weird absolute position

[instinct]

I've been trying to understand why my SceneNode has a weird absolute position for a couple of hours but i just cant find the reason why.

Situation:
I have a 'pallet', which is an AnimatedMeshSceneNode, with an emptySceneNode as parent. It's position is correct.

I also have a 'box', which also is an AnimatedMeshSceneNode, with the pallet as parent. This box has a weird absolute position.

Code: Select all

emptySceneNode->addChild(pallet); 
pallet->setPosition(RelativePositionPallet);
pallet->addChild(box);
box->setPosition(RelativePositionBox);
box->updateAbsolutePosition();

vector3df AbsolutePos = box->getAbsolutePosition();

Some debug info:

Absolute position pallet: (118, -36 , -410)
Relative position box: (-5, 10, -4)

Absolute position box: (68, -10, -475)

How is this possible? What am I doing wrong?

[Acki]

I didn't check this, but maybe this box->updateAbsolutePosition(); should be

Code: Select all

pallet->updateAbsolutePosition();

(or maybe both ???)

[instinct]

Unfortunately that didnt solve the problem

[hybrid]

Yes, you need to call updateAbsolutePosition on all(!) nodes up to the root.

[instinct]

Can i do this by simply calling smgr->getRootSceneNode()->updateAbsolutePosition() or do i have to do it individually?

[CuteAlien]

Wow, that's something I had missed so far... I always thought of that as recursive. I guess I was lucky so far it didn't mess stuff up (or I didn't notice).

You have to start with the root, so the easiest way is probably to do it recursively:

Code: Select all

//! update absolute positions for node including all it's parents, starting from the top-most parent
void RecursiveUpdateAbsolutePosition(irr::scene::ISceneNode * node)
{
	if ( node )
	{
		if ( node->getParent() )
		{
			RecursiveUpdateAbsolutePosition(node->getParent());
		}
		node->updateAbsolutePosition();
	}
}

[instinct]

thanks CuteAlien

[Arcoroc]

Wow, that's something I had missed so far... I always thought of that as recursive. I guess I was lucky so far it didn't mess stuff up (or I didn't notice).

You have to start with the root, so the easiest way is probably to do it recursively:

Code: Select all

//! update absolute positions for node including all it's parents, starting from the top-most parent
void RecursiveUpdateAbsolutePosition(irr::scene::ISceneNode * node)
{
	if ( node )
	{
		if ( node->getParent() )
		{
			RecursiveUpdateAbsolutePosition(node->getParent());
		}
		node->updateAbsolutePosition();
	}
}

Wouldn't we have to process all tree nodes to move the scene, not just the path to root?

[CuteAlien]

Wouldn't we have to process all tree nodes to move the scene, not just the path to root?

The idea here isn't to move the scene but to ensure that the absolute position of just that node is up-to-date. But the calculation does access the positions of the parent so those have to be updated first. Note that you only need that if you need to access changed positions before the drawAll call which will update the whole scene.

[Arcoroc]

Wouldn't we have to process all tree nodes to move the scene, not just the path to root?

The idea here isn't to move the scene but to ensure that the absolute position of just that node is up-to-date. But the calculation does access the positions of the parent so those have to be updated first. Note that you only need that if you need to access changed positions before the drawAll call which will update the whole scene.

thanks - makes sense.