contrib/src/ogl/oglmisc.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 #if wxUSE_PROLOGIO
  28 #include <wx/deprecated/wxexpr.h>
  29 #endif
  30
  31 #include <wx/types.h>
  32
  33 #ifdef new
  34 #undef new
  35 #endif
  36
  37 #include <ctype.h>
  38 #include <math.h>
  39 #include <stdlib.h>
  40
  41 #include "wx/ogl/ogl.h"
  42
  43
  44 wxFont*         g_oglNormalFont;
  45 wxPen*          g_oglBlackPen;
  46 wxPen*          g_oglWhiteBackgroundPen;
  47 wxPen*          g_oglTransparentPen;
  48 wxBrush*        g_oglWhiteBackgroundBrush;
  49 wxPen*          g_oglBlackForegroundPen;
  50 wxCursor*       g_oglBullseyeCursor = NULL;
  51
  52 wxChar*           oglBuffer = NULL;
  53
  54 wxList          oglObjectCopyMapping(wxKEY_INTEGER);
  55
  56
  57
  58 void wxOGLInitialize()
  59 {
  60   g_oglBullseyeCursor = new wxCursor(wxCURSOR_BULLSEYE);
  61
  62   g_oglNormalFont = new wxFont(10, wxSWISS, wxNORMAL, wxNORMAL);
  63
  64   g_oglBlackPen = new wxPen(wxT("BLACK"), 1, wxSOLID);
  65
  66   g_oglWhiteBackgroundPen = new wxPen(wxT("WHITE"), 1, wxSOLID);
  67   g_oglTransparentPen = new wxPen(wxT("WHITE"), 1, wxTRANSPARENT);
  68   g_oglWhiteBackgroundBrush = new wxBrush(wxT("WHITE"), wxSOLID);
  69   g_oglBlackForegroundPen = new wxPen(wxT("BLACK"), 1, wxSOLID);
  70
  71   OGLInitializeConstraintTypes();
  72
  73   // Initialize big buffer used when writing images
  74   oglBuffer = new wxChar[3000];
  75
  76 }
  77
  78 void wxOGLCleanUp()
  79 {
  80     if (oglBuffer)
  81     {
  82         delete[] oglBuffer;
  83         oglBuffer = NULL;
  84     }
  85     oglBuffer = NULL;
  86
  87     if (g_oglBullseyeCursor)
  88     {
  89         delete g_oglBullseyeCursor;
  90         g_oglBullseyeCursor = NULL;
  91     }
  92
  93     if (g_oglNormalFont)
  94     {
  95         delete g_oglNormalFont;
  96         g_oglNormalFont = NULL;
  97     }
  98     if (g_oglBlackPen)
  99     {
 100         delete g_oglBlackPen;
 101         g_oglBlackPen = NULL;
 102     }
 103     if (g_oglWhiteBackgroundPen)
 104     {
 105         delete g_oglWhiteBackgroundPen;
 106         g_oglWhiteBackgroundPen = NULL;
 107     }
 108     if (g_oglTransparentPen)
 109     {
 110         delete g_oglTransparentPen;
 111         g_oglTransparentPen = NULL;
 112     }
 113     if (g_oglWhiteBackgroundBrush)
 114     {
 115         delete g_oglWhiteBackgroundBrush;
 116         g_oglWhiteBackgroundBrush = NULL;
 117     }
 118     if (g_oglBlackForegroundPen)
 119     {
 120         delete g_oglBlackForegroundPen;
 121         g_oglBlackForegroundPen = NULL;
 122     }
 123
 124     OGLCleanUpConstraintTypes();
 125 }
 126
 127 wxFont *oglMatchFont(int point_size)
 128 {
 129   wxFont *font = wxTheFontList->FindOrCreateFont(point_size, wxSWISS, wxNORMAL, wxNORMAL);
 130 #if 0
 131   switch (point_size)
 132   {
 133     case 4:
 134       font = swiss_font_4;
 135       break;
 136     case 6:
 137       font = swiss_font_6;
 138       break;
 139     case 8:
 140       font = swiss_font_8;
 141       break;
 142     case 12:
 143       font = swiss_font_12;
 144       break;
 145     case 14:
 146       font = swiss_font_14;
 147       break;
 148     case 18:
 149       font = swiss_font_18;
 150       break;
 151     case 24:
 152       font = swiss_font_24;
 153       break;
 154     default:
 155     case 10:
 156       font = swiss_font_10;
 157       break;
 158   }
 159 #endif
 160   return font;
 161 }
 162
 163 int FontSizeDialog(wxFrame *parent, int old_size)
 164 {
 165   if (old_size <= 0)
 166     old_size = 10;
 167   wxString buf;
 168   buf << old_size;
 169   wxString ans = wxGetTextFromUser(wxT("Enter point size"), wxT("Font size"), buf, parent);
 170   if (ans.Length() == 0)
 171     return 0;
 172
 173   long new_size = 0;
 174   ans.ToLong(&new_size);
 175   if ((new_size <= 0) || (new_size > 40))
 176   {
 177     wxMessageBox(wxT("Invalid point size!"), wxT("Error"), wxOK);
 178     return 0;
 179   }
 180   return new_size;
 181 /*
 182   char *strings[8];
 183   strings[0] = "4";
 184   strings[1] = "6";
 185   strings[2] = "8";
 186   strings[3] = "10";
 187   strings[4] = "12";
 188   strings[5] = "14";
 189   strings[6] = "18";
 190   strings[7] = "24";
 191   char *ans = wxGetSingleChoice("Choose", "Choose a font size", 8, strings, parent);
 192   if (ans)
 193   {
 194     int size;
 195     sscanf(ans, "%d", &size);
 196     return oglMatchFont(size);
 197   }
 198   else return NULL;
 199 */
 200 }
 201
 202 // Centre a list of strings in the given box. xOffset and yOffset are the
 203 // the positions that these lines should be relative to, and this might be
 204 // the same as m_xpos, m_ypos, but might be zero if formatting from left-justifying.
 205 void oglCentreText(wxDC& dc, wxList *text_list,
 206                 double m_xpos, double m_ypos, double width, double height,
 207                 int formatMode)
 208 {
 209   int n = text_list->GetCount();
 210
 211   if (!text_list || (n == 0))
 212     return;
 213
 214   // First, get maximum dimensions of box enclosing text
 215
 216   long char_height = 0;
 217   long max_width = 0;
 218   long current_width = 0;
 219
 220   // Store text extents for speed
 221   double *widths = new double[n];
 222
 223   wxNode *current = text_list->GetFirst();
 224   int i = 0;
 225   while (current)
 226   {
 227     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 228     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 229     widths[i] = current_width;
 230
 231     if (current_width > max_width)
 232       max_width = current_width;
 233     current = current->GetNext();
 234     i ++;
 235   }
 236
 237   double max_height = n*char_height;
 238
 239   double xoffset, yoffset, xOffset, yOffset;
 240
 241   if (formatMode & FORMAT_CENTRE_VERT)
 242   {
 243     if (max_height < height)
 244       yoffset = (double)(m_ypos - (height/2.0) + (height - max_height)/2.0);
 245     else
 246       yoffset = (double)(m_ypos - (height/2.0));
 247     yOffset = m_ypos;
 248   }
 249   else
 250   {
 251     yoffset = 0.0;
 252     yOffset = 0.0;
 253   }
 254
 255   if (formatMode & FORMAT_CENTRE_HORIZ)
 256   {
 257     xoffset = (double)(m_xpos - width/2.0);
 258     xOffset = m_xpos;
 259   }
 260   else
 261   {
 262     xoffset = 0.0;
 263     xOffset = 0.0;
 264   }
 265
 266   current = text_list->GetFirst();
 267   i = 0;
 268
 269   while (current)
 270   {
 271     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 272
 273     double x;
 274     if ((formatMode & FORMAT_CENTRE_HORIZ) && (widths[i] < width))
 275       x = (double)((width - widths[i])/2.0 + xoffset);
 276     else
 277       x = xoffset;
 278     double y = (double)(i*char_height + yoffset);
 279
 280     line->SetX( x - xOffset ); line->SetY( y - yOffset );
 281     current = current->GetNext();
 282     i ++;
 283   }
 284
 285   delete widths;
 286 }
 287
 288 // Centre a list of strings in the given box
 289 void oglCentreTextNoClipping(wxDC& dc, wxList *text_list,
 290                               double m_xpos, double m_ypos, double width, double height)
 291 {
 292   int n = text_list->GetCount();
 293
 294   if (!text_list || (n == 0))
 295     return;
 296
 297   // First, get maximum dimensions of box enclosing text
 298
 299   long char_height = 0;
 300   long max_width = 0;
 301   long current_width = 0;
 302
 303   // Store text extents for speed
 304   double *widths = new double[n];
 305
 306   wxNode *current = text_list->GetFirst();
 307   int i = 0;
 308   while (current)
 309   {
 310     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 311     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 312     widths[i] = current_width;
 313
 314     if (current_width > max_width)
 315       max_width = current_width;
 316     current = current->GetNext();
 317     i ++;
 318   }
 319
 320   double max_height = n*char_height;
 321
 322   double yoffset = (double)(m_ypos - (height/2.0) + (height - max_height)/2.0);
 323
 324   double xoffset = (double)(m_xpos - width/2.0);
 325
 326   current = text_list->GetFirst();
 327   i = 0;
 328
 329   while (current)
 330   {
 331     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 332
 333     double x = (double)((width - widths[i])/2.0 + xoffset);
 334     double y = (double)(i*char_height + yoffset);
 335
 336     line->SetX( x - m_xpos ); line->SetY( y - m_ypos );
 337     current = current->GetNext();
 338     i ++;
 339   }
 340   delete widths;
 341 }
 342
 343 void oglGetCentredTextExtent(wxDC& dc, wxList *text_list,
 344                               double WXUNUSED(m_xpos), double WXUNUSED(m_ypos), double WXUNUSED(width), double WXUNUSED(height),
 345                               double *actual_width, double *actual_height)
 346 {
 347   int n = text_list->GetCount();
 348
 349   if (!text_list || (n == 0))
 350   {
 351     *actual_width = 0;
 352     *actual_height = 0;
 353     return;
 354   }
 355
 356   // First, get maximum dimensions of box enclosing text
 357
 358   long char_height = 0;
 359   long max_width = 0;
 360   long current_width = 0;
 361
 362   wxNode *current = text_list->GetFirst();
 363   while (current)
 364   {
 365     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 366     dc.GetTextExtent(line->GetText(), &current_width, &char_height);
 367
 368     if (current_width > max_width)
 369       max_width = current_width;
 370     current = current->GetNext();
 371   }
 372
 373   *actual_height = n*char_height;
 374   *actual_width = max_width;
 375 }
 376
 377 // Format a string to a list of strings that fit in the given box.
 378 // Interpret %n and 10 or 13 as a new line.
 379 wxStringList *oglFormatText(wxDC& dc, const wxString& text, double width, double WXUNUSED(height), int formatMode)
 380 {
 381   // First, parse the string into a list of words
 382   wxStringList word_list;
 383
 384   // Make new lines into NULL strings at this point
 385   int i = 0; int j = 0; int len = text.Length();
 386   wxChar word[200]; word[0] = 0;
 387   bool end_word = FALSE; bool new_line = FALSE;
 388   while (i < len)
 389   {
 390     switch (text[i])
 391     {
 392       case wxT('%'):
 393       {
 394         i ++;
 395         if (i == len)
 396         { word[j] = wxT('%'); j ++; }
 397         else
 398         {
 399           if (text[i] == wxT('n'))
 400           { new_line = TRUE; end_word = TRUE; i++; }
 401           else
 402           { word[j] = wxT('%'); j ++; word[j] = text[i]; j ++; i ++; }
 403         }
 404         break;
 405       }
 406       case 10:
 407       {
 408         new_line = TRUE; end_word = TRUE; i++;
 409         break;
 410       }
 411       case 13:
 412       {
 413         new_line = TRUE; end_word = TRUE; i++;
 414       }
 415       case wxT(' '):
 416       {
 417         end_word = TRUE;
 418         i ++;
 419         break;
 420       }
 421       default:
 422       {
 423         word[j] = text[i];
 424         j ++; i ++;
 425         break;
 426       }
 427     }
 428     if (i == len) end_word = TRUE;
 429     if (end_word)
 430     {
 431       word[j] = 0;
 432       j = 0;
 433       word_list.Add(word);
 434       end_word = FALSE;
 435     }
 436     if (new_line)
 437     {
 438       word_list.Append(NULL);
 439       new_line = FALSE;
 440     }
 441   }
 442   // Now, make a list of strings which can fit in the box
 443   wxStringList *string_list = new wxStringList;
 444
 445   wxString buffer;
 446   wxStringListNode *node = word_list.GetFirst();
 447   long x, y;
 448
 449   while (node)
 450   {
 451     wxString oldBuffer(buffer);
 452
 453     wxChar *s = (wxChar *)node->GetData();
 454     if (!s)
 455     {
 456       // FORCE NEW LINE
 457       if (buffer.Length() > 0)
 458         string_list->Add(buffer);
 459
 460       buffer.Empty();
 461     }
 462     else
 463     {
 464       if (buffer.Length() != 0)
 465         buffer += wxT(" ");
 466
 467       buffer += s;
 468       dc.GetTextExtent(buffer, &x, &y);
 469
 470       // Don't fit within the bounding box if we're fitting shape to contents
 471       if ((x > width) && !(formatMode & FORMAT_SIZE_TO_CONTENTS))
 472       {
 473         // Deal with first word being wider than box
 474         if (oldBuffer.Length() > 0)
 475           string_list->Add(oldBuffer);
 476
 477         buffer.Empty();
 478         buffer += s;
 479       }
 480     }
 481
 482     node = node->GetNext();
 483   }
 484   if (buffer.Length() != 0)
 485     string_list->Add(buffer);
 486
 487   return string_list;
 488 }
 489
 490 void oglDrawFormattedText(wxDC& dc, wxList *text_list,
 491                        double m_xpos, double m_ypos, double width, double height,
 492                        int formatMode)
 493 {
 494   double xoffset, yoffset;
 495   if (formatMode & FORMAT_CENTRE_HORIZ)
 496     xoffset = m_xpos;
 497   else
 498     xoffset = (double)(m_xpos - (width / 2.0));
 499
 500   if (formatMode & FORMAT_CENTRE_VERT)
 501     yoffset = m_ypos;
 502   else
 503     yoffset = (double)(m_ypos - (height / 2.0));
 504
 505   dc.SetClippingRegion(
 506                     (long)(m_xpos - width/2.0), (long)(m_ypos - height/2.0),
 507                     (long)width, (long)height);
 508
 509   wxNode *current = text_list->GetFirst();
 510   while (current)
 511   {
 512     wxShapeTextLine *line = (wxShapeTextLine *)current->GetData();
 513
 514     dc.DrawText(line->GetText(), WXROUND(xoffset + line->GetX()), WXROUND(yoffset + line->GetY()));
 515     current = current->GetNext();
 516   }
 517
 518   dc.DestroyClippingRegion();
 519 }
 520
 521 /*
 522  * Find centroid given list of points comprising polyline
 523  *
 524  */
 525
 526 void oglFindPolylineCentroid(wxList *points, double *x, double *y)
 527 {
 528   double xcount = 0;
 529   double ycount = 0;
 530
 531   wxNode *node = points->GetFirst();
 532   while (node)
 533   {
 534     wxRealPoint *point = (wxRealPoint *)node->GetData();
 535     xcount += point->x;
 536     ycount += point->y;
 537     node = node->GetNext();
 538   }
 539
 540   *x = (xcount/points->GetCount());
 541   *y = (ycount/points->GetCount());
 542 }
 543
 544 /*
 545  * Check that (x1, y1) -> (x2, y2) hits (x3, y3) -> (x4, y4).
 546  * If so, ratio1 gives the proportion along the first line
 547  * that the intersection occurs (or something like that).
 548  * Used by functions below.
 549  *
 550  */
 551 void oglCheckLineIntersection(double x1, double y1, double x2, double y2,
 552                              double x3, double y3, double x4, double y4,
 553                              double *ratio1, double *ratio2)
 554 {
 555   double denominator_term = (y4 - y3)*(x2 - x1) - (y2 - y1)*(x4 - x3);
 556   double numerator_term = (x3 - x1)*(y4 - y3) + (x4 - x3)*(y1 - y3);
 557
 558   double line_constant;
 559   double length_ratio = 1.0;
 560   double k_line = 1.0;
 561
 562   // Check for parallel lines
 563   if ((denominator_term < 0.005) && (denominator_term > -0.005))
 564     line_constant = -1.0;
 565   else
 566     line_constant = numerator_term/denominator_term;
 567
 568   // Check for intersection
 569   if ((line_constant < 1.0) && (line_constant > 0.0))
 570   {
 571     // Now must check that other line hits
 572     if (((y4 - y3) < 0.005) && ((y4 - y3) > -0.005))
 573       k_line = ((x1 - x3) + line_constant*(x2 - x1))/(x4 - x3);
 574     else
 575       k_line = ((y1 - y3) + line_constant*(y2 - y1))/(y4 - y3);
 576
 577     if ((k_line >= 0.0) && (k_line < 1.0))
 578       length_ratio = line_constant;
 579     else
 580       k_line = 1.0;
 581   }
 582   *ratio1 = length_ratio;
 583   *ratio2 = k_line;
 584 }
 585
 586 /*
 587  * Find where (x1, y1) -> (x2, y2) hits one of the lines in xvec, yvec.
 588  * (*x3, *y3) is the point where it hits.
 589  *
 590  */
 591 void oglFindEndForPolyline(double n, double xvec[], double yvec[],
 592                            double x1, double y1, double x2, double y2, double *x3, double *y3)
 593 {
 594   int i;
 595   double lastx = xvec[0];
 596   double lasty = yvec[0];
 597
 598   double min_ratio = 1.0;
 599   double line_ratio;
 600   double other_ratio;
 601
 602   for (i = 1; i < n; i++)
 603   {
 604     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[i], yvec[i],
 605                             &line_ratio, &other_ratio);
 606     lastx = xvec[i];
 607     lasty = yvec[i];
 608
 609     if (line_ratio < min_ratio)
 610       min_ratio = line_ratio;
 611   }
 612
 613   // Do last (implicit) line if last and first doubles are not identical
 614   if (!(xvec[0] == lastx && yvec[0] == lasty))
 615   {
 616     oglCheckLineIntersection(x1, y1, x2, y2, lastx, lasty, xvec[0], yvec[0],
 617                             &line_ratio, &other_ratio);
 618
 619     if (line_ratio < min_ratio)
 620       min_ratio = line_ratio;
 621   }
 622
 623   *x3 = (x1 + (x2 - x1)*min_ratio);
 624   *y3 = (y1 + (y2 - y1)*min_ratio);
 625
 626 }
 627
 628 /*
 629  * Find where the line hits the box.
 630  *
 631  */
 632
 633 void oglFindEndForBox(double width, double height,
 634                       double x1, double y1,         // Centre of box (possibly)
 635                       double x2, double y2,         // other end of line
 636                       double *x3, double *y3)       // End on box edge
 637 {
 638   double xvec[5];
 639   double yvec[5];
 640
 641   xvec[0] = (double)(x1 - width/2.0);
 642   yvec[0] = (double)(y1 - height/2.0);
 643   xvec[1] = (double)(x1 - width/2.0);
 644   yvec[1] = (double)(y1 + height/2.0);
 645   xvec[2] = (double)(x1 + width/2.0);
 646   yvec[2] = (double)(y1 + height/2.0);
 647   xvec[3] = (double)(x1 + width/2.0);
 648   yvec[3] = (double)(y1 - height/2.0);
 649   xvec[4] = (double)(x1 - width/2.0);
 650   yvec[4] = (double)(y1 - height/2.0);
 651
 652   oglFindEndForPolyline(5, xvec, yvec, x2, y2, x1, y1, x3, y3);
 653 }
 654
 655 /*
 656  * Find where the line hits the circle.
 657  *
 658  */
 659
 660 void oglFindEndForCircle(double radius,
 661                          double x1, double y1,  // Centre of circle
 662                          double x2, double y2,  // Other end of line
 663                          double *x3, double *y3)
 664 {
 665   double H = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 666
 667   if (H == 0.0)
 668   {
 669     *x3 = x1;
 670     *y3 = y1;
 671   }
 672   else
 673   {
 674    *y3 = radius * (y2 - y1)/H + y1;
 675    *x3 = radius * (x2 - x1)/H + x1;
 676   }
 677 }
 678
 679 /*
 680  * Given the line (x1, y1) -> (x2, y2), and an arrow size of given length and width,
 681  * return the position of the tip of the arrow and the left and right vertices of the arrow.
 682  *
 683  */
 684
 685 void oglGetArrowPoints(double x1, double y1, double x2, double y2,
 686                       double length, double width,
 687                       double *tip_x, double *tip_y,
 688                       double *side1_x, double *side1_y,
 689                       double *side2_x, double *side2_y)
 690 {
 691   double l = (double)sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
 692
 693   if (l < 0.01)
 694     l = (double) 0.01;
 695
 696   double i_bar = (x2 - x1)/l;
 697   double j_bar = (y2 - y1)/l;
 698
 699   double x3 = (- length*i_bar) + x2;
 700   double y3 = (- length*j_bar) + y2;
 701
 702   *side1_x = width*(-j_bar) + x3;
 703   *side1_y = width*i_bar + y3;
 704
 705   *side2_x = -width*(-j_bar) + x3;
 706   *side2_y = -width*i_bar + y3;
 707
 708   *tip_x = x2; *tip_y = y2;
 709 }
 710
 711 /*
 712  * Given an ellipse and endpoints of a line, returns the point at which
 713  * the line touches the ellipse in values x4, y4.
 714  * This function assumes that the centre of the ellipse is at x1, y1, and the
 715  * ellipse has a width of width1 and a height of height1. It also assumes you are
 716  * wanting to draw an arc FROM point x2, y2 TOWARDS point x3, y3.
 717  * This function calculates the x,y coordinates of the intersection point of
 718  * the arc with the ellipse.
 719  * Author: Ian Harrison
 720  */
 721
 722 void oglDrawArcToEllipse(double x1, double y1, double width1, double height1, double x2, double y2, double x3, double y3,
 723   double *x4, double *y4)
 724 {
 725   double a1 = (double)(width1/2.0);
 726   double b1 = (double)(height1/2.0);
 727
 728   // These are required to give top left x and y coordinates for DrawEllipse
 729 //  double top_left_x1 = (double)(x1 - a1);
 730 //  double top_left_y1 = (double)(y1 - b1);
 731 /*
 732   // Check for vertical line
 733   if (fabs(x2 - x3) < 0.05)
 734   {
 735     *x4 = x3;
 736     if (y2 < y3)
 737       *y4 = (double)(y1 - b1);
 738     else
 739       *y4 = (double)(y1 + b1);
 740     return;
 741   }
 742 */
 743   // Check that x2 != x3
 744   if (fabs(x2 - x3) < 0.05)
 745   {
 746     *x4 = x2;
 747     if (y3 > y2)
 748       *y4 = (double)(y1 - sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 749     else
 750       *y4 = (double)(y1 + sqrt((b1*b1 - (((x2-x1)*(x2-x1))*(b1*b1)/(a1*a1)))));
 751     return;
 752   }
 753
 754   // Calculate the x and y coordinates of the point where arc intersects ellipse
 755
 756   double A, B, C, D, E, F, G, H, K;
 757   double ellipse1_x, ellipse1_y;
 758
 759   A = (double)(1/(a1 * a1));
 760   B = (double)((y3 - y2) * (y3 - y2)) / ((x3 - x2) * (x3 - x2) * b1 * b1);
 761   C = (double)(2 * (y3 - y2) * (y2 - y1)) / ((x3 - x2) * b1 * b1);
 762   D = (double)((y2 - y1) * (y2 - y1)) / (b1 * b1);
 763   E = (double)(A + B);
 764   F = (double)(C - (2 * A * x1) - (2 * B * x2));
 765   G = (double)((A * x1 * x1) + (B * x2 * x2) - (C * x2) + D - 1);
 766   H = (double)((y3 - y2) / (x3 - x2));
 767   K = (double)((F * F) - (4 * E * G));
 768
 769   if (K >= 0)
 770   // In this case the line intersects the ellipse, so calculate intersection
 771   {
 772     if(x2 >= x1)
 773     {
 774       ellipse1_x = (double)(((F * -1) + sqrt(K)) / (2 * E));
 775       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 776     }
 777     else
 778     {
 779       ellipse1_x = (double)(((F * -1) -  sqrt(K)) / (2 * E));
 780       ellipse1_y = (double)((H * (ellipse1_x - x2)) + y2);
 781     }
 782   }
 783   else
 784   // in this case, arc does not intersect ellipse, so just draw arc
 785   {
 786     ellipse1_x = x3;
 787     ellipse1_y = y3;
 788   }
 789   *x4 = ellipse1_x;
 790   *y4 = ellipse1_y;
 791
 792 /*
 793   // Draw a little circle (radius = 2) at the end of the arc where it hits
 794   // the ellipse .
 795
 796   double circle_x = ellipse1_x - 2.0;
 797   double circle_y = ellipse1_y - 2.0;
 798   m_canvas->DrawEllipse(circle_x, circle_y, 4.0, 4.0);
 799 */
 800 }
 801
 802 // Update a list item from a list of strings
 803 void UpdateListBox(wxListBox *item, wxList *list)
 804 {
 805   item->Clear();
 806   if (!list)
 807     return;
 808
 809   wxNode *node = list->GetFirst();
 810   while (node)
 811   {
 812     wxChar *s = (wxChar *)node->GetData();
 813     item->Append(s);
 814     node = node->GetNext();
 815   }
 816 }
 817
 818 bool oglRoughlyEqual(double val1, double val2, double tol)
 819 {
 820     return ( (val1 < (val2 + tol)) && (val1 > (val2 - tol)) &&
 821              (val2 < (val1 + tol)) && (val2 > (val1 - tol)));
 822 }
 823
 824 /*
 825  * Hex<->Dec conversion
 826  */
 827
 828 // Array used in DecToHex conversion routine.
 829 static wxChar sg_HexArray[] = { wxT('0'), wxT('1'), wxT('2'), wxT('3'),
 830                                 wxT('4'), wxT('5'), wxT('6'), wxT('7'),
 831                                 wxT('8'), wxT('9'), wxT('A'), wxT('B'),
 832                                 wxT('C'), wxT('D'), wxT('E'), wxT('F')
 833 };
 834
 835 // Convert 2-digit hex number to decimal
 836 unsigned int oglHexToDec(wxChar* buf)
 837 {
 838   int firstDigit, secondDigit;
 839
 840   if (buf[0] >= wxT('A'))
 841     firstDigit = buf[0] - wxT('A') + 10;
 842   else
 843     firstDigit = buf[0] - wxT('0');
 844
 845   if (buf[1] >= wxT('A'))
 846     secondDigit = buf[1] - wxT('A') + 10;
 847   else
 848     secondDigit = buf[1] - wxT('0');
 849
 850   return firstDigit * 16 + secondDigit;
 851 }
 852
 853 // Convert decimal integer to 2-character hex string
 854 void oglDecToHex(unsigned int dec, wxChar *buf)
 855 {
 856     int firstDigit = (int)(dec/16.0);
 857     int secondDigit = (int)(dec - (firstDigit*16.0));
 858     buf[0] = sg_HexArray[firstDigit];
 859     buf[1] = sg_HexArray[secondDigit];
 860     buf[2] = 0;
 861 }
 862
 863 // 3-digit hex to wxColour
 864 wxColour oglHexToColour(const wxString& hex)
 865 {
 866     if (hex.Length() == 6)
 867     {
 868         long r, g, b;
 869         r = g = b = 0;
 870         hex.Mid(0,2).ToLong(&r, 16);
 871         hex.Mid(2,2).ToLong(&g, 16);
 872         hex.Mid(4,2).ToLong(&b, 16);
 873         return wxColour(r, g, b);
 874     }
 875     else
 876         return wxColour(0,0,0);
 877 }
 878
 879 // RGB to 3-digit hex
 880 wxString oglColourToHex(const wxColour& colour)
 881 {
 882     wxChar buf[7];
 883     unsigned int red = colour.Red();
 884     unsigned int green = colour.Green();
 885     unsigned int blue = colour.Blue();
 886
 887     oglDecToHex(red, buf);
 888     oglDecToHex(green, buf+2);
 889     oglDecToHex(blue, buf+4);
 890
 891     return wxString(buf);
 892 }
 893
 894