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Thread: collision

  1. #1
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    Default collision

    i am running into problem here. I have a arraylist called rect which store all bounds for ground. i am looping though it and checking for collision between player and arraylist bounds.

    tile map 2d array:

    1 = player
    2 = ground
    0 = background
     
    1,0,0,0
    2,2,0,2
    I want to print "FLAG 1" if its collisied but if its not than print "FLAG 2". I am not 100% sure but i think the problem is the loop.

    if arraylist size is 10 than, if player is standing on ground than it will print "FLAG 1" but than it will print 9 times "FLAG 2"


    public void collision(Player p){
    this.getBounds();for(int i = 0; i < rect.size(); i++){
        if(p.getBounds().intersects(this.rect.get(i)))
              System.out.println("FLAG 1");
        else
                     System.out.println("FLAG 2");
    }
    }

    not sure if i made my question clear. I want to only print "Flag 1" if its touch the ground. and when its not touching than i only want to print "Flag 2"


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: collision

    You're code is checking to see if the player intersects every part of the ground instead of if it intersects anywhere on the ground (big difference).

    A good method to do the latter:

    1. Initialize a flag which assumes the player is not intersecting anywhere with the ground.
    2. For each part of the ground, check to see if it intersects. If it does, set the flag and stop searching.
    3. If the flag indicates the player is intersecting the ground, output "Flag 1". Otherwise, output "Flag 2".

  3. #3
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    Default Re: collision

    o found the problem i think. the problem is here. i am testing player intersects with the whole arraylist. so if arraylist size is 20 than it will print "hi" once and it will print nothing 19 times bc no else.

    for(int i = 0; i < rect.size(); i++){
    if(p.getBounds().intersects(this.rect.get(i)))
    System.out.println("FLAG 1");
    else
    System.out.println("FLAG 2");
    }

    so i was thinking some thing like this. this way it will only test if player is intersect any rect in arraylist.
    for(int i = 0; i < rect.size(); i++)
    {
          if(p.getBounds().intersects(this.rect.get(i))){
               flag = true;
              break;
          }
        else
           flag = false;
    }
     
    System.out.println(flag);
    if(flag )
       System.out.println("Flag1");
    else
    System.out.println("flag2");
    now flag prints:
    true
    false
    false
    false
    ....

    it should prints true, true, true, true, true, bc player is touching the ground rect from arraylist.

  4. #4
    Super Moderator jps's Avatar
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    Default Re: collision

    Quote Originally Posted by game06 View Post
    it should prints true, true, true, true, true, bc player is touching the ground rect from arraylist.
    is touching, or is intersecting? Are you sure they are actually intersecting and not beside one another? Check the values of the bounding boxes manually when you believe they should be intersecting and see what the numbers show

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