Simple task question

Scripting Issues
1

Hello

I have a little question about tasks. This is a piece of my code:

def catchInput(task):
            self.accept("escape", sys.exit)
            self.accept('arrow_up', movePandaForward)
            self.accept('arrow_down', movePandaBackward)
            #print task.time
            
            return task.cont
        
       taskMgr.add(catchInput, "keys")

Now, If I press the ‘arrow_up’ button, my panda does move, but only once, I expected that it would keep moving forward. I don’t get it, my ‘catchInput’ doesn’t seem to accept my buttonpress every frame, but only once. Anybody has an idea what I’m doing wrong, what’s happening?

2

Key events only fire once when you press it down. The usual way to do it is to listen for the down event and the up event (arrow_up-up), storing the key state in a variable, and create a movement task that moves it by the speed multiplied by the elapsed time (globalClock.getDt()) to get a correct result.

Don’t put your accept() calls into a task. You should only bind them once.

I would advise you to study the Roaming Ralph sample program, it shows how to deal with this.

3

Indeed I got it working now. Roaming Ralph is a very good sample program!

Only one extra question. Why use the globalClock.getDt() function? Why don’t just do actor.setX(actor.getX + 1) for example?

I don’t realy get what that clock has to do with movement.

Thanks for the answer!

4

The trick with the lobalClock.getDt()is to make the movement independent from the frame rate.

If you’d move the avatar (let’s say he’s in a car) 1 meter every frame then at 30fps he would move at 30 m/s (~108km/h) with a frame rate of 120 fps he’d blazed at 430km/h

5

Oh yes Wezu, you’re so true, that I didn’t even think of that!

Programming with frames is a little different than ‘normal’ programming! Yet quiet interesting, thanks :slight_smile: