How to make a similar animation to Flappy Bird in Libgdx? - java

I'm creating a game like flappy bird where the bird flaps his wings only when the screen is touched, but I'm having a problem activating the animation when the screen is touched.
batch.draw(animation.getKeyFrame(myTimeState, false), x, y); //the myTimeState is 0 to render the 1st frame only.
Then when the screen is touched I do this:
//myTimeStep is just basically a controllable timeState for the animation only
if(Gdx.input.justTouched){
myTimeState = timeState;
}else if(Gdx.input.justTouched == false && animation.isAnimationFinished(timeState)){
myTimeState = 0;
}
I don't think the animation is able to play all the frames because myTimeStep become 0 immediately after finishing to touch the screen. Also I don't think this is the right way of doing it, if you guys have better ideas or solution please help. Thanks in advance.

There are probably several ways to achieve this. You'll need to increment your timeState, of course, and also it depends how long your animation is and if you want it to loop.
If you've created your animation to play only once, and then stop (until the screen is touched again), you could simply set your myTimeState to 0 when the screen is touched, and then increment it every frame. The animation will run through and then "stop" on its own when it reaches the end (as you said no loop). The next time someone touches the screen, your myTimeState is set back to 0 and the animation starts again.

Firstly, you have to ensure your animation's playmode is set to Animation.PlayMode.NORMAL. It's a default setting, but if you set it somewhere to LOOPED, nothing would work as expected.
Secondly, I wouldn't use Input.justTouched() in this case. Instead, a listener in your input processor would be a great fit. Here's an example with Stage. If you have no idea what input processor is, here's tutorial on event handling and class documentation.
stage.addListener(new ClickListener() {
#Override
public boolean touchDown(InputEvent event, float x, float y, int pointer, int button) {
if(button == Input.Buttons.LEFT) {
timeState = 0;
}
return super.touchDown(event, x, y, pointer, button);
}
});
You can pick what's going to be displayed (animation's keyframe or sprite) based on result of animation.isAnimationFinished()
if(animation.isAnimationFinished(timeState)) {
//draw some sprite
} else {
//draw animation keyframe
}
I haven't checked it but there's a possibility, that this could lead to the last frame being cut out, because as soon as it gets displayed, animation.isAnimationFinished() will return true. I may be wrong, so you'll have to check it. If it becomes an issue, you can add your sprite as the last frame of your animation. When animation ends, it frezzes on the last frame, which would be your static sprite.
In both cases you'll get your animation played at the beginning of game because timeStep equal to 0. I see 2 solutions, I advise you to take the second:
Set timeStep to a large number, that is for sure larger than your animation's duration. Animation.isAnimationFinished() will then return true.
Introduce boolean variable isAnimationPlayed that:
is initialized with false,
gets set to true in your click listener,
gets set to false during isAnimationFinished(), which is called each frame only when isAnimationPlayed is true,
is used in draw() method to determine what to display.

You could just set your timeState to the duration of the animation.

Related

what is stopping my screen from rendering as planned?

#Override
public void render(float delta) {
Gdx.gl.glClearColor(0,0,0,1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
combattext.setText(combatstring);
stage.act();
stage.draw();
}
combatstring is a string that displays what happened in my game. when enemies attacks, it says what happened. when I attack, it says what happens. As of now my game has a loop when in combat that runs a turncounting instance. When it's time for a turn, it runs that participants turn, and when their turn is over it updates combatstring.
I have 2 combatstrings. One is for my characters, and one is for enemies. Here is an example of what happens when it's an enemies turn.
if(thisencounter.monster1turn){ //monster1's turn goes in here
thiscombat.getTarget(1); //get enemy's target
thiscombat.calculateVars(1); //calculate all combat variables for
// this turn
thiscombat.theyAttack();
combatstring = thisencounter.thisenemy.species+
" "+thiscombat.action+
" "+thiscombat.theirtarget.species+
" for "+thiscombat.effect;
thisencounter.monster1turn=false;
}
This works fine, my combattext label updates instantly when a monster goes.
For my characters, their turns make buttons visible on my screen. The buttons have listeners that determine actions, here is an example:
monster1.addListener(new ClickListener(){ //makes the first enemy's
//image clickable, but only
//when the attack button
//has been clicked
#Override
public void clicked(InputEvent event, float x, float y) {
thiscombat.ChooseTarget(1); //various methods that calculate damage,
//output what happened, and put us back in
thiscombat.calculateVars(4); //the loop to wait for next
//participant's turn
thiscombat.youAttack();
combatstring = thisencounter.thisspirit.species+
" "+thiscombat.action+
" "+thiscombat.yourtarget.species+
" for "+thiscombat.effect;
monster1.clear();
monster2.clear();
monster3.clear();
try {
combatloop();
} catch (InterruptedException ex) {
Logger.getLogger(map1field.class.getName()).
log(Level.SEVERE, null, ex);
}
}});
This also works fine, EXCEPT on the turn just before a monster goes. Since there is no wait between my turn and the monster's turn, the combattext just instantly displays what the monster does.
I assumed 'oh hey this is because there is no delay between the two turns'. So, I threw a thread.sleep(2000) just before where it updates the monsters combatstring.
But that does not fix it. It still does not show the text for my character that goes just before a monster. Also, since fighting starts right when you go to this screen in the game, it waits about 2 seconds before it displays anything on the screen.
For the life of me I don't understand why it behaves like this. Can someone explain what is happening to me? Is it because it isn't rendering before it gets to thread.sleep ?
If that's the case, how do I force it to render before it does thread.sleep, or what should I be using instead of thread.sleep ?

scrolling never-ending background in Game not working as expected

I am working on my first side-scroller game and am trying to achieve a neverending background effect and it's nearly working as i would expect but there are little glitches.
I have 2 instances of the background (each fills the screen width), with one placed at the bottom left corner of the screen and one off the screen to the right. I am then moving my camera each frame to the right and when the first background instance is completely offscreen to the left i reset its X to the right of the camera so that it is now (relative to the camera) off the right of the screen. this is working a lot of the time, but every now and again it seems the method to reset its x position is getting called a few frames late and results in a gap in the background.
the update code i am using in the main game is -
private void update(float delta){
//update camera and world
camera.position.set(camera.position.x+scrollSpeed, camera.position.y, 0);
camera.update();
world.step(step, velocityIterations, positionIterations);
if(gameInProgress){
//backgrounds (array holds the 2 instances of the background)
for(int i=0; i< bgFillArray.size; i++){
bgFillArray.get(i).update();
}
}
stage.act(delta);
tweenManager.update(delta);
}
the update method in the BgFill class -
public void update(){
float currentXPos = getX();
float leftBoundary = camera.position.x-1200;
float rightOfScreen = camera.position.x+400;
if(active){
//check to see if the camera has gone past this instance. if so then move to right
if(currentXPos <= leftBoundary){
setX(rightOfScreen);
}
}
}
Firstly, is this the usual way (or even close) to do a continuous scrolling background?
if it is, what am I doing wrong?

Create Java 2D gravity?

I'm creating java game (I'm a beginner with this for now) and I'd like to start with some kind of platform game.
I'd like to know how I can make the player jump (I know how to move him up and down), but I don't know how how to make him go back down after going up.
Here is my code:
public void keyPress() {
if (listener.arrowUp) {
Jump();
}
}
private void Jump() {
if(player.get(1).getPosY() > maxJump) {
player.get(1).moveY(-10);
} else if(player.get(1).getPosY() == maxJump) {
player.get(1).moveY(85);
}
}
So.. the player moves -10px upwards as long as i press 'w' and when he hits maxJump (which is 375 and players position at the start is 465) he "teleports" back to 465 instead of sliding back down like he does when going up.. It's really hard to explain this without a video, but i hope somebody understands and can help me with this.
This question gives a basic answer to yours. Now in your jump function, you have to set the vertical_speed only once and only call fall() every frame and add some moveY.
Here are two alternatives:
Option 1. Simulating some very simple physics. You add forces to your player, so pressing the up arrow will add a force that makes the player move upwards. Gravity is constantly applied and thus it will gradually cancel out the force you applied when the up arrow was pressed. Perhaps you only want to use forces in the vertical direction you do something like this:
// Each frame
if(notOnTheGround){
verticalVelocity -= GRAVITATIONAL_CONSTANT;
}
// When user jumps
vertivalVelocity += JUMP_FORCE;
Option 2. An alternative is to kind of animate the jumps using projectile motion.
// Each frame
if(isJumping){
verticalVelocity = initialVelocity*sin(angle) - g*animationTime;
animationTime += TIME_STEP;
}
// When user jumps
isJumping = true;
animationTime = 0;
initialVelocity = ... // calculate initial velocity

Java Game Dev: How to put a timer around this code?

I'm making a "space-invaders style" game. You(the player) move left and right at the bottom of the screen. There will be one enemy in each window, and you have to move to the window and shoot.
I'm working on the enemies popping up system. The window in which an enemy is random and should change every 3 seconds. Here's my code for this:
int enemylocation = new Random().nextInt(2) +1;
if(enemylocation==1){
enemy1.setFilter(Image.FILTER_NEAREST);
enemy1.draw(200,170,s*10);
}
if(enemylocation==2){
enemy2.setFilter(Image.FILTER_NEAREST);
enemy2.draw(200,360,s*10);
}
Everything works, but the random number part is always picking a new number, so both windows are flickering. How can I delay the timer to change the value of enemylocation every 3 seconds and not constantly?
Thanks
I'd say the "right" way to do this is to have a game loop that ticks x times per second. You decide to change the value of the enemylocation every x ticks. If you tick 60 times per second, that means 3 seconds will be 60 * 3 = 180. That means you can change the enemylocation when tickNumber % 180 == 0
I am guessing you already have a gameloop with a timer since you are able to render, the flickering comes from enemylocation being set too often so the enemy is rendered all over the place. What I would do is to implement a cooldown. In pseudo-ish code (no IDE):
int enemySpawnRate = 3000;
int timeElapsed = enemySpawnRate+1; //Spawn the first time
void spawnEnemy(int delta) {
timeElapsed +=delta;
if(timeElapsed>enemySpawnRate) {
//spawn enemy as before, your code snippet
timeElapsed=0;
}
}
Where delta is the ammount of time that has passed since the previous run of your gameloop.
Note this depends entirely on you have a timerbased gameloop, if you don't and you are rendering on INPUT (eg render if key pressed) the code will be different, you would have to utilize a timertask or a swingtimer if you are using swing.

Detecting mouse movement for a 3D first person world in Java

I am working on a first person game in Java, and I am trying to get the 3D movement working.
My problem is I would like to capture mouse movement, yet keep the mouse inside the window. After I capture the mouse movement, I figure the best way to keep the mouse in my window is to center the mouse in the window after moving, using Robot.moveMouse(x,y). This works fine, however the movement from the Robot triggers an event in my window which then gets interpreted as a normal event, and thus moves my character in the world.
I've tried various schemes of keeping state and ignoring movements until I am in the center, but they all seem finicky and don't quite detect which events are user vs Robot controlled.
Is there an easy way to detect that a mouse movement came from the Robot?
Is there perhaps a simpler way to solve my problem that I am overlooking?
I solved this by switching to NEWT with JOGL 2.0 RC4. In particular, I use GLWindow and warpPointer instead of an AWT Frame with the Robot.mouseMove. With the switch, I instantly got smooth movements. Some sample code similar to what I'm doing (mileage may vary):
public class MyClass implements MouseListener {
private GLWindow window;
private int centeredX = -1;
private int centeredY = -1;
// ...
public void mouseMoved(MouseEvent e) {
if (centeredX == -1 || centeredY == -1) {
center();
return;
}
int deltaX = e.getX() - centeredX;
int deltaY = e.getY() - centeredY;
// ... Do something with the deltas
centeredX = window.getWidth() / 2;
centeredY = window.getHeight() / 2;
window.warpPointer(centeredX, centeredY);
}
}
Well, I'm not 100% about this, but have you used the getsource() or getComponent() functions on your mouse event? They may return the robot as the source of it. Barring that, I would have a class variable like boolean robotControlling and anytime it takes control of the mouse, set that to true. Then, in you mouseListener, do a if(!robotControlling){...}. Hope this helps.
EDIT: if you have unused mouse buttons in your application (Java has Button 1, Button 2 and Button 3), you could make the robot press that, and in your mouse listener ignore any events with that code pressed. (use evt.getButton() for this) Of course, thats not exactly the cleanest solution :P

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