# Event Listeners
***
### EntitySubscribeTriggerEnter
This guide provides instructions for setting up the **EntitySubscribeTriggerEnter** trigger. In the sample app below, the trigger areas are outlined in blue. Once the avatar enters into the blue area, an action occurs.
| | |
| ----------------------------------------------------------------------------- | -------------------------------------------------------------------------- |
| The avatar is outside the blue trigger area and the gold coin is not visible. | The avatar has entered the blue trigger area and the gold coin is visible. |
In our example above, a trigger area is created. When the avatar enters the trigger area, an action is then initiated. Any object can be used as a trigger, as long as the object has a collision component. Our example uses a 3D box as the trigger area.
#### **Create a trigger for when an object enters an area**
{% stepper %}
{% step %}
**Create a trigger area**
A. Create a new **3D Box** entity.
B. Add a **Collision** component.
C. Adding a material is optional. A transparent material has been added so that the trigger area is visible in play mode.
D. Click the **Edit Viverse Extension** button.
{% endstep %}
{% step %}
**Add the** *EntitySubscribeTriggerEnter* **trigger**
A. In the VIVERSE extension, select the **TriggerAndAction** plugin for the **Select plugins** dropdown.
B. Add a **Trigger** and select **EntitySubscribeTriggerEnter**.
C. Add **local-player** to the **tags to filter** field.
D. Add an **Action** and select **EntityEnableById.**
E. Add an object that will be enabled when the avatar enters the trigger area. The **golden\_coin** entity has been added to the **pick up specify execution entity**. The **golden\_coin** entity has also been disabled by default.
{% endstep %}
{% endstepper %}
### EntitySubscribeTriggerLeave
This guide provides instructions for setting up the **EntitySubscribeTriggerLeave** trigger. In the sample app, the trigger areas are outlined in blue. Once the avatar leaves the blue area, an action occurs.
| | |
| ---------------------------------------------------------------------------- | ------------------------------------------------------------------------------- |
| The avatar is inside the the blue trigger area and the gold coin is visible. | The avatar leaves the blue trigger area and the gold coin is no longer visible. |
In this example, a trigger area is created and when the avatar leaves the trigger area, an action is initiated. Any object can be used as a trigger, as long as the object has a collision component. This example uses a 3D box as the trigger area.
#### **Create a trigger for when an object leaves an area**
{% stepper %}
{% step %}
**Create a trigger area**
A. Create a new **3D Box** entity.
B. Add a **Collision** component.
C. Adding a material is optional. A transparent material has been added so that the trigger area is visible in play mode.
D. Adding a material is optional. A transparent material has been added so that the trigger area is visible in play mode.
{% endstep %}
{% step %}
**Add the** *EntitySubscribeTriggerLeave* **trigger**
A. In the VIVERSE extension, select the **TriggerAndAction** plugin for the **Select plugins** dropdown.
B. Add a **Trigger** and select **EntitySubscribeTriggerLeave**.
C. Add **local-player** to the **tags to filter** field.
D. Add an **Action** and select **EntityDisableById.**
E. Add an object that will be disabled when the avatar leaves the trigger area. The **golden\_coin** entity has been added to the **pick up specify execution entity**.
{% endstep %}
{% endstepper %}
### EntitySubscribeCollisionStart
This guide provides instructions for setting up the **EntitySubscribeCollisionStart** trigger. In the sample app, the **golden\_coin** is a trigger. Once the avatar collides with the **golden\_coin**, an action occurs.
| | |
| ------------------------------------------------------------------- | ---------------------------------------------------------------------- |
| The avatar approaches the gold coin. | Once the avatar collides with the gold coin, the gold coin is removed. |
In this example, a trigger is created and when the avatar collides with the trigger, an action is initiated. Any object can be used as a trigger, as long as the object has a collision component. Because this specific example uses a 3D object that the avatar can collide with, a **RigidBody** component needs to be added. In this example, the object **golden\_coin** is used, but a simple cube will suffice.
#### **Create a trigger for when an object collides with another object**
{% stepper %}
{% step %}
**Create the 3D object that the avatar will collide with**
A. Add 3D object to the scene.
B. Add a **Collision** component.
C. Add a **Rigidbody** component.
D. Click the **Edit Viverse Extension** button.
{% endstep %}
{% step %}
**Add the** *EntitySubscribeCollisionStart* **trigger**
A. In the VIVERSE extension, select the **TriggerAndAction** plugin for the **Select plugins** dropdown.
B. Add a **Trigger** and select **EntitySubscribeCollisionStart**.
C. Add **local-player** to the **tags to filter** field.
D. Add an **Action** and select **EntityDisable.**
{% endstep %}
{% endstepper %}
### EntitySubscribeCollisionEnd
This guide provides instructions for setting up the **EntitySubscribeCollisionEnd** trigger. In the sample app, a flattened 3D cube is a trigger. Once the avatar stops colliding with the cube, an action occurs.
| | |
| ------------------------------------------------------------------- | ------------------------------------------------------------------------------------------- |
| The avatar is colliding with the red platform. | Once the avatar stops colliding with the red platform, the red platform begins to fade out. |
In this example, a trigger is created and when the avatar or other objects collide with the trigger, an action is initiated. Any object can be used as a trigger, as long as the object has a collision component. Because this specific example uses a 3D object that the avatar can collide with, a **RigidBody** component needs to be added.
#### **Create A Trigger Based On When An Object Stops Colliding With Another Object**
{% stepper %}
{% step %}
**Create the 3D object that the avatar will collide with**
A. Add 3D object to the scene.
B. Add a **Collision** component.
C. Add a **Rigidbody** component.
D. Click the **Edit Viverse Extension** button.
{% endstep %}
{% step %}
**Add the** *EntitySubscribeCollisionEnd* **trigger**
A. In the VIVERSE extension, select the **TriggerAndAction** plugin for the **Select plugins** dropdown.
B. Add a **Trigger** and select **EntitySubscribeCollisionEnd**.
C. Add **local-player** to the **tags to filter** field.
D. Add an **Action** and select **EntityFadeOut.**
{% endstep %}
{% endstepper %}
### NotificationCenterSubscribeEntityPicking
This guide provides instructions for setting up the **NotificationCenterSubscribeEntityPicking** trigger. In the sample app, the user clicks on the buttons to show and hide the whale.
| | |
| ------------------------------------------------------------------- | ------------------------------------------------------------------- |
| The whale is visible. | When the user clicks on the whale, the whale is disabled. |
In this example, a trigger area is created on a button. When the user clicks on the trigger area, an action causes the 3D model to be disabled. Any object can be used as a trigger, as long as the object has a collision component.
#### **Create a trigger for when a user clicks an object**
{% stepper %}
{% step %}
**Create the 3D object that the user will click on**
A. Add a 3D object to the scene. In this example, a button is used, but any 3D object will work.
B. Add a **Collision** component.
C. Click the **Edit Viverse Extension** button.
{% endstep %}
{% step %}
**Add the** *NotificationCenterSubscribeEntityPicking* **trigger**
A. In the VIVERSE extension, select the **TriggerAndAction** plugin for the **Select plugins** dropdown.
B. Add a **Trigger** and select **NotificationCenterSubscribeEntityPicking**.
C. Add an **Action** and select **EntityDisable.** Add an object that will be disabled.
{% endstep %}
{% endstepper %}
### NotificationCenterPublish & NotificationCenterSubscribe
This guide provides instructions for setting up the **NotificationCenterPublish** action and the **NotificationCenterSubscribe** trigger. In the sample app, every time the avatar enters the green trigger area, a notification is sent to the wall and the collider on the wall is toggled on/off. The wall is green when the avatar can pass through and red when the avatar can not pass through.
| | |
| -------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
| Before the avatar enters the green trigger area, the wall is red and the avatar can not pass through the wall. | Once the avatar enters the green trigger area, the green trigger sends a notification to the wall and the collider on the wall is disabled. |
In this example, a trigger is created and when the avatar enters the trigger area, an action sends a notification to another object. The other object receives the notification via trigger, then initiates an action.
#### **Action and Trigger combination to send a notification from one object to another**
{% stepper %}
{% step %}
**Create the 3D object that will send the notification**
A. Add a 3D object to the scene.
B. The **Collision** component is not required for **NotificationCenterPublish** action or **NotificationCenterSubscribe** trigger to work. The **Collision** component is required for the **EntitySubscribeTriggerEnter** trigger that will be used in this example.
C. Click the **Edit Viverse Extension** button.
{% endstep %}
{% step %}
**Add the** *NotificationCenterPublish* **action**
A. In the VIVERSE extension, select the **TriggerAndAction** plugin for the **Select plugins** dropdown.
B. Add a **Trigger** and select **EntitySubscribeTriggerEnter**.
C. Add **local-player** to the **tags to filter** field.
D. Add an **Action** and select **NotificationCenterPublish.**
E. Create a unique notification name and add it to the **notification name to publish** field. In this example, the notification is called **ToggleWall**.
{% endstep %}
{% step %}
**Create the 3D object that will receive the notification**
A. Add a 3D object to the scene.
B. The **Collision** component is not required for **NotificationCenterPublish** action or **NotificationCenterSubscribe** trigger to work. The **Collision** component is required for the **EntityToggleCollision** action that will be used in this example.
C. The **Rigidbody** component is not required for the **NotificationCenterPublish** action or **NotificationCenterSubscribe** trigger to work. The **Rigidbody** component is required for the **EntityToggleCollision** action that will be used in this example.
D. Click the **Edit Viverse Extension** button.
{% endstep %}
{% step %}
**Add the** *NotificationCenterSubscribe* **action**
A. In the VIVERSE extension, select the **TriggerAndAction** plugin for the **Select plugins** dropdown.
B. Add a **Trigger** and select **NotificationCenterSubscribe**.
C. The same text that was added to the **notification name to publish** needs to be added to the **notification name to subscribe**.
D. Add an **Action** and select **EntityToggleCollision.**
{% endstep %}
{% endstepper %}
---
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