Sets or removes a category that this sprite can collide with. Sprites are assigned categories using SetSpriteCategoryBit. There are 16 categories, a value of 1 for that category represents that this sprite will collide with sprites from that category and 0 that it will not collide with that category, regardless of which category this sprite itself belongs to. By default all sprites belong to category 1 and collide with all categories. This command is similar to SetSpriteCategoryBits except this command sets one category at a time whilst that command sets them all at once using a bit mask.
By default this sets all shapes to the same value, you can set this value on a per shape basis by specifying a shapeID value greater than 0. Shape IDs start at 1 for the first shape, with shapeID 0 meaning apply it to all shapes.
SetSpriteCollideBit( iSpriteIndex, category, flag, shapeID )
SetSpriteCollideBit( iSpriteIndex, category, flag )