WED entity properties

Materials can now be directly assigned to entities from within Wed.

WED add texture

DDS images can be used for textures in WAD files and folders.

Angle and position correction

WED uses the same position and angle system as the engine: entities' z positions correspond to their origin now (not to their lowest point, as before). Pan angles are 0 in the direction pointed by the X axis and increase their values counterclockwise.

D3d_transform

D3d_transform is now always activated. The A5 renderer was abandoned.