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====== OFP ODOL ======

[[https://www.pmctactical.org/forum/viewforum.php?f=43|OFP Forum]], [[:ofp|OFP Home]], [[ofp:file_formats|OFP File Formats]], [[ofp:tools|OFP Tools]], [[ofp:missions|OFP Missions]], [[ofp:modeling|OFP 3D Modeling]], [[ofp:terrain|OFP Terrain]]

**Operation Flashpoint (OFP)** aka ArmA: Cold War Assault (CWA)

OFP ODOL file format is called v7 (while ArmA is called v40). This document discusses OFP ODOL.

**Overall**
<code>
// uint unsigned integer 32bit
// word unsigned short integer 16bit
// Note that potentically compressed arrays in these structures only have an known output length.
// the decompressor therefore must work on infinite input length.
// see example decompression at end of document
</code>

<code>
struct ODOL
  {
  char Signature[4]; //"ODOL"
  uint Version;     // 7
  uint LodCount;    // at least one
  struct Lod[LodCount]
  {
    uint VerticesCount;
    uint VerticesAttribs[VerticesCount]; // if > 255 then array is compresed

    uint VerticesCount; // again same value
    struct UVset[VerticesCount]; // if > 127 then array is compresed

    uint VerticesCount; // again same value
    struct VerticesPosition[VerticesCount];

    uint VerticesCount; // again same value
    struct VerticesNormal[VerticesCount];

    float fvalue[12];  // unknown values // containts some max/min vertices positions and so far

    uint TexturesCount;
    char Textures[...]; // zero ended 'C' strings 'd','a','t','a','\','1','.','p','a','a','\0','d','a','t','a','\','2','.','p','a','a','\0'...
    //read until count of founded char('\0') equil TexturesCount;

    uint Table1stCount;
    word Table1st[Table1stCount];// if > 511 array compresed
    uint Table2ndCount; // Table2ndCount is same value like VerticesCount
    word Table2nd[Table2ndCount];// > 511 then array is compresed
    //tables can by used to join vertices, each face has got 3 or 4 vertices that are seperated for each face in odol format
    //every vertex is owned only by 1 face
    //mlodvertexindex = Table1st[ Table2nd[ odolvertexindex ] ];

    uint FacesCount;
    uint uvalue;  // unknown value
    struct Face[FacesCount];

    uint uvalue2; // unknown value
    char uchar[18*uvalue2]; // unknown value

    uint NamedSelectionCount
    struct NamedSelection[NamedSelectionCount]

    uint NamedPropetiesCount;
    struct NamedPropeties[NamedPropetiesCount]

    uint uvalue7;// unknown value ???
    struct ustruct[uvalue7]; // unknown value

    uint ProxiCount;
    struct Proxi[ProxiCount];
  }; // end of lod
uint ResolutionCount; // same as LODCount
float  Resolution[ResolutionCount];
.
.
. // folows some unknow data.
}; // end of ODOL;
</code>

**Faces**

<code>
struct Face
    {
      uint Attribs;
      word TextureIndex; //if ((int)TextureIndex==-1) no texture;
      char CountOfVertices;  // 3 or 4
      word VerticesIndex[CountOfVertices]; //! size of array is not constant.
    };
</code>

**NamedSelection**

<code>
  struct NamedSelection
    {
      char name[...]; // zero ended string

      uint VerticesSelectedCount;
      word VerticesSelected[VerticesSelectedCount];// if VerticesSelectedCount > 511 then array is compresed by LZ algorithm. see LZ in ODOL.

      uint uvalue3; // unknown value
      word uarray[uvalue3];// unknown value

      uint uvalue4; // unknown value
      uint uarray[uvalue4];// unknown value // if VerticesSelectedCount > 255 then array is compresed by LZ algorithm. see LZ in ODOL.

      char uchar; // unknown value

      uint uvalue5; // unknown value
      uint uarray[uvalue5];// unknown value

      uint FacesSelectedCount;
      word FacessSelected[FacesSelectedCount]// if FacesSelectedCount > 511 then array is compresed by LZ algorithm. see LZ in ODOL.

      uint uvalue6; // unknown value
      char uarray[uvalue6];// unknown value
    };
</code>

**VerticesPosition**

<code>
   struct VerticesPosition
    {
      float x,y,z;
    };
</code>

**VerticesNormal**

<code>
   struct VerticesNormal
    {
      float x,y,z;
    };
</code>

**UVset**

<code>
   struct UVset
    {
      float U,V;
    };
</code>

**Proxi**

<code>
  struct Proxi
    {
      char Name[...] // zero ended  string
      float rotationMatrix[9];
      float translation[3];
    };
</code>

**ustruct**

<code>
  struct ustruct // unknown value
    {
      uint uvalue8;// unknown value
      uint uvalue9;// unknown value
      char uarray[12*uvalue9];// unknown value :-( i know nothing about it
    };
</code>

**NamedPropeties**

<code>
  struct NamedPropeties
    {
      char Name[...];
      char Value[...]; // 'n','o','s','h','a','d','o','w','\0','1','\0'...
    };
</code>

====== LZ in ODOL ======

Lempel-Ziv compression

Note1.

Rregardless of method, 4 extra bytes representing the checksum exist at end of the data count.

Note2. The compression code is identical to that employed by pbo packed structures. However, unlike pbo's, the size of the compressed data is unknown, only it's ultimate length. The code below fudges it.

====== Pascal Code ======

<code>
function LZBlockRead(var F:file; var outdata:array of byte;szout:integer):byte;
var
k, r, pr, pi,po,i,j:integer;
flags:word;
buf:array[0..$100e] of byte;
c:byte;
crc:integer;
begin
po:=0;
pi:=0;
flags:=0;
r:=0;
for k := 0 to $100F-1 do buf[k] := $20;
       while (po < szout) do
        begin
           flags:= flags shr 1;
           if ((flags and $100)= 0) then
               begin
                 BlockRead(F,c,1);   // direct reading from file
                 inc(pi);
                 flags := c or $ff00;
               end;
           if (flags and 1)=1 then
                begin
                  if (po >= szout)then break;
                  BlockRead(F,c,1);   // direct reading from file
                  inc(pi);
                  outdata[po] := c;
                  inc(po);
                  buf[r] := c;
                  inc(r);
                  r :=r and $fff;
                end
           else
                begin
                  i:=0;
                  BlockRead(F,i,1);  // direct reading from file
                  inc(pi);
                  j:=0;
                  BlockRead(F,j,1); // direct reading from file
                  inc(pi);
                  i :=i or ((j and $f0) shl 4);
                  j := (j and $0f) + 2;
                  pr := r;
                  for k := 0 to j do
                    begin
                      c := buf[(pr - i + k) and $fff];
                      if (po >= szout) then break;
                      outdata[po]:= c;
                      inc(po);
                      buf[r]:= c;
                      inc(r);
                      r :=r and $fff;
                    end;
             end;
       end;
     BlockRead(F,crc,4);   // 4 byte checksum.
     result:= pi;
end;
</code>

====== C Code ======

<code>
int Decode(unsigned char *in,unsigned char *out,int szin,int szout)
{
       szin = szin > 0? szin: 0x7fffffff;
       int  i, j, k, r = 0, pr, pi = 0,po = 0;
       unsigned int  flags = 0;
       unsigned char buf[0x100F], c;
       for (i = 0; i < 0x100F; buf[i] = 0x20, i++);
       while (pi < szin && po < szout)
       {
               if (((flags >>= 1) & 256) == 0)
               {
                       if(pi >= szin)break;
                       c = in[pi++];
                       flags = c | 0xff00;
               }
               if (flags & 1)
               {
                       if(pi >= szin || po >= szout)break;
                       c = in[pi++];
                       out[po++] = c;
                       buf[r++] = c;
                       r &= 0xfff;
               } else
               {
                       if(pi + 1 >= szin)break;
                       i = in[pi++];
                       j = in[pi++];
                       i |= (j & 0xf0) << 4;
                       j  = (j & 0x0f) + 2;
                       pr = r;
                        for (k = 0; k <= j; k++)
                       {
                               c = buf[(pr - i + k) & 0xfff];
                               if(po >= szout)break;
                               out[po++] = c;
                               buf[r++] = c;
                               r &= 0xfff;
                       }
               }
       }
       return pi;// next 4 bytes = checksum
}
</code>