#include "sprite.h"

#include "SpriteLayer.proto.h"

typedef struct spriteLayer {

    struct spriteLayer  *next;      // the layer in back of this one

    struct spriteLayer  *prev;      // the layer in front of this one

    spritePtr   *sprites;           // the sprites in this layer

    GWorldPtr   tween;              // the work GWorld for this layer

    GWorldPtr   backdrop;           // the background for this layer

    WindowPtr   window;             // the window this layer ends up in

    long        layerFlags;

    long        layerID;

    long        layerRefcon;

} spriteLayer, *spriteLayerPtr;

static spriteLayerPtr   MasterSpriteHead;

static spriteLayerPtr   MasterSpriteTail;

OSErr   CreateSpriteLayer(spriteLayerPtr *retSprite, 

                            GWorldPtr tween, 

                            GWorldPtr backdrop, 

                            WindowPtr spriteWin)

{

    OSErr           err;

    spriteLayerPtr  sl;

    sl = (spriteLayerPtr)NewPtrClear(sizeof(spriteLayer));

    if(!sl) {

        err = MemError();

        ErrMsgCode("\pCreateSpriteLayer NewPtrClear failed.",err);

    }

    if(err == noErr) {

        sl->tween = tween;

        sl->backdrop = backdrop;

        sl->window = spriteWin;

    }

    if(MasterSpriteTail) {

        sl->prev = MasterSpriteTail;

        MasterSpriteTail->next = sl;

        MasterSpriteTail = sl;

    } else {

        MasterSpriteHead = MasterSpriteTail = sl;

    }

    *retSprite = sl;

    return err;

}