System.GetTimeFrac bugged

[Player701]

As far as I can gather, this function is supposed to return the fraction of the current game tick that has already passed. However, its behavior appears to be bugged:

• In release builds, the first time this function is called within any method body, the return value is always infinity.
• In debug builds, every call appears to return infinity before some significant amount of time has passed.

The difference between debug and release builds indicates that some kind of undefined behavior might be involved.

The following example demonstrates the buggy behavior in GZDoom 4.8.0 (official release build):

Code: Select all

class TestInv : Inventory
{
    override void Tick()
    {
        Super.Tick();

        Test();
        Console.Printf("---");
        Test();
        Console.Printf("---");
    }

    private void Test()
    {
        Console.Printf("%d: %f", GetAge(), System.GetTimeFrac());
        Console.Printf("%d: %f", GetAge(), System.GetTimeFrac());
    }
}

Example output after give testinv:

Code: Select all

10: inf
10: 0.000000
---
10: inf
10: 0.000000
---
11: inf
11: 0.000000
---
11: inf
11: 0.000000
...

The following example demonstrates the buggy behavior in GZDoom g4.9pre-17-g2397b9c11 (debug configuration compiled with Visual Studio 2022):

Code: Select all

class TestInv : Inventory
{
    override void Tick()
    {
        Super.Tick();

        Console.Printf("%d: %f", GetAge(), System.GetTimeFrac());
        Console.Printf("%d: %f", GetAge(), System.GetTimeFrac());

        if (Owner != null)
        {
            let it = BlockThingsIterator.Create(Owner, 1024);
            int cnt = 0;

            while (it.Next())
            {
                cnt++;
            }

            Console.Printf("%d: %f (%d)", GetAge(), System.GetTimeFrac(), cnt);
        }

        Console.Printf("---");
    }
}

Example output after give testinv (Doom II MAP29):

Code: Select all

10: inf
10: inf
10: 0.342887 (29)
---
11: inf
11: inf
11: 0.400922 (29)
---
...

[Graf Zahl]

fixed. this actually didn't work at all, even the values you got are just random.