irrlicht - SetAbsolutePosition

BlitzMax Forums/BlitzMax Programming/irrlicht - SetAbsolutePosition

UNZ	(Posted 2013) [#1]

Hi,

I have an animated mesh which I want to control. I have global positions the joints should go to but unfortunately SetPosition() always calulates from the parent's node.

I found http://irrlicht.sourceforge.net/forum/viewtopic.php?t=42342 but it doesn't work for me. I don't know why.

The code

'mesh is an animated scene node
ConnectChildren(mesh)
Function ConnectChildren(parent:ISceneNode)
	Local children:ISceneNode[] = parent.getChildren()
	If Not children Then Return
	For Local c:ISceneNode= EachIn children
		Local matr:Matrix4 = c.getAbsoluteTransformation()
		Local temp:Matrix4 = parent.getAbsoluteTransformation()
		Local w2n:Matrix4= New Matrix4.create()
		temp.getInverse(w2n)
		matr = w2n.Mult(matr)

		Local pos:Vector3df = matr.getTranslation()

		c.setPosition(pos)
		'c.SetRotation(matr.getRotationDegrees() )
		c.updateAbsolutePosition()
		
		ConnectChildren(c)
	Next
End Function

does not work.

What I'm looking for is a method 'setAbsolutePosition' which would return the original in 'c.setAbsolutePosition(c.getAbsolutePosition())'

Thought this would be easy...

Kryzon

(Posted 2013) [#2]

It appears to be correct, in theory; You are getting the child's world transformation, transforming it by the parent's inverse world transformation which should give the child's transformation relative to the parent.

The only thing I can think of is that 'matr = w2n.Mult(matr)' operation.
Are you sure it's not 'matr = matr.Mult(w2n)' ?

EDIT: I don't understand that 'w2n:Matrix4 = New Matrix4.Create()'.
If you're calling 'Create()', it should return an instance already - you wouldn't have to use New as well.
Generally inside the Create() function of a Type the programmer uses New to create a new instance and returns it so you don't have to use New yourself.

EDIT2: After hunting for the source, yeah, you should not use New. Just call Create:

Function Create:Matrix4(eConstructor:Int=EM4CONST_IDENTITY)
	Return createFromHandle(IrrCore_Matrix4_new(eConstructor),True)
EndFunction

Function createFromHandle:Matrix4(pMat:Int,bMustDel:Int=True)
	If Not pMat Then Return Null
	Local oRetVal:Matrix4=New Matrix4 '<--- It already creates a New one for you.
	oRetVal.attach(pMat,bMustDel)
	Return oRetVal
EndFunction

Brucey

(Posted 2013) [#3]

Unless Create() is a Method which returns Self.

I usually construct my Type hierarchies in this way, so you can have a constructor with parameters - unlike New which takes none.