contrib/src/ogl/misc.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        misc.cpp
   3 // Purpose:     Miscellaneous OGL support functions
   4 // Author:      Julian Smart
   5 // Modified by:
   6 // Created:     12/07/98
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) Julian Smart
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 #ifdef __GNUG__
  13 #pragma implementation "misc.h"
  14 #endif
  15
  16 // For compilers that support precompilation, includes "wx.h".
  17 #include "wx/wxprec.h"
  18
  19 #ifdef __BORLANDC__
  20 #pragma hdrstop
  21 #endif
  22
  23 #ifndef WX_PRECOMP
  24 #include <wx/wx.h>
  25 #endif
  26
  27 #include <wx/wxexpr.h>
  28
  29 #include <wx/types.h>
  30
  31 #ifdef new
  32 #undef new
  33 #endif
  34
  35 #if wxUSE_IOSTREAMH
  36 #include <iostream.h>
  37 #else
  38 #include <iostream>
  39 #endif
  40 #include <ctype.h>
  41 #include <math.h>
  42 #include <stdlib.h>
  43
  44 #include <wx/ogl/basic.h>
  45 #include <wx/ogl/basicp.h>
  46 #include <wx/ogl/misc.h>
  47 #include <wx/ogl/constrnt.h>
  48 #include <wx/ogl/composit.h>
  49
  50 wxFont*         g_oglNormalFont;
  51 wxPen*          g_oglBlackPen;
  52 wxPen*          g_oglTransparentPen;
  53 wxPen*          g_oglBlackForegroundPen;
  54 wxPen*          g_oglWhiteBackgroundPen;
  55 wxBrush*        g_oglWhiteBackgroundBrush;
  56
  57 char*           oglBuffer = NULL;
  58
  59 wxList          oglObjectCopyMapping(wxKEY_INTEGER);
  60
  61
  62
  63 void wxOGLInitialize()
  64 {
  65   g_oglNormalFont = wxTheFontList->FindOrCreateFont(10, wxSWISS, wxNORMAL, wxNORMAL);
  66   g_oglBlackPen = wxThePenList->FindOrCreatePen(wxT("BLACK"), 1, wxSOLID);
  67   g_oglTransparentPen = wxThePenList->FindOrCreatePen(wxT("WHITE"), 1, wxTRANSPARENT);
  68   g_oglBlackForegroundPen = wxThePenList->FindOrCreatePen(wxT("BLACK"), 1, wxSOLID);
  69   g_oglWhiteBackgroundPen = wxThePenList->FindOrCreatePen(wxT("WHITE"), 1, wxSOLID);
  70   g_oglWhiteBackgroundBrush = wxTheBrushList->FindOrCreateBrush(wxT("WHITE"), wxSOLID);
  71
  72   OGLInitializeConstraintTypes();
  73
  74   // Initialize big buffer used when writing images
  75   oglBuffer = new char[3000];
  76
  77 }
  78
  79 void wxOGLCleanUp()
  80 {
  81     if (oglBuffer)
  82     {
  83         delete[] oglBuffer;
  84         oglBuffer = NULL;
  85     }
  86     oglBuffer = NULL;
  87
  88     g_oglNormalFont = NULL;             // These will be cleaned up by their GDI list
  89     g_oglBlackPen = NULL;
  90     g_oglTransparentPen = NULL;
  91     g_oglBlackForegroundPen = NULL;
  92     g_oglWhiteBackgroundPen = NULL;
  93     g_oglWhiteBackgroundBrush = NULL;
  94
  95     OGLCleanUpConstraintTypes();
  96 }
  97
  98 wxFont *oglMatchFont(int point_size)
  99 {
 100   wxFont *font = wxTheFontList->FindOrCreateFont(point_size, wxSWISS, wxNORMAL, wxNORMAL);
 101 #if 0
 102   switch (point_size)
 103   {
 104     case 4:
 105       font = swiss_font_4;
 106       break;
 107     case 6:
 108       font = swiss_font_6;
 109       break;
 110     case 8:
 111       font = swiss_font_8;
 112       break;
 113     case 12:
 114       font = swiss_font_12;
 115       break;
 116     case 14:
 117       font = swiss_font_14;
 118       break;
 119     case 18:
 120       font = swiss_font_18;
 121       break;
 122     case 24:
 123       font = swiss_font_24;
 124       break;
 125     default:
 126     case 10:
 127       font = swiss_font_10;
 128       break;
 129   }
 130 #endif
 131   return font;
 132 }
 133
 134 int FontSizeDialog(wxFrame *parent, int old_size)
 135 {
 136   if (old_size <= 0)
 137     old_size = 10;
 138   wxString buf;
 139   buf << old_size;
 140   wxString ans = wxGetTextFromUser(wxT("Enter point size"), wxT("Font size"), buf, parent);
 141   if (ans.Length() == 0)
 142     return 0;
 143
 144   long new_size = 0;
 145   ans.ToLong(&new_size);
 146   if ((new_size <= 0) || (new_size > 40))
 147   {
 148     wxMessageBox(wxT("Invalid point size!"), wxT("Error"), wxOK);
 149     return 0;
 150   }
 151   return new_size;
 152 /*
 153   char *strings[8];
 154   strings[0] = "4";
 155   strings[1] = "6";
 156   strings[2] = "8";
 157   strings[3] = "10";
 158   strings[4] = "12";
 159   strings[5] = "14";
 160   strings[6] = "18";
 161   strings[7] = "24";
 162   char *ans = wxGetSingleChoice("Choose", "Choose a font size", 8, strings, parent);
 163   if (ans)
 164   {
 165     int size;
 166     sscanf(ans, "%d", &size);
 167     return oglMatchFont(size);
 168   }
 169   else return NULL;
 170 */
 171 }
 172
 173 // Centre a list of strings in the given box. xOffset and yOffset are the
 174 // the positions that these lines should be relative to, and this might be
 175 // the same as m_xpos, m_ypos, but might be zero if formatting from left-justifying.
 176 void oglCentreText(wxDC& dc, wxList *text_list,
 177                 double m_xpos, double m_ypos, double width, double height,
 178                 int formatMode)
 179 {
 180   int n = text_list->Number();
 181
 182   if (!text_list || (n == 0))
 183     return;
 184
 185   // First, get maximum dimensions of box enclosing text
 186
 187   long char_height = 0;
 188   long max_width = 0;
 189   long current_width = 0;
 190
 191   // Store text extents for speed
 192   double *widths = new double[n];
 193
 194   wxNode *current = text_list->First();
 195   int i = 0;
 196   while (current)
 197   {
 198     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 199     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 200     widths[i] = current_width;
 201
 202     if (current_width > max_width)
 203       max_width = current_width;
 204     current = current->Next();
 205     i ++;
 206   }
 207
 208   double max_height = n*char_height;
 209
 210   double xoffset, yoffset, xOffset, yOffset;
 211
 212   if (formatMode & FORMAT_CENTRE_VERT)
 213   {
 214     if (max_height < height)
 215       yoffset = (double)(m_ypos - (height/2.0) + (height - max_height)/2.0);
 216     else
 217       yoffset = (double)(m_ypos - (height/2.0));
 218     yOffset = m_ypos;
 219   }
 220   else
 221   {
 222     yoffset = 0.0;
 223     yOffset = 0.0;
 224   }
 225
 226   if (formatMode & FORMAT_CENTRE_HORIZ)
 227   {
 228     xoffset = (double)(m_xpos - width/2.0);
 229     xOffset = m_xpos;
 230   }
 231   else
 232   {
 233     xoffset = 0.0;
 234     xOffset = 0.0;
 235   }
 236
 237   current = text_list->First();
 238   i = 0;
 239
 240   while (current)
 241   {
 242     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 243
 244     double x;
 245     if ((formatMode & FORMAT_CENTRE_HORIZ) && (widths[i] < width))
 246       x = (double)((width - widths[i])/2.0 + xoffset);
 247     else
 248       x = xoffset;
 249     double y = (double)(i*char_height + yoffset);
 250
 251     line->SetX( x - xOffset ); line->SetY( y - yOffset );
 252     current = current->Next();
 253     i ++;
 254   }
 255
 256   delete widths;
 257 }
 258
 259 // Centre a list of strings in the given box
 260 void oglCentreTextNoClipping(wxDC& dc, wxList *text_list,
 261                               double m_xpos, double m_ypos, double width, double height)
 262 {
 263   int n = text_list->Number();
 264
 265   if (!text_list || (n == 0))
 266     return;
 267
 268   // First, get maximum dimensions of box enclosing text
 269
 270   long char_height = 0;
 271   long max_width = 0;
 272   long current_width = 0;
 273
 274   // Store text extents for speed
 275   double *widths = new double[n];
 276
 277   wxNode *current = text_list->First();
 278   int i = 0;
 279   while (current)
 280   {
 281     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 282     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 283     widths[i] = current_width;
 284
 285     if (current_width > max_width)
 286       max_width = current_width;
 287     current = current->Next();
 288     i ++;
 289   }
 290
 291   double max_height = n*char_height;
 292
 293   double yoffset = (double)(m_ypos - (height/2.0) + (height - max_height)/2.0);
 294
 295   double xoffset = (double)(m_xpos - width/2.0);
 296
 297   current = text_list->First();
 298   i = 0;
 299
 300   while (current)
 301   {
 302     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 303
 304     double x = (double)((width - widths[i])/2.0 + xoffset);
 305     double y = (double)(i*char_height + yoffset);
 306
 307     line->SetX( x - m_xpos ); line->SetY( y - m_ypos );
 308     current = current->Next();
 309     i ++;
 310   }
 311   delete widths;
 312 }
 313
 314 void oglGetCentredTextExtent(wxDC& dc, wxList *text_list,
 315                               double m_xpos, double m_ypos, double width, double height,
 316                               double *actual_width, double *actual_height)
 317 {
 318   int n = text_list->Number();
 319
 320   if (!text_list || (n == 0))
 321   {
 322     *actual_width = 0;
 323     *actual_height = 0;
 324     return;
 325   }
 326
 327   // First, get maximum dimensions of box enclosing text
 328
 329   long char_height = 0;
 330   long max_width = 0;
 331   long current_width = 0;
 332
 333   wxNode *current = text_list->First();
 334   int i = 0;
 335   while (current)
 336   {
 337     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 338     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 339
 340     if (current_width > max_width)
 341       max_width = current_width;
 342     current = current->Next();
 343     i ++;
 344   }
 345
 346   *actual_height = n*char_height;
 347   *actual_width = max_width;
 348 }
 349
 350 // Format a string to a list of strings that fit in the given box.
 351 // Interpret %n and 10 or 13 as a new line.
 352 wxStringList *oglFormatText(wxDC& dc, const wxString& text, double width, double height, int formatMode)
 353 {
 354   // First, parse the string into a list of words
 355   wxStringList word_list;
 356
 357   // Make new lines into NULL strings at this point
 358   int i = 0; int j = 0; int len = text.Length();
 359   wxChar word[200]; word[0] = 0;
 360   bool end_word = FALSE; bool new_line = FALSE;
 361   while (i < len)
 362   {
 363     switch (text[i])
 364     {
 365       case wxT('%'):
 366       {
 367         i ++;
 368         if (i == len)
 369         { word[j] = wxT('%'); j ++; }
 370         else
 371         {
 372           if (text[i] == wxT('n'))
 373           { new_line = TRUE; end_word = TRUE; i++; }
 374           else
 375           { word[j] = wxT('%'); j ++; word[j] = text[i]; j ++; i ++; }
 376         }
 377         break;
 378       }
 379       case 10:
 380       {
 381         new_line = TRUE; end_word = TRUE; i++;
 382         break;
 383       }
 384       case 13:
 385       {
 386         new_line = TRUE; end_word = TRUE; i++;
 387       }
 388       case wxT(' '):
 389       {
 390         end_word = TRUE;
 391         i ++;
 392         break;
 393       }
 394       default:
 395       {
 396         word[j] = text[i];
 397         j ++; i ++;
 398         break;
 399       }
 400     }
 401     if (i == len) end_word = TRUE;
 402     if (end_word)
 403     {
 404       word[j] = 0;
 405       j = 0;
 406       word_list.Add(word);
 407       end_word = FALSE;
 408     }
 409     if (new_line)
 410     {
 411       word_list.Append(NULL);
 412       new_line = FALSE;
 413     }
 414   }
 415   // Now, make a list of strings which can fit in the box
 416   wxStringList *string_list = new wxStringList;
 417
 418   wxString buffer;
 419   wxNode *node = word_list.First();
 420   long x, y;
 421
 422   while (node)
 423   {
 424     wxString oldBuffer(buffer);
 425
 426     char *s = (char *)node->Data();
 427     if (!s)
 428     {
 429       // FORCE NEW LINE
 430       if (buffer.Length() > 0)
 431         string_list->Add(buffer);
 432
 433       buffer.Empty();
 434     }
 435     else
 436     {
 437       if (buffer.Length() != 0)
 438         buffer += " ";
 439
 440       buffer += s;
 441       dc.GetTextExtent(buffer, &x, &y);
 442
 443       // Don't fit within the bounding box if we're fitting shape to contents
 444       if ((x > width) && !(formatMode & FORMAT_SIZE_TO_CONTENTS))
 445       {
 446         // Deal with first word being wider than box
 447         if (oldBuffer.Length() > 0)
 448           string_list->Add(oldBuffer);
 449
 450         buffer.Empty();
 451         buffer += s;
 452       }
 453     }
 454
 455     node = node->Next();
 456   }
 457   if (buffer.Length() != 0)
 458     string_list->Add(buffer);
 459
 460   return string_list;
 461 }
 462
 463 void oglDrawFormattedText(wxDC& dc, wxList *text_list,
 464                        double m_xpos, double m_ypos, double width, double height,
 465                        int formatMode)
 466 {
 467   double xoffset, yoffset;
 468   if (formatMode & FORMAT_CENTRE_HORIZ)
 469     xoffset = m_xpos;
 470   else
 471     xoffset = (double)(m_xpos - (width / 2.0));
 472
 473   if (formatMode & FORMAT_CENTRE_VERT)
 474     yoffset = m_ypos;
 475   else
 476     yoffset = (double)(m_ypos - (height / 2.0));
 477
 478   dc.SetClippingRegion(
 479                     (long)(m_xpos - width/2.0), (long)(m_ypos - height/2.0),
 480                     (long)width, (long)height);
 481
 482   wxNode *current = text_list->First();
 483   while (current)
 484   {
 485     wxShapeTextLine *line = (wxShapeTextLine *)current->Data();
 486
 487     dc.DrawText(line->GetText(), WXROUND(xoffset + line->GetX()), WXROUND(yoffset + line->GetY()));
 488     current = current->Next();
 489   }
 490
 491   dc.DestroyClippingRegion();
 492 }
 493
 494 /*
 495  * Find centroid given list of points comprising polyline
 496  *
 497  */
 498
 499 void oglFindPolylineCentroid(wxList *points, double *x, double *y)
 500 {
 501   double xcount = 0;
 502   double ycount = 0;
 503
 504   wxNode *node = points->First();
 505   while (node)
 506   {
 507     wxRealPoint *point = (wxRealPoint *)node->Data();
 508     xcount += point->x;
 509     ycount += point->y;
 510     node = node->Next();
 511   }
 512
 513   *x = (xcount/points->Number());
 514   *y = (ycount/points->Number());
 515 }
 516
 517 /*
 518  * Check that (x1, y1) -> (x2, y2) hits (x3, y3) -> (x4, y4).
 519  * If so, ratio1 gives the proportion along the first line
 520  * that the intersection occurs (or something like that).
 521  * Used by functions below.
 522  *
 523  */
 524 void oglCheckLineIntersection(double x1, double y1, double x2, double y2,
 525                              double x3, double y3, double x4, double y4,
 526                              double *ratio1, double *ratio2)
 527 {
 528   double denominator_term = (y4 - y3)*(x2 - x1) - (y2 - y1)*(x4 - x3);
 529   double numerator_term = (x3 - x1)*(y4 - y3) + (x4 - x3)*(y1 - y3);
 530
 531   double line_constant;
 532   double length_ratio = 1.0;
 533   double k_line = 1.0;
 534
 535   // Check for parallel lines
 536   if ((denominator_term < 0.005) && (denominator_term > -0.005))
 537     line_constant = -1.0;
 538   else
 539     line_constant = numerator_term/denominator_term;
 540
 541   // Check for intersection
 542   if ((line_constant < 1.0) && (line_constant > 0.0))
 543   {
 544     // Now must check that other line hits
 545     if (((y4 - y3) < 0.005) && ((y4 - y3) > -0.005))
 546       k_line = ((x1 - x3) + line_constant*(x2 - x1))/(x4 - x3);
 547     else
 548       k_line = ((y1 - y3) + line_constant*(y2 - y1))/(y4 - y3);
 549
 550     if ((k_line >= 0.0) && (k_line < 1.0))
 551       length_ratio = line_constant;
 552     else
 553       k_line = 1.0;
 554   }
 555   *ratio1 = length_ratio;
 556   *ratio2 = k_line;
 557 }
 558
 559 /*
 560  * Find where (x1, y1) -> (x2, y2) hits one of the lines in xvec, yvec.
 561  * (*x3, *y3) is the point where it hits.
 562  *
 563  */
 564 void oglFindEndForPolyline(double n, double xvec[], double yvec[],
 565                            double x1, double y1, double x2, double y2, double *x3, double *y3)
 566 {
 567   int i;
 568   double lastx = xvec[0];
 569   double lasty = yvec[0];
 570
 571   double min_ratio = 1.0;
 572   double line_ratio;
 573   double other_ratio;
 574
 575   for (i = 1; i < n; i++)
 576   {
 577     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[i], yvec[i],
 578                             &line_ratio, &other_ratio);
 579     lastx = xvec[i];
 580     lasty = yvec[i];
 581
 582     if (line_ratio < min_ratio)
 583       min_ratio = line_ratio;
 584   }
 585
 586   // Do last (implicit) line if last and first doubles are not identical
 587   if (!(xvec[0] == lastx && yvec[0] == lasty))
 588   {
 589     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[0], yvec[0],
 590                             &line_ratio, &other_ratio);
 591
 592     if (line_ratio < min_ratio)
 593       min_ratio = line_ratio;
 594   }
 595
 596   *x3 = (x1 + (x2 - x1)*min_ratio);
 597   *y3 = (y1 + (y2 - y1)*min_ratio);
 598
 599 }
 600
 601 /*
 602  * Find where the line hits the box.
 603  *
 604  */
 605
 606 void oglFindEndForBox(double width, double height,
 607                       double x1, double y1,         // Centre of box (possibly)
 608                       double x2, double y2,         // other end of line
 609                       double *x3, double *y3)       // End on box edge
 610 {
 611   double xvec[5];
 612   double yvec[5];
 613
 614   xvec[0] = (double)(x1 - width/2.0);
 615   yvec[0] = (double)(y1 - height/2.0);
 616   xvec[1] = (double)(x1 - width/2.0);
 617   yvec[1] = (double)(y1 + height/2.0);
 618   xvec[2] = (double)(x1 + width/2.0);
 619   yvec[2] = (double)(y1 + height/2.0);
 620   xvec[3] = (double)(x1 + width/2.0);
 621   yvec[3] = (double)(y1 - height/2.0);
 622   xvec[4] = (double)(x1 - width/2.0);
 623   yvec[4] = (double)(y1 - height/2.0);
 624
 625   oglFindEndForPolyline(5, xvec, yvec, x2, y2, x1, y1, x3, y3);
 626 }
 627
 628 /*
 629  * Find where the line hits the circle.
 630  *
 631  */
 632
 633 void oglFindEndForCircle(double radius,
 634                          double x1, double y1,  // Centre of circle
 635                          double x2, double y2,  // Other end of line
 636                          double *x3, double *y3)
 637 {
 638   double H = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 639
 640   if (H == 0.0)
 641   {
 642     *x3 = x1;
 643     *y3 = y1;
 644   }
 645   else
 646   {
 647    *y3 = radius * (y2 - y1)/H + y1;
 648    *x3 = radius * (x2 - x1)/H + x1;
 649   }
 650 }
 651
 652 /*
 653  * Given the line (x1, y1) -> (x2, y2), and an arrow size of given length and width,
 654  * return the position of the tip of the arrow and the left and right vertices of the arrow.
 655  *
 656  */
 657
 658 void oglGetArrowPoints(double x1, double y1, double x2, double y2,
 659                       double length, double width,
 660                       double *tip_x, double *tip_y,
 661                       double *side1_x, double *side1_y,
 662                       double *side2_x, double *side2_y)
 663 {
 664   double l = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 665
 666   if (l < 0.01)
 667     l = (double) 0.01;
 668
 669   double i_bar = (x2 - x1)/l;
 670   double j_bar = (y2 - y1)/l;
 671
 672   double x3 = (- length*i_bar) + x2;
 673   double y3 = (- length*j_bar) + y2;
 674
 675   *side1_x = width*(-j_bar) + x3;
 676   *side1_y = width*i_bar + y3;
 677
 678   *side2_x = -width*(-j_bar) + x3;
 679   *side2_y = -width*i_bar + y3;
 680
 681   *tip_x = x2; *tip_y = y2;
 682 }
 683
 684 /*
 685  * Given an ellipse and endpoints of a line, returns the point at which
 686  * the line touches the ellipse in values x4, y4.
 687  * This function assumes that the centre of the ellipse is at x1, y1, and the
 688  * ellipse has a width of width1 and a height of height1. It also assumes you are
 689  * wanting to draw an arc FROM point x2, y2 TOWARDS point x3, y3.
 690  * This function calculates the x,y coordinates of the intersection point of
 691  * the arc with the ellipse.
 692  * Author: Ian Harrison
 693  */
 694
 695 void oglDrawArcToEllipse(double x1, double y1, double width1, double height1, double x2, double y2, double x3, double y3,
 696   double *x4, double *y4)
 697 {
 698   double a1 = (double)(width1/2.0);
 699   double b1 = (double)(height1/2.0);
 700
 701   // These are required to give top left x and y coordinates for DrawEllipse
 702 //  double top_left_x1 = (double)(x1 - a1);
 703 //  double top_left_y1 = (double)(y1 - b1);
 704 /*
 705   // Check for vertical line
 706   if (fabs(x2 - x3) < 0.05)
 707   {
 708     *x4 = x3;
 709     if (y2 < y3)
 710       *y4 = (double)(y1 - b1);
 711     else
 712       *y4 = (double)(y1 + b1);
 713     return;
 714   }
 715 */
 716   // Check that x2 != x3
 717   if (fabs(x2 - x3) < 0.05)
 718   {
 719     *x4 = x2;
 720     if (y3 > y2)
 721       *y4 = (double)(y1 - sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 722     else
 723       *y4 = (double)(y1 + sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 724     return;
 725   }
 726
 727   // Calculate the x and y coordinates of the point where arc intersects ellipse
 728
 729   double A, B, C, D, E, F, G, H, K;
 730   double ellipse1_x, ellipse1_y;
 731
 732   A = (double)(1/(a1 * a1));
 733   B = (double)((y3 - y2) * (y3 - y2)) / ((x3 - x2) * (x3 - x2) * b1 * b1);
 734   C = (double)(2 * (y3 - y2) * (y2 - y1)) / ((x3 - x2) * b1 * b1);
 735   D = (double)((y2 - y1) * (y2 - y1)) / (b1 * b1);
 736   E = (double)(A + B);
 737   F = (double)(C - (2 * A * x1) - (2 * B * x2));
 738   G = (double)((A * x1 * x1) + (B * x2 * x2) - (C * x2) + D - 1);
 739   H = (double)((y3 - y2) / (x3 - x2));
 740   K = (double)((F * F) - (4 * E * G));
 741
 742   if (K >= 0)
 743   // In this case the line intersects the ellipse, so calculate intersection
 744   {
 745     if(x2 >= x1)
 746     {
 747       ellipse1_x = (double)(((F * -1) + sqrt(K)) / (2 * E));
 748       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 749     }
 750     else
 751     {
 752       ellipse1_x = (double)(((F * -1) -  sqrt(K)) / (2 * E));
 753       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 754     }
 755   }
 756   else
 757   // in this case, arc does not intersect ellipse, so just draw arc
 758   {
 759     ellipse1_x = x3;
 760     ellipse1_y = y3;
 761   }
 762   *x4 = ellipse1_x;
 763   *y4 = ellipse1_y;
 764
 765 /*
 766   // Draw a little circle (radius = 2) at the end of the arc where it hits
 767   // the ellipse .
 768
 769   double circle_x = ellipse1_x - 2.0;
 770   double circle_y = ellipse1_y - 2.0;
 771   m_canvas->DrawEllipse(circle_x, circle_y, 4.0, 4.0);
 772 */
 773 }
 774
 775 // Update a list item from a list of strings
 776 void UpdateListBox(wxListBox *item, wxList *list)
 777 {
 778   item->Clear();
 779   if (!list)
 780     return;
 781
 782   wxNode *node = list->First();
 783   while (node)
 784   {
 785     char *s = (char *)node->Data();
 786     item->Append(s);
 787     node = node->Next();
 788   }
 789 }
 790
 791 bool oglRoughlyEqual(double val1, double val2, double tol)
 792 {
 793     return ( (val1 < (val2 + tol)) && (val1 > (val2 - tol)) &&
 794              (val2 < (val1 + tol)) && (val2 > (val1 - tol)));
 795 }
 796
 797 /*
 798  * Hex<->Dec conversion
 799  */
 800
 801 // Array used in DecToHex conversion routine.
 802 static wxChar sg_HexArray[] = { wxT('0'), wxT('1'), wxT('2'), wxT('3'),
 803                                 wxT('4'), wxT('5'), wxT('6'), wxT('7'),
 804                                 wxT('8'), wxT('9'), wxT('A'), wxT('B'),
 805                                 wxT('C'), wxT('D'), wxT('E'), wxT('F')
 806 };
 807
 808 // Convert 2-digit hex number to decimal
 809 unsigned int oglHexToDec(wxChar* buf)
 810 {
 811   int firstDigit, secondDigit;
 812
 813   if (buf[0] >= wxT('A'))
 814     firstDigit = buf[0] - wxT('A') + 10;
 815   else
 816     firstDigit = buf[0] - wxT('0');
 817
 818   if (buf[1] >= wxT('A'))
 819     secondDigit = buf[1] - wxT('A') + 10;
 820   else
 821     secondDigit = buf[1] - wxT('0');
 822
 823   return firstDigit * 16 + secondDigit;
 824 }
 825
 826 // Convert decimal integer to 2-character hex string
 827 void oglDecToHex(unsigned int dec, wxChar *buf)
 828 {
 829     int firstDigit = (int)(dec/16.0);
 830     int secondDigit = (int)(dec - (firstDigit*16.0));
 831     buf[0] = sg_HexArray[firstDigit];
 832     buf[1] = sg_HexArray[secondDigit];
 833     buf[2] = 0;
 834 }
 835
 836 // 3-digit hex to wxColour
 837 wxColour oglHexToColour(const wxString& hex)
 838 {
 839     if (hex.Length() == 6)
 840     {
 841         long r, g, b;
 842         r = g = b = 0;
 843         hex.Mid(0,2).ToLong(&r, 16);
 844         hex.Mid(2,2).ToLong(&g, 16);
 845         hex.Mid(4,2).ToLong(&b, 16);
 846         return wxColour(r, g, b);
 847     }
 848     else
 849         return wxColour(0,0,0);
 850 }
 851
 852 // RGB to 3-digit hex
 853 wxString oglColourToHex(const wxColour& colour)
 854 {
 855     wxChar buf[7];
 856     unsigned int red = colour.Red();
 857     unsigned int green = colour.Green();
 858     unsigned int blue = colour.Blue();
 859
 860     oglDecToHex(red, buf);
 861     oglDecToHex(green, buf+2);
 862     oglDecToHex(blue, buf+4);
 863
 864     return wxString(buf);
 865 }
 866
 867