BLS |
From WoWDev
Contents |
BLS Files
BLS specify specific instructions to the video card as to how to render parts of the world and how to do certain effects.
There are two major types of shaders: fragment shaders (also known as pixel shaders) and vertex shaders. Fragment shaders are executed on a per-pixel basis, thus can influence texture fetching and combining operations, whereas vertex shaders are executed on a per-vertex basis. These can change vertex positions to achieve mesh animation, particle systems, and texture animation.
BLS files can be found in misc.MPQ under Shaders\Pixel\. They are referenced directly from WoW.exe, so there is no client database pointing to them.
File format
Header
Main header (0xC bytes)
| Offset | Type | Description |
|---|---|---|
| 0x0 | char[4] | Chunk identifier - in reverse character order: "SVXG" in case of a vertex shader, "SPXG" in case of a fragment shader |
| 0x4 | uint32 | Always 0x10003 - version 1.3 of format |
| 0x8 | uint32 | Permutation count |
After this is a sub header (0x18 bytes for VS, 0x30 bytes for PS) immediatly after main header. This is a table of offsets, pointing to permutation blocks for up to six (in case of VS) or 12 (in case of PS) shading language profiles.
Vertex program profiles
| ID | Description |
|---|---|
| 1 | vs2_0 (Direct3D) |
| 2 | ARBvp1 (OpenGL) |
Pixel/fragment program profiles
| ID | Description |
|---|---|
| 0 | ps1_1 (Direct3D) |
| 1 | ps1_2 (Direct3D) |
| 2 | ps1_3 (Direct3D) |
| 3 | ps1_4 (Direct3D) |
| 4 | ps2_0 (Direct3D) |
| 10 | ARBfp1 (OpenGL) |
Permutation block
16 bytes header
| Offset | Type | Description |
|---|---|---|
| 0x0 | uint32 | Generally 0, if > 0 there are (0x90 * the value of this uint32) bytes of extra header after this byte (some parameter name?) |
| 0x4 | uint32 | Generally 0, if > 0 there are (0x90 * the value of this uint32) bytes of extra header after this byte (some texture name?) (Ive seen this go up to 5) |
| 0x8 | uint32 | Unknown flag; always 0 or 2 |
| 0xC | uint32 | Block size |
After this are blocksize bytes, then starts another similar block. For direct3d these data bytes appear to be a binary representation of the shader, for GL they are ARBVB text.
