1/*
2
3Copyright 1987, 1998  The Open Group
4
5Permission to use, copy, modify, distribute, and sell this software and its
6documentation for any purpose is hereby granted without fee, provided that
7the above copyright notice appear in all copies and that both that
8copyright notice and this permission notice appear in supporting
9documentation.
10
11The above copyright notice and this permission notice shall be included
12in all copies or substantial portions of the Software.
13
14THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
15OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
16MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
17IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
18OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20OTHER DEALINGS IN THE SOFTWARE.
21
22Except as contained in this notice, the name of The Open Group shall
23not be used in advertising or otherwise to promote the sale, use or
24other dealings in this Software without prior written authorization
25from 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
88typedef 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
98typedef 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
105typedef 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
119typedef 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
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
183extern _X_EXPORT Bool miCreateETandAET(
184    int /*count*/,
185    DDXPointPtr /*pts*/,
186    EdgeTable * /*ET*/,
187    EdgeTableEntry * /*AET*/,
188    EdgeTableEntry * /*pETEs*/,
189    ScanLineListBlock * /*pSLLBlock*/
190);
191
192extern _X_EXPORT void miloadAET(
193    EdgeTableEntry * /*AET*/,
194    EdgeTableEntry * /*ETEs*/
195);
196
197extern _X_EXPORT void micomputeWAET(
198    EdgeTableEntry * /*AET*/
199);
200
201extern _X_EXPORT int miInsertionSort(
202    EdgeTableEntry * /*AET*/
203);
204
205extern _X_EXPORT void miFreeStorage(
206    ScanLineListBlock * /*pSLLBlock*/
207);
208