src/polymod.c

   1 /*
   2  * This program is free software: you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation, either version 3 of the License, or
   5  * (at your option) any later version.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  14  */
  15 #include "polymod.h"
  16
  17 #include "video.h"
  18 #include "gameglobals.h"
  19
  20
  21 typedef struct PolyPoint {
  22   int next; // -1: none
  23   int x;
  24 } PolyPoint;
  25
  26
  27 static int polyPointPoolSize = 0;
  28 static int polyPointPoolPos = 0;
  29 static PolyPoint *polyPointPool = NULL;
  30 static int polyScans[200]; // index of the first point of each scan; -1: none
  31 static int firstX, firstY;
  32 static int lastX, lastY;
  33 static int firstPoint;
  34
  35
  36 void polymodInitialize (void) {
  37   for (int f = 0; f < 200; ++f) polyScans[f] = -1;
  38   polyPointPool = NULL;
  39   polyPointPoolSize = 0;
  40   polyPointPoolPos = 0;
  41   firstPoint = 1;
  42 }
  43
  44
  45 void polymodDeinitialize (void) {
  46   if (polyPointPool != NULL) free(polyPointPool);
  47   polyPointPool = NULL;
  48   polyPointPoolSize = 0;
  49   polyPointPoolPos = 0;
  50   firstPoint = 1;
  51 }
  52
  53
  54 static inline int allocPolyPoint (int x, int next) {
  55   if (polyPointPoolPos+1 > polyPointPoolSize) {
  56     int newsz = polyPointPoolSize+8192;
  57     PolyPoint *nn = realloc(polyPointPool, sizeof(PolyPoint)*newsz);
  58     //
  59     if (nn == NULL) fatal("out of memory in polymod");
  60     polyPointPool = nn;
  61     polyPointPoolSize = newsz;
  62   }
  63   polyPointPool[polyPointPoolPos].x = x;
  64   polyPointPool[polyPointPoolPos].next = next;
  65   return polyPointPoolPos++;
  66 }
  67
  68
  69 static inline void insertPoint (int x, int y) {
  70   if (y >= 0 && y < 200) {
  71     int n;
  72     //
  73     //fprintf(stderr, "pt: (%d, %d)\n", x, y);
  74     if ((n = polyScans[y]) != -1) {
  75       int p;
  76       //
  77       for (p = -1; n != -1 && x > polyPointPool[n].x; p = n, n = polyPointPool[n].next) ;
  78       if (n != -1 && x == polyPointPool[n].x) return; // duplicate point
  79       if (p == -1) {
  80         // this is new first point
  81         //fprintf(stderr, " first\n");
  82         polyScans[y] = allocPolyPoint(x, n);
  83       } else {
  84         // insert new point after p; n is the next point
  85         //fprintf(stderr, " mid\n");
  86         polyPointPool[p].next = allocPolyPoint(x, n);
  87       }
  88     } else {
  89       // first
  90       //fprintf(stderr, " first\n");
  91       polyScans[y] = allocPolyPoint(x, -1);
  92     }
  93   }
  94 }
  95
  96
  97 static void lineDDA (int x0, int y0, int x1, int y1) {
  98   //fprintf(stderr, "*(%d,%d)-(%d,%d)\n", x0, y0, x1, y1);
  99   if (x0 == x1 && y0 == y1) return;
 100   //
 101   if (x0 == x1) {
 102     // straight vertical line
 103     if (y0 < y1) for (int y = y0; y < y1; ++y) insertPoint(x0, y);
 104     else for (int y = y0; y > y1; --y) insertPoint(x0, y);
 105     return;
 106   }
 107   //
 108   if (y0 == y1) {
 109     // straight horizontal line
 110     insertPoint(x0, y0);
 111     return;
 112   }
 113   // draw vertical
 114   if (y0 < y1) {
 115     double x = x0, dx = (double)(x1-x0)/(double)(y1-y0);
 116     //
 117     for (int y = y0; y < y1; ++y) { insertPoint(x+0.5, y); x += dx; }
 118   } else {
 119     double x = x0, dx = (double)(x1-x0)/(double)(y0-y1);
 120     //
 121     for (int y = y0; y > y1; --y) { insertPoint(x+0.5, y); x += dx; }
 122   }
 123 }
 124 void polymodStart (void) {
 125   for (int f = 0; f < 200; ++f) polyScans[f] = -1;
 126   polyPointPoolPos = 0;
 127   firstPoint = 1;
 128 }
 129
 130
 131 void polymodAddPoint (int x, int y) {
 132   if (!firstPoint) lineDDA(lastX, lastY, x, y); else { firstX = x; firstY = y; firstPoint = 0; }
 133   lastX = x;
 134   lastY = y;
 135 }
 136
 137
 138 void polymodEnd (void) {
 139   if (!firstPoint) lineDDA(lastX, lastY, firstX, firstY);
 140 }
 141
 142
 143 void polymodFill (SDL_Surface *frame, Uint8 color, Uint8 alpha) {
 144   for (int y = 0; y < 200; ++y) {
 145     int p = polyScans[y];
 146     //
 147     if (p >= 0) {
 148       while (p >= 0 && polyPointPool[p].x < 320) {
 149         int n = polyPointPool[p].next/*, ex*/;
 150         //
 151         if (n < 0) {
 152           //putPixelA2x(frame, polyPointPool[p].x, y, color, alpha);
 153           putPixel2x(frame, polyPointPool[p].x, y, color);
 154           break;
 155         }
 156         //fprintf(stderr, "y: %d; x0: %d; x1: %d\n", y, polyPointPool[p].x, polyPointPool[n].x);
 157         //ex = polyPointPool[n].x;
 158         //for (int x = polyPointPool[p].x; x <= ex; ++x) putPixelA2x(frame, x, y, color, alpha);
 159         hline2x(frame, polyPointPool[p].x, y, polyPointPool[n].x-polyPointPool[p].x+1, color);
 160         p = polyPointPool[n].next;
 161       }
 162     }
 163   }
 164 }