metaballs/Assets/metaball/Scripts/BouncingBall.cs

using UnityEngine;
using System.Collections;

namespace MetaBalls
{
    public class BouncingBall : MetaBall
    {
        public float speed;

        private Container container;
        private Vector3 direction;

        private Vector3 lastPos;

        override public void OnDrawGizmos()
        {
            base.OnDrawGizmos();
        }
        public override void Start()
        {
            base.Start();
            this.direction = Random.onUnitSphere;
            this.container = this.GetComponentInParent<Container>();
        }

        override public void Update()
        {
            base.Update();
            if (Application.isPlaying)
            {
                if (transform.position != lastPos && speed != 0)
                {
                    lastPos = transform.position;
                    this.updatePosition(Time.deltaTime);
                }
            }
        }

        public void updatePosition(float dt)
        {
            float posX = this.transform.position.x, posY = this.transform.position.y, posZ = this.transform.position.z;
            Vector3 containerPosition = this.container.transform.position;
            Vector3 containerScale = this.container.transform.localScale;

            if (posX + this.radius + this.container.safeZone > containerPosition.x + containerScale.x / 2)
            {
                posX -= 0.01f;
                this.direction = Vector3.Reflect(this.direction, Vector3.left);
            }
            else if (posX - this.radius - this.container.safeZone < containerPosition.x - containerScale.x / 2)
            {
                posX += 0.01f;
                this.direction = Vector3.Reflect(this.direction, Vector3.right);
            }

            if (posY + this.radius + this.container.safeZone > containerPosition.y + containerScale.y / 2)
            {
                posY -= 0.01f;
                this.direction = Vector3.Reflect(this.direction, Vector3.down);
            }
            else if (posY - this.radius - this.container.safeZone < containerPosition.y - containerScale.y / 2)
            {
                posY += 0.01f;
                this.direction = Vector3.Reflect(this.direction, Vector3.up);
            }

            if (posZ + this.radius + this.container.safeZone > containerPosition.z + containerScale.z / 2)
            {
                posZ -= 0.01f;
                this.direction = Vector3.Reflect(this.direction, Vector3.back);
            }
            else if (posZ - this.radius - this.container.safeZone < containerPosition.z - containerScale.z / 2)
            {
                posZ += 0.01f;
                this.direction = Vector3.Reflect(this.direction, Vector3.forward);
            }

            this.transform.position = new Vector3(posX, posY, posZ) + this.direction * speed * dt;
        }
    }
}