dialogue-system

Dialogue System

Patterns for building a node-based dialogue tree system: define conversations as ScriptableObject graphs, process them at runtime with a DialogueRunner, display text with a typewriter effect, and integrate with quest/state systems through condition and event nodes.

Node Architecture

Dialogue is a directed graph of nodes. Each node has a unique ID and a type that determines its behavior.

Base Node

using UnityEngine;

public enum DialogueNodeType
{
    Text,
    Choice,
    Condition,
    Event
}

[System.Serializable]
public class DialogueNode
{
    public string nodeId;
    public DialogueNodeType nodeType;

    // Text node fields
    public string speakerName;
    public string speakerKey;       // Localization key for speaker name
    public Sprite speakerPortrait;
    public string text;
    public string textKey;          // Localization key: "dialogue.npc_greeting.001"
    public string nextNodeId;

    // Choice node fields
    public DialogueChoice[] choices;

    // Condition node fields
    public string conditionKey;     // Game state variable to check
    public string trueNodeId;
    public string falseNodeId;

    // Event node fields
    public string eventName;        // Event to trigger
    public string eventParameter;
    public string eventNextNodeId;
}

Choice Data

[System.Serializable]
public class DialogueChoice
{
    public string choiceText;
    public string choiceKey;        // Localization key
    public string nextNodeId;

    // Optional: conditions for showing this choice
    public string requiredConditionKey;
    public bool hideIfUnavailable;  // false = show grayed out; true = hide entirely
}

Dialogue Tree (ScriptableObject)

using System.Collections.Generic;
using UnityEngine;

[CreateAssetMenu(fileName = "New Dialogue", menuName = "Dialogue/Dialogue Tree")]
public class DialogueTree : ScriptableObject
{
    public string dialogueId;
    public string entryNodeId;
    public List<DialogueNode> nodes = new();

    private Dictionary<string, DialogueNode> _lookup;

    public DialogueNode GetNode(string nodeId)
    {
        if (_lookup == null) BuildLookup();
        _lookup.TryGetValue(nodeId, out var node);
        return node;
    }

    public DialogueNode GetEntryNode()
    {
        return GetNode(entryNodeId);
    }

    private void BuildLookup()
    {
        _lookup = new Dictionary<string, DialogueNode>();
        foreach (var node in nodes)
        {
            if (string.IsNullOrEmpty(node.nodeId)) continue;
            _lookup[node.nodeId] = node;
        }
    }

    private void OnEnable()
    {
        _lookup = null; // Force rebuild on load
    }
}