xorg-server-1.4/mi/mipoly.h

   1 /*
   2
   3 Copyright 1987, 1998  The Open Group
   4
   5 Permission to use, copy, modify, distribute, and sell this software and its
   6 documentation for any purpose is hereby granted without fee, provided that
   7 the above copyright notice appear in all copies and that both that
   8 copyright notice and this permission notice appear in supporting
   9 documentation.
  10
  11 The above copyright notice and this permission notice shall be included
  12 in all copies or substantial portions of the Software.
  13
  14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  15 OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  16 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  17 IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
  18 OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20 OTHER DEALINGS IN THE SOFTWARE.
  21
  22 Except as contained in this notice, the name of The Open Group shall
  23 not be used in advertising or otherwise to promote the sale, use or
  24 other dealings in this Software without prior written authorization
  25 from The Open Group.
  26
  27 */
  28
  29
  30 /*
  31  *     fill.h
  32  *
  33  *     Created by Brian Kelleher; Oct 1985
  34  *
  35  *     Include file for filled polygon routines.
  36  *
  37  *     These are the data structures needed to scan
  38  *     convert regions.  Two different scan conversion
  39  *     methods are available -- the even-odd method, and
  40  *     the winding number method.
  41  *     The even-odd rule states that a point is inside
  42  *     the polygon if a ray drawn from that point in any
  43  *     direction will pass through an odd number of
  44  *     path segments.
  45  *     By the winding number rule, a point is decided
  46  *     to be inside the polygon if a ray drawn from that
  47  *     point in any direction passes through a different
  48  *     number of clockwise and counter-clockwise path
  49  *     segments.
  50  *
  51  *     These data structures are adapted somewhat from
  52  *     the algorithm in (Foley/Van Dam) for scan converting
  53  *     polygons.
  54  *     The basic algorithm is to start at the top (smallest y)
  55  *     of the polygon, stepping down to the bottom of
  56  *     the polygon by incrementing the y coordinate.  We
  57  *     keep a list of edges which the current scanline crosses,
  58  *     sorted by x.  This list is called the Active Edge Table (AET)
  59  *     As we change the y-coordinate, we update each entry in
  60  *     in the active edge table to reflect the edges new xcoord.
  61  *     This list must be sorted at each scanline in case
  62  *     two edges intersect.
  63  *     We also keep a data structure known as the Edge Table (ET),
  64  *     which keeps track of all the edges which the current
  65  *     scanline has not yet reached.  The ET is basically a
  66  *     list of ScanLineList structures containing a list of
  67  *     edges which are entered at a given scanline.  There is one
  68  *     ScanLineList per scanline at which an edge is entered.
  69  *     When we enter a new edge, we move it from the ET to the AET.
  70  *
  71  *     From the AET, we can implement the even-odd rule as in
  72  *     (Foley/Van Dam).
  73  *     The winding number rule is a little trickier.  We also
  74  *     keep the EdgeTableEntries in the AET linked by the
  75  *     nextWETE (winding EdgeTableEntry) link.  This allows
  76  *     the edges to be linked just as before for updating
  77  *     purposes, but only uses the edges linked by the nextWETE
  78  *     link as edges representing spans of the polygon to
  79  *     drawn (as with the even-odd rule).
  80  */
  81
  82 /*
  83  * for the winding number rule
  84  */
  85 #define CLOCKWISE          1
  86 #define COUNTERCLOCKWISE  -1
  87
  88 typedef struct _EdgeTableEntry {
  89      int ymax;             /* ycoord at which we exit this edge. */
  90      BRESINFO bres;        /* Bresenham info to run the edge     */
  91      struct _EdgeTableEntry *next;       /* next in the list     */
  92      struct _EdgeTableEntry *back;       /* for insertion sort   */
  93      struct _EdgeTableEntry *nextWETE;   /* for winding num rule */
  94      int ClockWise;        /* flag for winding number rule       */
  95 } EdgeTableEntry;
  96
  97
  98 typedef struct _ScanLineList{
  99      int scanline;              /* the scanline represented */
 100      EdgeTableEntry *edgelist;  /* header node              */
 101      struct _ScanLineList *next;  /* next in the list       */
 102 } ScanLineList;
 103
 104
 105 typedef struct {
 106      int ymax;                 /* ymax for the polygon     */
 107      int ymin;                 /* ymin for the polygon     */
 108      ScanLineList scanlines;   /* header node              */
 109 } EdgeTable;
 110
 111
 112 /*
 113  * Here is a struct to help with storage allocation
 114  * so we can allocate a big chunk at a time, and then take
 115  * pieces from this heap when we need to.
 116  */
 117 #define SLLSPERBLOCK 25
 118
 119 typedef struct _ScanLineListBlock {
 120      ScanLineList SLLs[SLLSPERBLOCK];
 121      struct _ScanLineListBlock *next;
 122 } ScanLineListBlock;
 123
 124 /*
 125  * number of points to buffer before sending them off
 126  * to scanlines() :  Must be an even number
 127  */
 128 #define NUMPTSTOBUFFER 200
 129
 130 \f
 131 /*
 132  *
 133  *     a few macros for the inner loops of the fill code where
 134  *     performance considerations don't allow a procedure call.
 135  *
 136  *     Evaluate the given edge at the given scanline.
 137  *     If the edge has expired, then we leave it and fix up
 138  *     the active edge table; otherwise, we increment the
 139  *     x value to be ready for the next scanline.
 140  *     The winding number rule is in effect, so we must notify
 141  *     the caller when the edge has been removed so he
 142  *     can reorder the Winding Active Edge Table.
 143  */
 144 #define EVALUATEEDGEWINDING(pAET, pPrevAET, y, fixWAET) { \
 145    if (pAET->ymax == y) {          /* leaving this edge */ \
 146       pPrevAET->next = pAET->next; \
 147       pAET = pPrevAET->next; \
 148       fixWAET = 1; \
 149       if (pAET) \
 150          pAET->back = pPrevAET; \
 151    } \
 152    else { \
 153       BRESINCRPGONSTRUCT(pAET->bres); \
 154       pPrevAET = pAET; \
 155       pAET = pAET->next; \
 156    } \
 157 }
 158
 159
 160 /*
 161  *     Evaluate the given edge at the given scanline.
 162  *     If the edge has expired, then we leave it and fix up
 163  *     the active edge table; otherwise, we increment the
 164  *     x value to be ready for the next scanline.
 165  *     The even-odd rule is in effect.
 166  */
 167 #define EVALUATEEDGEEVENODD(pAET, pPrevAET, y) { \
 168    if (pAET->ymax == y) {          /* leaving this edge */ \
 169       pPrevAET->next = pAET->next; \
 170       pAET = pPrevAET->next; \
 171       if (pAET) \
 172          pAET->back = pPrevAET; \
 173    } \
 174    else { \
 175       BRESINCRPGONSTRUCT(pAET->bres); \
 176       pPrevAET = pAET; \
 177       pAET = pAET->next; \
 178    } \
 179 }
 180
 181 /* mipolyutil.c */
 182
 183 extern Bool miCreateETandAET(
 184     int /*count*/,
 185     DDXPointPtr /*pts*/,
 186     EdgeTable * /*ET*/,
 187     EdgeTableEntry * /*AET*/,
 188     EdgeTableEntry * /*pETEs*/,
 189     ScanLineListBlock * /*pSLLBlock*/
 190 );
 191
 192 extern void miloadAET(
 193     EdgeTableEntry * /*AET*/,
 194     EdgeTableEntry * /*ETEs*/
 195 );
 196
 197 extern void micomputeWAET(
 198     EdgeTableEntry * /*AET*/
 199 );
 200
 201 extern int miInsertionSort(
 202     EdgeTableEntry * /*AET*/
 203 );
 204
 205 extern void miFreeStorage(
 206     ScanLineListBlock * /*pSLLBlock*/
 207 );