Improved Lesson 1.3 – XML vs. Programming: Defining Data vs. Defining Actions

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Understanding the Roles: XML vs. C# Code

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It's crucial to understand that XML is not a programming language like C# (the language Bannerlord's engine primarily uses). They serve very different, but complementary, purposes:
 

• XML (Markup Language): Focuses on Data and Structure

  • It describes what things are and their properties.

  • Think of it as creating detailed lists and blueprints.

  • Example: "This <NPCCharacter> block defines a troop. Its id is imperial_recruit, its level is 6, and it uses this specific equipment (<equipment ... />)."

  • XML files essentially act as configuration data or databases for the game.

• C# (Programming Language): Focuses on Behavior and Logic

  • It describes what things do and the rules they follow.

  • Think of it as writing instructions, procedures, and decision-making processes.

  • Example: "This C# code makes an NPC decide which enemy to target, calculate the damage when its weapon hits, and determine if it should block or flee based on its health."
     

How They Work Together in Bannerlord:
 

When Bannerlord starts up or loads data, its core C# game engine reads the XML files. The engine understands that an <NPCCharacter> tag means "load the definition of a character" and uses the attributes (id, level, skills, etc.) defined in the XML to create that character's data inside the game's memory.

Later, during gameplay, the C# code uses that data (loaded from XML) to run the simulation – moving troops, resolving combat, handling AI, etc.
 

Analogy: The Blueprint and the Construction Crew
 

This is a great way to visualize it:
 

• XML is the detailed blueprint for a house. It defines the number of rooms, their dimensions, the materials to use (wood, brick), the placement of doors and windows – essentially, what the house is made of and its structure.

• C# Code is the construction crew and their tools. They read the blueprint and perform the actions needed to build the house – pouring the foundation, framing the walls, installing the plumbing, wiring the electricity – following the specifications laid out in the blueprint.
   

The crew can't build without the blueprint, and the blueprint doesn't build anything by itself.
 

What Can You Control with Just XML in Bannerlord?
 

XML gives you tremendous power over the game's data. Here's a quick overview:
 

Game SystemControlled Primarily by XML
 

Troops & Upgrade Trees           ✅ Yes    Define stats, skills, appearance, equipment, and how troops upgrade.

Lords, Clans, Kingdoms           ✅ Yes     Define characters, families, factions, their members, culture, banners, colors, relationships.

Items (Weapons, Armor)           ✅ Yes    Define item stats, appearance, cost, properties (e.g., swing/thrust                                                                          damage, armor value).

Cultures                                     ✅ Yes    Define cultural traits, naming, base relations, default troops.

Dialogue                                    ✅ Yes   (Content/Structure)XML (often via separate localization files) holds the                                                                    dialogue text lines and basic connections.

Quests & Game Logic               ❌ (Complex Logic)XML might define quest text or basic rewards, but C# is                                                                                          needed for branching logic, triggers, conditions.

AI Behavior                                ❌ (Core Logic)XML defines troop stats which influence AI, but the core                                                                                        decision-making AI is C#.

New Game Mechanics              ❌  Adding fundamentally new features (e.g., magic system, naval combat)                                                                requires C# programming.
 

(Note on Dialogue/Quests: While XML holds text, complex choices or quest steps that check game conditions or trigger unique events usually require C# intervention.)

You'll typically find Bannerlord's core XML files within the game's Modules directory, often inside Bannerlord/ModuleData subfolders. We'll explore specific files later.

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The Power of XML Modding:
 

This separation is fantastic for modders! It means you can use XML alone to make significant and exciting changes to Bannerlord. You can create entirely new factions with unique troop trees, add custom lords and clans, introduce powerful new items, and rebalance existing ones – all by editing these structured data files, often without needing to dive into complex C# programming. This makes a huge range of modding accessible to beginners!