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I wonder how to decode a three-dimensional dynamic array of a custom type written to a binary file in VB6.

The custom type is defined as follows:

Type XYByte
    X As Byte
    Y As Byte
End Type

It represents two coordinates of a contact point.

The three-dimensional array represents pre-computed contact point positions for a minigolf track relief. The track is viewed as a two-dimensional height map. For each possible ball position on the map, contact points are computed that there can be more for a map coordinate, so hence the third dimension.

Dim ContactPointMap() As XYByte
ReDim ContactPointMap(Width - 1, Height - 1, MaxContactPointCount - 1)

That array gets saved into a binary file that includes that track shape.

Open FileName For Binary As #1
...
Put #1, , ContactPointMap()
...
Close #1

OK, this is how I did it in VB6. Now I re-write the mini-golf simulator in FPC/Lazarus and wonder how to decipher the three-dimensional array data witten by VB6.

It's interesting that it's pretty straightforward to read a two-dimensional array of "Single" precision float values that I use as the relief map itself and as a source for contact point calculation:

Dim Map() As Single
ReDim Map(Width - 1, Height - 1)

The data is saved in a logical order. I can recognize rows and columns and the reading goes well.

But by that three-dimensional contact point map, every try to read it fails. I used a hexeditor to see the binary data and it's stored in a way that I can't understand.

OK, I already can read the relief map and as a backup option, I can re-compute the contact points in FPC, change the format and save the contact point map in a non-cryptic way. BTW, I stored that information in the track files only for speed reasons (it was faster to read that array on play time than to calculate it).

I no longer have access to VB6. I only have the code and the compiled executable.

But does anyone know how would I basically decipher a three-dimensional dynamic array of user-defined type written by VisualBasic 6?

Cigydd
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  • http://zetcode.com/lang/visualbasic/arrays/ or vb6 specifically: http://www.codeguru.com/vb/gen/vb_misc/algorithms/article.php/c7495/How-Visual-Basic-6-Stores-Data.htm – Marco van de Voort Jun 04 '15 at 15:35
  • Marco, especially the second article seems to say much about my topic. Will examine how much it's useful for reading the data from binary files. – Cigydd Jun 06 '15 at 00:13

1 Answers1

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It clears out that I used damaged data for my research.

And I had bad dimension sizes.

And I wasn't clear about the dimension order in my algorithms.

Only the array data is saved to the file, coding the first dimension at the first place, then the second, and so on.

The coding of the three-dimensional array is the same straightforward as every other multi-dimensional array.

This link from Marco van de Voort helped me out: http://www.codeguru.com/vb/gen/vb_misc/algorithms/article.php/c7495/How-Visual-Basic-6-Stores-Data.htm

Cigydd
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