Re: Porting this to event-based? - C# Discussion Boards

24-Sep-06 12:31

Hello everyone!
OK, I want to port this from C++:

// Main game loop<br />
	while (true)<br />
	{<br />
		// Get the current time<br />
		float newTime = (float) SDL_GetTicks();<br />
<br />
		float deltaTime = newTime - currentTime;<br />
		currentTime = newTime;<br />
<br />
		accumulator += deltaTime;<br />
<br />
		while (accumulator >= dt)<br />
		{<br />
			game.Respond();<br />
			t += dt;<br />
			accumulator -= dt;<br />
		}<br />
<br />
		game.Render();<br />
<br />
		SDL_Delay(10);<br />
	}

But there's a little problem... I put all of the event getting in game.Respond. But now in C# they have events, so I can't do that... Help? Thanks!

Windows Calculator told me I will die at 28. Frown | :(

Nader Elshehabi24-Sep-06 12:44

24-Sep-06 12:44

Hello

You can Use these event handlers to set variable flags -like Left = true, Right = true, etc...- and check them in the Respond() as you did in C++, or a neater way is to devide your Respond() code in the handlers accordingly.

Regards

Lord Kixdemp24-Sep-06 14:27

24-Sep-06 14:27

That's what I'm doing... I'm setting the keys in the KeyboardDown and unsetting them in KeyboardUp... But this piece of code makes it so that the game will run at the same speed on any computer... And it doesn't work... Any more ideas? Thanks! Wink | ;)

Windows Calculator told me I will die at 28. Frown | :(

Nader Elshehabi24-Sep-06 14:54

24-Sep-06 14:54

Lord Kixdemp wrote:
And it doesn't work

I don't understand what exactly that doesn't work? More details would be very helpful.

Regards

Lord Kixdemp24-Sep-06 15:13

24-Sep-06 15:13

Well... OK, what I posted in the first post was my main game loop... See the second while loop? Well, that's when I'm supposed to get user input through SDL events (non-.NET, just a switch statement)... That's done so that the game runs at the same speed on any computer it runs on (it runs faster at 2.8GHz than at 1.4GHz...). So, now I have the events loop, it's out of my control (SDL.NET), the events only raise when that specific... event happens. So now I want to do the same thing I did in C++ in C#. Thanks! Wink | ;)

Windows Calculator told me I will die at 28. Frown | :(

Nader Elshehabi24-Sep-06 15:30

24-Sep-06 15:30

1- Forgive my ignorance, but what is SDL?
2- Do you have the source code of game.Respond()?
3- SDL.Net is that another language? How does it handle events?
4- The speed control of the game. Did you write its algorithm or is it a 3rd party library?
5- Even in C++ events were simply messages sent to the game. If so then your C++ code should still be able to process these messages or otherwise you simply kick these messages to it manually.

Regards

Lord Kixdemp25-Sep-06 11:25

25-Sep-06 11:25

1- Simple DirectMedia Layer is a graphics library, based in OpenGL... Poke tongue | ;-P

2- In my C++ code I did, here:

bool Game::Respond()
{
	// Poll for SDL events
	SDL_Event event;
	while (SDL_PollEvent(&event))
	{
		switch (event.type)
		{
			// Key presses
		case SDL_KEYDOWN:
			switch (event.key.keysym.sym)
			{
				// Arrows
			case SDLK_LEFT:
				this->gLtKey = 1;
				break;
			case SDLK_RIGHT:
				this->gRtKey = 1;
				break;
			case SDLK_UP:
				this->gUpKey = 1;
				break;
			case SDLK_DOWN:
				this->gDnKey = 1;
				break;
				// Press Shift to start running
			case SDLK_LSHIFT:
				this->gRun	 = 1;
				break;
			default:
                break;
			}
			break;

			// Key releases
		case SDL_KEYUP:
			switch (event.key.keysym.sym)
			{
				// Quit key
			case SDLK_ESCAPE:
				exit(0);
				// Arrows
			case SDLK_LEFT:
				this->gLtKey = 0;
				break;
			case SDLK_RIGHT:
				this->gRtKey = 0;
				break;
			case SDLK_UP:
				this->gUpKey = 0;
				break;
			case SDLK_DOWN:
				this->gDnKey = 0;
				break;
			// Release Shift to stop running
			case SDLK_LSHIFT:
				this->gRun	 = 0;
				break;
			default:
                break;
			}
			break;
		case SDL_QUIT:
			exit(0);
		}
	}
}

(There was more after that, but that's the part that matters...)

3- SDL.NET is the C#/.NET port of SDL... It handles events the same way .NET Windows Forms does, with delegates and stuff.

4- Nah, I did it, that's what the code in my first post does. Poke tongue | ;-P

5- See the code I posted in #2? That's what events in SDL looked like...

Sorry for causing such confusion, I'm a n00b! Thanks! Wink | ;)

Windows Calculator told me I will die at 28. Frown | :(

Nader Elshehabi25-Sep-06 11:44

25-Sep-06 11:44

So I guess that when the user presses a key, there is an SDL event that will be fired? Well, I still don't see aproblem:
1- Make a thread fro the game loop
2- Make flags for each Key to be pressed
3- Raise that flag in the KeyDown, and make it false in KeyUp events -whether windows or SDL events-
4- On each loop render the game accordingly -change the position of the spirit if the key is pressed otherwise stay on course for example-
5- You will still be able to control the speed of excution in the thread by many ways includeing the Thread.Sleep() and specify the interval of sleep based on the speed of excution -you can get the speed of excution by many ways like Timers-.

I hope that was what you were looking for, but somehow i think you already did all this. Where is your problem?

Regards

Lord Kixdemp25-Sep-06 14:27

25-Sep-06 14:27

That's exactly what I'm doing... Frown | :(

Here's my KeyDown/KeyUp events:

private void OnKeyboardDown(object sender, KeyboardEventArgs e)
{
    // Don't do anything if we can't process input
    if (!canRespond) return;

    switch (e.Key)
    {
        // Arrows
        case Key.LeftArrow:
            this.lKey = true;
            break;
        case Key.RightArrow:
            this.rKey = true;
            break;
        case Key.UpArrow:
            this.uKey = true;
            break;
        case Key.DownArrow:
            this.dKey = true;
            break;

            // Press Shift to start running
        case Key.LeftShift:
            this.running = true;
            break;
    }
}

private void OnKeyboardUp(object sender, KeyboardEventArgs e)
{
    // Don't do anything if we can't process input
    if (!canRespond) return;

    switch (e.Key)
    {
        // Arrows
        case Key.LeftArrow:
            this.lKey = false;
            break;
        case Key.RightArrow:
            this.rKey = false;
            break;
        case Key.UpArrow:
            this.uKey = false;
            break;
        case Key.DownArrow:
            this.dKey = false;
            break;

        // Release Shift to stop running
        case Key.LeftShift:
            this.running = false;
            break;

        // Press Esc to quit
        case Key.Escape:
            On = false;
            break;
    }
}

And here's my main loop:

public void Loop()
{
    while (On)
    {
        float t = 0.0f;
        const float dt = 30;
        float currentTime = 0.0f;
        float accumulator = 0.0f;

        // Get the current time
        float newTime = SdlDotNet.Timer.TicksElapsed;

        float deltaTime = newTime - currentTime;
        currentTime = newTime;

        accumulator += deltaTime;

        while (accumulator >= dt)
        {
            canRespond = true;
            t += dt;
            accumulator -= dt;
        }
        canRespond = false;

        Render();

        // Sleep a bit so we don't use 100% CPU
        Thread.Sleep(10);
    }

    Quit(null, null);
}

See, if canRespond is false, the events don't execute...

Is that what you meant or did I misunderstand? Poke tongue | ;-P

Thanks!

Windows Calculator told me I will die at 28. Frown | :(

Nader Elshehabi25-Sep-06 14:36

25-Sep-06 14:36

Why do you make things complicated for yourself. Simply use the KeyUp/KeyDown events to raise flags. Omit the CanRespond flag as it is very error brone. Now only raise flags in the KeyUp/KeyDown event and process them when you can in the loop thread. Of course you put this loop on another thread right? And why is Loop() public? It should be a private method in your form.

Anyway all I'm saying that omit the canResond totally. If the user presses a key while you are rendering it won't really hurt. Process that key when you see fit.

Regards

Lord Kixdemp25-Sep-06 15:02

25-Sep-06 15:02

Oohh... So remove all the canRespond stuff? I made the loop like this, but it still runs slower on the 1.4GHz: Frown | :(

void Loop()
{
    while (On)
    {
        Render();

        // Sleep a bit so we don't use 100% CPU
        Thread.Sleep(10);
    }

    Quit(null, null);
}

Just in case, here's my Render() methamphetamethod ( Laugh | :laugh:

void Render()
{
    if (lKey) mainPlayer.Pos.X -= (int)Game.WALK_SPEED;
    if (rKey) mainPlayer.Pos.X += (int)Game.WALK_SPEED;
    if (uKey) mainPlayer.Pos.Y -= (int)Game.WALK_SPEED;
    if (dKey) mainPlayer.Pos.Y += (int)Game.WALK_SPEED;

    // Check out-of-bounds for x-axis
    if (mainPlayer.Pos.X < 0)
        mainPlayer.Pos.X = 0;
    else if (mainPlayer.Pos.X > Game.SCR_WIDTH - Game.TILE_WIDTH - 1)
        mainPlayer.Pos.X = Game.SCR_WIDTH - Game.TILE_WIDTH - 1;

    // Check out-of-bounds for y-axis
    if (mainPlayer.Pos.Y < 0)
        mainPlayer.Pos.Y = 0;
    else if (mainPlayer.Pos.Y > Game.SCR_HEIGHT - Game.TILE_HEIGHT - 1)
        mainPlayer.Pos.Y = Game.SCR_HEIGHT - Game.TILE_HEIGHT - 1;

    // Place player
    Video.Screen.Blit(mainPlayer.Surf, mainPlayer.Pos);

    // Update whole screen
    Video.Screen.Update();

    return;
}

I read this page about timers:
http://msdn.microsoft.com/coding4fun/gamedevelopment/beginning/default.aspx
And it's what I was doing, but it only shows 3 lines of what's supposed to be longer... Frown | :(

Anything wrong with Render() or something? Thanks! Wink | ;)

Windows Calculator told me I will die at 28. Frown | :(

Nader Elshehabi25-Sep-06 15:31

25-Sep-06 15:31

Well, I don't understand much of the code as it's a library that I haven't worked with. Yet about the timer issue and about the processing speed you can make something like a speed factor. Make a few statements, say a while loop that makes a small computation. Now make a long variable that will take the DateTime.Ticks before excuting the loops, and another one after excuting that loop. Take the excution speed as the speed factor of your machine and determine the sleep interval of each target machine dynamically at runtime using the speed factor of each machine. I hope I make sense here!! Big Grin | :-D

To sum up.
1- Make the loop to work best on your computer.
2- Take the SpeedFactor of you computer and the sleep interval as default values in the code.
3- Make that dummy speed test loop -with any statments-, to test the speed of excution.
4- Depending on the SpeedFactor at runtime the sleep interval should be changed -along with any other time dependant factor-.

I hope that worked.

Regards

Lord Kixdemp26-Sep-06 14:55

26-Sep-06 14:55

Erm... Am I on those dreams that incoherent things happen, or is this supposed to work? OMG | :OMG:

void Loop()
{
    while (On)
    {
        Render();

        Thread.Sleep(1000/20);
    }

    Quit(null, null);
}

It... works... He moves at the same speed on both comps! How could it be so simple? D'Oh! | :doh:

Thanks!

Windows Calculator told me I will die at 28. Frown | :(

Christian Graus24-Sep-06 15:12

Christian Graus

24-Sep-06 15:12

Lord Kixdemp wrote:
But now in C# they have events, so I can't do that...

Why can't you ?

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

Lord Kixdemp24-Sep-06 15:17

24-Sep-06 15:17

Because SDL.NET uses C# events rather than switch statement events, like the C++ version of SDL... So I can't have one function to do all my event handling, instead I have one for each C# event:

Events.KeyboardDown += new KeyboardEventHandler(this.OnKeyboardDown);

Thanks! Wink | ;)

(PS: Oh, you hang out here in C# too? You do live here after all... Laugh | :laugh:

)

Windows Calculator told me I will die at 28. Frown | :(

Christian Graus24-Sep-06 15:29

Christian Graus

24-Sep-06 15:29

But I don't see any events being handled here ? A game rendering loop looks like this precisely so that it renders as many FPS as the processor can handle.

You can handle the WndProc in .NET if you want to. You can also set event handlers on your window which store the result for your main rendering loop, or call that loop.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

Lord Kixdemp25-Sep-06 8:14

Re: add column to dataset

25-Sep-06 8:14

Yeah... I want it to render as fast as it can, but not the input... Like, I want to make it so that if I hold the Left key pressed on 2 computers, I want it to get to the left side at the same time, but it doesn't... On C++ I had the input on the same loop as the rendering, so it only read the input if (while) accumulator >= dt, but now the events loop is handled by C#... Frown | :(

You see what I mean? Thanks! Wink | ;)

Windows Calculator told me I will die at 28. Frown | :(

add column to dataset

Mohammed Elkholy24-Sep-06 10:39

Mohammed Elkholy

24-Sep-06 10:39

i have a dataset it includes one table ,i would like to add a computed column in this table to calculate 2 fields

thanks for help

MD_NADA

Nader Elshehabi24-Sep-06 12:08

Re: extracting a message value from LParam in Message in WndProc(...)

24-Sep-06 12:08

Hello

md_nada wrote:
i would like to add a computed column in this table

Use DataTable.Columns.Add() method to add columns to your DataTable.

md_nada wrote:
to calculate 2 fields

What do you mean by fields? Maybe you mean the values in another two columns of the same row like MyColumn = Column1 + Column2?

Regards

[Message Deleted]

code_wiz24-Sep-06 8:06

code_wiz

24-Sep-06 8:06

[Message Deleted]

Christian Graus24-Sep-06 11:58

Christian Graus

24-Sep-06 11:58

Sounds like the LPARAM contains two values. The way to get the part you want is to use LOWORD and HIWORD.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

Re: extracting a message value from LParam in Message in WndProc(...)

Nader Elshehabi24-Sep-06 12:04