Change speed over time

[Ilkzz]

Hi,

Im creating a new game mode for my game, where the objects instantiated move faster as time goes on, or even every 15 seconds etc.

void FixedUpdate () {
		if (isBackground == false){

		speed -= 1f * Time.deltaTime;
			
		Vector2 velocity = new Vector2(speed, 0);
		rigidbody2D.velocity = velocity;

		Destroy(gameObject,destroyTime);
		}

}

Here my code increases speed over time, where the speed starts at 0, and reaches till destroyTime. However, I want the speed to be constant for a duration of time, then increase it after a couple seconds.

How can I go about doing this?

Thanks

[NoseKills]

You could use a simple countdown variable to see when it’s time to change the speed

const float SPEED_INCREASE_INTERVAL = 3f; // how often do you want the speed to change
const float SPEED_CHANGE = 1; // how much do you want the speed to change 
float _ItervalTimer = SPEED_INCREASE_INTERVAL;

void FixedUpdate () 
{
   if (isBackground == false){
       _ItervalTimer -= Time.deltaTime;
       if (_IntervalTimer < 0)
       {
           speed -= SPEED_CHANGE;
 
           Vector2 velocity = new Vector2(speed, 0);
           rigidbody2D.velocity = velocity;
 
           Destroy(gameObject,destroyTime);
           _IntervalTimer = SPEED_INCREASE_INTERVAL;
       }

   }
}

EDIT:
To keep spawning objects with increased moving speeds as requested:

You need to have a script that stores the time when the level started. This timestamp needs to be captured before every time you enter a level to play it (don’t put this into every GameObject. Put it in just one)

    public static float _TimeSinceStart;

	public void StartGame() // call this every time the player enters a level to play it
	{
		_TimeSinceStart = Time.realtimeSinceStartup;
	}

Then you can spawn objects that move faster depending on how long the level has been played:

const float SPEED_INCREASE_INTERVAL = 15f; // how often do you want the speed to change
	const float SPEED_CHANGE = -1; // how much do you want the speed to change
	const float SPEED_AT_START = -2;

	void FixedUpdate () 
	{
		if (isBackground == false)
		{
			// how much time has passed since game started
			int secondsSinceGameStart = (int)(Time.realtimeSinceStartup - Game._TimeSinceStart);

			// how many times has the speed changing interval passed
			int interval = secondsSinceGameStart / SPEED_INCREASE_INTERVAL;

			// current speed = start speed + speed increase for every interval that has passed 
			speed -= SPEED_AT_START + (interval * SPEED_CHANGE);
			
			Vector2 velocity = new Vector2(speed, 0);
			rigidbody2D.velocity = velocity;
			
			Destroy(gameObject, destroyTime);
		}
	}