Alien Trilogy BND

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BND

• Format Type : File container
  
• Extensions: bnd and b16 for 16-bit sprites
  
• Platforms: PC/PS1/Sega Saturn
  
• Endian Order : Little Endian/Big Endian

Format Description

A container file that can store sprites, textures, models, palette, texture mesh for models. Each file is divided into "sections" that have "names". The problem with this format is that one and the same file is used for different types of data, and different types of data are specified just by "sections" within the file itself. There are the following "section names":

• F000(#1,2,3....) F? - Frame, this section is used for sprites. Most sprites have compression, do not have information about frame sizes (hardcoded into the game engine in animation structures)
  
• T000(#1,2,3....) T? - Texture, in this section there are standard "descriptions" of images - size, color, no compression, resources can be ripped out with tools such as XWE, TiledGGD.
  
• M000(#1,2,3....) M? - Model, section contains models. Contains a list of vertices and quads. The peculiarity with quads is apparently due to the fact that the game was originally developed for the Sega Saturn console, which supports them in hardware better than polygon
  
• BX00(#1,2,3....) - Texture mesh, usually located next to the texture section and has the same numbering. Contains a "list" of quads for texturing.
  
• CX00(#1,2,3....) - urrently unencrypted section
  
• C000(#1,2,3....) - C? - Color, specific section, only available in b16 file variations. Contains a 16-bit palette.
  

Format Specifications

This is a generic "template" for a file. As mentioned above, the rest of the data is determined by the game by the "names / identifiers" of the sections within the file itself. As a rule - this section comes in 16-bit versions of images at the very end of the file, outside the limits of the file size. Consider this when you use these templates to develop your programs!

// Alien Trilogy
// BND(B16) file format

 size                                                  comment

-----------------------------------------------------------------------------

 0x04        46 4F 52 4D            FORM
 0x04        -                      file data size in bytes, BIG-ENDIAN
 0x04        -                      number of sections in a file, text(string?)
 0x04        -                      format \ section identifier(F000\T000\M000....)
 0x0...      -                      data, for each section have its own structure

F000(#1,2,3....) Sprite Section

This section contains sprites of enemies and weapons.
These files contain such sections:
Enemyes:
BURSTER.BND(B16) COLONIST.BND(B16)
DOG.BND(B16) DOGCEIL.BND(B16)
EGGS.BND(B16) FINGERS.BND(B16)
GUARD.BND(B16) HANDLER.BND(B16)
HUGGER.BND(B16) QUEEN.BND(B16)
SOLDIERSYNTH.BND(B16) WAR.BND(B16)
WARCEIL.BND(B16)
Wepons:
MM9.BND(B16) PULSE.BND(B16)
SHOTGUN.BND(B16)FLAME.BND(B16)
SMART.BND(B16)

Does not contain image size information. All sizing information is contained in the game engine in animation structures. Most of the sprites in the PC version of the game are compressed by the LZW algorithm, which works the other way around. Those. - the principle of "sliding window" is applied and subsequent pixels are built from the previous ones. The .B16 format uses in addition a section C000 with a 16-bit palette of 2 bytes per color.

Sprite Section Specifications

// Alien Trilogy
// Sprite Section format(combine in Container Format)
 
 Size                                                Comment

-----------------------------------------------------------------------------

 0x04        46 4F 52 4D                             FORM
 0x04        -                                       File data size in bytes, BIG-ENDIAN
 0x04        -                                       Number of sections in a file, text(string?)
 0x04        -                                       Format \ section identifier F000...(Char "F" + 3 bytes section number)
 0x04        -                                       Section Lenth
 0x0...      -                                       Sprite Data

Sprite decompression function

One section can contain several sprites, some of which may not be compressed. Take this into account when using the function.

void PicDecoder(uint8_t *p, uint8_t *u) {
int32_t i, offs, size;
  i = 0;
  while (1) {
    while (1) {
      i >>= 1;
      if (!(i & 0xFF00)) {
        i = 0xFF00 | *p;
        p++;
      }
      if (i & 1) { break; }
      *u = *p;
      u++;
      p++;
    }
    if (*p >= 96) {
      offs = *p - 256;
      size = 3;
      p++;
    } else {
      size = (*p & 0xF0) >> 4;
      offs = (*p & 0x0F) << 8;
      p++;
      offs |= *p;
      p++;
      if (!offs) { break; }
      offs = -offs;
      if (size == 5) {
        size = *p + 9;
        p++;
      } else {
        size = size + 4;
      }
    }
    while (--size) {
      *u = u[offs];
      u++;
    }
  }
}

C000(#1,2,3....) Color Section

This section appears in B16 variants of the file. Contains a palette of colors. The format is 2 bytes per color. Apparently, this section is available only in the PC version of the game.As a rule - this section comes in 16-bit versions of images at the very end of the file, outside the limits of the file size. Consider this when you use these templates to develop your programs!

Color Section Specifications

 Size                                                Comment

-----------------------------------------------------------------------------

 0x04        -                                       C000(Char "C" + 3 bytes section number)
 0x04        -                                       Number of files allocated for the palette
 0x0...      -                                       Color Data

M000(#1,2,3....) Models Section

This section contains models. Models have vertices and quads in their composition. The nuance with quads, apparently, is due to the fact that the game was originally developed for the Sega Saturn, where quads work better in hardware than polygons. Vertex coordinates have integer values! Many models have a textured mesh
These files contain such sections:
PICKMOD.BND - pickup models
OPTOBJ.BND - menu option models
OBJ3D.BND - other models

Model Section Specifications

// Alien Trilogy
// Model Section format(combine in Container Format)

 Size                                                Comment

-----------------------------------------------------------------------------

 0x04        46 4F 52 4D                             FORM
 0x04        -                                       File data size in bytes, BIG-ENDIAN
 0x04        -                                       Number of sections in a file, text(string?)
 0x04        -                                       Format \ section identifier M000...(Char "M" + 3 bytes model number)
 0x04        -                                       Model data size in bytes, BIG-ENDIAN
 0x04        4F 42 4A 31                             OBJ1
 0x08        00 00 00 00 00 00 00 00                 Unknown value?
 0x04        -                                       The number of quads in the model. LITTLE-ENDIAN
 0x04        -                                       The number of vertices in the model?
 0x14*N      -                                       Quads in turn (see format below)
 0x08*N      -                                       Vertices in turn (see format below)

- Quad format:
 Size                                                Comment
-------------------------------------------------------------------------------------------------------------------------
 0x04        -                                       First point index. LITTLE-ENDIAN
 0x04        -                                       Second point index. LITTLE-ENDIAN
 0x04        -                                       Third point index. LITTLE-ENDIAN
 0x04        -                                       Fourth point index. Maybe -1 (0xFFFFFFFF), then this is a triangle and the third point must be duplicated.
 0x02        -                                       Quad texture index
 0x02        -                                       Some parameter. Maybe 11, then the texture should be flipped along Y (?). Maybe 128. no one knows why.

- Vertices format:
 Size                                                Comment
-------------------------------------------------------------------------------------------------------------------------
 0x02        -                                       X coordinate (signed, LITTLE-ENDIAN, short)
 0x02        -                                       Y coordinate (signed, LITTLE-ENDIAN, short)
 0x02        -                                       Z coordinate (signed, LITTLE-ENDIAN, short)
 0x02        -                                       Unknown value, always zero. Apparently serves to make the data multiples of 4

BX00(#1,2,3....) Texture Mesh Section

This section contains a texture mesh for models. This section has the same numbers as the texture sections. These files have the following section:
PICKGFX.BND - pickup models
PANELGFX.BND - Has a textured mesh for switches
PANEL3GF.BND - same as above
OPTGFX.BND - models from the game menu (Has a B16 option).

The most interesting thing about this section is that it is used not only for models, but also for simple textures, apparently to indicate the "required sizes" (in addition to the size of the image itself).

Texture Mesh Section Specifications

The format of this section is poorly understood, due to the small number of experiments. However, having this description in hand, you can convert pickup / menu models.

// Alien Trilogy
// Texture Mesh Section format
 
 Size                                                Comment

-----------------------------------------------------------------------------
 0x04           42 58 30 30                          BX00
 0x04           -                                    section data size in bytes, BIG-ENDIAN
 0x04           -                                    number of rectangles
 0x0...         -                                    rectangles in turn (see format below)

- BX00 texture rectangle format
size                                               Comment
--------------------------------------------------------------------------------
 0x01           -                                  X size (-1 pixel, i.e. 31 instead of 32, and so on)
 0x01           -                                  Y size (-1 pixel)
 0x01           -                                  unknown value
 0x01           -                                  unknown value
 0x01           -                                  X offset from the end (i.e. you need to subtract the width before using)
 0x01           -                                  Y offset

T000(#1,2,3....) Texture Section

This section contains the texture. Textures are not compressed by the compression algorithm, unlike sprites, so they are easy enough to extract with third-party tools such as XWE, TiledGGD and others. In this section, the texture has dimension data.

Texture Section Specifications

// Alien Trilogy
// Texture Section format(combine BND Format)
 
 Size                                   Comment

-----------------------------------------------------------------------------
 0x04        46 4F 52 4D                  FORM
 0x04        -                            file data size in bytes, BIG-ENDIAN
 0x04        50 53 58 54                  PSXT (probably format identifier)

- further (in no particular order?) sections INFO, TP00, CL00, BX00.....
- section INFO
 Size                                   Comment
-------------------------------------------------------------------------------
 0x04        49 4E 46 4F                   INFO
 0x04        -                             section data size in bytes, BIG-ENDIAN
 0x02        -                             texture size X
 0x02        -                             texture size Y
 0x0C        -                             unknown information, 12 bytes

 - section TP00
here WxH pixels. each pixel = 1 byte. shift to the palette of the current screen. can be found in PALS / WSELECT.PAL (768 bytes, 3 bytes for each color, multiplied by 4 for each component, for 8-bit color variations)