GameObject.md

GameObject Class Documentation

Function Overview

Visibility	Function	Description
public	GameObject(String name)	Constructs a GameObject with a name and initializes its Transform.
public	addChild(GameObject child)	Adds a child GameObject by parenting its Transform.
public	addComponent(Component component)	Adds a component to this GameObject.
public	getComponent(Class type)	Gets the first component of the specified type.
public	fixedUpdate()	Called at a fixed interval for physics/timed logic.
public	update()	Called every frame for logic updates.
public	render(Camera camera, int layerMask)	Called every frame for rendering.
public	debugRender()	Called for debug rendering.
public	UpdateLocation()	Updates the Location string recursively.
public static	Location(GameObject gb)	Returns the hierarchical path of a GameObject.
public static	findGameObject(String path, GameObject root)	Finds a GameObject by path (recursive).
public static	findGameObjectItrative(String path, GameObject root)	Finds a GameObject by path (iterative).
public	printHierarchy()	Prints the hierarchy tree.
public	reparentTo(GameObject newParent)	Reparents this GameObject.
public	getLayerBit()	Gets the layer bitmask.
public	setLayer(int newLayer)	Sets the layer bitmask.
public	setLayerOnly(int newLayer)	Sets the layer for this object only.
public	setLayerRecursively(int layerBit)	Sets the layer for this object and all children.
public	setLayerByName(String layerName, boolean recursive)	Sets the layer by name (optionally recursive).
public	toString()	Returns a string representation.
public	getAllComponents()	Returns all components.
public	removeComponent(Component cmp)	Removes a component.
public static	destroy(GameObject thisGb)	Destroys a GameObject and its children.
public	getId(), setId(int)	Gets/Sets the unique ID.
public	getName(), setName(String)	Gets/Sets the name.
public	getTransform(), setTransform(Transform)	Gets/Sets the transform.
public	getLayer(), setLayer(int)	Gets/Sets the layer.
public	getComponents(), setComponents(List)	Gets/Sets the components list.
public	getComponentCount()	Returns the number of components.

Overview

The GameObject class represents an entity in the scene graph. It can have components, children, and a transform for position, rotation, and scale. GameObjects are the core building blocks for all objects in the engine, similar to Unity's GameObject.

Class Definition

package org.PiEngine.GameObjects;
public class GameObject

Properties

Property	Type	Description
Name	String	The name of the GameObject
transform	Transform	The Transform component for position, rotation, scale
id	int	Unique identifier for this GameObject
Location	String	Hierarchical path of this GameObject
layer	int	Layer bitmask for rendering and filtering
components	List	List of attached components

Methods

/**
 * Constructs a GameObject with a given name and initializes its Transform.
 * @param name The name of the GameObject
 */
public GameObject(String name)

/**
 * Adds a child GameObject by parenting its Transform to this GameObject's Transform.
 * @param child The child GameObject to add
 */
public void addChild(GameObject child)

/**
 * Adds a component to this GameObject.
 * @param component The component instance to attach
 */
public void addComponent(Component component)

/**
 * Retrieves the first component of the specified type attached to this GameObject.
 * @param <T> The class type of the component
 * @param type The class object representing the desired component type
 * @return The component instance if found; otherwise, null
 */
public <T extends Component> T getComponent(Class<T> type)

/**
 * Called at a fixed interval (using Time.fixedDeltaTime).
 * Typically used for physics or time-consistent logic.
 */
public void fixedUpdate()

/**
 * Called once every frame. Updates all components and recursively updates all children.
 */
public void update()

/**
 * Called once every frame after update(). Responsible for rendering this GameObject and its children.
 * @param camera The camera to render with
 * @param layerMask The layer mask for rendering
 */
public void render(Camera camera, int layerMask)

/**
 * Called after render(), only in debug mode or when needed. Used to draw debug visuals like bounding boxes, axis lines, etc.
 */
public void debugRender()

/**
 * Recursively updates the Location string for this GameObject and all children.
 */
public void UpdateLocation()

/**
 * Returns the hierarchical path of the GameObject in the scene tree.
 * @param gb The GameObject
 * @return The path string
 */
public static String Location(GameObject gb)

/**
 * Finds a GameObject by its path, recursively searching the hierarchy.
 * @param path The path string
 * @param root The root GameObject to search from
 * @return The found GameObject, or null if not found
 */
public static GameObject findGameObject(String path, GameObject root)

/**
 * Finds a GameObject by its path using an iterative approach.
 * @param path The path string
 * @param root The root GameObject to search from
 * @return The found GameObject, or null if not found
 */
public static GameObject findGameObjectItrative(String path, GameObject root)

/**
 * Recursively prints the hierarchy of GameObjects starting from this one.
 */
public void printHierarchy()

/**
 * Reparents this GameObject to a new parent GameObject, preserving world transform.
 * @param newParent The GameObject to become the new parent
 */
public void reparentTo(GameObject newParent)

/**
 * Gets the layer bitmask.
 * @return The layer bitmask
 */
public int getLayerBit()

/**
 * Sets the layer bitmask.
 * @param newLayer The new layer bitmask
 */
public void setLayer(int newLayer)

/**
 * Sets the layer for this object only.
 * @param newLayer The new layer bitmask
 */
public void setLayerOnly(int newLayer)

/**
 * Sets the layer for this object and all its children recursively.
 * @param layerBit The new layer bitmask
 */
public void setLayerRecursively(int layerBit)

/**
 * Sets the layer from layer(bit) name (for convenience).
 * @param layerName The name of the layer
 * @param recursive Whether to set recursively
 */
public void setLayerByName(String layerName, boolean recursive)

/**
 * Returns a readable string representation of the GameObject.
 * @return String representation
 */
@Override
public String toString()

/**
 * Returns all the components of a GameObject.
 * @return List of components
 */
public List<Component> getAllComponents()

/**
 * Removes a component from this GameObject.
 * @param cmp The component to remove
 */
public void removeComponent(Component cmp)

/**
 * Destroys a GameObject and all its children, removing them from the hierarchy and clearing components.
 * @param thisGb The GameObject to destroy
 */
public static void destroy(GameObject thisGb)

/**
 * Gets/Sets the unique ID, name, transform, layer, and components.
 */
public int getId(); public void setId(int id);
public String getName(); public void setName(String name);
public Transform getTransform(); public void setTransform(Transform transform);
public int getLayer(); public void setLayer(int layer);
public List<Component> getComponents(); public void setComponents(List<Component> components);
public int getComponentCount();

Example Usage

GameObject player = new GameObject("Player");
player.addComponent(new PlayerController());
GameObject enemy = new GameObject("Enemy");
player.addChild(enemy);

player.update(); // Calls update on player and all children

// Find a GameObject by path
GameObject found = GameObject.findGameObject("/Player/Enemy", root);

// Set layer recursively
player.setLayerRecursively(2);

Best Practices

• Use addComponent to attach logic/behavior to GameObjects
• Use addChild to build hierarchies (e.g., player with weapon as child)
• Use findGameObject for path-based lookups
• Use setLayerRecursively for group rendering/filtering

See Also

• Transform
• IDGenerator