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arma:file_formats:paa [2007/07/06 01:40] – moved paa page here snakemanarma:file_formats:paa [2024/08/01 08:04] (current) – links added. snakeman
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 +====== ArmA 1 PAA / PAC File Format ======
 +
 +[[https://www.pmctactical.org/forum/viewforum.php?f=42|ArmA 1 Forum]], [[:arma|ArmA 1 Home]], [[arma:config|ArmA 1 Config]], [[arma:tools|ArmA 1 Tools]], [[arma:file_formats|ArmA 1 File Formats]], [[arma:missions|ArmA 1 Missions]], [[arma:modeling|ArmA 1 3D Modeling]], [[arma:terrain|ArmA 1 Terrain]], [[arma:texturing|ArmA 1 Texturing]], [[arma:scripting|ArmA 1 Scripting]]
 +
 +**ArmA 1** aka Armed Assault (ArmA)
 +
 +
 ====== Introduction ====== ====== Introduction ======
  
-Of the many image file formats 'out there', such as jpeg, such as gif. BI choose to use a specially developed file format (paa) as the base texture file for all engine types. The reason for this is the raw data within the file can be passed directly to Miscrosft's Direct X as a DCT1 picture (eg) without further massaging. While all engines except Elite also support JPG files, PAA files can result in much better performance.+Of the many image file formats 'out there', such as jpeg, such as gif. bis choose to use a specially developed file format (paa) as the base texture file for all engine types. The reason for this is the raw data within the file can be passed directly to Miscrosft's Direct X as a DCT1 picture (eg) without further massaging. While all engines except Elite also support JPG files, PAA files can result in much better performance. 
  
 ====== Main Format ====== ====== Main Format ======
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 Overall structure of a Paa file is Overall structure of a Paa file is
  
-<code>+<code cpp>
 struct overall struct overall
 { {
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 Every PAA file starts with a **TypeOfPaa** Every PAA file starts with a **TypeOfPaa**
-<code> +<code cpp> 
-ushort TypeOfPaa;  // type of texture, known values are +ushort TypeOfPaa;  // type of texture, known values are
     // 0xFF01 DXT1 compressed texture (may have 1 bit alpha map, check MSDN documentation for details)     // 0xFF01 DXT1 compressed texture (may have 1 bit alpha map, check MSDN documentation for details)
     // 0x1555 Uncompressed RGBA 5:5:5:1 texture     // 0x1555 Uncompressed RGBA 5:5:5:1 texture
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 followed by **optional** header tags followed by **optional** header tags
  
-<code>+<code cpp>
 struct PAA_Tag { struct PAA_Tag {
- byte    name[8]; // name of tag is actually reversed when written in file, + byte    name[8]; // name of tag is actually reversed when written in file,
  // so OFFSTAGG would be written as GGATSFFO. See  below for known tags.  // so OFFSTAGG would be written as GGATSFFO. See  below for known tags.
  ULONG tag_size; // size of this tag  ULONG tag_size; // size of this tag
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 **Special Case** **Special Case**
  
-TypeOfPaa 0x4747 Uncompressed Index Palette texture +TypeOfPaa 0x4747 Uncompressed Index Palette texture
  
-This is a corrupt entry in the sense that it does not have a TypeOfPaa! It is the lead in bytes to a standard AVCGTAGG. The next block of data is, the palette. Followed by 'standard' mip-data blocks. +This is a corrupt entry in the sense that it does not have a TypeOfPaa! It is the lead in bytes to a standard AVCGTAGG. The next block of data is, the palette. Followed by 'standard' mip-data blocks.
  
 Indecipherable commentary from Feersum:\\ Indecipherable commentary from Feersum:\\
 If format not 0x4747 then end of header tag data is marked by UWORD 0x0000, else this is a `size of palette` and next block it`s a palette(sizeof = `size of palette` * 2) If format not 0x4747 then end of header tag data is marked by UWORD 0x0000, else this is a `size of palette` and next block it`s a palette(sizeof = `size of palette` * 2)
 +
  
 ====== HexDump ====== ====== HexDump ======
  
-{{http://tactical.nekromantix.com/images/wiki/Paacformat.gif}}+{{https://pmc.editing.wiki/images/Paacformat.gif}} 
  
 ====== Known Header Tags ====== ====== Known Header Tags ======
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 **OFFSTAGG** **OFFSTAGG**
  
-<code>+<code cpp>
 Sizeof Data (16 x ULONGS) Sizeof Data (16 x ULONGS)
 Example: Example:
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 </code> </code>
  
-MipMap data is presented in 'blocks'. One or more 'blocks' exist in a paa file. This is a pointless and redundant tag that declares where each of these blocks are in the file, relative to start of file. The location of each block is already known, relative to the size of the previous block (if any). So, although almost always present in paa files, it's use, is redundant. This tag always contains 16 ULONG offsets. Each one is a hard offset to actual mipmap data relative to start of file. Not all entries are used (obvuously) since most paa files contain less than 16 mipmaps. Unused offsets contain the value 0x00000000. There are no known examples of splattered offset entries. All offsets after the first 0 entry are 0 as well.+MipMap data is presented in 'blocks'. One or more 'blocks' exist in a paa file. This is a pointless and redundant tag that declares where each of these blocks are in the file, relative to start of file. The location of each block is already known, relative to the size of the previous block (if any). So, although almost always present in paa files, it's use, is redundant. This tag always contains 16 ULONG offsets. Each one is a hard offset to actual mipmap data relative to start of file. Not all entries are used (obviously) since most paa files contain less than 16 mipmaps. Unused offsets contain the value 0x00000000. There are no known examples of splattered offset entries. All offsets after the first 0 entry are 0 as well.
  
 **AVGCTAGG** **AVGCTAGG**
  
 Average Colour Average Colour
-<code>+<code cpp>
 Sizeof Data (1 x ULONG) Sizeof Data (1 x ULONG)
 example: GGATCGVA = FF443D39 example: GGATCGVA = FF443D39
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 </code> </code>
  
-Swizzle is apparently used to modify texture components processing like swizzle modifiers in pixel shaders. For example ArmA sky texture has green channel stored in alpha channel and inversed to take advantage from feature that in DXT5 64 bits are used for alpha channel in each block and 64 bits for RBG, giving double the accuracy to green channel as opposed to storing texture just normally. Exact format of swizzle data is still unknown.+Swizzle is apparently used to modify texture components processing like swizzle modifiers in pixel shaders. For example ArmA sky texture has green channel stored in alpha channel and inverted to take advantage from feature that in DXT5 64 bits are used for alpha channel in each block and 64 bits for RBG, giving double the accuracy to green channel as opposed to storing texture just normally. Exact format of swizzle data is still unknown. 
  
 ====== Mipmap Data ====== ====== Mipmap Data ======
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 After end-of-header marker, actual mipmap data follows. Tag OFFSTAGG (if supplied) contains (up to) 16 offsets. Each offset points to the following struct type (relative to start of the file). After end-of-header marker, actual mipmap data follows. Tag OFFSTAGG (if supplied) contains (up to) 16 offsets. Each offset points to the following struct type (relative to start of the file).
  
-<code>+<code cpp>
 struct Mipmap_Data { struct Mipmap_Data {
  UWORD width; // width of this mipmap  UWORD width; // width of this mipmap
  UWORD height; // height of this mipmap  UWORD height; // height of this mipmap
- UCHAR size[3]; // size of compressed texture data. this is 24-bit unsigned integer.  + UCHAR size[3]; // size of compressed texture data. this is 24-bit unsigned integer. 
- UCHAR data[size]; // actual texture data + UCHAR data[size]; // actual texture data
 }; };
 </code> </code>
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 **Decompression Code** **Decompression Code**
  
-<code>+<code cpp>
 /* /*
 by Flea by Flea
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 After last mipmap, there are six (6) bytes set to 0x00 to mark end of texture data. And,consequently, end of file. No further data is known to occur after this End mark. After last mipmap, there are six (6) bytes set to 0x00 to mark end of texture data. And,consequently, end of file. No further data is known to occur after this End mark.
 +
  
 ====== Alpha Channel Interpolation ====== ====== Alpha Channel Interpolation ======
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 **FLAGTAGG = 1, interpolated alpha channel (default behaviour)** **FLAGTAGG = 1, interpolated alpha channel (default behaviour)**
  
-{{http://tactical.nekromantix.com/images/wiki/paa_alpha_channel_default.jpg}}+{{https://pmc.editing.wiki/images/paa_alpha_channel_default.jpg}}
  
 **FLAGTAGG = 2, alpha channel interpolation disabled** **FLAGTAGG = 2, alpha channel interpolation disabled**
  
-{{http://tactical.nekromantix.com/images/wiki/paa_alpha_channel_no_interpolation.jpg}}+{{https://pmc.editing.wiki/images/paa_alpha_channel_no_interpolation.jpg}} 
  
 ====== Bibliography ====== ====== Bibliography ======
  
-Feersum's original posting on BIS forums: [[http://www.flashpoint1985.com/cgi-bin/ikonboard311/ikonboard.cgi?;act=ST;f=50;t=38131|Paa/pac texture format documentation]]\\ 
 MSDN documentation on DXT1 textures: [[http://msdn.microsoft.com/library/default.asp?url=/library/en-us/directx9_c/Opaque_and_1_Bit_Alpha_Textures.asp|DirectX: Opaque and 1-Bit Alpha Textures]]\\ MSDN documentation on DXT1 textures: [[http://msdn.microsoft.com/library/default.asp?url=/library/en-us/directx9_c/Opaque_and_1_Bit_Alpha_Textures.asp|DirectX: Opaque and 1-Bit Alpha Textures]]\\
 Squish Compression [[http://www.sjbrown.co.uk/?code=squish|DXTn compress/decompress]] Squish Compression [[http://www.sjbrown.co.uk/?code=squish|DXTn compress/decompress]]
 +
arma/file_formats/paa.1183686035.txt.gz · Last modified: 2007/07/10 09:52 (external edit)
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