# Use of two-dimensional logic script

This chapter mainly introduces how to write and use scripts in a two-dimensional scene. Such as simple touch and click processing, add or delete node components on the field

Script components can be considered as ordinary components and execute together with ordinary components Life Cycle Update.

# Use logic

Create a new logic script Project panel right click-New-script
Write the required script content
Add the script component to the desired node.

# Get/Add/Delete node components on the field

Get the node, According to the name, traverse the node Transform tree, match and return the corresponding node Transform

public getChildByName(transform, name) {
    const getNode = transform.findChildByName(name);
    if (getNode === null) {
      for (let i = 0; i <transform._children.length; i++) {
        const childNode = this.getChildByName(transform._children[i], name);
        if (childNode != null) {
          return childNode;
        }
      }
      return null;
    } else {
      return getNode;
    }
  }

Add and delete nodes View details

// Add node
parentTransform.addChild(transform);
// delete node
parentTransform.removeChild(transform);
transform.destroy();
// ...

Get/add components View details

// add components
entity.addComponent(engine.UISprite);
// Get node
const comp = entity.getComponent(engine.UISprite);
// ...

# Touch, click to mount

If the node where the script component is mounted has a TouchInputComponent component, The built-in touch and click processing functions can be added directly to the script component to use.

export default class touchHandler extends engine.Script {

  public onTouchStart(t: engine.TouchInputComponent, e: TouchInputEvent){}
  public onTouchMove(t: engine.TouchInputComponent, e: TouchInputEvent){}
  public onTouchEnd(t: engine.TouchInputComponent, e: TouchInputEvent){}
  public onTouchCancel(t: engine.TouchInputComponent, e: TouchInputEvent){}
  public onTouchEnter(t: engine.TouchInputComponent, e: TouchInputEvent){}
  public onTouchLevel(t: engine.TouchInputComponent, e: TouchInputEvent){}
  public onTouchOver(t: engine.TouchInputComponent, e: TouchInputEvent){}
  public onTouchOut(t: engine.TouchInputComponent, e: TouchInputEvent){}
  public onTouchUp(t: engine.TouchInputComponent, e: TouchInputEvent){}
  public onClick(t: engine.TouchInputComponent, e: TouchInputEvent){}

}

The script gets the node with the TouchInputComponent component, Add components in the form of listeners

function touchStartHandler (t: engine.TouchInputComponent, e: TouchInputEvent) {}

const touchTransform = this.getChildByName(this.entity.transform2D,'close-button');
const buttonClose = touchTransform.entity.getComponent(engine.TouchInputComponent);
buttonClose.onTouchStart.add(touchStartHandler);
// ...

# Touch, click to use

export default class touchHandler extends engine.Script {

  public onTouchMove(t: engine.TouchInputComponent, e: TouchInputEvent){
    // current click event
    const changedTouch = e.touches[0];

    // current click coordinates
    const clientX = changedTouch.clientX;
    const clientY = changedTouch.clientY;
  }
}