Json Levels plugin documentation

Table of content

1. Overview
2. Blueprints
3. C++
4. Examples
5. Support

Overview

Json Levels is a plugin that helps users to generate text-based (JSON) representations of levels via an editor tool and then construct levels based on the text via a runtime solution. Perfect for casual games with multiple levels (e.g. match-3, puzzles, arkanoid), but can be used in other scenarios to dynamically generate actors based on text data.

JSON -> Level

C++ Tutorial (a bit more technical)

Add UJlsGenerator actor component to one of your game objects (e.g. game mode or game state). It has 2 functions:

/** Parse Json and spawn objects listed in it. Once all objects are spawned, call OnObjectsSpawned callback. 
* @param Json String representation of a Json that contains data about actors that should be spawned. */
UFUNCTION(BlueprintCallable, Category = "JsonLevels")  
void GenerateLevel(const FString& Json);

/** Remove all actors that implement IJlsGameplayActor interface from the scene */  
UFUNCTION(BlueprintCallable, Category = "JsonLevels")  
void ClearLevel();

And OnObjectsSpawned delegate that is being called once all objects from JSON are spawned and the level is ready.

/** Callback that is being called once all actors from Json are spawned by GenerateLevel() */  
UPROPERTY(BlueprintAssignable, Category="LevelToJson")  
FOnObjectsSpawned OnObjectsSpawned;

Actors that will be part of JSON data should implement IJlsGameplayActor interface and overwrite 2 functions:

/** Convert AActor into a string of a Json format (serialize). 
 * @return String of a Json format. https://en.wikipedia.org/wiki/JSON */
UFUNCTION(BlueprintCallable, BlueprintNativeEvent, CallInEditor, Category = "JsonLevels")  
UJlsObjectWrapper* CreateJsonFromActor();

/** Configure AActor based on values stored in Json object associated with the actor (deserialize). 
* @param Json String representation of a Json object associated with the actor. 
* @return True if everything went well, false otherwise */
UFUNCTION(BlueprintCallable, BlueprintNativeEvent, CallInEditor, Category = "JsonLevels")  
bool CreateActorFromJson(UJlsObjectWrapper* Json);

In CreateJsonFromActor(...) user should construct JSON object and add fields representing the actor to it. In CreateActorFromJson(...)user should read JSON object and overwrite actor values using values from JSON.

To set and then get values from JSON, use functions from UJlsObjectWrapper . It has setters / getters for the following types of data:

• Transform
• Transform array
• Vector
• Vector array
• Bool
• Bool array
• Number (float)
• Number (float) array
• String
• String array
• Object
• Object array

Once you have an object with UJlsGenerator actor component and actors implementing IJlsGameplayActor you can call GenerateLevel(...) function of UJlsGenerator using a JSON that we will generate in the Level -> JSON part of the tutorial.

Blueprints Tutorial (a bit less technical)

Add JlsGenerator actor component to one of your game objects (e.g. game mode or game state). It has functions to generate a level and clear a level. Also the component has a delegate that is being called once level is generated. Actors that will be part of JSON data should implement JlsGameplayActor interface and overwrite 2 functions. In CreateJsonFromActor(...) user should construct JSON object and add fields representing the actor to it. In CreateActorFromJson(...)user should read JSON object and overwrite actor values using values from JSON.

Imagine, we're making a cool RPG game, and need to create a JSON with information about an enemy:

Once you have an object with JlsGenerator actor component and actors implementing JlsGameplayActor you can call GenerateLevel(...) function of JlsGenerator using a JSON that we will generate in the Level -> JSON part of the tutorial.

Level -> JSON

During the previous step you've overwritten JlsGameplayActor interface function in an actor(s). Place actors on the scene You can also notice 'Enemy data' tab in actor details section. These fields were added as a part of RPG enemy example and will be added to JSON during the JSON creation process and then overwritten in the actor during the level creation process. Open list of editing modes and select JsonLevels Then click 'Create JSON' button. Generated JSON will appear in the text box: Remember cube Jake? That's how he looks now:

{
    "Transform":
    {
        "Location":
        {
            "x": -140.72625732421875,
            "y": -74.195877075195312,
            "z": 120.40150451660156
        },
        "Rotation":
        {
            "x": 0,
            "y": 0,
            "z": 0
        },
        "Scale":
        {
            "x": 1,
            "y": 1,
            "z": 2
        }
    },
    "Health": 50,
    "Name": "Jake",
    "Loot":
    {
        "Gold": 10,
        "Items":
        [
            "Potato",
            "Carrot",
            "Fork"
        ]
    }
}

Examples

Plugin has 2 folders with examples: C++: JsonLevels\Source\JsonLevels\Public\Examples
Blueprints: JsonLevels\Content\Examples\

Support

If you need help, have a feature request or experience troubles, please contact me: https://discord.com/channels/590187986495209472/1060275483603894322