An Amazon Sumerian script that will make the entity it is attached to orient itself smoothly so that it always faces another entity.

SmoothTargetTracking.js

'use strict';

/**
 * This script will make the entity it is attached to orient itself smoothly so that it always
 * faces the entity assigned to the `lookAtEntity` script parameter.
 */

function setup(args, ctx) {
	
	// The point to focus on, expressed in world space.
	ctx.entityData.focusPoint = args.lookAtEntity.transformComponent.getWorldTranslation();
	
	lookAtWorldPoint(ctx.entity, ctx.entityData.focusPoint);
}


function update(args, ctx) {
	
	const newFocusPoint = args.lookAtEntity.transformComponent.getWorldTranslation();
	const oldFocusPoint = ctx.entityData.focusPoint;
	
	let focusPoint;
	if (args.smoothing <= 0) {
		
		focusPoint = newFocusPoint;
		
	} else {
		
		const frameTime = ctx.world.tpf;
		focusPoint = ctx.entityData.focusPoint = oldFocusPoint.clone().lerp(newFocusPoint, frameTime / args.smoothing);

	}
	
	lookAtWorldPoint(ctx.entity, focusPoint);
	
	// Store the current focus point for use in later smoothing interpolation.
	ctx.entityData.focusPoint = focusPoint;
}


/**
 * Orients an entity to face the specified point in world space.
 */
function lookAtWorldPoint(entity, worldPoint) {
	
	let parentEntity = entity.parent().first();
	let point = parentEntity ? worldPointToLocal(worldPoint, parentEntity) : worldPoint;
	entity.lookAt(point);
}


/**
 * Converts a point expressed in world space to a point expressed in the entity's local space.
 */
function worldPointToLocal(point, entity) {
	
	let invertedWorld = entity.transformComponent.worldTransform.clone().invert();
	let out_point = new sumerian.Vector3();
	invertedWorld.applyForward(point, out_point);
	
	return out_point;
}


var parameters = [
	{
		key: "lookAtEntity",
		type: "entity",
		default: null,
		description: "The entity to look at."
	},
	{
		key: "smoothing",
		type: "float",
		default: 0.4,
		description: "The amount of smoothing to apply to tracking."
	}
];