Components¶

Components in the Isetta Engine are similar to components in other engines, they should be designed for individal tasks and have minimal coupling with other components. Components cannot be standalone/instantiated in a level without being attached to an entity, done with entity->AddComponent<COMPONENT, bool isActive = true>(Component constructor args...). You can look at any of our example levels for usage

entity is an instantiated entity variable as shown above
COMPONENT is the class name of your component to add, ie. ExampleComponent
bool isActive = true is whether the component starts enabled/disabled and defaults to starting active
Component constructor args... are the arguments to pass to the component's constructor (can be empty to use the default constructor -- a component MUST have a default constructor in addition to any other constructors)

A component is created with Isetta component macros: DEFINE_COMPONENT(COMPONENT, PARENT, bool unique) and DEFINE_COMPONENT_END(COMPONENT_NAME, PARENT). Where: - COMPONENT is the name of your new component class, ie. ExampleComponent - PARENT is the name of the parent/base class of component, use Component if you have no base class - bool unique is whether the component must be unique on an entity (whether an entity could have multiple of this component) - The unique variable does NOT mean the component is unique across the level, ie. a singleton

To create a component, create a header (.h) and cpp (.cpp) file of the name of your component:

ExampleComponent.h

#pragma once
#include <IsettaEngine.h>
using namespace Isetta;

DEFINE_COMPONENT(ExampleComponent, Component, false)
private:
// Private variables of your component
public:
// A component MUST have a default constructor
ExampleComponent() = default;

// Awake is called once, immediately when the component is first created and enabled
void Awake() override;
// Start is called once, on the first update frame after the component is created and enabled
void Start() override;
// OnEnable is called immediately each time the component becomes active, including after creation
void OnEnable() override;
// OnDisable is called immediately each time the component becomes inactive
void OnDisable() override;
// Update is called each frame (variable delta time)
void Update() override;
// GuiUpdate is called each frame (variable delta time), GUI can only be called in GuiUpdate
void GuiUpdate() override;
// LateUpdate is called each frame (variable delta time)
void LateUpdate() override;
// FixedUpdate is called on fixed time (constant delta time)
void FixedUpdate() override;
// OnDestroy is called once when the component is destroyed
void OnDestroy() override;

DEFINE_COMPONENT_END(ExampleComponent, Component)

The cpp file then contains the definitions for each of these functions. Not all functions need to be defined, if not overriden, the function update will run faster.

Example

Here are empty template of component header to copy:

#pragma once
#include <IsettaEngine.h>
using namespace Isetta;

DEFINE_COMPONENT(COMPONENT_NAME, Component, false)
private:
public:
COMPONENT_NAME() = default;
DEFINE_COMPONENT_END(COMPONENT_NAME, Component)

Warning

Every component must have a default constructor!

Warning

Components header currently cannot be wrapped in any namespace.

Essential API¶

Entity::AddComponent<T>: Add a component to an entity
Entity::GetComponent<T>: Get a component from an entity
Component::SetActive(bool active): Toggle active state
Component::entity*: Components have a pointer to its owner entity
Component::transform*: Components have a pointer to its entity's transform
Life time methods see above

Predefined Components¶

In our engine, we have lots of predefined components that you can use out of the box! - AI - No Documentation Yet:

Component Name	Component Description
`Nav2DAgent`	Agent that is moved on a Nav2DPlane.

Audio - Documentation:

Component Name	Component Description
`AudioSource`	...
`AudioListener`	...

Collisions - Documentation:

Component Name	Component Description
`BoxCollider`	...
`CapsuleCollider`	...
`SphereCollider`	...
`CollisionHandler`	...

General Components - Documentation:

Component Name	Component Description
`AxisDrawer`	...
`FlyController`	...
`GridComponent`	...
`NetworkMonitor`	...

Graphics - Documentation:

Component Name	Component Description
`AnimationComponent`	...
`CameraComponent`	...
`LightComponent`	...
`MeshComponent`	...
`ParticleSystemComponent`	...

Networking - Documentation:

Component Name	Component Description
`NetworkDiscovery`	...
`NetworkId`	...
`NetworkTransform`	...