libGDX InputProcessor：如何为每个android touch创建一个新对象？

Question

Within the libGDX InputProcessor's touchDown() I am developing a way to create a new TouchPoint rectangle object per screen touch.

I have tried put a constraint on the maximum number of TouchPoint rectangles creatable to two; I only need to work with two screen touches. Each unique object should be updated to its new screen touch location within touchDragged(), then deleted on touchUp().

I have successfully been able to create the desired result for single touches, but not for multiple screen touches. For the second concurrent touch, the TouchPoint rectangle object disappears from the first touch, then shows at the second touch location. Upon touchUp() of the second touch, the object reappears at the touch location of the first touch.

1. Which piece of code logic contains the error?

2. How do I fix it?

    /*experiment*/ public Vector3 tps[] = new Vector3[2]; /*experiment*/ @Override public boolean touchDown(int screenX, int screenY, int pointer, int button) { /*experiment*/ if(pointer < 2){ if(pointer == 0) { Vector3 touchPosition1 = new Vector3(); tps[pointer] = touchPosition1; tps[pointer].set(screenX, screenY, 0); gameScreen.getWorldRenderer().getCamera().unproject(tps[pointer]); touchPoint1 = new TouchPoint(52, 52, new Vector2(tps[pointer].x - 26, tps[pointer].y - 26)); gameScreen.getWorld().getTouchPoints().add(touchPoint1); Gdx.app.log("TOUCH DOWN", "pointer: " + pointer + " x: " + tps[pointer].x + " y: " + tps[pointer].y); } if(pointer == 1) { Vector3 touchPosition2 = new Vector3(); tps[pointer] = touchPosition2; tps[pointer].set(screenX, screenY, 0); gameScreen.getWorldRenderer().getCamera().unproject(tps[pointer]); touchPoint2 = new TouchPoint(52, 52, new Vector2(tps[pointer].x - 26, tps[pointer].y - 26)); gameScreen.getWorld().getTouchPoints().add(touchPoint2); Gdx.app.log("TOUCH DOWN", "pointer: " + pointer + " x: " + tps[pointer].x + " y: " + tps[pointer].y); } } return false; } @Override public boolean touchUp(int screenX, int screenY, int pointer, int button) { /*experiment*/ gameScreen.getWorld().getTouchPoints().removeIndex(pointer); //note: dispose of unused vector3 objects //note: dispose of all other unused objects /*experiment*/ return false; } @Override public boolean touchDragged(int screenX, int screenY, int pointer) { /*experiment*/ tps[pointer].set(screenX, screenY, 0); gameScreen.getWorldRenderer().getCamera().unproject(tps[pointer]); for(TouchPoint tp: gameScreen.getWorld().getTouchPoints()) { tp.moveRectangleToPosition(new Vector2(tps[pointer].x - 26, tps[pointer].y - 26)); tp.updateRectangleBoundaries(); } Gdx.app.log("TOUCH DRAGGING", "pointer: " + pointer + " x: " + tps[pointer].x + " y: " + tps[pointer].y); /*experiment*/ } 

Furthermore, the program crashes if a third screen touch occurs.
LogCat:

08-27 14:08:31.808: W/dalvikvm(9988): threadid=11: thread exiting with uncaught exception (group=0x41711438)
08-27 14:08:31.808: E/AndroidRuntime(9988): FATAL EXCEPTION: GLThread 40874
08-27 14:08:31.808: E/AndroidRuntime(9988): java.lang.IndexOutOfBoundsException: 2
08-27 14:08:31.808: E/AndroidRuntime(9988):     at com.badlogic.gdx.utils.Array.removeIndex(Array.java:229)
08-27 14:08:31.808: E/AndroidRuntime(9988):     at com.manytouches.controller.InputHandler.touchUp(InputHandler.java:104)

Thanks for your time.

Answer 1

Apply the check

If(pointer<2) .....

At touchup and touch dragged as well... You are getting exception at touch up event

Also you be using arraylist for touchpoints so when you add touchpoint on touch down it add the objects at the last of the list so this may because of this... So create a array of touchpoints at your screen instead of array list

You can make the code generic instead of using if pointer==1 or ==0 what you can do is create a array of touchpoint at inputprocessor and assign the value as Touchpoint[pointer].set(x,y,z) this will make code more readable as you are doing same things at both the conditions..