read only files

Is it possible to change a file from read only and back in Blitz 3d?

Yes you can ( be careful - I checked it and it worked - don't test your own values ;-) don't know the result other than using Bits 0 1 2 5 and 8 )
The first 3 lines go into Userlib\kernel32.decls (without the leading semicolon and without lines that already exist)

;.lib "kernel32.dll"
;GetFileAttributes%(filename$):"GetFileAttributesA"
;SetFileAttributes(FileName$,param):"SetFileAttributesA"

;param 1=ReadOnly 2=Hidden 4=System 16=ADirectory 32=Archive 128=NoOtherAtrributes 2048=CompressedFileOrDir

Graphics 800,600,0,2

Fil$="TestFile.txt"
f=WriteFile(Fil$)
WriteLine f,"Test - This is a Test"
CloseFile f

Print "New File written"
Attrib=GetFileAttributes(Fil$)
Print GetAttribS$(Attrib)

SetFileAttributes(Fil$,Attrib Or 1)
Print "Set to ReadOnly (Other Bits are kept)"
Attrib=GetFileAttributes(fil$)
Print GetAttribS$(Attrib)

SetFileAttributes(Fil$, Attrib Or 1 Or 2 Or 4)
Print "Set to ReadOnly Hidden and System (Other Bits are kept)"
Attrib=GetFileAttributes(Fil$)
Print GetAttribS$(Attrib)

SetFileAttributes(Fil$, 128)
Print "Set to nothing"
Attrib=GetFileAttributes(Fil$)
Print GetAttribS$(Attrib)

WaitKey()
End

Function GetAttribS$(a)
	If (a And 1) = 1 Then o$="R" Else o$="-"
	If (a And 2) = 2 Then o$=o$+"H" Else o$=o$+"-"
	If (a And 4) = 4 Then o$=o$+"S" Else o$=o$+"-"
	If (a And 32) = 32 Then o$=o$+"A" Else o$=o$+"-"
;the following not seen in action yet
	If (a And 16) = 16 Then o$=o$+"D" Else o$=o$+"-"
	If (a And 2048) = 2048 Then o$=o$+"C" Else o$=o$+"-"
	Return o$
End Function