[openvrml-develop] Tracking down wrong value of d_relativeUrl

[Damian M. <da...@er...>]

With 'GTKLOOKAT', I am reading a ( boring but small sample ) file

	a.wrl

which 'inlines' a URL file

	model/c.wrl

which in turn reads a URL (image) files

	image/asp.jpg

The file a.wrl resides in the current directory, as does the
directory 'model'.  Directory 'image' resides within 'model'.

In the first pass through the VRML nodes, done with readWwl ( which is
associated with a Doc ), the part of each included file, i.e. the
d_relativeUrl, is correct.  It uses

	VrmlNodeInline::addToScene
		which (calls) VrmlNodeInline::load
			which (calls) VrmlScene::readWrl


However, on a second pass through, the 2nd level nested file, sky.jpg,
thinks its parent is a.wrl, not model/c.wrl. As a result, the nested image
cannot be found. I do not know where these nodes are being processed.  It
is definitely not readWrl.  If I ensure that the directory image is in the
same directory as 'a.wrl', this solves the problem but that isn't the
point.  I don't have control like this all the time.  VRML is supposed to
take care of nesting.

I can't even figure out which routine is used to make the second pass
but it isn't the same as the first pass.  There seem like there are
many routines that do fundamentally the same thing and I am lost.

The offending (underlying) variable is d_relativeUrl.  This is a field
of

	VrmlNodeTexture
	....AudioClip
	....Background


To track this down, I need some help on understanding the structure
of these heavily nested classes.

1)
	How, from a VrmlNodeTexture node, get the d_url that belongs to
	its associated VrmlNodeImageTexture ( I have one image associated
	with each texture ).  Note that d_url belongs in

		VrmlNodeImageTexture
		........MovieTexture
		........AudioClip
		........Anchor
		........Inline

2)
	Where would the actual URL ( filename in my case ) of

		url "filename.jpg"

	be actually copied into ( what appears to be the VrmlMFString )
	d_url in VrmlNodeImageTexture which is later extracted as
	an array of URLs with the method

		d_url.get()
	or
		(char *) d_url.getElement(0)

	This might help me to isolate where the corruption is occuring.

3)
	Any other suggestions are welcomed.

Don't tell me to use 'GDB' because to use that effectively assumes you
know something about the structure and where to jump to.  I'm hoping that
somebody out there already knows the structure.  My UNIX data files are
included.

I am not a VRML expert.  I just want to view files created by anther
programs.  Before this exercise, I thought I knew something about
object-oriented programming and C++ and reusability. I am starting to
doubt that now.

As an aside, and while I marvel at this body of work, has anybody ever
pulled apart 'vrm97node.cpp' to work with each class.  10,000 lines is a
nightmare.

Thanks - Damian (McGuckin)

Pacific Engineering Systems International, 22/8 Campbell St, Artarmon NSW 2064
Ph:+61-2-99063377 .. Fx:+61-2-99063468   | unsolicited email not wanted here !
Views and opinions here are mine and not those of any past or present employer