How to track elapsed time in Java third-party API "LibGDX"?

Question

I am making a game in which a player ("Bob") moves vertically and continuously collects coins. If a player fails to collect any coins within 5 seconds, “Bob” begins to fall. As time continues to count down, it will fall faster.

My question is: How to track elapsed time in a LibGDX (Java) application?

The following is sample code.

public void update (float deltaTime) { `velocity.add(accel.x * deltaTime,accel.y*deltaTime);` position.add(velocity.x * deltaTime, velocity.y * deltaTime); bounds.x = position.x - bounds.width / 2; bounds.y = position.y - bounds.height / 2; if (velocity.y > 0 && state == BOB_COLLECT_COINE) { if (state== BOB_STATE_JUMP) { state = BOB_STATE_Increase; stateTime = 0; } else { if(state != BOB_STATE_JUMP) { state = BOB_STATE_JUMP;//BOB_STATE_JUMP stateTime = 0; } } } if (velocity.y < 0 && state != BOB_COLLECT_COINE) { if (state != BOB_STATE_FALL) { state = BOB_STATE_FALL; stateTime = 0; } } if (position.x < 0) position.x = World.WORLD_WIDTH; if (position.x > World.WORLD_WIDTH) position.x = 0; stateTime += deltaTime; } public void hitSquirrel () { velocity.set(0, 0); state = BOB_COLLECT_COINE;s stateTime = 0; } public void collectCoine() { state = BOB_COLLECT_COINE; velocity.y = BOB_JUMP_VELOCITY *1.5f; stateTime = 0; } 

and call the collectmethod method in the World class in upate Bob as -

  private void updateBob(float deltaTime, float accelX) { diff = collidetime-System.currentTimeMillis(); if (bob.state != Bob.BOB_COLLECT_COINE && diff>2000) //bob.position.y <= 0.5f) { bob.hitSquirrel(); } 

Answer 1

Having seen how many views there are in this answer, I must point out the problem with the accepted answer and provide an alternative solution.

Your “timer” will slowly drift longer than you run the program due to rounding caused by the following line of code:

 time = 0; 

The reason is the if condition, if the time value is greater than or equal to 5 (it is very likely that it will be longer due to rounding errors, and the time between frames can change). A more reliable solution is not to "reset" the time, but to subtract the timeout:

 private static final float WAIT_TIME = 5f; float time = 0; public void update(float deltaTime) { time += deltaTime; if (time >= WAIT_TIME) { // TODO: Perform your action here // Reset timer (not set to 0) time -= WAIT_TIME; } } 

You probably won’t notice this subtle problem during quick tests, but run the application in a couple of minutes, you can start to notice it if you carefully look at the time of events.

Answer 2

I did it like this:

 float time=0; public void update(deltaTime){ time += deltaTime; if(time >= 5){ //Do whatever u want to do after 5 seconds time = 0; //i reset the time to 0 } } 

Answer 3

You tried to use Gdx.graphics.getElapsedTime()
(not necessarily with the exact function name)

The method, as in assembly 0.9.7, is "Gdx.graphics.getDeltaTime ()", so the above sentence is absolutely in place.

Answer 4

it

 float time = 0; //in update/render time += Gdx.app.getGraphics().getDeltaTime(); if(time >=5) { //do your stuff here Gdx.app.log("timer ", "after 5 sec :>"); time = 0; //reset }