descent2/SOURCE/2D/CLIP.H

/*
THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
SOFTWARE CORPORATION ("PARALLAX").  PARALLAX, IN DISTRIBUTING THE CODE TO
END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
IN USING, DISPLAYING,  AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
FREE PURPOSES.  IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES.  THE END-USER UNDERSTANDS
AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.  
COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
*/


#define MIN(a,b)        (((a) < (b)) ? (a) : (b))
#define MAX(a,b)        (((a) > (b)) ? (a) : (b))
#define IABS(x)         (((x) < 0) ?  -(x) : (x))

#define EXCHG(a,b) do {                                                 \
    int __temp__ = (a);                                                 \
    (a) = (b);                                                          \
    (b) = __temp__;                                                     \
} while(0)

// sort two values
#define SORT2(a,b) do {                                                 \
    if((a) > (b)) EXCHG(a,b);                                           \
} while(0)

# define SCALE(var,arg,num,den)                                         \
    ((var) = ((arg) * (num)) / (den))

# define USCALE(var,arg,num,den)                                        \
	((var) = ((unsigned)(arg) * (unsigned)(num)) / (unsigned)(den))

# define FSCALE(var,arg,num,den) ((var) = fixmuldiv((arg),(num),(den)))

#define CLIPDOT(xx,yy,WHEN_OUTSIDE,WHEN_CLIPPED) {                                              \
    if((xx > XMAX) || (xx < XMIN)) { WHEN_OUTSIDE; }  \
    if((yy > YMAX) || (yy < YMIN)) { WHEN_OUTSIDE; }  \
}

#define CLIPHLINE(x1,x2,yy,WHEN_OUTSIDE,WHEN_CLIPPED) {                                         \
    if(x1 > x2) EXCHG(x1,x2);                                           \
    if((x1 > XMAX) || (x2 < XMIN)) { WHEN_OUTSIDE; }  \
    if((yy > YMAX) || (yy < YMIN)) { WHEN_OUTSIDE; }  \
    if(x1 < XMIN) { x1 = XMIN; WHEN_CLIPPED; }        \
    if(x2 > XMAX) { x2 = XMAX; WHEN_CLIPPED; }        \
}

#define CLIPVLINE(xx,y1,y2,WHEN_OUTSIDE,WHEN_CLIPPED) {                                         \
    if(y1 > y2) EXCHG(y1,y2);                                           \
    if((xx > XMAX) || (xx < XMIN)) { WHEN_OUTSIDE; }  \
    if((y1 > YMAX) || (y2 < YMIN)) { WHEN_OUTSIDE; }  \
    if(y1 < YMIN) { y1 = YMIN; WHEN_CLIPPED; }        \
    if(y2 > YMAX) { y2 = YMAX; WHEN_CLIPPED; }        \
}

#define CLIPBOX(x1,y1,x2,y2,WHEN_OUTSIDE,WHEN_CLIPPED) {                               \
    if(x1 > x2) EXCHG(x1,x2);                                           \
    if(y1 > y2) EXCHG(y1,y2);                                           \
    if((x1 > XMAX) || (x2 < 0)) { WHEN_OUTSIDE; }                 \
    if((y1 > YMAX) || (y2 < 0)) { WHEN_OUTSIDE; }                 \
    if(x1 < 0) { x1 = 0; WHEN_CLIPPED; }                                \
    if(y1 < 0) { y1 = 0; WHEN_CLIPPED; }                                \
    if(x2 > XMAX) { x2 = XMAX; WHEN_CLIPPED; }              \
    if(y2 > YMAX) { y2 = YMAX; WHEN_CLIPPED; }              \
}
    
#define CLIPLINE(x1,y1,x2,y2,XMIN,YMIN,XMAX,YMAX,WHEN_OUTSIDE,WHEN_CLIPPED,MY_SCALE) do {                                    \
    register int temp;                                                  \
                                                                        \
    if(y1 > y2)                                                         \
        { EXCHG(y1,y2); EXCHG(x1,x2); }                                 \
    if((y2 < YMIN) || (y1 > YMAX))                    \
        { WHEN_OUTSIDE; }                                               \
    if(x1 < x2) {                                                       \
        if((x2 < XMIN) || (x1 > XMAX)) {              \
            WHEN_OUTSIDE;                                               \
        }                                                               \
        if(x1 < XMIN) {                                        \
			MY_SCALE(temp,(y2 - y1),(XMIN - x1),(x2 - x1));      \
            if((y1 += temp) > YMAX) { WHEN_OUTSIDE; }          \
            x1 = XMIN;                                         \
            WHEN_CLIPPED;                                               \
        }                                                               \
        if(x2 > XMAX) {                                        \
			MY_SCALE(temp,(y2 - y1),(x2 - XMAX),(x2 - x1));      \
            if((y2 -= temp) < YMIN) { WHEN_OUTSIDE; }          \
            x2 = XMAX;                                         \
            WHEN_CLIPPED;                                               \
        }                                                               \
        if(y1 < YMIN) {                                        \
			MY_SCALE(temp,(x2 - x1),(YMIN - y1),(y2 - y1));      \
            x1 += temp;                                                 \
            y1 = YMIN;                                         \
            WHEN_CLIPPED;                                               \
        }                                                               \
        if(y2 > YMAX) {                                        \
			MY_SCALE(temp,(x2 - x1),(y2 - YMAX),(y2 - y1));      \
            x2 -= temp;                                                 \
            y2 = YMAX;                                         \
            WHEN_CLIPPED;                                               \
        }                                                               \
    }                                                                   \
    else {                                                              \
        if((x1 < XMIN) || (x2 > XMAX)) {              \
            WHEN_OUTSIDE;                                               \
        }                                                               \
        if(x1 > XMAX) {                                        \
			MY_SCALE(temp,(y2 - y1),(x1 - XMAX),(x1 - x2));      \
            if((y1 += temp) > YMAX) { WHEN_OUTSIDE; }          \
            x1 = XMAX;                                         \
            WHEN_CLIPPED;                                               \
        }                                                               \
        if(x2 < XMIN) {                                        \
			MY_SCALE(temp,(y2 - y1),(XMIN - x2),(x1 - x2));      \
            if((y2 -= temp) < YMIN) { WHEN_OUTSIDE; }          \
            x2 = XMIN;                                         \
            WHEN_CLIPPED;                                               \
        }                                                               \
        if(y1 < YMIN) {                                        \
			MY_SCALE(temp,(x1 - x2),(YMIN - y1),(y2 - y1));      \
            x1 -= temp;                                                 \
            y1 = YMIN;                                         \
            WHEN_CLIPPED;                                               \
        }                                                               \
        if(y2 > YMAX) {                                        \
			MY_SCALE(temp,(x1 - x2),(y2 - YMAX),(y2 - y1));      \
            x2 += temp;                                                 \
            y2 = YMAX;                                         \
            WHEN_CLIPPED;                                               \
        }                                                               \
    }                                                                   \
} while(0)