Customizing MoLang Scripts & Animations

Relevant source files

The following files were used as context for generating this wiki page:

• src/HoloPrint.js
• src/index.js
• src/index.html
• src/translations/en_US.json
• src/packTemplate/manifest.json

The HoloPrint system utilizes Minecraft's MoLang scripting language to manage dynamic holograms within Resource Packs. MoLang allows the resource pack to handle logic such as layer switching, transparency adjustments, and block validation without the need for Behavior Packs or external mods. This is achieved by injecting generated scripts into Armor Stand entities and Player render controllers during the pack generation process.

Customization is driven by the web interface, which maps user-defined settings (like item criteria for controls) into MoLang variables and state machine transitions.

Script Generation Pipeline

The generation of MoLang scripts occurs primarily in the makePack function. The system takes configuration objects and converts them into MoLang strings that are then embedded into the JSON files of the resource pack.

Variable Injection Logic

The application uses helper utilities like functionToMolang and itemCriteriaToMolang to translate JavaScript logic and configuration into a format compatible with Minecraft's client-side engine. Key variables include:

• v.hologram.rendering: Toggles the visibility of the structure.
• v.hologram.layer: Tracks the currently selected Y-level.
• v.hologram.structure_index: Identifies which structure in a multi-structure pack is being displayed.
• v.hologram.layer_mode: Determines if a single layer or all layers below the current index are shown.

Animation Controllers and State Machines

HoloPrint generates complex Animation Controllers to manage the state of the hologram. These controllers act as state machines, transitioning based on MoLang expressions that evaluate player interactions or internal variables.

Layer Transition Logic

Layer management is handled by makeLayerAnimations. It creates animation states for every Y-level in the structure. The transitions between these states are controlled by the v.hologram.layer variable and the v.hologram.layer_mode enum.

State Name	Transition Condition	Action
default	v.hologram.layer == -1	Show full structure
l_{y}	v.hologram.layer == y && mode == SINGLE	Isolate specific layer
l_{y}-	v.hologram.layer == y && mode == ALL_BELOW	Show layer and those below

Bounding Box and Validation Particles

The system dynamically generates particle effect scripts to provide visual feedback.

• Bounding Box: Controlled via addBoundingBoxParticles, which uses MoLang to set the size (v.size), direction (v.dir), and color (v.r, v.g, v.b) of the outline based on the structure dimensions.
• Block Validation: The addBlockValidationParticles function creates states that trigger particles only when v.hologram.validating is true and the specific block coordinates match the user's position.

Sources: src/HoloPrint.js:538-608, src/HoloPrint.js:615-645

In-Game Player Controls

To allow players to interact with the hologram, HoloPrint patches the vanilla player.render_controllers.json. This is a specialized technique that allows passing data from the player to the hologram entity by utilizing MoLang variables within the texture or material fields of the player's render controller.

Control Item Mapping

The ItemCriteria system allows users to define which items (by ID or Tag) trigger specific actions.

Action Configuration Table

These controls are defined in DEFAULT_PLAYER_CONTROLS and can be overridden in the UI.

Control Action	Default Item	MoLang Purpose
TOGGLE_RENDERING	Brick	Toggles v.hologram.rendering
CHANGE_LAYER	Leather	Increments v.hologram.layer
MOVE_HOLOGRAM	Stick	Adjusts offset variables
ROTATE_HOLOGRAM	Copper Ingot	Modifies v.hologram.rotation
TOGGLE_VALIDATING	Iron Ingot	Enables block check particles

Sources: src/HoloPrint.js:25-50, src/HoloPrint.js:724-746, src/index.html:132-154

Implementation Details

Armor Stand Initialization

When a pack is generated, an initialization script is injected into the armor stand. This script sets the starting state for all HoloPrint variables.

// Example of initialization injection in src/HoloPrint.js
entityDescription["scripts"]["initialize"].push(functionToMolang(entityScripts.armorStandInitialization, {
    structureSize: structureSizes[0],
    initialOffset: config.INITIAL_OFFSET,
    defaultTextureIndex,
    singleLayerMode: HOLOGRAM_LAYER_MODES.SINGLE,
    structureCount: structureFiles.length
}));

Sources: src/HoloPrint.js:308-315

Coordinate Lock Logic

If the "Coordinate Lock" feature is enabled in the UI (settings.coordinate_lock), the script generation omits relative offset logic and instead generates hardcoded MoLang expressions that pin the hologram to specific global coordinates. This is handled by switching between animation.holoprint.hologram.offset and animation.holoprint.hologram.coordinate_lock.

Sources: src/HoloPrint.js:291-304, src/index.js:210-230

Conclusion

MoLang customization in HoloPrint is the bridge between the static structure data and an interactive in-game experience. By dynamically generating animation controllers and patching render controllers, the system provides a robust building tool that remains performant within the limitations of the Minecraft Bedrock Edition engine.