libakgl/include/akgl/iterator.h

/**
 * @file iterator.h
 * @brief The work order handed to a registry sweep.
 *
 * There is no iterator object with a `next()` on it. Traversal is SDL's --
 * `SDL_EnumerateProperties` over a registry -- and this struct is the `userdata`
 * carried into each callback, telling it *which* entries to touch and *what* to
 * do to each one. akgl_registry_iterate_actor and
 * akgl_registry_iterate_character are the callbacks that read it;
 * akgl_game_update, akgl_physics_simulate, and akgl_render_2d_draw_world are the
 * entry points that take one.
 *
 * The operations are independent bits, not an enum: a single sweep can update,
 * scale, and render, and they run in that fixed order regardless of how the bits
 * were set. Passing `NULL` where an `akgl_Iterator *` is expected is not an
 * error at the top-level entry points -- each substitutes its own default set --
 * but it *is* an error once inside a callback.
 */

#ifndef _AKGL_ITERATOR_H_
#define _AKGL_ITERATOR_H_

/** @brief Selects operations and an optional layer for actor traversal. */
typedef struct {
    uint32_t flags;     /**< Bitwise OR of the `AKGL_ITERATOR_OP_*` values below. */
    uint8_t layerid;    /**< Layer to restrict the sweep to. Read only when #AKGL_ITERATOR_OP_LAYERMASK is set. */
} akgl_Iterator;

#define AKGL_ITERATOR_OP_UPDATE                1                    // 1    Call the actor's updatefunc
#define AKGL_ITERATOR_OP_RENDER                1 << 1               // 2    Call the actor's renderfunc
#define AKGL_ITERATOR_OP_RELEASE               1 << 2               // 4    Release the object back to its heap layer
#define AKGL_ITERATOR_OP_LAYERMASK             1 << 3               // 8    Skip anything whose layer != layerid
#define AKGL_ITERATOR_OP_TILEMAPSCALE          1 << 4               // 16   Scale actors to the tilemap; otherwise force scale 1.0
#define AKGL_ITERATOR_OP_UNDEFINED_5           1 << 5               // 32
#define AKGL_ITERATOR_OP_UNDEFINED_6           1 << 6               // 64
#define AKGL_ITERATOR_OP_UNDEFINED_7           1 << 7               // 128
#define AKGL_ITERATOR_OP_UNDEFINED_8           1 << 8               // 256
#define AKGL_ITERATOR_OP_UNDEFINED_9           1 << 9               // 512
#define AKGL_ITERATOR_OP_UNDEFINED_10          1 << 10              // 1024
#define AKGL_ITERATOR_OP_UNDEFINED_11          1 << 11              // 2048
#define AKGL_ITERATOR_OP_UNDEFINED_12          1 << 12              // 4096
#define AKGL_ITERATOR_OP_UNDEFINED_13          1 << 13              // 8192
#define AKGL_ITERATOR_OP_UNDEFINED_14          1 << 14              // 16384
#define AKGL_ITERATOR_OP_UNDEFINED_15          1 << 15              // 32768
#define AKGL_ITERATOR_OP_UNDEFINED_16          1 << 16              // 65536
#define AKGL_ITERATOR_OP_UNDEFINED_17          1 << 17              // 131072
#define AKGL_ITERATOR_OP_UNDEFINED_18          1 << 18              // 262144
#define AKGL_ITERATOR_OP_UNDEFINED_19          1 << 19              // 524288
#define AKGL_ITERATOR_OP_UNDEFINED_20          1 << 20              // 1048576
#define AKGL_ITERATOR_OP_UNDEFINED_21          1 << 21              // 2097152
#define AKGL_ITERATOR_OP_UNDEFINED_22          1 << 22              // 4194304
#define AKGL_ITERATOR_OP_UNDEFINED_23          1 << 23              // 8388608
#define AKGL_ITERATOR_OP_UNDEFINED_24          1 << 24              // 16777216
#define AKGL_ITERATOR_OP_UNDEFINED_25          1 << 25              // 33554432
#define AKGL_ITERATOR_OP_UNDEFINED_26          1 << 26              // 67108864
#define AKGL_ITERATOR_OP_UNDEFINED_27          1 << 27              // 134217728
#define AKGL_ITERATOR_OP_UNDEFINED_28          1 << 28              // 268435456
#define AKGL_ITERATOR_OP_UNDEFINED_29          1 << 29              // 536870912
#define AKGL_ITERATOR_OP_UNDEFINED_30          1 << 30              // 1073741824
#define AKGL_ITERATOR_OP_UNDEFINED_31          1 << 31              // 2147483648


#endif // _AKGL_ITERATOR_H_