[Gambas-user] gb3: using array of structures with dimensions unknown until runtime

[Kevin Fishburne]

On 07/04/2012 12:06 AM, Kevin Fishburne wrote:
> I need to create a 2D array of a structure like this:
>
> Public Struct Tile_Normals
>     A[3] As Single  ' Normal for quad subsurface A.
>     B[3] As Single  ' Normal for quad subsurface B.
> End Struct
>
> Dim Normals As New Tile_Normals[TileGrid.Size, TileGrid.Size]
>
> When I try to assign a value to an array element like this:
>
> Normals[TileGridX, TileGridY].A = Convert.Normal(P1, P2, P3)
>
> I get a "null object" error. While the 2D array of structures seems to
> be created correctly, all its initial values are indeed "null". Do I
> need to create the structure or array differently so I can properly
> assign values to it?
>
> Previously I knew all the dimensions of my arrays of structures so they
> were statically defined, but in this case I don't know the array
> dimensions until after the program has started running. Thanks everyone.
>

One addition. I've discovered that if I publicly declare a 2D array of 
the structure it shows "bad number of dimensions" and "out of bounds" 
errors when I double-click it after creation:

' Tile grid normal structure.
Public Struct Tile_Normals
   A As Single[]  ' Normal for quad subsurface A.
   B As Single[]  ' Normal for quad subsurface B.
End Struct
Public Normals[32, 32] As Struct Tile_Normals

Declaring it as a 1D array it behaves normally:

' Tile grid normal structure.
Public Struct Tile_Normals
   A As Single[]  ' Normal for quad subsurface A.
   B As Single[]  ' Normal for quad subsurface B.
End Struct
Public Normals[32] As Struct Tile_Normals

It also doesn't make any difference if I define the structure like this:

' Tile grid normal structure.
Public Struct Tile_Normals
   A[3] As Single  ' Normal for quad subsurface A.
   B[3] As Single  ' Normal for quad subsurface B.
End Struct

Maybe that's related to what's happening, or a separate issue?

-- 
Kevin Fishburne
Eight Virtues
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