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Revision as of 11:34, 24 January 2015

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The VBUF section defines vertex buffers; each buffer can have different vertex types, with different strides and attributes.
The VBUF section defines vertex buffers; each buffer can have different vertex types, with different strides and attributes.
==== Header ====


{| class="wikitable"
{| class="wikitable"
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|-
|-
| 0x1C
| 0x1C
| colspan=2 | End of MESH header
| colspan=2 | End of VBUF header
|}
|}
==== Vertex Buffer ====


{|class="wikitable"
{|class="wikitable"
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! Description
! Description
|-
|-
|  
| 0x0
| 4
| '''Vertex count'''
|-
| 0x4
| 4
| '''Attrib count''' (AC)
|-
| 0x8
| 0x14 × AC
| '''Vertex attributes'''
|-
| colspan=3 | End of vertex buffer
|}
 
==== Vertex Attribute ====
 
{|class="wikitable"
! Offset
! Size
! Description
|-
| 0x0
| 4
| Unknown
|-
| 0x4
| 4
| '''Offset'''
|-
| 0x8
| 4
| '''Stride'''
|-
| 0xC
| 4
| Unknown
|-
| 0x10
| 4
| Unknown (likely attrib type/format)
|-
| 0x14
| colspan=2 | End of attribute
|}
 
=== IBUF ===
 
Just like how the VBUF section defines vertex buffers, the IBUF section defines index buffers. Each index buffer only has one value associated with it, so it's fairly simple, and you generally will only see one or two index buffers per file.
 
==== Header ====
 
{| class="wikitable"
! Offset
! Size
! Description
|-
| 0x0
| 24
| '''"IBUF" [[Section Header (Tropical Freeze)|section header]]
|-
| 0x18
| 4
| Index buffer count
|-
| 0x1C
| colspan=2 | End of IBUF header
|}
|}
==== Index Buffer ====
{| class="wikitable"
! Offset
! Size
! Description
|-
| 0x0
| 4
| '''Format''' (1 means unsigned short; 2 means unsigned long)
|-
| 0x4
| colspan=2 | End of index buffer
|}
=== GPU ===
The GPU section contains raw buffer data that's fed to the GPU. It's essentially just a giant blob with all the vertex and index buffers laid out next to each other. The tricky part is, all the buffer data is LZSS-compressed, and not only is the metadata required to decompress it is stored in the pak, rather than in the model files themselves, but that metadata is also the only way to distinguish the different buffers from each other (especially the index buffers, since they have no count value you can use to calculate the size of the buffer).
As such, this section can't be read correctly if the model file is unpacked and completely left as-is; it needs to be either read directly from the pak, or the metadata needs to be included in the file in some way. A good unpacker should append the metadata to the end of the file.
Note: Page explaining the compression algorithm and how to decompress it is coming soon.
== PAK Metadata ==
The pak metadata for the model formats contains mainly information related to the size and layout of the GPU section, and the metadata required to locate and decompress specific buffers within it.
{| class="wikitable"
! Offset
! Size
! Description
|-
| 0x0
| 4
| Unknown; always 4?
|-
| 0x4
| 4
| '''GPU section offset'''
|-
| 0x8
| 4
| '''GPU chunk count''' (CC)
|-
| 0x8
| 8 × CC
| '''GPU chunk definitions'''
|-
| -
| 4
| '''Compressed vertex buffer count''' (VC)
|-
| -
| 0x10 × VC
| '''Vertex buffer definitions'''
|-
| -
| 4
| '''Compressed index buffer count''' (IC)
|-
| -
| 0x10 × IC
| '''Index buffer definitions'''
|-
| colspan = 3 | End of pak metadata
|}
=== GPU Chunk ===
For large models, the GPU section might be split up into multiple chunks, rather than read as one data buffer; all offsets into the GPU section will be relative to the start of the chosen chunk.
{| class="wikitable"
! Offset
! Size
! Description
|-
| 0x0
| 4
| '''Size'''
|-
| 0x4
| 4
| '''Offset'''
|-
| 0x8
| colspan=2 | End of GPU chunk definition
|}
=== Compressed Buffer ===
The format for compressed buffer definitions is the same regardless of buffer type (vertex/index).
{| class="wikitable"
! Offset
! Size
! Description
|-
| 0x0
| 4
| '''GPU chunk index'''
|-
| 0x4
| 4
| '''Start offset''' (relative to the start of the chosen GPU chunk)
|-
| 0x8
| 4
| '''Compressed size'''
|-
| 0xC
| 4
| '''Decompressed size'''
|-
| 0x10
| colspan=2 | End of compressed buffer definition
|}
[[Category:File Formats]]
[[Category:Donkey Kong Country: Tropical Freeze]]
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