PK_boolean_material_t

typedef int PK_boolean_material_t;

Used in:

PK_BODY_boolean_o_t
PK_FACE_boolean_o_t
PK_FACE_instance_bodies_o_t

PK_boolean_material_t has three values:
    PK_boolean_material_none_c      neither side of face is solid material
    PK_boolean_material_inside_c    face normals point away from solid material
    PK_boolean_material_outside_c   face normals point into solid material
    PK_boolean_material_default_c   material side implied by body type