node:

local isManual = strategy.isManualProxy and strategy:isManualProxy()
if dz > 5 or isManual then
    _, _, dz = localToLocal(self.vehicle:getAIDirectionNode(),
                            self:getPipeOffsetReferenceNode(), 0, 0, 0)
    local lookahead = isManual
            and (self.ppc.normalLookAheadDistance or 6)
            or self.ppc:getLookaheadDistance()
    gx, gy, gz = localToWorld(self:getPipeOffsetReferenceNode(),
            self:getPipeOffset(self.combineToUnload), 0, dz + lookahead)
end

For manual combines, a goal point is computed every frame regardless of dz. The goal is always normalLookAheadDistance meters ahead of the cart's current longitudinal position in the combine's own local frame, at the pipe's lateral offset. As the combine turns, getPipeOffsetReferenceNode() rotates with it — so the goal point rotates too, and the cart naturally follows curves.

Why normalLookAheadDistance instead of getLookaheadDistance():
getLookaheadDistance() inflates the lookahead up to 2× the base value when cross-track error is large (which it always is, since the cart is far from the stale placeholder course). A 12 m lookahead makes the cart too slow to respond to gentle heading changes. normalLookAheadDistance (≈5–6 m) is constant and un-inflated, enabling tight S-curve tracking.

CP-driven combines: zero behavior change. The isManual branch is not taken, and the existing dz > 5 gate applies as before.

4d. unloadMovingCombine() — Off-track suppression during manual unloading

Because the placeholder course is intentionally stale (steering is derived from the live pipe reference node, not the course), the grain cart WILL drift far from the placeholder during curves. Without suppression, the PPC's off-track detection would fire. This is suppressed per-tick:

if combineStrategy and combineStrategy.isManualProxy and combineStrategy:isManualProxy() then
    if self.ppc and self.ppc.disableStopWhenOffTrack then
        self.ppc:disableStopWhenOffTrack(5000)
    end
end

The 5000 ms TTL (much longer than any realistic frame interval) ensures there is no gap between ticks where the check can briefly re-enable.

4e. startCourseFollowingCombine() — Placeholder course for manual combines

The PPC requires a course object to be initialised. For manual combines, a placeholder is built from the combine's current position in its current heading direction (100 m straight forward). This course is never used for steering — driveBesideCombine() returns the live goal point every frame, overriding the PPC's course-based calculation.

local combineX, _, combineZ = getWorldTranslation(self.combineToUnload:getAIDirectionNode())
local forwardX, _, forwardZ = localToWorld(self.combineToUnload:getAIDirectionNode(), 0, 0, 100)
local placeholder = Course.createFromTwoWorldPositions(
        self.vehicle, combineX, combineZ, forwardX, forwardZ,
        0, 0, 0, 10, false)
self.followCourse = placeholder
self.followCourse:setOffset(self.followingCourseOffset, 0)
startIx = 1

No periodic refresh of this course is needed or performed.

4f. ignoreProximityObject() — Terrain hits during approach and unloading

Windrows and straw swaths are height-map physics objects. The proximity sensor's raycasts hit them as hitTerrain = true, slowing the grain cart to a crawl mid-approach. Terrain hits are now ignored in the relevant states:

function AIDriveStrategyUnloadCombine:ignoreProximityObject(object, vehicle, moveForwards, hitTerrain)
    return (self.state == self.states.UNLOADING_ON_THE_FIELD and hitTerrain) or
            (self.state == self.states.DRIVING_TO_COMBINE and hitTerrain) or
            (self.state == self.states.UNLOADING_MOVING_COMBINE and hitTerrain) or
            (self.state == self.states.UNLOADING_MOVING_COMBINE and vehicle == self.combineToUnload) or
            (self.state == self.states.HANDLE_CHOPPER_HEADLAND_TURN and vehicle == self.combineToUnload)
end

4g. calculateAutoAimPipeOffsetX() — Nil guard for forage harvesters

getFruitAtSides() can return nil before checkFruit() has run (e.g., when a chopper just started). This caused a Lua arithmetic error on line 1022:

local fruitLeft, fruitRight = strategy:getFruitAtSides()
fruitLeft = fruitLeft or 0
fruitRight = fruitRight or 0

4h. driveToCombine() — Smarter approach redirect

The original approach redirect fired every 10 seconds unconditionally, causing the grain cart to swerve even on a stable straight approach. The redirect now only fires when the combine's pipe reference node has moved >15 m from the last redirect target:

local pipeMoved = MathUtil.vector2Length(cX - lastX, cZ - lastZ)
if combineAhead and angleToCombieDeg < 40 and pipeMoved > 15 then
    -- redirect
end

Redirect tracking (lastApproachRedirectX/Z, lastApproachRedirectTime) is reset after each successful pathfinding completion so the next approach starts fresh.

4i. Fill level exit condition — discharge check

if fillPct <= 0.1 and not isDischarging and not combineStrategy:alwaysNeedsUnloader() then

Previously, the fillPct <= 0.1 check could fire at exactly 10% fill while the pipe was still open, causing a tarp-open/close cycle. The not isDischarging guard ensures the cart only leaves after the pipe has actually closed. (For manual combines this is moot since getFillLevelPercentage() always returns 1, but the fix is correct for all combines.)

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5. Modified: scripts/ai/PurePursuitController.lua

Soft-recovery hook before hard shutdown

Before calling vehicle:stopCurrentAIJob(AIMessageCpError.new()), the PPC now checks whether the current drive strategy implements onOffTrackShutdown():

if (now - self.offTrackShutdownSince) >= offTrackGracePeriodMs then
    local strategy = self.vehicle.getCpDriveStrategy and self.vehicle:getCpDriveStrategy()
    if strategy and strategy.onOffTrackShutdown then
        local handled = strategy:onOffTrackShutdown()
        if handled then
            CpUtil.infoVehicle(self.vehicle,
                    'vehicle off track, strategy performed soft recovery instead of shutdown.')
            self.offTrackShutdownSince = nil
            break
        end
    end
    CpUtil.infoVehicle(self.vehicle, 'vehicle off track, shutting off Courseplay now.')
    self.vehicle:stopCurrentAIJob(AIMessageCpError.new())
    return
end

If the strategy returns true from onOffTrackShutdown(), the PPC resets its shutdown timer and continues running. This hook is intentionally generic — any strategy can implement it to provide graceful degradation instead of a hard stop.

---

6. Modified: scripts/pathfinder/PathfinderUtil.lua

Defensive windrow filtering in hasFruit()

Added name-based checks to skip windrow, swath, straw and chaff fill types in the fruit detection loop:

local name = string.lower(fruitType.name or '')
if string.find(name, 'windrow') or string.find(name, 'swath')
        or name == 'straw' or name == 'chaff' then
    ignoreThis = true
end

Note: Windrows are height-map physics objects, not fruit density map objects, so getFruitArea() will not detect them regardless of this filter. The filter is defensive coding only and has no functional effect on current game versions. It is safe to remove if the maintainer prefers.

---

7. Modified: config/VehicleSettingsSetup.xml

callUnloaderPercent minimum lowered to 20%

<!-- Before -->
<Setting ... name="callUnloaderPercent" min="60" max="90" ... />

<!-- After -->
<Setting ... name="callUnloaderPercent" min="20" max="90" ... />

The minimum threshold for "Call Unloader at" is reduced from 60% to 20%. High-yield crops (e.g., corn) fill combines faster; a lower call threshold lets CP-driven combines summon unloaders earlier, keeping combines harvesting continuously without stopping to wait for an unloader.

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Interaction with CP-Driven Combines

All changes are backward-compatible. The two-combine scenario (one manual + one CP-driven, served by one or two grain carts) works correctly:

• Manual-specific code is gated by combineStrategy:isManualProxy().
• Shared changes (proximity terrain ignore, PPC soft-recovery hook, off-track grace period extension) benefit CP-driven unloaders as well.
• The callUnloaderPercent slider change applies to all combines regardless of control mode.

[antler22]

Hidden Whitespace.. I think?

[pvaiko]

LIkely this PR needs a rebase.

[antler22]

You're right. The MotorController changes weren't intentional for this PR — they crept in as part of a big umbrella commit. Happy to rebase and clean that up so it doesn't appear in the diff at all.

[pvaiko]

why is this guard needed?

[antler22]

The comments pretty much explain, but what I was noticing when pathfinder fails or cannot find a path, it releases the CP driver. If driving a combine manually, its inconvenient to tab to the vehicle again and restart. So I wanted CP to try harder/longer to find a path.

[pvaiko]

I am talking about the if CollisionAvoidanceController and if ProximityController parts. I can't imagine any scenario where those wouldn't be loaded.

[pvaiko]

why is this guard needed?

[antler22]

Similar to the last comment. Added defensively to try and avoid releasing the CP driver. Might be overly guarded now?

[pvaiko]

I am talking about the if CollisionAvoidanceController and if ProximityController parts. I can't imagine any scenario where those wouldn't be loaded.

[pvaiko]

This is one of the most important modules of CP. I'm not able to review the changes until GitHub shows a proper diff.

[antler22]

The actual changes are small: a grace-period class constant (offTrackGracePeriodMs), a offTrackShutdownSince state variable in init(), and the soft-recovery block that replaces the single-line hard shutdown. I'll rebuild now