CODEWITHSUNDEEP
flutterflame
Melissa Worthington
Melissa Worthington

Reputation: 33

Flutter/Flame limiting the drag area in a game

I am trying to move my player by dragging, but I don't want my player to go out of the screen. How can I limit it in a decent way?

void onPanUpdate(DragUpdateDetails details) {
  if(game.screenSize.width >= playerRect.right && playerRect.left >= 0
      && game.screenSize.height >= playerRect.bottom && playerRect.top >= 0) {
    playerRect = playerRect.translate(details.delta.dx, details.delta.dy);
  } else { 
    playerRect = playerRect.translate(-details.delta.dx*4.2, -details.delta.dy*4.2);
  }
}

I came up with this solution but as you know it is not cool. I appriciate any kind help.

Upvotes: 1

Views: 1936

Answers (1)

spydon
spydon

Reputation: 11552

Happy to see another user of our game engine! The delta also has to be taken into consideration in the check. Something like this should work:

void onPanUpdate(DragUpdateDetails details) {
  final delta = details.delta;
  final size = game.screenSize
  double translateX = delta.dx;
  double translateY = delta.dy;
  // Make sure that the player never goes outside of the screen in the X-axis
  if (playerRect.right + delta.dx >= size.width) {
      translateX = size.width - playerRect.right; 
  } else if (playerRect.left + delta.dx <= 0) {
      translateX = -playerRect.left; 
  }
  // Make sure that the player never goes outside of the screen in the Y-axis
  if (playerRect.bottom + delta.dy >= size.height) {
      translateY = size.height - playerRect.bottom; 
  } else if (playerRect.top + delta.dy <= 0) {
      translateY = -playerRect.top; 
  }
  playerRect = playerRect.translate(translateX, translateY);
}

If you have more in-depth questions I suggest that you join our discord too: https://discord.gg/pxrBmy4

Upvotes: 1

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