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   1  /*
   2   * see COPYRIGHT
   3   */
   4  
   5  #include <stdio.h>
   6  #include <stdlib.h>
   7  #include "bzscreen.h"
   8  
   9  /*
  10   * functions to draw the bezier curves in text mode 
  11   */
  12  
  13  double
  14  fmin(a,b)
  15      double a, b;
  16  {
  17      if(a<b)
  18          return a;
  19      else
  20          return b;
  21  }
  22  
  23  int
  24  abs(x)
  25      int x;
  26  {
  27      if(x<0)
  28          return -x;
  29      else
  30          return x;
  31  }
  32  
  33  void
  34  initscreen(physx, physy, cols, rows, xoff, yoff, minx, miny, maxx, maxy)
  35      unsigned physx, physy, cols, rows, xoff, yoff, minx, miny, maxx, maxy;
  36  {
  37      int i,j;
  38      double yxscale;
  39  
  40      if(screen.dots != NULL)
  41          free(screen.dots);
  42  
  43      if(physx==0 || physy==0 || rows==0 || cols==0) {
  44          fprintf(stderr, "*** negative or zero screen size\n");
  45          exit(1);
  46      }
  47  
  48      if(physx+xoff > cols || physy+yoff > rows) {
  49          fprintf(stderr, "*** drawable area out of screen\n");
  50          exit(1);
  51      }
  52  
  53      if(minx>maxx || miny>maxy) {
  54          fprintf(stderr, "*** empty drawable area\n");
  55          exit(1);
  56      }
  57  
  58      screen.physx = physx;
  59      screen.physy = physy;
  60      screen.rows = rows; 
  61      screen.cols = cols+2; /* for '\n\0' */
  62      screen.xoff = xoff;
  63      screen.yoff = yoff;
  64      screen.minx = minx;
  65      screen.miny = miny;
  66  
  67      if(( screen.dots=malloc(screen.rows*screen.cols) )==NULL) {
  68          perror("*** no memory for screen: ");
  69          exit(1);
  70      }
  71  
  72      j=screen.rows*screen.cols;
  73      for(i=0; i<j; i++)
  74          screen.dots[i]=' ';
  75  
  76      /* scale of Y to X on the screen, i.e. x=YXSCALE*y */
  77      /* 3/4 is the approx. ratio of Y/X sizes of the physical screen */
  78      yxscale = ((double)physx/(double)physy*3.0/4.0);
  79  
  80      /* scale of "logical" to "physical", i.e. physical=PHYSSCALE*logical */
  81      screen.yscale = fmin( ((double)physy-0.51)/(maxy+1-miny), 
  82          ((double)physx-0.51)/yxscale/(maxx+1-minx) );
  83      screen.xscale = yxscale * screen.yscale;
  84  }
  85  
  86  void
  87  drawcurve(mark, ax,ay, bx,by, cx,cy, dx,dy)
  88      int mark, ax,ay, bx,by, cx,cy, dx,dy;
  89  {
  90      int i,j,n,c;
  91      int maxn=(screen.physx + screen.physy)*2;
  92  
  93      ax-=screen.minx; bx-=screen.minx; cx-=screen.minx; dx-=screen.minx;
  94      ay-=screen.miny; by-=screen.miny; cy-=screen.miny; dy-=screen.miny;
  95  
  96      for(i=0; i<=maxn; i++) {
  97          double t, t2, t3, nt, nt2, nt3;
  98  
  99          t=(double)i/(double)maxn; t2=t*t; t3=t2*t;
 100          nt=1-t; nt2=nt*nt; nt3=nt2*nt;
 101  
 102          setfdot(
 103              mark, 
 104              ( ax*t3 + bx*3*t2*nt + cx*3*t*nt2 + dx*nt3 ),
 105              ( ay*t3 + by*3*t2*nt + cy*3*t*nt2 + dy*nt3 )
 106          );
 107      }
 108  }
 109  
 110  /* draw curve and mark direction at the ends */
 111  
 112  void
 113  drawcurvedir(mark, ax,ay, bx,by, cx,cy, dx,dy)
 114      int mark, ax,ay, bx,by, cx,cy, dx,dy;
 115  {
 116      int i,j,n,c;
 117      int maxn=(screen.physx + screen.physy)*2;
 118      double t, t2, t3, nt, nt2, nt3;
 119      int markb, marke;
 120  
 121      ax-=screen.minx; bx-=screen.minx; cx-=screen.minx; dx-=screen.minx;
 122      ay-=screen.miny; by-=screen.miny; cy-=screen.miny; dy-=screen.miny;
 123  
 124      if(bx==ax && by==ay) {
 125          markb=mark;
 126      } else if( abs(by-ay) > abs(bx-ax) ) {
 127          if(by>ay)
 128              markb='^';
 129          else
 130              markb='v';
 131      } else {
 132          if(bx>ax)
 133              markb='>';
 134          else
 135              markb='<';
 136      }
 137  
 138      if(dx==cx && dy==cy) {
 139          marke=mark;
 140      } else if( abs(dy-cy) > abs(dx-cx) ) {
 141          if(dy>cy)
 142              marke='^';
 143          else
 144              marke='v';
 145      } else {
 146          if(dx>cx)
 147              marke='>';
 148          else
 149              marke='<';
 150      }
 151  
 152      for(i=1; i<maxn; i++) {
 153          t=(double)i/(double)maxn; t2=t*t; t3=t2*t;
 154          nt=1-t; nt2=nt*nt; nt3=nt2*nt;
 155  
 156          setfdot(
 157              mark,
 158              ( ax*t3 + bx*3*t2*nt + cx*3*t*nt2 + dx*nt3 ),
 159              ( ay*t3 + by*3*t2*nt + cy*3*t*nt2 + dy*nt3 )
 160          );
 161      }
 162      /* mark the ends */
 163      setfdot( markb, (double)ax, (double)ay );
 164      setfdot( marke, (double)dx, (double)dy );
 165  }
 166  
 167  void
 168  drawdot(mark, x, y)
 169      int mark;
 170      int x, y;
 171  {
 172      x=(int)((x-screen.minx)*screen.xscale+0.5);
 173      y=(int)((y-screen.miny)*screen.yscale+0.5);
 174  
 175      if(y<0 || y>=screen.physy || x<0 || x>=screen.physx)
 176          return;
 177      screendot(x,y)=mark;
 178  }
 179  
 180  void
 181  setabsdot(mark, x, y)
 182      int x, y, mark;
 183  {
 184      if(y<0 || y>=screen.rows || x<0 || x>=screen.cols-2)
 185          return;
 186      screenabsdot(x,y)=mark;
 187  }
 188  
 189  void
 190  setfdot(mark, fx, fy)
 191      int mark;
 192      double fx, fy;
 193  {
 194      int x, y;
 195  
 196      x=(int)(fx*screen.xscale+0.5);
 197      y=(int)(fy*screen.yscale+0.5);
 198  
 199      if(y<0 || y>=screen.physy || x<0 || x>=screen.physx)
 200          return;
 201      screendot(x,y)=mark;
 202  }
 203  
 204  /* destructive */
 205  void
 206  printscreen(f)
 207      FILE *f;
 208  {
 209      int r;
 210      char *pi, *pc;
 211  
 212      for(r=screen.rows-1; r>=0; r--) {
 213          pc=&screenabsdot(0,r);
 214          for(pi=&screenabsdot(-2,r+1); pi>=pc && *pi == ' '; pi--)
 215              {}
 216          pi[1]='\n';
 217          pi[2]=0;
 218          fputs(pc, f);
 219      }
 220  }