typedef struct ResolverObject {

	byte callback;

	uint32 callback_param1;

	uint32 callback_param2;

	byte trigger;

	uint32 last_value;

	uint32 reseed;

	VarSpriteGroupScope scope;

	union {

		struct {

			const struct Vehicle *self;

			const struct Vehicle *parent;

		} vehicle;

		struct {

			TileIndex tile;

			const struct Station *st;

			const struct StationSpec *statspec;

		} station;

	};

	uint32 (*GetRandomBits)(const struct ResolverObject*);

	uint32 (*GetTriggers)(const struct ResolverObject*);

	void (*SetTriggers)(const struct ResolverObject*, int);

	uint32 (*GetVariable)(const struct ResolverObject*, byte, byte);

	uint32 (*ResolveReal)(const struct ResolverObject*, uint, uint, bool*);

} ResolverObject;

/* Base sprite group resolver */

const SpriteGroup *Resolve(const SpriteGroup *group, ResolverObject *object);