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rhumbaflappy

Disassembler for vtp and lwm files

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Just now I uploaded a first (beta) version of a disassembler for files containing vtp and lwm data. I tested it with files assembled from sourcecode with bglc and with original scenery files from MS. It works for all those files that contain lwm data or vtp polys which are not lines. This is still impossible until we understand what the extra bits in the "reserved" areas of structures really do. I have the impression that its mainly the bits in VTPWidePoint type of structures that cause the disassembler to fail.I would be grateful for any comments by members of this group.- osman

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Sorry, I forgot to mention that it is contained in BglAna.zip in the AVSIM library as an addition to the disassembler for other "normal" bgl-code.- osman

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Hi Winfried.A huge thank you!Your disassembler is my favorite FS design program. This addition makes it even better.Hopefully, one of us will crack the "extra bits", and we'll be able to use it for VTP lines someday. For now, it's just great!Dick

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By looking to line structures in tmfviewer it occurred to me that different signatures are used for the points. The starting point seems always to be a green square, some intermediate points are blue squares, and there are some brown squares too. Maybe only the green points represent the usual VTPWidePoint structure. And sometimes (I am not sure if always) it seems not to be a coincidence that if you find a "7" in the reserved bits, there are seven blue points following the green one before the next green one comes. So I wonder if the reserved bits just indicate the number of slightly different records that follow the "normal" one. Another point: the SDK says that if you use Method 2 for VTP Polys, you should selt the wU and wV fields in the VTPDataArea record to zero. This seems not to be correct, because in MS files with VTP code these fields are set to different values, even of Method 2 is to be used. Anyone found an explanation for that?- osman

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Hi Winfried.I usually leave in the wU and wV ( the Area designation ) in my code. I don't think it does anything, but it does help me to keep trak of what area of the cell I started the line or poly in.==========I also noted that the '7' in the reserved part seems to relate to some kind of line start sequence.VTP lines are normally tapered at the ends, like worms. We usually code our own to compact, or backtrack the points to be able to start the line somewhat square. Apparently MS uses the '7', in the reserved part, to add an automatic end-squaring routine... but it throws the count off. Perhaps, the first point is followed by another point that marks the end spot of the squaring sequence(?), and then the points progress normally, until the end sequence ( which sometimes set the reserved part to '7' again!... to end the line with a square )."rdl564184.bgl" is a very small roadline in Canada ( somewhere )... and has square ends and the '7' setting.The picture show the end of the line.Dick

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