- vol0 = (1.0f-air)*attn*(1.0f-slide),
- vol1 = air *attn,
- vol2 = (1.0f-air)*attn*slide;
+ grind = player_skate.activity == k_skate_activity_grind,
+ vol0 = (1.0f-air)*attn*(1.0f-slide)*(1.0f-grind),
+ vol1 = air *attn*(1.0f-grind),
+ vol2 = (1.0f-air)*attn*slide*(1.0f-grind),
+ vol4 = grind*2.0f;