Disposed meshes still colliding

[TechSlave]

Hey there!

I'm making a game based on Megamania (Atari 2600) for my end of graduation work and i'm having problems with the Dispose function.

When i click the mouse, the ship shot a bullet, then it "intersectsmesh" with a box, the box and the bullet are disposed, but "something" invisible stays in the place, if i shoot at that place again the bullet is destroyed even if technically nothing is there.

this is the function:

window.addEventListener("click", function(e) {
      console.log(score);
      scene.registerBeforeRender(function() {
        bullet.position.y = bullet.position.y + 10;
      })

      var bullet = BABYLON.Mesh.CreateCylinder("bullet", 5, 1, 1, 6, 1, scene);

      var BstartPos = ship.position;
      var posVec = new BABYLON.Vector3(BstartPos.x, BstartPos.y + 17, BstartPos.z);
      bullet.position = posVec;

      scene.registerBeforeRender(function shot() {
        for(var i1 = 0; i1 < enemy1.length; i1++) {
          if(enemy1[i1].intersectsMesh(bullet, true)) {
            bullet.dispose();
            enemy1[i1].dispose();

            score = score + 1;
          scene.unregisterBeforeRender(shot);

}
        }
        for(var i2 = 0; i1 < enemy2.length; i2++) {
          if(enemy2[i2].intersectsMesh(bullet, true)) {
            bullet.dispose();
            enemy2[i2].dispose();
            scene.unregisterBeforeRender(shot);
            score = score + 1;
          }
        }
         for(var i3 = 0; i3 < enemy3.length; i3++) {
          if(enemy3[i3].intersectsMesh(bullet, true)) {
            bullet.dispose();
            enemy3[i3].dispose();
            scene.unregisterBeforeRender(shot);
            score = score + 1;
          }
        }

        if(bullet.position.y < -250 || bullet.position.y > 250) {
          bullet.dispose();
          scene.unregisterBeforeRender(shot);
        }
      });

    });

 

i've tried "enemy3[i3].intersectsMesh(bullet, true)" and "bullet.intersectsMesh(enemy3[i3], true)", the results are the same.

if you check the score in the console, you'll see that the numbers doesn't makes sense too, they grow exponentially...

here's the code: http://techslave.com.br/games/dispose/js/core.js

and here's the game: http://techslave.com.br/games/dispose/

 

not in the playground because there's a lot of files

 

can someone help me?

[Wingnut]

Hi @TechSlave, welcome to the BJS forum.  I'm no expert, but you could try setting whatevermesh.setEnabled(false); just before the dispose attempts.

[TechSlave]

Just tried that, no success...

 

i've tried console.log(bullet.isDisposed()); and console.log(enemy3[i3].isDisposed());

it returns true, but the "thing" is still there...

 

 

BTW, thank you!

[TechSlave]

Still couldn't solve this... can't even figure out what stays in the place

[fenomas]

I'm no expert but I don't think this is a bug. When you dispose a mesh, BJS removes it from various lists and whatnot, but it doesn't destroy it or zero out all its properties. If you then ask BJS to do a collision check with it, I think BJS does the right thing if it does a normal collision check.

(If you were just registering for collision events and leaving BJS to do the checking, I'd expect a disposed mesh to stop issuing events, but since you're specifically asking for a collision check between two meshes, I think BJS is doing the right thing.)

So I think the fix here is that when an enemy gets destroyed, you should remove it from the list of things you do collision checks against.

[TechSlave]

I'm doind the collision check with "intersectsmesh", which just check against everything, because i have a lot of things to check collision...

I'm searching for a way of remove the collision check with one mesh only, let's see if i find it out, thank you!

 

but still, is there any way of remove a mesh of the stage leaving no traces behind?

[fenomas]

Ohhh, I see, so each "enemies" object that you're testing against is a whole row of enemies, right? The code sample doesn't include the createEnemy function so it's hard to tell what's going on.

Are the individual enemies child meshes of the row, or how do they get added?

[TechSlave]

They are arrays, this:

 

 var enemy1 = createEnemy(scene);
    var enemy2 = createEnemy2(scene);
    var enemy3 = createEnemy3(scene);
   

then enemy.js:

 

function createEnemy(scene){
  this.scene = scene;
  var nomeCons = "enemy1";
  var enemy1 = new Array(11);
  var nome;
  var stPos = startPos[0]-250;
  j = 0;
  for(i = 0; i < 11; i++) {
    if(i==0){
      enemy1[0] = BABYLON.Mesh.CreateBox(enemy1, 10.0, scene);
      enemy1[0].position.y = row[0];
      enemy1[0].position.x = stPos;
      j=i+1;

    }
    else{
      j=i-1;
      nomeInv = nomeCons + i;
      enemy1 = BABYLON.Mesh.CreateBox(nomeInv, 10.0, scene);
      enemy1.position.y = row[0];
      enemy1.position.x = enemy1[j].position.x + 31;
      //enemy.position.x = col;

    }
  }
  return enemy1;
}

 

then i check the collision like this:

for(var i1 = 0; i1 < enemy1.length; i1++) {
          if(enemy1[i1].intersectsMesh(bullet, true)) {
            bullet.setEnabled(false);
            bullet.dispose();
            enemy1[i1].setEnabled(false);
            enemy1[i1].dispose();

            score = score + 1;
            scene.unregisterBeforeRender(shot);

          }

 

 basically i create each enemy in a n array then i use a For to check collision against each of the enemies individually.

[fenomas]

Okay, thanks. I think you should probably just remove the enemy object from the enemy array when you destroy it.

for(var i=0; i<enemy.length; i++) {
    if(enemy[i].intersectsMesh(bullet, true)) {
        enemy[i].dispose()
        enemy.splice(i, 1)
        i--

        // ...
    }
}

The issue here is, intersectsMesh just tells you whether two meshes have positions that overlap. When you dispose something it is "removed" from the scene, in the sense that it no longer renders, etc. But its position and size don't change, so intersectsMesh still works as before, and I think that's probably the correct behavior.

[Pryme8]

just from a quick glance that is because you are using the same bullet, use an array of bullets and make sure you are disposing the correct one.  Handle the bullets just like you would and enemy.

What im assuming is happening is you are disposing the bullet and then reusing it but not updating its bounding information or something like that...

[fenomas]

The bullet is being created in a function closure that's called for each click, so I don't think anything's being reused there.

[Pryme8]

Just now, fenomas said:

The bullet is being created in a function closure that's called for each click, so I don't think anything's being reused there.

not from what i saw, I just see var bullet.

[fenomas]

The var statement is inside a click event handler, so a new cylinder is getting created each time the user clicks.

[TechSlave]

i've tried 'teleporting' the bullet to the ship aftter the collision, but no succes either

 

[Pryme8]

uh ok i see 1 second, @ first i was gonna say you mistaken about the scope but i re-looked before i went to bed here.

I bet a lot of this is happening from the multiple beforescenes being registered and not cleared.

[Pryme8]

The correct structure would be to just fire a function from inside the mouseclick and have the bullet defined outside of the scope of it and have hit responses. also arrays on a single before register loop to control everything.

I thought there was another closure there.
Im going to bed, this is set up really loopy, ill help tomorrow.

[TechSlave]

good morning!

 

I'm at work now but just quickly tried 2 things:

bullet = null

after every other sets when the bullet hits, it crashes the game, console shows something in babylon.js being null

 

removing bullet.dispose()

the bullet will pass through everything, but won't create that piece of nothing that is making me crazy, but one shot can destroy 3 enemies that way, it's not the purpose

but i think knowing this helps in some way

[Pryme8]

Yes I will help today, it's Labor Day so I get to be lazy...  Umm I'll show you what's happening it's because of how your generating the before scene registers and everything your scope is really not set up correctly.

 

[Pryme8]

Whoa, just looked at the script lets go over a few things:
1- You are calling multiple nested functions and they all have their own registers and scopes.

2- Your arrays should be constructed on the main loop and referenced in a single before scene register.
3- There is never a time to add this much nested stuff on a click.

Ok lets do this up for you... give me like a hour or something.

[Pryme8]

well, I was well on my way to fixing it for you when:

Compilation error

Line 4:9720 - Cannot read property 'precision' of null
I cant get anything on the playground to work at all right now... so yeah.
@Deltakosh - is the playground down or is it just for me?

-It was just me nevermind

[Pryme8]

http://www.babylonjs-playground.com/#24D4QT#0

here you go bro, I had to redo it and it does not have any of the hits or controls but fire, but this is the correct structure.

Think Arrays Arrays Array my friend... also when you add in the hit tests, only do it on the bullet, the enemys will not need it and vice versa, and just dispose the targets attached to the collision event and the bullet... make sure you splice your arrays correctly when it happens though.

Also with a set up like this it is way easier to tailor it, you now can do shot speeds (and upgrades), new spawn points for enemy's, different enemy's, different bullet types, faster spawn times (levels) ect.

this would be the right way to structure a retro shooter, and it took like what 20 mins? So the structure is definitely choice.

[TechSlave]

holy smokes, you just did it in 40 minutes, took me months lol

 

i had to learn javascript and babylon, that's why i didn't used OOP

 

u've used functions i was not aware of, like MeshBuilder, nice to know

 

thank you a lot!

[Pryme8]

no problem, if you need anymore help feel free to tag me in questions... I'm around and am more then willing to help.  I am super impressed with anyone who learns JavaScript just to do a project so don't feel bad this is all a learning process and 16 years ago I was going through what you are now.

[TechSlave]

thank you again!

i was testing your code, looks like it's not colliding, but you did a function to destroy the enemies, can't see what's the problem

[Pryme8]

yea i did not script in anything for collisions, I was just showing you the correct structure, I was gonna leave it for you to develop the whole system though, but given the new model you should be able to figure it out.

Just at a listener on the enemy or the bullet when you spawn it for a collision and then output the event to your console and see what your working with.  Should be able to figure it out from there ^_^. I could give you a fully deployed system but whats the fun in that? and then you wont learn.