[Bug?] 2.0.20 Tier 2: agk::GetNextContact Reference Out of Bounds Exception

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mrradd

9

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Joined: 24th Feb 2015

Location: CA, USA

Posted: 22nd Aug 2016 18:43 Edited at: 29th Aug 2016 20:46

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Hello,

I have a basic while loop that attempts to go through the contact list and handle the collisions for each pair of Sprite IDs; my code is below--it's a rough draft, so be nice. By the time I get to the last line in the loop, it "contact = agk::GetNextContact();" I get an immediate Reference Out of Bounds Exception. If I take the line out, it works. If I put the line anywhere else, it breaks. I should get a 0 or 1, correct?. Any ideas with what I am doing wrong? I'm using VS2013 and Windows 7 if that matters,.

void MainScene::checkCollision()
  {
  unsigned spriteID1;
  unsigned spriteID2;
  Node*     node1;
  Node*     node2;

/** A collision occured. */
  int contact = agk::GetFirstContact();
  while(contact > 0)
    {
    /** Find the sprites involved in the collision by ID. */
    spriteID1 = agk::GetContactSpriteID1();
    spriteID2 = agk::GetContactSpriteID2();
    node1     = nullptr;
    node2     = nullptr;

/** Find the two Nodes involved, and hold on to their values. */
    vector<Node*>::iterator it;
    for(it = mVecNodes.begin(); it != mVecNodes.end(); ++it)
      {
      if((*it)->getSourceID() == spriteID1)
        node1 = *it;

if((*it)->getSourceID() == spriteID2)
        node2 = *it;

if(node1 != nullptr && node2 != nullptr)
        break;
      }

/** Handle the collision. */
    if(node1 != nullptr && node2 != nullptr)
      {
      node1->handleCollision(node2);
      node2->handleCollision(node1);
      }
    
    //This throws a reference out of bounds exception.
    contact = agk::GetNextContact();
    }
  }

+ Code Snippet

 
void MainScene::checkCollision()
  {
  unsigned spriteID1;
  unsigned spriteID2;
  Node*     node1;
  Node*     node2;

  /** A collision occured. */
  int contact = agk::GetFirstContact();
  while(contact > 0)
    {
    /** Find the sprites involved in the collision by ID. */
    spriteID1 = agk::GetContactSpriteID1();
    spriteID2 = agk::GetContactSpriteID2();
    node1     = nullptr;
    node2     = nullptr;

    /** Find the two Nodes involved, and hold on to their values. */
    vector<Node*>::iterator it;
    for(it = mVecNodes.begin(); it != mVecNodes.end(); ++it)
      {
      if((*it)->getSourceID() == spriteID1)
        node1 = *it;

      if((*it)->getSourceID() == spriteID2)
        node2 = *it;

      if(node1 != nullptr && node2 != nullptr)
        break;
      }

    /** Handle the collision. */
    if(node1 != nullptr && node2 != nullptr)
      {
      node1->handleCollision(node2);
      node2->handleCollision(node1);
      }
    
    //This throws a reference out of bounds exception.
    contact = agk::GetNextContact();
    }
  }

[EDIT] NOT AN AppGameKit BUG. MY POINTERS ARE GETTING SMASHED SOMEWHERE.

make -C ../NagGaCreMo/2016 -f aGame.mk
Missile Commandish [WIP]

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mrradd

9

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Joined: 24th Feb 2015

Location: CA, USA

Posted: 24th Aug 2016 05:32

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Strange development: for some reason it works in XCode on Mac with the same code... I have no idea what's going on.

make -C ../NagGaCreMo/2016 -f aGame.mk
Missile Commandish [WIP]

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Ancient Lady

Valued Member

20

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Joined: 17th Mar 2004

Location: Anchorage, Alaska, USA

Posted: 27th Aug 2016 03:01

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Are you using the correct libraries (in <agkdir>\Tier 2\platform\windows\Lib\VS2013)?

Have you tried using the debugger to watch values?

Are you sure that mVecNodes is getting initialized? And how is it defined?

As a general coding recommendation (I've been programming professionally for 38 years), if there is more than one logical thing in an 'if' statement, it is a good idea to group things with parenthesis to make sure that the code gets done in the order you want.

For instance, this "if(node1 != nullptr && node2 != nullptr)" would be better written as "if ((node1 != nullptr) && (node2 != nullptr))".

While compilers should follow the expected operator precedence, I've discovered that they sometimes don't.

Cheers,
Ancient Lady

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mrradd

9

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Joined: 24th Feb 2015

Location: CA, USA

Posted: 29th Aug 2016 20:44

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I'm using the 2013 libs. I took out the for loop, and I haven't seen an error yet which does point me to an issue with my objects possibly getting smashed somewhere. Odd that it is fine on Mac with the same code.

make -C ../NagGaCreMo/2016 -f aGame.mk
Missile Commandish [WIP]

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AppGameKit Classic Chat / [Bug?] 2.0.20 Tier 2: agk::GetNextContact Reference Out of Bounds Exception