koobas.hobune.stream
Code with Coroutine not working as intended.
I would like the following code to create a cube every second but it operates otherwise:it waits a second and then creates all of them without waiting a second. How can i change this code to make it create a cube, wait a second, and then create another? Thanks for your time.
public int numCubes = 10;
// Use this for initialization
void Start () {
for (int i = 0; i< numCubes ; i++)
{
for (int j = 0; j < numCubes; j++)
{
StartCoroutine(CreateCube (i,j));
}
}
}
IEnumerator CreateCube (int i, int j)
{
GameObject box = GameObject.CreatePrimitive (PrimitiveType.Cube);
box.transform.position = new Vector3 (i * 2.0f, j * 2.0f, 0f);
yield return new WaitForSeconds(1f);
}
Your problem is that you start many coroutines at once that will spawn 1 cube each instead of starting one coroutine that will spawn many. This is the corrected version of your code:
public int numCubes = 10;
void Start()
{
StartCoroutine(CreateCube());
}
IEnumerator CreateCube()
{
for (int i = 0; i < numCubes; i++)
{
for (int j = 0; j < numCubes; j++)
{
GameObject box = GameObject.CreatePrimitive(PrimitiveType.Cube);
box.transform.position = new Vector3(i * 2.0f, j * 2.0f, 0f);
yield return new WaitForSeconds(1f);
}
}
}
Your Start method starts 100 coroutines at once. Those will all run "simultaneously" (not actually but from the a concept point of view). Waiting can only happen inside a coroutine. A coroutine runs independent from the code that started the coroutine unless you yield on that coroutine as well. However that is only possible when the starting code is also inside a coroutine.
So your Start method would need to be a coroutine as well:
IEnumerator Start ()
{
for (int i = 0; i< numCubes ; i++)
{
for (int j = 0; j < numCubes; j++)
{
yield return StartCoroutine(CreateCube (i,j));
}
}
}
This would work, however it creates a lot of overhead / garbage for each started coroutine. Such a simple thing would be better implemented like this:
IEnumerator Start ()
{
for (int i = 0; i< numCubes ; i++)
{
for (int j = 0; j < numCubes; j++)
{
CreateCube(i, j);
yield return new WaitForSeconds(1f);
}
}
}
void CreateCube (int i, int j)
{
GameObject box = GameObject.CreatePrimitive (PrimitiveType.Cube);
box.transform.position = new Vector3 (i * 2.0f, j * 2.0f, 0f);
}
Here you only have one coroutine (the start method) and CreateCube is a normal method.
Thanks. One Question: If the Start method is an IEnumerator will it still be automatically called by the unity engine?
Yes.
You can see that for yourself simply by using example provided by Bunny83 or if you want to convert my example you will simply need to remove whole Start function and rename CreateCube function to Start, e.g.:
public int numCubes = 10;
IEnumerator Start()
{
for (int i = 0; i < numCubes; i++)
{
for (int j = 0; j < numCubes; j++)
{
GameObject box = GameObject.CreatePrimitive(PrimitiveType.Cube);
box.transform.position = new Vector3(i * 2.0f, j * 2.0f, 0f);
yield return new WaitForSeconds(1f);
}
}
}
Yes, i saw that. Problem solved. Thanks. Though the concept is the same here, and that is the main thing, i prefer your original version because it seems more general and does not tie the start method to this particular problem.
