TypeError: Error #2007: Parameter hitTestObject must be non-null.

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i'm making a game in AS3 in keyframe where there is a movieclip (killer) that has to collide with a child(trail) from the move clip(snake) . I like to call add "_mc" for movieclip and "_ins" for instance. Anyways this is my code

stage.addEventListener(Event.ENTER_FRAME, killsnake);
function killsnake(event:Event)
{
if (killer_ins.hitTestObject(snake_ins.children))
{
trace("asnltsatopgameal;ntaetnaen");
}
}

it keeps giving me the error. I'm not sure how to solve this without it saying "undefined property blablabla" or the error up top. What's a way I can do this?

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kglad

Community Expert

loop through all snake children and hittest each. ie, use numChildren and getChildAt in your for loop.

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chienbleuAuthor

Known Participant

like this?

for (var i:uint = 0; i < snake_ins.numChildren; i++)
if (snake_ins.getChildAt(i) is snake)
{
trace("asnltsatopgameal;ntaetnaen");
}

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kglad

Community Expert

no:

for(var i:int=0;i<snake_ins.numChildren;i++){

if(killer_ins.hitTestObject(snake_ins.getChildAt(i)){

// do whatever other than remove children.

}

if you're going to be removing some of the children, loop backward:

for(var i:int=snake_ins.numChildren-1, i>=0;i--){

if(killer_ins.hitTestObject(snake_ins.getChildAt(i)){

// do whatever

}

p.s. your instance naming convention precludes more than one instance. it would be better to use a different convention. eg, killer_1, killer_2, etc

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