Wrath Blending

Blending States

When blending is enabled, Wrath of the Lich King always uses FUNC_ADD for the blending equation.

State	Name	Src	Dest	Comment
0	Blend_Opaque	ONE	ZERO	Blending disabled
1	Blend_AlphaKey	ONE	ZERO	Blending disabled
2	Blend_Alpha	SRC_ALPHA	ONE_MINUS_SRC_ALPHA	Standard blending func
3	Blend_Add	SRC_ALPHA	ONE	Additive blending func
4	Blend_Mod	DST_COLOR	ZERO	Modulative blending func
5	Blend_Mod2x	DST_COLOR	SRC_COLOR	2x modulative blending func
6	Blend_ModAdd	DST_COLOR	ONE	Modulative + additive
7	Blend_InvSrcAlphaAdd	ONE_MINUS_SRC_ALPHA	ONE

M2 Blending Modes

M2Material defines a blendingMode, but the blendingMode isn't a direct lookup in the blending states table.

For M2s without header flag 0x08 set, the M2Material blendingMode is looked up in a default mapping table:

Default Mapping Table

Value	State	State Name	Example
0	0	Blend_Opaque	WORLD\EXPANSION01\DOODADS\GENERIC\DRAENEI\LAMPPOSTS\DR_LAMPPOST_01.m2
1	1	Blend_AlphaKey	World\GENERIC\NIGHTELF\PASSIVE DOODADS\LAMPS\KalidarStreetLamp02.m2
2	2	Blend_Alpha	WORLD\EXPANSION01\DOODADS\GENERIC\DRAENEI\LAMPPOSTS\DR_LAMPPOST_01.m2
3	?	?	?
4	3	Blend_Add	World\GENERIC\NIGHTELF\PASSIVE DOODADS\LAMPS\KalidarStreetLamp02.m2
5	4	Blend_Mod	WORLD\EXPANSION01\DOODADS\THEEXODAR\PASSIVEDOODADS\LIGHT_SCONCES\EXODAR_SCONCE_MAGENTA.M2
6	5	Blend_Mod2x	World\GENERIC\GNOME\PASSIVE DOODADS\GNOMEMACHINE\GnomeSubwayGlass.m2

M2 Fog Modes

Because blending modes change how color is applied, fog color needs to be taken into account for more interesting blending modes. The client does this with the s_fogModeList table.

On-Disk Blending Mode Value	State	State Name	Fog Mode	Action
4	3	Blend_Add	2	Override fog color to 0x000000 (black)
5	4	Blend_Mod	3*	Override fog color to 0xFFFFFF (white)
6	5	Blend_Mod2x	4*	Override fog color to 0x808080 (half white)

* indicates theory, not tested