M2/Rendering
WIP
Blending Modes
Wrath of the Lich King and Cataclysm do not use separate alpha blending. Later expansion clients likely do use separate alpha blending.
Blend_BlendAdd was added after Cataclysm.
Values for functions match OpenGL, but each has a D3D equivalent.
| blendStateIdx | Mode | Blending Enabled | Src Color | Dest Color | Src Alpha | Dest Alpha |
|---|---|---|---|---|---|---|
| 0 | Blend_Opaque | Disabled | ONE | ZERO | ONE | ZERO |
| 1 | Blend_AlphaKey | Disabled | ONE | ZERO | ONE | ZERO |
| 2 | Blend_Alpha | Enabled | SRC_ALPHA | ONE_MINUS_SRC_ALPHA | ONE | ONE_MINUS_SRC_ALPHA |
| 3 | Blend_Add | Enabled | SRC_ALPHA | ONE | ZERO | ONE |
| 4 | Blend_Mod | Enabled | DST_COLOR | ZERO | DST_ALPHA | ZERO |
| 5 | Blend_Mod2x | Enabled | DST_COLOR | SRC_COLOR | DST_ALPHA | SRC_ALPHA |
| 6 | Blend_ModAdd | Enabled | DST_COLOR | ONE | DST_ALPHA | ONE |
| 7 | Blend_InvSrcAlphaAdd | Enabled | ONE_MINUS_SRC_ALPHA | ONE | ONE_MINUS_SRC_ALPHA | ONE |
| 8 | Blend_InvSrcAlphaOpaque | Enabled | ONE_MINUS_SRC_ALPHA | ZERO | ONE_MINUS_SRC_ALPHA | ZERO |
| 9 | Blend_SrcAlphaOpaque | Enabled | SRC_ALPHA | ZERO | SRC_ALPHA | ZERO |
| 10 | Blend_NoAlphaAdd | Enabled | ONE | ONE | ZERO | ONE |
| 11 | Blend_ConstantAlpha | Enabled | CONSTANT_ALPHA | ONE_MINUS_CONSTANT_ALPHA | CONSTANT_ALPHA | ONE_MINUS_CONSTANT_ALPHA |
| 12 | Blend_Screen | Enabled | ONE_MINUS_DST_COLOR | ONE | ONE | ZERO |
| 13 | Blend_BlendAdd | Enabled | ONE | ONE_MINUS_SRC_ALPHA | ONE | ONE_MINUS_SRC_ALPHA |
Credits: Deamon, for unearthing blending mode names and laying out the table; relaxok, for checking D3D state at runtime; schlumpf, for all the initial reversing work; fallenoak, for mapping Deamon's table to OpenGL enums.
Fog Modes
Because blending modes adjust how color is applied during a draw call, fog color often has to be modified accordingly. The client maps blending modes to fog modes using s_fogModeList.
Additionally, M2Material flag 0x02 causes fog mode 0 (disabled) to always be selected, regardless of blending mode.
The following fog modes were taken from Mists of Pandaria (build 15662).
| Fog Mode | Action | Blending Modes |
|---|---|---|
| 0 | Disable fog logic in shader | - |
| 1 | ? possibly: use fog color without changes ? | Blend_Opaque, Blend_AlphaKey, Blend_Alpha |
| 2 | Override fog color to 0x000000 (black) | Blend_Add, possibly: Blend_NoAlphaAdd |
| 3 | Override fog color to 0xFFFFFF (white) | Blend_Mod |
| 4 | Override fog color to 0x808080 (half white) | Blend_Mod2x |
| 5 | ? submerged camera related ? | - |
| 6 | ? liquid plane related ? | - |
Lighting Modes
Similar to fog modes above, blending modes also impact lighting. The client maps blending modes to lighting modes using s_shadedList.
Additionally, M2Material flag 0x01 always causes lighting mode 0 (disabled) to be selected.
The following lighting modes were taken from Mists of Pandaria (build 15662).
| Lighting Mode | Action | Blending Modes |
|---|---|---|
| 0 | Disable lighting logic in shader | Blend_Mod, Blend_Mod2x |
| 1 | Enable lighting logic in shader | Blend_Opaque, Blend_AlphaKey, Blend_Alpha, Blend_Add, possibly: Blend_NoAlphaAdd |