Android Can't get two virtual joysticks to move independently but at the same time

Question

   @Override
    public boolean onTouch(View v, MotionEvent event) {
        // TODO Auto-generated method stub

        float r = 70;
        float centerLx = (float) (screenWidth*.3425);
        float centerLy = (float) (screenHeight*.4958);
        float centerRx = (float) (screenWidth*.6538);
        float centerRy = (float) (screenHeight*.4917);
        float dx = 0;
        float dy = 0;
        float theta;
        float c;

        int action = event.getAction(); 
        int actionCode = action & MotionEvent.ACTION_MASK; 
        int pid = (action & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
        int fingerid = event.getPointerId(pid);
        int x = (int) event.getX(pid);
        int y = (int) event.getY(pid);




            c = FloatMath.sqrt(dx*dx + dy*dy);
            theta = (float) Math.atan(Math.abs(dy/dx));


            switch (actionCode) {
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_POINTER_DOWN:

                //if touching down on left stick, set leftstick ID to this fingerid.                                                             
                if(x < screenWidth/2 && c<r*.8) {
                    lsId = fingerid;
                                    dx = x-centerLx;
                        dy = y-centerLy;
                    touchingLs = true;
                }
                else if(x > screenWidth/2 && c<r*.8) {
                    rsId = fingerid;
                                    dx = x-centerRx;
                                    dy = y-centerRy;
                    touchingRs = true;
                }



                    break;
            case MotionEvent.ACTION_MOVE:


            if (touchingLs && fingerid == lsId) { 
                dx = x - centerLx;
                dy = y - centerLy;
            }else if (touchingRs && fingerid == rsId) { 
                dx = x - centerRx;
                dy = y - centerRy;
            }


                c = FloatMath.sqrt(dx*dx + dy*dy);
                theta = (float) Math.atan(Math.abs(dy/dx));


                //if touching outside left radius and moving left stick
                if(c >= r && touchingLs && fingerid == lsId) {
                    if(dx>0 && dy<0) { //top right quadrant
                        lsX = r * FloatMath.cos(theta);
                        lsY = -(r * FloatMath.sin(theta));
                        Log.i("message", "top right");
                    }

                    if(dx<0 && dy<0) { //top left quadrant
                        lsX = -(r * FloatMath.cos(theta));
                        lsY = -(r * FloatMath.sin(theta));
                        Log.i("message", "top left");
                    }

                    if(dx<0 && dy>0) { //bottom left quadrant
                        lsX = -(r * FloatMath.cos(theta));
                        lsY = r * FloatMath.sin(theta);
                        Log.i("message", "bottom left");
                    }


                    else if(dx > 0 && dy > 0){ //bottom right quadrant
                        lsX = r * FloatMath.cos(theta);
                        lsY = r * FloatMath.sin(theta);
                        Log.i("message", "bottom right");
                    }


                }
                if(c >= r && touchingRs && fingerid == rsId) {
                    if(dx>0 && dy<0) { //top right quadrant
                        rsX = r * FloatMath.cos(theta);
                        rsY = -(r * FloatMath.sin(theta));
                        Log.i("message", "top right");
                    }
                    if(dx<0 && dy<0) { //top left quadrant
                        rsX = -(r * FloatMath.cos(theta));
                        rsY = -(r * FloatMath.sin(theta));
                        Log.i("message", "top left");
                    }
                    if(dx<0 && dy>0) { //bottom left quadrant
                        rsX = -(r * FloatMath.cos(theta));
                        rsY = r * FloatMath.sin(theta);
                        Log.i("message", "bottom left");
                    }
                    else if(dx > 0 && dy > 0) {
                        rsX = r * FloatMath.cos(theta);
                        rsY = r * FloatMath.sin(theta);
                        Log.i("message", "bottom right");
                    }
                }
                else {
                    if(c < r && touchingLs && fingerid == lsId) {
                        lsX = dx;
                        lsY = dy;
                    }
                    if(c < r && touchingRs && fingerid == rsId){
                        rsX = dx;
                        rsY = dy;
                    }

                } 

                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_POINTER_UP:

            if (fingerid == lsId) { 
                lsId = -1;
                lsX = 0;
                lsY = 0;
                touchingLs = false;
            } else if (fingerid == rsId) { 
                rsId = -1;
                rsX = 0;
                rsY = 0;
                touchingRs = false;
            }


                break;
            }



        return true;
    }

There's a left joystick and a right joystick. Right now only one will move at a time. If someone could set me on the right track I would be incredibly grateful cause I've been having nightmares about this problem.

score 1 · Answer 1 · answered Oct 24 '13 at 20:16

The main problem I see is that you're only handling one pointer when you receive an ACTION_MOVE. Android will often batch multiple events into one MotionEvent, so unless you update both pointers, you won't be able to make both move at once.

Forget about the way you're currently using fingerId. When you get an ACTION_MOVE, get the x/y for both pointers and use them. Something like:

case ACTION_MOVE:
    int x;
    int y;

    int leftIndex = event.findPointerIndex(lsId);
    x = (int)event.getX(leftIndex);
    y = (int)event.getY(leftIndex);
    /// ... do stuff with left coordinates
    ...
    int rightIndex = event.findPointerIndex(rsId);
    x = (int)event.getX(rightIndex);
    y = (int)event.getY(rightIndex);
    /// ... do stuff with right coordinates
    ...
    break;

Android Can't get two virtual joysticks to move independently but at the same time

1 Answers1