Attack Roll System

[FirebrickRed]

Summary

Handle attack rolls with multiple input modes to accommodate different play styles. Support automatic rolling, modifier display, player-provided rolls, and manual totals. Include critical hit/miss detection and weapon range display.

Phase: MVP Combat System
Systems: Combat System, Dice Rolling, Weapon System

Prerequisites

• Combat Session Foundation & Initiative System #97 - Combat Session Foundation & Initiative System

Goals

• Multiple attack input modes (auto, show mods, player roll, total)
• Attack modifier calculation (ability mod + proficiency + magic)
• Critical hit (nat 20) and critical miss (nat 1) detection
• Compare to target AC and announce hit/miss
• Weapon range display for ranged weapons
• Combat log integration
• Foundation for advantage/disadvantage (future)

Commands

Attack Modes

# AUTO MODE (default) - Roll d20 and add all modifiers
/combat attack goblin_chief
> Alice attacks Goblin Chief with Longsword!
> Roll: 14 + 5 (STR +3, Prof +2) = 19
> vs AC 15 → HIT!

# SHOW MODS - Display modifiers, player rolls physical dice
/combat attack goblin_chief --showmods
> Attacking Goblin Chief with Longsword
> Your modifiers: +5 (STR +3, Proficiency +2)
> Target AC: 15
> [Roll your d20 and use /combat attack goblin_chief --roll <result>]

# PLAYER ROLL - Player provides d20 result, system adds modifiers
/combat attack goblin_chief --roll 14
> Alice attacks Goblin Chief with Longsword!
> Roll: 14 + 5 (STR +3, Prof +2) = 19
> vs AC 15 → HIT!

# MANUAL TOTAL - Player provides final number (did all math)
/combat attack goblin_chief --total 19
> Alice attacks Goblin Chief with Longsword!
> Attack roll: 19 vs AC 15 → HIT!

Weapon Selection

# Attack with specific weapon (if multiple equipped)
/combat attack goblin_chief --weapon dagger
> Alice attacks Goblin Chief with Dagger!

# Default: Use main hand weapon or last used weapon

Attack Modifier Calculation

int attackBonus = 0;

// 1. Ability modifier (STR for melee, DEX for ranged/finesse)
if (weapon.hasProperty("finesse")) {
    // Player can choose STR or DEX - use higher
    attackBonus += Math.max(strMod, dexMod);
} else if (weapon.hasProperty("ranged")) {
    attackBonus += dexMod;
} else {
    attackBonus += strMod;
}

// 2. Proficiency bonus (if proficient with weapon type)
if (character.isProficientWith(weapon)) {
    attackBonus += proficiencyBonus;
}

// 3. Magic weapon bonus (future)
// attackBonus += weapon.getMagicBonus();

// 4. Other bonuses (Fighting Style, etc. - future)

Critical Hits & Misses

# Natural 20
/combat attack goblin_chief
> Alice attacks Goblin Chief with Longsword!
> Roll: ★ NATURAL 20 ★ + 5 = 25
> CRITICAL HIT! 
> [Proceed to damage with double dice]

# Natural 1
/combat attack goblin_chief
> Alice attacks Goblin Chief with Longsword!
> Roll: ✗ NATURAL 1 ✗ + 5 = 6
> CRITICAL MISS! (Auto-miss regardless of AC)

Critical Damage (MVP: Double Dice)

// On critical hit, damage dice are doubled
// Example: Longsword 1d8+3 becomes 2d8+3
// Future config: Option for "roll twice" instead of "double dice"

Weapon Range Display

# For ranged weapons, show range in attack feedback
/combat attack goblin_chief --weapon longbow
> Alice attacks Goblin Chief with Longbow!
> Range: 150/600 ft | Target distance: ~45 ft (in range)
> Roll: 16 + 5 = 21 vs AC 15 → HIT!

# Out of range warning
/combat attack distant_enemy --weapon shortbow
> ⚠ Warning: Target is ~400 ft away
> Shortbow range: 80/320 ft
> Attack at long range (disadvantage) or beyond max range (impossible)

Hit/Miss Determination

int roll = rollD20();  // or use player-provided roll
int total = roll + attackBonus;
int targetAC = target.getArmorClass();

boolean isNat20 = (roll == 20);
boolean isNat1 = (roll == 1);

if (isNat1) {
    return AttackResult.CRITICAL_MISS;
} else if (isNat20) {
    return AttackResult.CRITICAL_HIT;
} else if (total >= targetAC) {
    return AttackResult.HIT;
} else {
    return AttackResult.MISS;
}

Combat Log Output

[Combat Log]
Round 2 | Alice's Turn
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
ATTACK: Alice → Goblin Chief
Weapon: Longsword (1d8 slashing)
Roll: 14 + 5 (STR +3, Prof +2) = 19
Target AC: 15
Result: HIT
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Advantage/Disadvantage (Future Enhancement)

# Stub for future - note in help text
/combat attack goblin_chief --adv
> [Future: Roll 2d20, take higher]

/combat attack goblin_chief --dis  
> [Future: Roll 2d20, take lower]

For MVP, these flags will show a message:

Advantage/disadvantage not yet implemented. 
Roll manually and use --roll or --total.
See issue #61 for tracking.

Right-Click Weapon Attack (Future Enhancement)

Future: Right-click equipped weapon to initiate attack
- Opens target selection
- Uses weapon stats automatically
- See issue #85 for dual interaction system

Entity Attacks

Entities use their defined attacks from YAML:

# From entity YAML
attacks:
  - name: "Scimitar"
    to_hit: +4
    reach: 5
    damage: "1d6+2"
    damage_type: "slashing"

# DM attacking as entity (see #102)
/combat enemy goblin_chief attack Alice
> Goblin Chief attacks Alice with Scimitar!
> Roll: 12 + 4 = 16 vs AC 14 → HIT!

Tab Completion

• /combat attack <TAB> → List valid targets in combat
• /combat attack target --weapon <TAB> → List equipped weapons
• /combat attack target --roll <TAB> → Suggest "1-20"

Related Issues

• DM can prompt and grant advantage/disadvantage for ability/skill/save checks #61 - Advantage/Disadvantage system (referenced for future)
• Dual Interaction System (Commands + Right-Click) #85 - Dual Interaction System (right-click weapons)
• Combat Session Foundation & Initiative System #97 - Combat Foundation (prerequisite)
• Damage & Healing System #100 - Damage System (follows successful hit)
• Enemy Visibility & DM Control #102 - Enemy Visibility & DM Control (entity attacks)