| 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 | * fill.h |
| 31 | * |
| 32 | * Created by Brian Kelleher; Oct 1985 |
| 33 | * |
| 34 | * Include file for filled polygon routines. |
| 35 | * |
| 36 | * These are the data structures needed to scan |
| 37 | * convert regions. Two different scan conversion |
| 38 | * methods are available -- the even-odd method, and |
| 39 | * the winding number method. |
| 40 | * The even-odd rule states that a point is inside |
| 41 | * the polygon if a ray drawn from that point in any |
| 42 | * direction will pass through an odd number of |
| 43 | * path segments. |
| 44 | * By the winding number rule, a point is decided |
| 45 | * to be inside the polygon if a ray drawn from that |
| 46 | * point in any direction passes through a different |
| 47 | * number of clockwise and counter-clockwise path |
| 48 | * segments. |
| 49 | * |
| 50 | * These data structures are adapted somewhat from |
| 51 | * the algorithm in (Foley/Van Dam) for scan converting |
| 52 | * polygons. |
| 53 | * The basic algorithm is to start at the top (smallest y) |
| 54 | * of the polygon, stepping down to the bottom of |
| 55 | * the polygon by incrementing the y coordinate. We |
| 56 | * keep a list of edges which the current scanline crosses, |
| 57 | * sorted by x. This list is called the Active Edge Table (AET) |
| 58 | * As we change the y-coordinate, we update each entry in |
| 59 | * in the active edge table to reflect the edges new xcoord. |
| 60 | * This list must be sorted at each scanline in case |
| 61 | * two edges intersect. |
| 62 | * We also keep a data structure known as the Edge Table (ET), |
| 63 | * which keeps track of all the edges which the current |
| 64 | * scanline has not yet reached. The ET is basically a |
| 65 | * list of ScanLineList structures containing a list of |
| 66 | * edges which are entered at a given scanline. There is one |
| 67 | * ScanLineList per scanline at which an edge is entered. |
| 68 | * When we enter a new edge, we move it from the ET to the AET. |
| 69 | * |
| 70 | * From the AET, we can implement the even-odd rule as in |
| 71 | * (Foley/Van Dam). |
| 72 | * The winding number rule is a little trickier. We also |
| 73 | * keep the EdgeTableEntries in the AET linked by the |
| 74 | * nextWETE (winding EdgeTableEntry) link. This allows |
| 75 | * the edges to be linked just as before for updating |
| 76 | * purposes, but only uses the edges linked by the nextWETE |
| 77 | * link as edges representing spans of the polygon to |
| 78 | * drawn (as with the even-odd rule). |
| 79 | */ |
| 80 | |
| 81 | /* |
| 82 | * for the winding number rule |
| 83 | */ |
| 84 | #define CLOCKWISE 1 |
| 85 | #define COUNTERCLOCKWISE -1 |
| 86 | |
| 87 | typedef struct _EdgeTableEntry { |
| 88 | int ymax; /* ycoord at which we exit this edge. */ |
| 89 | BRESINFO bres; /* Bresenham info to run the edge */ |
| 90 | struct _EdgeTableEntry *next; /* next in the list */ |
| 91 | struct _EdgeTableEntry *back; /* for insertion sort */ |
| 92 | struct _EdgeTableEntry *nextWETE; /* for winding num rule */ |
| 93 | int ClockWise; /* flag for winding number rule */ |
| 94 | } EdgeTableEntry; |
| 95 | |
| 96 | typedef struct _ScanLineList { |
| 97 | int scanline; /* the scanline represented */ |
| 98 | EdgeTableEntry *edgelist; /* header node */ |
| 99 | struct _ScanLineList *next; /* next in the list */ |
| 100 | } ScanLineList; |
| 101 | |
| 102 | typedef struct { |
| 103 | int ymax; /* ymax for the polygon */ |
| 104 | int ymin; /* ymin for the polygon */ |
| 105 | ScanLineList scanlines; /* header node */ |
| 106 | } EdgeTable; |
| 107 | |
| 108 | /* |
| 109 | * Here is a struct to help with storage allocation |
| 110 | * so we can allocate a big chunk at a time, and then take |
| 111 | * pieces from this heap when we need to. |
| 112 | */ |
| 113 | #define SLLSPERBLOCK 25 |
| 114 | |
| 115 | typedef struct _ScanLineListBlock { |
| 116 | ScanLineList SLLs[SLLSPERBLOCK]; |
| 117 | struct _ScanLineListBlock *next; |
| 118 | } ScanLineListBlock; |
| 119 | |
| 120 | /* |
| 121 | * number of points to buffer before sending them off |
| 122 | * to scanlines() : Must be an even number |
| 123 | */ |
| 124 | #define NUMPTSTOBUFFER 200 |
| 125 | \f |
| 126 | /* |
| 127 | * |
| 128 | * a few macros for the inner loops of the fill code where |
| 129 | * performance considerations don't allow a procedure call. |
| 130 | * |
| 131 | * Evaluate the given edge at the given scanline. |
| 132 | * If the edge has expired, then we leave it and fix up |
| 133 | * the active edge table; otherwise, we increment the |
| 134 | * x value to be ready for the next scanline. |
| 135 | * The winding number rule is in effect, so we must notify |
| 136 | * the caller when the edge has been removed so he |
| 137 | * can reorder the Winding Active Edge Table. |
| 138 | */ |
| 139 | #define EVALUATEEDGEWINDING(pAET, pPrevAET, y, fixWAET) { \ |
| 140 | if (pAET->ymax == y) { /* leaving this edge */ \ |
| 141 | pPrevAET->next = pAET->next; \ |
| 142 | pAET = pPrevAET->next; \ |
| 143 | fixWAET = 1; \ |
| 144 | if (pAET) \ |
| 145 | pAET->back = pPrevAET; \ |
| 146 | } \ |
| 147 | else { \ |
| 148 | BRESINCRPGONSTRUCT(pAET->bres); \ |
| 149 | pPrevAET = pAET; \ |
| 150 | pAET = pAET->next; \ |
| 151 | } \ |
| 152 | } |
| 153 | |
| 154 | /* |
| 155 | * Evaluate the given edge at the given scanline. |
| 156 | * If the edge has expired, then we leave it and fix up |
| 157 | * the active edge table; otherwise, we increment the |
| 158 | * x value to be ready for the next scanline. |
| 159 | * The even-odd rule is in effect. |
| 160 | */ |
| 161 | #define EVALUATEEDGEEVENODD(pAET, pPrevAET, y) { \ |
| 162 | if (pAET->ymax == y) { /* leaving this edge */ \ |
| 163 | pPrevAET->next = pAET->next; \ |
| 164 | pAET = pPrevAET->next; \ |
| 165 | if (pAET) \ |
| 166 | pAET->back = pPrevAET; \ |
| 167 | } \ |
| 168 | else { \ |
| 169 | BRESINCRPGONSTRUCT(pAET->bres); \ |
| 170 | pPrevAET = pAET; \ |
| 171 | pAET = pAET->next; \ |
| 172 | } \ |
| 173 | } |
| 174 | |
| 175 | /* mipolyutil.c */ |
| 176 | |
| 177 | extern _X_EXPORT Bool miCreateETandAET(int /*count */ , |
| 178 | DDXPointPtr /*pts */ , |
| 179 | EdgeTable * /*ET*/, |
| 180 | EdgeTableEntry * /*AET*/, |
| 181 | EdgeTableEntry * /*pETEs */ , |
| 182 | ScanLineListBlock * /*pSLLBlock */ |
| 183 | ); |
| 184 | |
| 185 | extern _X_EXPORT void miloadAET(EdgeTableEntry * /*AET*/, EdgeTableEntry * /*ETEs */ |
| 186 | ); |
| 187 | |
| 188 | extern _X_EXPORT void micomputeWAET(EdgeTableEntry * /*AET*/); |
| 189 | |
| 190 | extern _X_EXPORT int miInsertionSort(EdgeTableEntry * /*AET*/); |
| 191 | |
| 192 | extern _X_EXPORT void miFreeStorage(ScanLineListBlock * /*pSLLBlock */ |
| 193 | ); |