BG类层，立绘层，字符层，ui层。目前还没有好的方法将这些层统一为一种概念，排序也没有考虑，Game逻辑部分管理BG, ACTOR层。

typedef enum {

    SF_BAD = -,

    SF_HIDE,    // effect使用

    SF_PIC,    // bg, actor

    SF_POLY,    // 绘制多边形

    SF_SHEET    // 绘制字符，粒子类

}surfaceType_t;

bg及立绘层定义

struct drawSurf_t {

    int     sort;

    surfaceType_t    *surface;

    drawSurf_t() : sort(-), surface(NULL) {}

};

struct srfPic_t {

    surfaceType_t    surfaceType;

    ALLEGRO_BITMAP    *image;

    float    sx, sy, sw, sh;     //size

    ALLEGRO_COLOR    color;

    float    dx, dy, dw, dh;

    float    cx, cy, angle;

    void Clear() {

        surfaceType = SF_BAD;

        image = NULL;

        sx = sy = sw = sh = 0.0f;

        color.a = ;

        color.r = ;

        color.g = ;

        color.b = ;

        dx = dy = dw = dh = ;

        cx = cy = angle = ;

    }

    srfPic_t() {

        Clear();

    }

};

struct sheetSize_t {

    float    sx, sy, sw, sh;

    float    dx, dy;

};

struct srfSheet_t {

    surfaceType_t    surfaceType;

    ALLEGRO_BITMAP    *image;

    ALLEGRO_COLOR    color;

    int     numSheets;

    sheetSize_t     *sheets;

    void Clear() {

    surfaceType = SF_BAD;

    image = NULL;

    color.a = ;

    color.r = ;

    color.g = ;

    color.b = ;

    numSheets = ;

    sheets = NULL;

    }

    srfSheet_t() {

        Clear();

    }

};