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TheCompBoy

[JAVA]Explosion animation problem

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TheCompBoy    120
Hello guys!
I've been looking on the internet now after i tried myself for 2 hours without any succes, I tryed with loops i tried with timers.. Nothing worked for me..

My problem is when you kill a monster in my game i whant the to explode.. And for that i need like 5 different pictures but i don't know how to make it like show picture 1 then sleep then show picture 2 then sleep and so on.. Cus if i just write

[code]
if(health <= 0){
setGraphic(explosion);
setGraphic(explosion2);
setGraphic(explosion3);
setGraphic(explosion4);
setGraphic(explosion5);
this.destroy();
}[/code]

then the pictures will show so fast that the user wont even see that it changes picture..

Please help me! Or show me where i can read about the problem.
Thanks!

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beatlefan    198
Well a simplish solution is to add a 'timeTillNextFrame' float variable to your class. Then every time your update function is called just minus the time since the last update from your 'timeTillNextFrame'. Then if it is less than or equal to zero change your explosion sprite.

Also, timeTillNextFrame should be measured in milliseconds.

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TheCompBoy    120
Am not sure im understanding 100% what you mean.. What i whant to do is something like this:

[code]
if(health <= 0){
setGraphic(explosion);
sleep(500);
setGraphic(explosion2);
sleep(500);
setGraphic(explosion3);
sleep(500);
setGraphic(explosion4);
sleep(500);
setGraphic(explosion5);
sleep(500);
this.destroy();
}[/code]

But i need something else like a timer instead of the sleep.. And i need some help to do it.. Or how i should do it.

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beatlefan    198
Well what I told you was kinda a timer. I forgot that Java has timers, so you could use Java's timers, it wouldn't be as efficient because I think it makes a new thread...

This is what I was talking about, it's in C# and XNA, but hopefully you can convert.

[code]

public void Update(GameTime gameTime)
{
timeTillNextFrame -= ((float)gameTime.ElapsedGameTime.Milliseconds / 1000f); // converts milliseconds to seconds

if ( !done && timeTillNextFrame <= 0) // If its time to change the picture
{
currentFrame++;
if (currentFrame > maxFrames)
done = true;

SetGraphic(picture[currentFrame]); // This is where you would change your picture

timeTillNextFrame = 1f; // I set it to 1 so that the picture changes once every second
}

}
[/code] Edited by beatlefan

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beatlefan    198
[quote name='TheCompBoy' timestamp='1311377670' post='4839147']
Bump
[/quote]

Why didn't you try what I did, it works fine.

Perhaps you can't figure out how to calculate the time that has past?

Try this:
[code]

private long lastTime, currentTime;
public void Update()
{
lastTime = currentTime;
currentTime = System.currentTimeMillis();

timeTillNextUpdate -= ( (currentTime - lastTime) / 1000f); // divide by a thousand to make it into seconds (unless game is updating slowly, it will probably be a fraction of a second)

// then just do what I posted in my last post
}
[/code]

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beatlefan    198
[quote name='TheCompBoy' timestamp='1311378842' post='4839151']
I will try.. But there is nothing in the java that you created with the update metod "GameTime gametime"
[/quote]


That's why I said it was in XNA...

[quote name='TheCompBoy' timestamp='1311378842' post='4839151']
[color=#1C2837][size=2]EDIT: Didn't realy work..[/size][/color]
[/quote]

hmm... Well it should, can you post your code?

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TheCompBoy    120
Where i commented Thread.sleep thats were i need the application to sleep without using the "Sleep" because that freezes the whole application.

[code] public void collisionResponse(Entity e){
health = health - 50;
if(health <= 0){
graphic = 1;
if(graphic == 1){
setGraphic(explosion);
//Thread.sleep(500);
graphic++;
}
if(graphic == 2){
setGraphic(explosion2);
//Thread.sleep(500);
graphic++;
}
if(graphic == 3){
setGraphic(explosion3);
//Thread.sleep(500);
graphic++;
}
if(graphic == 4){
setGraphic(explosion4);
//Thread.sleep(500);
graphic++;
}
if(graphic == 5){
setGraphic(explosion5);
//Thread.sleep(500);
this.destroy();
graphic = 0;
}
}
}[/code]

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beatlefan    198
Well you should make a boolean called Dead, and when health is less than or equal to zero, Dead = true. Then in your Update function have:

[code]
if(Dead)
{
//then implement the update function I wrote
}
[/code]
That's mostly all you have to do. Also when you go to check for collision stuff, you would probably want to check if Dead equals false, and if it does continue checking if there is a collision (you would do this so a bullet, or something, wouldn't do damage to something that's already dead).

If you still can't get that to work you can use timers.

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TheCompBoy, what you are facing is a common problem that people face when new-ish to programming. Once you get it, though, it'll make perfect sense.

Every frame, your object is updated, right?
So when it dies, give it a variable called something like 'isDead'... but don't delete it yet!
At the same time, give it a variable called 'timeOfDeath' and set it to the current time.

Then every time you update it, check if enough time has passed, and then change the graphic.

Look at this update function: (It's in fake code, and you can easily figure out how to convert it to Java)
[code]Update
{
if(isDead == false)
{
setGraphic(normal)
}
else
{
amountOfTimePassedSinceDeath = currentTime - timeOfDeath;

if(amountOfTimePassedSinceDeath > 2.5 seconds)
deleteObject
else if(amountOfTimePassedSinceDeath > 2.0)
setGraphic(explosion5);
else if(amountOfTimePassedSinceDeath > 1.5)
setGraphic(explosion4);
else if(amountOfTimePassedSinceDeath > 1.0)
setGraphic(explosion3);
else if(amountOfTimePassedSinceDeath > 0.5)
setGraphic(explosion2);
else
setGraphic(explosion1);
}
}[/code]

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TheCompBoy    120
Alright.. Still im getting some errors from beatlefan's posts since there is no such thing as GameTime in the java library plus i don't realy know what to replace it with.

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beatlefan    198
[quote name='TheCompBoy' timestamp='1311382153' post='4839169']
Alright.. Still im getting some errors from beatlefan's posts since there is no such thing as GameTime in the java library plus i don't realy know what to replace it with.
[/quote]

I told you what to do a couple posts up...

[quote name='beatlefan']
[code]
private long lastTime, currentTime;
public void Update()
{
lastTime = currentTime;
currentTime = System.currentTimeMillis();

timeTillNextUpdate -= ( (currentTime - lastTime) / 1000f); // divide by a thousand to make it into seconds (unless game is updating slowly, it will probably be a fraction of a second)

// then just do what I posted in my last post
}
[/code]
[/quote]

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TheCompBoy    120
[quote name='beatlefan' timestamp='1311382760' post='4839172']
[quote name='TheCompBoy' timestamp='1311382153' post='4839169']
Alright.. Still im getting some errors from beatlefan's posts since there is no such thing as GameTime in the java library plus i don't realy know what to replace it with.
[/quote]

I told you what to do a couple posts up...

[quote name='beatlefan']
[code]
private long lastTime, currentTime;
public void Update()
{
lastTime = currentTime;
currentTime = System.currentTimeMillis();

timeTillNextUpdate -= ( (currentTime - lastTime) / 1000f); // divide by a thousand to make it into seconds (unless game is updating slowly, it will probably be a fraction of a second)

// then just do what I posted in my last post
}
[/code]
[/quote]
[/quote]

Exacyly but in your code it says: // then just do what I posted in my last post
And thats why i added what you posted before also..

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beatlefan    198
[quote name='TheCompBoy' timestamp='1311382856' post='4839173']
Exacyly but in your code it says: // then just do what I posted in my last post
And thats why i added what you posted before also..
[/quote]


???

Well the code should be something like:
[code]
bool done = false;

private long lastTime, currentTime;
private float timeTillNextUpdate = 1f;
public void Update()
{
if(Dead)
{
lastTime = currentTime;
currentTime = System.currentTimeMillis();

timeTillNextUpdate -= ( (currentTime - lastTime) / 1000f);


if ( !done && timeTillNextFrame <= 0)
{
currentFrame++;
if (currentFrame > maxFrames)
done = true;

SetGraphic(picture[currentFrame]);

timeTillNextFrame = 1f;
}
}
}
[/code]

or you could do something similar to Servant of the Lord's code


[code]

private long timeOfDeath, currentTime;
private float amountOfTimePassedSinceDeath;
public void Update()
{

if(isDead == false)
{
setGraphic(normal)
}
else
{
currentTime = System.currentTimeMillis();
amountOfTimePassedSinceDeath = ( (currentTime - timeOfDeath) / 1000f);

if(amountOfTimePassedSinceDeath > 2.5)
deathAnimationDone = true;
else if(amountOfTimePassedSinceDeath > 2.0)
SetGraphic(explosion5);
else if(amountOfTimePassedSinceDeath > 1.5)
SetGraphic(explosion4);
else if(amountOfTimePassedSinceDeath > 1.0)
SetGraphic(explosion3);
else if(amountOfTimePassedSinceDeath > 0.5)
SetGraphic(explosion2);
else
SetGraphic(explosion1);
}
}
[/code] Edited by beatlefan

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TheCompBoy    120
This is what i did.. And doesn't work at all.. Not showing any of the sprites.
[code]
public void collisionResponse(Entity exe){
health = health - 50;
if(health <= 0){
isDead = true;

if(isDead){
currentTime = System.currentTimeMillis();
amountOfTimePassedSinceDeath = ( (currentTime - timeOfDeath));

if(amountOfTimePassedSinceDeath > 2500)
deathAnimationDone = true;
else if(amountOfTimePassedSinceDeath > 2000)
setGraphic(explosion5);
else if(amountOfTimePassedSinceDeath > 1500)
setGraphic(explosion4);
else if(amountOfTimePassedSinceDeath > 1000)
setGraphic(explosion3);
else if(amountOfTimePassedSinceDeath > 500)
setGraphic(explosion2);
else
setGraphic(explosion);

}

if(deathAnimationDone){
this.destroy();
}
}
}[/code]

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beatlefan    198
Well that's cause you have to put everything after 'isDead = true' into an Update function that should be called before you draw everything, because no time (except maybe 1 or 2 milliseconds) will past in your collisionResponse function so the graphic won't change.

Also, make sure you set timeOfDeath.

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bloodisblue    137
[quote name='TheCompBoy' timestamp='1311384361' post='4839178']
This is what i did.. And doesn't work at all.. Not showing any of the sprites.
[code]
public void collisionResponse(Entity exe){
health = health - 50;
if(health <= 0){
isDead = true;
}

if(isDead){
currentTime = System.currentTimeMillis();
amountOfTimePassedSinceDeath = ( (currentTime - timeOfDeath));

if(amountOfTimePassedSinceDeath > 2500)
deathAnimationDone = true;
else if(amountOfTimePassedSinceDeath > 2000)
setGraphic(explosion5);
else if(amountOfTimePassedSinceDeath > 1500)
setGraphic(explosion4);
else if(amountOfTimePassedSinceDeath > 1000)
setGraphic(explosion3);
else if(amountOfTimePassedSinceDeath > 500)
setGraphic(explosion2);
else
setGraphic(explosion);

}



if(deathAnimationDone){
this.destroy();
}
}[/code]
[/quote]

You misplaced the this.destroy();, it will never reach it where you had it. Also the brackets were placed kind of weirdly so I fixed that. I have the feeling that the problem may lie in the update method more so then this method because everything you have written is correct. Make sure that when the thing dies you make sure to set timeOfDeath = System.currentTimeMillis(); otherwise you wouldn't get anything.

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That code shouldn't be in a 'collision response' function. It should be in a 'update' or 'tick' function that runs every frame.

This goes is in your collision response function:
[code]
public void collisionResponse(Entity exe){
health = health - 50;
if(health <= 0){
isDead = true;
timeOfDeath = System.currentTimeMillis();
}
}

[/code]

And [i]this [/i]goes in your 'called every frame' function.
[code]
public void update()
{
if(isDead){
currentTime = System.currentTimeMillis();
amountOfTimePassedSinceDeath = ( (currentTime - timeOfDeath));

if(amountOfTimePassedSinceDeath > 2500)
deathAnimationDone = true;
else if(amountOfTimePassedSinceDeath > 2000)
setGraphic(explosion5);
else if(amountOfTimePassedSinceDeath > 1500)
setGraphic(explosion4);
else if(amountOfTimePassedSinceDeath > 1000)
setGraphic(explosion3);
else if(amountOfTimePassedSinceDeath > 500)
setGraphic(explosion2);
else
setGraphic(explosion);

}

if(deathAnimationDone){
this.destroy();
}
}
}[/code]

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TheCompBoy    120
Oh man!! It realy works now.. Thanks dude!! Thousand thanks! Just gona edit the time now so it looks better :D

Thanks again.. You saved my day, I will now try remember this and try do the same thing but in different ways so i learn from it.

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