Android Animation Question

Question

I am trying to write the logic for an animation sequence and can't seem to get the thing right. What I want to happen is: if the user clicks on the screen, the method takes in the touchEvent coordinates, and then changes the movement variables of a sprite so that the sprite travels to where the user touched the screen. I have my "launch" event setup like this.

 public void launch(float eventX, float eventY) {
    //get the touch event coords and then move the banana to them.
    fire = true;
               //the x and y variables for the sprite
    getX();
    getY();
               //the target x and y variables
    targetX = eventX;
    targetY = eventY;
               //the total distance the two variable have to "travel"
    distanceX = x - targetX;
    distanceY = y - targetY;
               //variables to update the movement
    moveX = distanceX;
    moveY = distanceY;
}

Then, I thought I was supposed to put the movement variables in the update method like this:

 public void update(long gameTime) {
    if(gameTime > frameTicker + framePeriod) {
        frameTicker = gameTime;
        currentFrame++;
        if(currentFrame >= frameNbr){
            currentFrame = 0;

        }
    }
    this.sourceRect.left = currentFrame * spriteWidth;
    this.sourceRect.right = this.sourceRect.left + spriteWidth;
    if(fire == true){
        x = (int) moveX;
        y = (int) moveY;
    }

If the user clicks as it is, the animation shows up like it's supposed to, but then instantaneously goes to the top left corner of the screen or what I have come to understand is (0,0) on a coordinate system. I can't figure out how to slow it down so that it moves at a reasonable space and goes where it is supposed to.

Answer 1

You could put the whole animation in your launch() function if you want.

For instance, at the end of the function something like:

float incrementX = distanceX / 100;
float incrementY = distanceY / 100;
float spriteX = getX();
float spriteY = getY();
bool xDone = false;
bool yDone = false;

while(!(xDone && yDone)) {
  if (distanceX <= spriteX) {
    spriteX += incrementX; // update the sprite's x coordinate as well
  }
  if (distanceY <= spriteY) {
    spriteY += incrementY; // update the sprite's y coordinate as well
  }
  try{ Thread.sleep(10) } catch(Exception e) {}
}

That code relies on the sprite starting at a lower x and y than the event; if that's not the case it needs to be modified.