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vtex_c File Structure

Headers

Main File

• 4 bytes: size of entire file
• 4 bytes: header version
• 4 bytes: ?
• 4 bytes: number of blocks

Block Headers

• 4 bytes: Block name (RERL, REDI, NTRO, and/or DATA). RERL seems to be optional.
• 4 bytes: offset from this location where this block starts
• 4 bytes: length of block

Block Types

• RERL: Lists external and deferred resources by ID. Not typically used in vtex_c files.
• REDI: Resource Edit Info Block. Seems to be stuff related to how the file was compiled.
• NTRO: Resource Introspection Manifest. This block holds the keys for the DATA block's values.
• DATA: The data values.
• After DATA: Raw binary data. Image data in the case of vtex_c.

Block: DATA

• 2 bytes: texture width
• 2 bytes: texture height
• 2 bytes: texture depth
• 1 byte: texture format
• 1 byte: mip count
• 6 bytes: ???
• 8 bytes: texture flags
• 4 bytes: texture reflectivity
• 15 bytes: ???
• x bytes: fallback texture bits

Raw Binary Data

• Starts immediately after the DATA block.
• Organized consecutively by mip level, largest number (smallest in size) to smallest number (largest in size).
• Mip level 0 (largest mip image size) is listed last with its last byte being the last byte in the vtex_c file. This is the mip level that is extracted to the .tga file.
• Each mip level can have multiple images depending on the texture depth and if it is a cubemap or not.
• Each image is stored as DXT1 or DXT5 (so far) raw binary data with no DDS/DXT headers.
• Normal maps are stored in DXT5-nm format with the Red channel in the Alpha channel, the Blue channel removed, and the Green channel unchanged. The Blue channel will need to be recomputed at run-time in the pixel shader. Good info about DXT5-nm: http://tech-artists.org/wiki/Normal_map_compression