Display progress in a long loop in Unity3d - loops

Question

I'm building a space game, populated by thousands of star systems. Right now, there is a function that generates these thousands of systems. It takes about 5-10 seconds to generate, and I would like to have a simple progress bar updating the user in the progress.
After some searching I've decided to use a coroutine, however there is a little problem: when I call the function to generate star systems, the code that called the function keeps on going, reporting zero stars (because they haven't been generated yet).
I have a feeling coroutines are not an answer for me. Basically, I am simply looking for a way to simulate Application.DoEvents to update the GUI.
Here is a sample of my code:
// Start generating thousands of systems
StartCoroutine(GalacticMap.GenerateRandomGalaxy());
// after the universe is generated...
Game.myGalaxy.StarSystems = GalacticMap.myGalaxy.StarSystems;
// report back the number of systems
print(String.Format("Generated {0} systems", Game.myGalaxy.StarSystems.Count));
In the GalacticMap.GenerateRandomGalaxy() I am yielding back like this yield return new WaitForSeconds(0.1f); however, the effect is not what I am looking for: execution goes right through to print statement while the generation is still on going.
So how do I do this?
EDIT 1:
I've cooked up a sample code to illustrate my issue.
The caller code:
Debug.Log ("Start generating");
StartCoroutine(GenerateMeGalaxy());
Debug.Log ("Finish generating");
The code I call:
public static IEnumerator GenerateMeGalaxy ()
{
Debug.Log ("GenerateMeGalaxy start");
int numberOfStars = 1000;
for (int i=0;i<=numberOfStars;i++)
{
// generate galaxy
// display progress bar on screen
Debug.Monitor(String.Format("{0}% completed", ((i*100)/numberOfStars)),2);
yield return new WaitForSeconds(0.001f);
}
Debug.Log ("GenerateMeGalaxy end");
}
In the code above, Debug.Log displays string on the screen, on a new line so you can read previous logged strings of whatever. This is to debug code execution. Debug.Monitor has a fixed location on the screen and will overwrite previous string. This is where I display progress percentage. What I see after running this code is:
Start generating
GenerateMeGalaxy start
Finish generating
GenerateMeGalaxy end
What I want to see is:
Start generating
GenerateMeGalaxy start
GenerateMeGalaxy end
Finish generating
... and also the progress update is happening in between:
GenerateMeGalaxy start
Finish generating

Answer 1

I think you are misunderstanding how Unity coroutines work. What the yield return new WaitForSeconds(0.1f) is essentially saying is "go do other stuff and come back to me after 0.1 second". So naturally Unity will go ahead and do other stuff, including the print statement.
What you want is something along the lines of the following pattern:
IEnumerator GenerateRandomGalaxy()
{
int numSystems = 5000; // however many systems you want to generate
foreach(int i = 0; i < numSystems; i++)
{
// insert code here that generates system i
// insert code here that updates the progress bar
yield return null;
}
// put logic that prints out final number of systems generated here
}
What this does is generate a system, update the status bar, and then -- with the yield return null statement -- tell Unity to take over (so that it do other stuff, including rendering the updated progress bar) and come back and continue the loop as soon as possible.
Finally, the print statement only happens after the loop is finished, as you intend.