Countdown Timer - UI

I am trying to create a countdown timer using Text. When the user presses a certain key, I want the seconds value to update on the screen as it counts down from 5. The code below uses a Urho3D::Timer, but it doesn’t display the text on the screen until after the timer has counted all the way down. Any suggestions would be appreciated.

ResourceCache* cache = GetSubsystem<ResourceCache>();
	UI* ui = GetSubsystem<UI>();
	// Construct new Text object, set string to display and font to use
	Text* instructionText = ui->GetRoot()->CreateChild<Text>();
	instructionText->SetFont(cache->GetResource<Font>("Fonts/Anonymous Pro.ttf"), 48);
	instructionText->SetColor(Color(0.0f, 1.0f, 0.0f));
	instructionText->SetTextAlignment(HA_CENTER);
	instructionText->SetHorizontalAlignment(HA_CENTER);
	instructionText->SetVerticalAlignment(VA_CENTER);
	instructionText->SetPosition(0, ui->GetRoot()->GetHeight() / 4);
	instructionText->SetText("Countdown");
	// Add Text instance to the UI root element
	GetSubsystem<UI>()->GetRoot()->AddChild(instructionText);

	for (int i = 5; i >= 1; i--)
	{
		instructionText->SetText("Countdown " + String(i));
		Timer tmr = Timer();
		do {} 
		while (tmr.GetMSec(false) < 1000);
		// reset the timer
		tmr.Reset();

		if (DEBUG) URHO3D_LOGINFOF("Tick %d", i);
	}

The program cannot draw countdown because Engine doesn’t draw anything until you exit all your functions and let internal rendering routines go.

Understanding a bit about Urho3D’s game loop might help - I’ll keep it short.
Like many game engines, Urho3D’s game loop consists of (listing from Urho3D/Core/CoreEvents.h):

1 - E_BEGINFRAME, BeginFrame
2 - E_UPDATE, Update
3 - E_POSTUPDATE, PostUpdate
4 - E_RENDERUPDATE, RenderUpdate
5 - E_POSTRENDERUPDATE, PostRenderUpdate
6 - E_ENDFRAME, EndFrame

For simplicity, treat these as sequential stages that gets processed every frame, and in each stage processes some subsystem required for that stage, e.g graphics and UI needs to render in stage 4.
Most of the user’s game logic ends up in stage 2, in Update(). However, if your Update stage looks like:

Update-Stage()
{
  for-loop(...)
  {
    do{} while (somevalue == valid);
  }
}

rest of the stages are waiting their turn to process but cannot get there until update() completes.

Better method for your countdown in Update()

if (countDownTimer_.GetMSec(false) > 1000 && countDown_ > 0)
{
  instructionText->SetText("Countdown " + String(--countDown_));
  countDownTimer_.Reset();
}

@Lumak, Thanks for this answer, it is very helpful. This is my first gaming engine and I’m still trying to get my head wrapped around how everything works.

@Lumak, using your suggested approach, I was able to implement my countdown timer exactly as I wanted to. Thanks again!

I would mark this issue [SOLVED] but I don’t see any buttons or links to do so.

Here should be one more button:
But maybe topics in this forum category doesn’t have such feature, I’m not 100% sure.

Indeed only topics in the Support category can be marked solved.

It appears that only certain users have the checkbox to mark a reply as solving the problem. For example, neither @Lumak nor I have this checkbox but @Eugene and @Modanung do. Not sure what’s up with that…

I did have to change the topic’s category (allowed at trust level 4) first and refresh the page for the button to appear.