DRAFT PR: Breaching! Infantry vs Infantry Combat Inside TO:AR Buildings by psikomonkie · Pull Request #7847 · MegaMek/megamek

psikomonkie · 2025-12-30T23:13:34Z

Closes #3551

TO:AR p. 169-174 infantry vs. infantry combat inside TO:AR Advanced Buildings.

I can't believe I got tricked into implementing boarding rules.

Breaching!

New action for infantry (CI & BA) during the Pre-End phase to start an "Infantry v Infantry combat" in their current hex. Only available if there is a hostile TO:AR Advanced Building.
New action for infantry (CI & BA) during the Infantry vs Infantry Combat phase to withdraw or reinforce from "Infantry v Infantry combat" that it's currently participating in. Only available if the unit is engaged in combat or able to reinforce an existing combat.
TO:AR Advanced Building crews may participate in the defense of their building during "Infantry v Infantry combat" - they can opt to reinforce during the Infantry vs Infantry Combat phase..
Marine Point Score: Implemented the various Marine Point Score tables for calculating the MPS for different unit compositions. Get those BA vibro-claws ready!
Building Modifier: Very large buildings provide an additional bonus to the defender.
Infantry v Infantry Action Roll: Yeah all that nonsense, even the big table of different ratios and results.
Re-Converting Marine Points Score: Only the "complex" method, not the "simple" method.
Crew Losses & Crew Hits: Hits for non-infantry crew that're involved (Building crew, Dropship crew.....)
Collateral Damage: Combat inside structures is difficult - there's a chance to hit the structure (vessel or building) that the combat is taking place inside of.
Basic Princess Support: Princess will attempt to seize any TO:AR Advanced Buildings she moves infantry into if she thinks the attacking force is strong enough, and will reinforce to defend against player attempts at seizing princess's buildings. No logic to move the Infantry where it needs to be yet, just letting it use this if it happens to wander into the right hex.

Future Enhancements

Naval Boarding: Yarr, I'm excited for blackwater piracy, but not with this PR. This PR is designed with naval boarding in mind so it should mostly be a matter of getting naval grappling set up, then this should be plug and play.
Princess Rebalance: This makes Dropships much more vulnerable to infantry when grounded. In particular, I know Princess enjoys using grounded Aerodyne like a bad mobile structure - that'll be a terrible idea if 5 guys and a can opener can steal a Dropship. For my sanity, I think it'll be another PR.
Using a Captured Unit/Building: This is not part of this PR. This PR does let you use infantry to crew-kill a TO:AR Advanced Building, which should complement MekHQ's scenarios that request you to capture hostile structures.

Todo

Why is the end report skipping?
Ensure infantry combat data saves in the tiny window between the pre-end declarations and the end phase
Fix that it says "Attacking forces eliminated" even when it's the defenders being eliminated
Fix disabled tests
Untangle messy logic from changing course mid-way-through

codecov · 2025-12-30T23:17:42Z

Codecov Report

❌ Patch coverage is 29.47224% with 1029 lines in your changes missing coverage. Please review.
✅ Project coverage is 29.66%. Comparing base (e586f90) to head (9b354eb).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
.../phaseDisplay/InfantryVsInfantryCombatDisplay.java	0.00%	243 Missing ⚠️
...panels/phaseDisplay/PreEndDeclarationsDisplay.java	0.00%	208 Missing ⚠️
...src/megamek/server/totalWarfare/TWGameManager.java	39.77%	137 Missing and 22 partials ⚠️
...amek/client/bot/princess/InfantryCombatHelper.java	5.69%	115 Missing and 1 partial ⚠️
...amek/src/megamek/client/bot/princess/Princess.java	3.41%	111 Missing and 2 partials ⚠️
...ek/common/compute/MarinePointsScoreCalculator.java	38.09%	48 Missing and 4 partials ⚠️
megamek/src/megamek/common/units/Infantry.java	0.00%	31 Missing ⚠️
...mek/src/megamek/client/ui/clientGUI/ClientGUI.java	0.00%	18 Missing ⚠️
...c/megamek/common/units/AbstractBuildingEntity.java	36.00%	14 Missing and 2 partials ⚠️
...c/megamek/common/actions/InfantryCombatAction.java	0.00%	15 Missing ⚠️
... and 12 more

Additional details and impacted files

@@             Coverage Diff             @@
##               main    #7847     +/-   ##
===========================================
  Coverage     29.66%   29.66%             
- Complexity    16556    16705    +149     
===========================================
  Files          3136     3147     +11     
  Lines        302538   303993   +1455     
  Branches      53085    53367    +282     
===========================================
+ Hits          89741    90193    +452     
- Misses       203390   204355    +965     
- Partials       9407     9445     +38

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megamek/src/megamek/common/compute/MarinePointsScoreCalculator.java

megamek/unittests/megamek/client/ui/panels/phaseDisplay/DeploymentDisplayTest.java

megamek/src/megamek/common/compute/MarinePointsScoreCalculator.java

megamek/src/megamek/server/totalWarfare/TWGameManager.java

+        }
+
+        List<Integer> entityIds = isAttacker ? combat.attackerIds : combat.defenderIds;
+        String sideName = isAttacker ? "Attackers" : "Defenders";


megamek/src/megamek/server/totalWarfare/TWGameManager.java

+    /**
+     * Report combat ratio.
+     */
+    private void reportCombatRatio(megamek.common.units.AbstractBuildingEntity building,


megamek/src/megamek/server/totalWarfare/TWGameManager.java

+    /**
+     * Report combat roll and result.
+     */
+    private void reportCombatRoll(megamek.common.units.AbstractBuildingEntity building,


megamek/src/megamek/server/totalWarfare/TWGameManager.java

+     */
+    private void reportSideEliminated(InfantryBuildingCombatTracker.BuildingCombat combat,
+                                       InfantryBuildingCombatTracker tracker,
+                                       megamek.common.units.AbstractBuildingEntity building,


megamek/src/megamek/server/totalWarfare/TWGameManager.java

+     */
+    private void reportSideRepulsed(InfantryBuildingCombatTracker.BuildingCombat combat,
+                                     InfantryBuildingCombatTracker tracker,
+                                     megamek.common.units.AbstractBuildingEntity building) {


… pr/buildings/building-entity-test-3-marines

…ldings

…t just for buildings

Copilot

Pull request overview

This PR implements TO:AR page 169 infantry vs. infantry combat inside TO:AR Advanced Buildings, commonly known as "breaching" mechanics. The implementation allows conventional infantry and battle armor to engage in building-to-building combat during the Physical phase.

Key Changes:

New infantry combat action system with Marine Points Score (MPS) calculation and combat resolution tables
Building crew participation in defense with crew casualties tracking
Collateral damage system affecting building structure during combat
Integration with existing building collapse mechanics

Reviewed changes

Copilot reviewed 81 out of 81 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
InfantryActionTracker.java	New tracker class managing active infantry combat instances with attacker/defender lists
TWGameManager.java	Core combat resolution logic including MPS calculation, casualty application, and combat outcome handling
MarinePointsScoreCalculator.java	Implements TO:AR Marine Points Score tables for unit strength calculation
InfantryCombatTables.java	Combat resolution tables and ratio calculations
Entity.java	Added infantry combat state tracking fields and methods
BuildingEntity.java	Enhanced building entity with weapon arc support and crew type
BuildingCollapseHandler.java	Updated to handle building hex collapse during infantry combat
Multiple test files	Comprehensive test coverage for all new systems

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Copilot · 2026-01-01T22:43:41Z

megamek/src/megamek/common/LosEffects.java

+     *
+     * @return LOS effects between the given positions
+     */
+    public static LosEffects calculateLOS(final Game game, final @Nullable Entity attacker,


The method 'calculateLOS' may be confused with calculateLos.

Copilot · 2026-01-01T22:43:41Z

megamek/unittests/megamek/client/ui/panels/phaseDisplay/DeploymentDisplayTest.java

+        void beforeEach() {
+            coords = new Coords(1, 1);
+            entity = new BipedMek();
+            getGame().addEntity(entity);


A method declared in a superclass is called instead of a method with the same signature in an enclosing class.

Copilot · 2026-01-01T22:43:41Z

megamek/unittests/megamek/client/ui/panels/phaseDisplay/DeploymentDisplayTest.java

+            setBoard("BOARD");
+
+            mockEvent = mock(BoardViewEvent.class);
+            when(mockEvent.getBoardId()).thenReturn(getGame().getBoard().getBoardId());


A method declared in a superclass is called instead of a method with the same signature in an enclosing class.

Copilot · 2026-01-01T22:43:42Z

megamek/unittests/megamek/client/ui/panels/phaseDisplay/DeploymentDisplayTest.java

+            when(mockEvent.getButton()).thenReturn(MouseEvent.BUTTON1);
+            when(mockEvent.getModifiers()).thenReturn(0);
+            when(mockClient.isMyTurn()).thenReturn(true);
+            when(mockClient.getGame()).thenReturn(getGame());


A method declared in a superclass is called instead of a method with the same signature in an enclosing class.

Copilot · 2026-01-01T22:43:42Z

megamek/unittests/megamek/client/ui/panels/phaseDisplay/DeploymentDisplayTest.java

+        @BeforeEach
+        void setUpBoard() {
+            player = new Player(0, "Test Player");
+            getGame().addPlayer(0, player);


A method declared in a superclass is called instead of a method with the same signature in an enclosing class.

Copilot · 2026-01-01T22:43:42Z

megamek/unittests/megamek/client/ui/panels/phaseDisplay/DeploymentDisplayTest.java

+            groundEntity.setOwner(player);
+            groundBoard = getBoard("GROUND_BOARD");
+            coords = new Coords(0, 0);
+            getGame().addEntity(groundEntity);


A method declared in a superclass is called instead of a method with the same signature in an enclosing class.

Copilot · 2026-01-01T22:43:43Z

megamek/src/megamek/common/units/AbstractBuildingEntity.java

    public int locations() {
-        if (getInternalBuilding() == null || getInternalBuilding().getCoordsList() == null) {
+        // Map can be null during construction
+        if (locationToRelativeCoordsMap == null || locationToRelativeCoordsMap.isEmpty()) {


This check is useless. locationToRelativeCoordsMap cannot be null at this check, since new HashMap<Integer,CubeCoords>(...) always is non-null.

…-3-marines

…mbat

megamek/src/megamek/client/bot/princess/InfantryCombatHelper.java

+     * @return Best reinforcement unit, or null if none suitable
+     */
+    public static Entity findBestReinforcement(List<Entity> candidates,
+                                                 Entity target, Game game) {


# Conflicts: # megamek/resources/megamek/common/messages.properties # megamek/src/megamek/common/units/Entity.java

…ry vs Infantry combat

PR: Infantry vs Infantry Combat Inside TO:AR Advanced Buildings

e8ad359

psikomonkie added In Development (Draft) An additional way to mark something as a draft. Make it stand out more. Draft Work in Progress labels Dec 30, 2025

github-advanced-security bot found potential problems Dec 30, 2025

View reviewed changes

psikomonkie added 5 commits December 30, 2025 21:33

Merge branch 'main' into pr/buildings/building-entity-test-3-marines

7f3b54a

Merge branch 'pr/buildings/building-entity-test-2-princess-time' into…

a10f792

… pr/buildings/building-entity-test-3-marines

PR MegaMek#7847: Infantry v Infantry Combat Inside TO:AR Advanced Bui…

11becfc

…ldings

PR MegaMek#7847: Ratios Edge Cases

2a481c7

PR MegaMek#7847: Fixing Unit Tests and making it more clear this isn'…

06031b7

…t just for buildings

psikomonkie changed the title ~~DRAFT PR: Infantry vs Infantry Combat Inside TO:AR Buildings~~ DRAFT PR: Breaching! nfantry vs Infantry Combat Inside TO:AR Buildings Dec 31, 2025

psikomonkie changed the title ~~DRAFT PR: Breaching! nfantry vs Infantry Combat Inside TO:AR Buildings~~ DRAFT PR: Breaching! Infantry vs Infantry Combat Inside TO:AR Buildings Dec 31, 2025

psikomonkie added the Infantry Issues related to Conventional Infantry. label Dec 31, 2025

HammerGS requested a review from Copilot January 1, 2026 22:38

Copilot started reviewing on behalf of HammerGS January 1, 2026 22:38 View session

Copilot AI reviewed Jan 1, 2026

View reviewed changes

psikomonkie added 2 commits January 1, 2026 18:47

Merge branch 'refs/heads/main' into pr/buildings/building-entity-test…

55b5947

…-3-marines

PR MegaMek#7847: New phases to better support Infantry vs Infantry co…

fdb3835

…mbat

psikomonkie added the Implementation of Missing Official Rule Used with the RFE tag for the implementation of missing official rule label Jan 2, 2026

github-advanced-security bot found potential problems Jan 2, 2026

View reviewed changes

psikomonkie added 4 commits January 8, 2026 11:40

Merge branch 'main' into pr/buildings/building-entity-test-3-marines

7493038

# Conflicts: # megamek/resources/megamek/common/messages.properties # megamek/src/megamek/common/units/Entity.java

PR MegaMek#7847: Improve messaging when units are destroyed in Infant…

45c0ff9

…ry vs Infantry combat

PR MegaMek#7847: Better button handling and target selection

d622a4e

PR MegaMek#7847: Better can-reinforce logic for players

15f476c

psikomonkie mentioned this pull request Jan 10, 2026

[RFE] Allow infantry to disable turrets in a building that they occupy. #3551

Open

psikomonkie added this to Bug & Feature Catcher: Buildings Jan 10, 2026

psikomonkie moved this to In Progress in Bug & Feature Catcher: Buildings Jan 10, 2026

psikomonkie added 2 commits January 10, 2026 12:45

Merge branch 'main' into pr/buildings/building-entity-test-3-marines

7bb58a9

Merge branch 'main' into pr/buildings/building-entity-test-3-marines

9b354eb

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psikomonkie commented Dec 30, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Breaching!

Future Enhancements

Todo

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psikomonkie commented Dec 30, 2025 •

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