git.hungrycats.org Git - xscreensaver/blob - hacks/glx/escher.c

   1 /* -*- Mode: C; tab-width: 4 -*-
   2  * escher.c - Shows some Escher like scenes
   3  */
   4 #if !defined( lint ) && !defined( SABER )
   5 static const char sccsid[] = "@(#)escher.c      4.04 97/07/28 xlockmore";
   6 #endif
   7
   8 #undef DEBUG_LISTS
   9
  10 /* Permission to use, copy, modify, and distribute this software and its
  11  * documentation for any purpose and without fee is hereby granted,
  12  * provided that the above copyright notice appear in all copies and that
  13  * both that copyright notice and this permission notice appear in
  14  * supporting documentation.
  15  *
  16  * This file is provided AS IS with no warranties of any kind.  The author
  17  * shall have no liability with respect to the infringement of copyrights,
  18  * trade secrets or any patents by this file or any part thereof.  In no
  19  * event will the author be liable for any lost revenue or profits or
  20  * other special, indirect and consequential damages.
  21  *
  22  * The RotateAroundU() routine was adapted from the book
  23  *    "Computer Graphics Principles and Practice
  24  *     Foley - vanDam - Feiner - Hughes
  25  *     Second Edition" Pag. 227, exercise 5.15.
  26  *
  27  * This mode shows some interesting scenes that are impossible OR very
  28  * wierd to build in the real universe. Much of the scenes are inspirated
  29  * on Mauritz Cornelis Escher's works which derivated the mode's name.
  30  * M.C. Escher (1898-1972) was a dutch artist and many people prefer to
  31  * say he was a mathematician.
  32  *
  33  * Thanks goes to Brian Paul for making it possible and inexpensive to use
  34  * OpenGL at home.
  35  *
  36  * Since I'm not a native english speaker, my apologies for any gramatical
  37  * mistake.
  38  *
  39  * My e-mail addresses are
  40  * vianna@cat.cbpf.br
  41  *         and
  42  * marcelo@venus.rdc.puc-rio.br
  43  *
  44  * Marcelo F. Vianna (Jun-01-1997)
  45  *
  46  * Revision History:
  47  * 08-Jun-97: New scene implemented: "Impossible Cage" based in a M.C. Escher's
  48  *            painting with the same name (quite similar). The first GL mode
  49  *            to use texture mapping.
  50  *            The "Impossible Cage" scene doesn't use DEPTH BUFFER, the
  51  *            wood planks are drawn consistently using GL_CULL_FACE, and
  52  *            the painter's algorithm is used to sort the planks.
  53  *            Marcelo F. Vianna.
  54  * 07-Jun-97: Speed ups in Moebius Strip using GL_CULL_FACE.
  55  *            Marcelo F. Vianna.
  56  * 03-Jun-97: Initial Release (Only one scene: "Moebius Strip")
  57  *            The Moebious Strip scene was inspirated in a M.C. Escher's
  58  *            painting named Moebius Strip II in wich ants walk across a
  59  *            Moebius Strip path, sometimes meeting each other and sometimes
  60  *            being in "opposite faces" (note that the moebius strip has
  61  *            only one face and one edge).
  62  *            Marcelo F. Vianna.
  63  *
  64  */
  65
  66 /*-
  67  * Texture mapping is only available on RGBA contexts, Mono and color index
  68  * visuals DO NOT support texture mapping in OpenGL.
  69  *
  70  * BUT Mesa do implements RGBA contexts in pseudo color visuals, so texture
  71  * mapping shuld work on PseudoColor, DirectColor, TrueColor using Mesa. Mono
  72  * is not officially supported for both OpenGL and Mesa, but seems to not crash
  73  * Mesa.
  74  *
  75  * In real OpenGL, PseudoColor DO NOT support texture map (as far as I know).
  76  */
  77
  78 #include <X11/Intrinsic.h>
  79
  80 #ifdef STANDALONE
  81 # define PROGCLASS                                      "Escher"
  82 # define HACK_INIT                                      init_escher
  83 # define HACK_DRAW                                      draw_escher
  84 # define escher_opts                            xlockmore_opts
  85 # define DEFAULTS       "*count:                0       \n"                     \
  86                                         "*cycles:               1       \n"                     \
  87                                         "*delay:                100     \n"                     \
  88                                         "*wireframe:    False   \n"
  89 # include "xlockmore.h"                         /* from the xscreensaver distribution */
  90 #else  /* !STANDALONE */
  91 # include "xlock.h"                                     /* from the xlockmore distribution */
  92 #endif /* !STANDALONE */
  93
  94
  95 #ifdef USE_GL
  96
  97
  98 #include <GL/glu.h>
  99 #include "e_textures.h"
 100
 101 #define DEF_SOLIDMOEBIUS  "False"
 102 #define DEF_NOANTS  "False"
 103
 104 static int  solidmoebius;
 105 static int  noants;
 106
 107 static XrmOptionDescRec opts[] =
 108 {
 109    {"-solidmoebius", ".escher.solidmoebius", XrmoptionNoArg, (caddr_t) "on"},
 110   {"+solidmoebius", ".escher.solidmoebius", XrmoptionNoArg, (caddr_t) "off"},
 111         {"-noants", ".escher.noants", XrmoptionNoArg, (caddr_t) "on"},
 112         {"+noants", ".escher.noants", XrmoptionNoArg, (caddr_t) "off"}
 113 };
 114 static argtype vars[] =
 115 {
 116         {(caddr_t *) & solidmoebius, "solidmoebius", "Solidmoebius", DEF_SOLIDMOEBIUS, t_Bool},
 117         {(caddr_t *) & noants, "noants", "Noants", DEF_NOANTS, t_Bool}
 118 };
 119 static OptionStruct desc[] =
 120 {
 121         {"-/+solidmoebius", "select between a SOLID or a NET Moebius Strip"},
 122         {"-/+noants", "turn on/off walking ants"}
 123 };
 124
 125 ModeSpecOpt escher_opts =
 126 {4, opts, 2, vars, desc};
 127
 128 #define Scale4Window               0.3
 129 #define Scale4Iconic               0.4
 130
 131 #define sqr(A)                     ((A)*(A))
 132
 133 #ifndef Pi
 134 #define Pi                         M_PI
 135 #endif
 136
 137 /*************************************************************************/
 138
 139 typedef struct {
 140         GLint       WindH, WindW;
 141         GLfloat     step;
 142         GLfloat     ant_position;
 143         int         scene;
 144         int         AreObjectsDefined[3];
 145         GLXContext  glx_context;
 146 } escherstruct;
 147
 148 static float front_shininess[] =
 149 {60.0};
 150 static float front_specular[] =
 151 {0.7, 0.7, 0.7, 1.0};
 152 static float ambient[] =
 153 {0.0, 0.0, 0.0, 1.0};
 154 static float diffuse[] =
 155 {1.0, 1.0, 1.0, 1.0};
 156 static float position0[] =
 157 {1.0, 1.0, 1.0, 0.0};
 158 static float position1[] =
 159 {-1.0, -1.0, 1.0, 0.0};
 160 static float lmodel_ambient[] =
 161 {0.5, 0.5, 0.5, 1.0};
 162 static float lmodel_twoside[] =
 163 {GL_TRUE};
 164
 165 static float MaterialRed[] =
 166 {0.7, 0.0, 0.0, 1.0};
 167 static float MaterialGreen[] =
 168 {0.1, 0.5, 0.2, 1.0};
 169 static float MaterialBlue[] =
 170 {0.0, 0.0, 0.7, 1.0};
 171 static float MaterialCyan[] =
 172 {0.2, 0.5, 0.7, 1.0};
 173 static float MaterialYellow[] =
 174 {0.7, 0.7, 0.0, 1.0};
 175 static float MaterialMagenta[] =
 176 {0.6, 0.2, 0.5, 1.0};
 177 static float MaterialWhite[] =
 178 {0.7, 0.7, 0.7, 1.0};
 179 static float MaterialGray[] =
 180 {0.2, 0.2, 0.2, 1.0};
 181
 182 static escherstruct *escher = NULL;
 183 static GLuint objects;
 184
 185 #define NUM_SCENES      2
 186
 187 #define ObjMoebiusStrip 0
 188 #define ObjAntBody      1
 189 #define ObjWoodPlank    2
 190
 191 #define PlankWidth      3.0
 192 #define PlankHeight     0.35
 193 #define PlankThickness  0.15
 194
 195 static void
 196 mySphere(float radius)
 197 {
 198         GLUquadricObj *quadObj;
 199
 200         quadObj = gluNewQuadric();
 201         gluQuadricDrawStyle(quadObj, (GLenum) GLU_FILL);
 202         gluSphere(quadObj, radius, 16, 16);
 203         gluDeleteQuadric(quadObj);
 204 }
 205
 206 static void
 207 myCone(float radius)
 208 {
 209         GLUquadricObj *quadObj;
 210
 211         quadObj = gluNewQuadric();
 212         gluQuadricDrawStyle(quadObj, (GLenum) GLU_FILL);
 213         gluCylinder(quadObj, radius, 0, radius * 3, 8, 1);
 214         gluDeleteQuadric(quadObj);
 215 }
 216
 217 static void
 218 draw_escher_ant(escherstruct * ep, float *Material)
 219 {
 220         static float ant_step = 0;
 221         float       cos1 = cos(ant_step);
 222         float       cos2 = cos(ant_step + 2 * Pi / 3);
 223         float       cos3 = cos(ant_step + 4 * Pi / 3);
 224         float       sin1 = sin(ant_step);
 225         float       sin2 = sin(ant_step + 2 * Pi / 3);
 226         float       sin3 = sin(ant_step + 4 * Pi / 3);
 227
 228         glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, Material);
 229         if (!ep->AreObjectsDefined[ObjAntBody]) {
 230                 glNewList(objects + ObjAntBody, GL_COMPILE_AND_EXECUTE);
 231                 glEnable(GL_CULL_FACE);
 232                 glPushMatrix();
 233                 glScalef(1, 1.3, 1);
 234                 mySphere(0.18);
 235                 glScalef(1, 1 / 1.3, 1);
 236                 glTranslatef(0.00, 0.30, 0.00);
 237                 mySphere(0.2);
 238
 239                 glTranslatef(-0.05, 0.17, 0.05);
 240                 glRotatef(-90, 1, 0, 0);
 241                 glRotatef(-25, 0, 1, 0);
 242                 myCone(0.05);
 243                 glTranslatef(0.00, 0.10, 0.00);
 244                 myCone(0.05);
 245                 glRotatef(25, 0, 1, 0);
 246                 glRotatef(90, 1, 0, 0);
 247
 248                 glScalef(1, 1.3, 1);
 249                 glTranslatef(0.15, -0.65, 0.05);
 250                 mySphere(0.25);
 251                 glScalef(1, 1 / 1.3, 1);
 252                 glPopMatrix();
 253                 glDisable(GL_CULL_FACE);
 254                 glEndList();
 255                 ep->AreObjectsDefined[ObjAntBody] = 1;
 256 #ifdef DEBUG_LISTS
 257                 (void) printf("Ant drawn SLOWLY\n");
 258 #endif
 259         } else {
 260                 glCallList(objects + ObjAntBody);
 261 #ifdef DEBUG_LISTS
 262                 (void) printf("Ant drawn quickly\n");
 263 #endif
 264         }
 265
 266         glDisable(GL_LIGHTING);
 267         /* ANTENNAS */
 268         glBegin(GL_LINES);
 269         glColor3fv(Material);
 270         glVertex3f(0.00, 0.30, 0.00);
 271         glColor3fv(MaterialGray);
 272         glVertex3f(0.40, 0.70, 0.40);
 273         glColor3fv(Material);
 274         glVertex3f(0.00, 0.30, 0.00);
 275         glColor3fv(MaterialGray);
 276         glVertex3f(0.40, 0.70, -0.40);
 277         glEnd();
 278         glBegin(GL_POINTS);
 279         glColor3fv(MaterialRed);
 280         glVertex3f(0.40, 0.70, 0.40);
 281         glVertex3f(0.40, 0.70, -0.40);
 282         glEnd();
 283
 284         /* LEFT-FRONT ARM */
 285         glBegin(GL_LINE_STRIP);
 286         glColor3fv(Material);
 287         glVertex3f(0.00, 0.05, 0.18);
 288         glVertex3f(0.35 + 0.05 * cos1, 0.15, 0.25);
 289         glColor3fv(MaterialGray);
 290         glVertex3f(-0.20 + 0.05 * cos1, 0.25 + 0.1 * sin1, 0.45);
 291         glEnd();
 292
 293         /* LEFT-CENTER ARM */
 294         glBegin(GL_LINE_STRIP);
 295         glColor3fv(Material);
 296         glVertex3f(0.00, 0.00, 0.18);
 297         glVertex3f(0.35 + 0.05 * cos2, 0.00, 0.25);
 298         glColor3fv(MaterialGray);
 299         glVertex3f(-0.20 + 0.05 * cos2, 0.00 + 0.1 * sin2, 0.45);
 300         glEnd();
 301
 302         /* LEFT-BACK ARM */
 303         glBegin(GL_LINE_STRIP);
 304         glColor3fv(Material);
 305         glVertex3f(0.00, -0.05, 0.18);
 306         glVertex3f(0.35 + 0.05 * cos3, -0.15, 0.25);
 307         glColor3fv(MaterialGray);
 308         glVertex3f(-0.20 + 0.05 * cos3, -0.25 + 0.1 * sin3, 0.45);
 309         glEnd();
 310
 311         /* RIGHT-FRONT ARM */
 312         glBegin(GL_LINE_STRIP);
 313         glColor3fv(Material);
 314         glVertex3f(0.00, 0.05, -0.18);
 315         glVertex3f(0.35 - 0.05 * sin1, 0.15, -0.25);
 316         glColor3fv(MaterialGray);
 317         glVertex3f(-0.20 - 0.05 * sin1, 0.25 + 0.1 * cos1, -0.45);
 318         glEnd();
 319
 320         /* RIGHT-CENTER ARM */
 321         glBegin(GL_LINE_STRIP);
 322         glColor3fv(Material);
 323         glVertex3f(0.00, 0.00, -0.18);
 324         glVertex3f(0.35 - 0.05 * sin2, 0.00, -0.25);
 325         glColor3fv(MaterialGray);
 326         glVertex3f(-0.20 - 0.05 * sin2, 0.00 + 0.1 * cos2, -0.45);
 327         glEnd();
 328
 329         /* RIGHT-BACK ARM */
 330         glBegin(GL_LINE_STRIP);
 331         glColor3fv(Material);
 332         glVertex3f(0.00, -0.05, -0.18);
 333         glVertex3f(0.35 - 0.05 * sin3, -0.15, -0.25);
 334         glColor3fv(MaterialGray);
 335         glVertex3f(-0.20 - 0.05 * sin3, -0.25 + 0.1 * cos3, -0.45);
 336         glEnd();
 337
 338         glBegin(GL_POINTS);
 339         glColor3fv(MaterialMagenta);
 340         glVertex3f(-0.20 + 0.05 * cos1, 0.25 + 0.1 * sin1, 0.45);
 341         glVertex3f(-0.20 + 0.05 * cos2, 0.00 + 0.1 * sin2, 0.45);
 342         glVertex3f(-0.20 + 0.05 * cos3, -0.25 + 0.1 * sin3, 0.45);
 343         glVertex3f(-0.20 - 0.05 * sin1, 0.25 + 0.1 * cos1, -0.45);
 344         glVertex3f(-0.20 - 0.05 * sin2, 0.00 + 0.1 * cos2, -0.45);
 345         glVertex3f(-0.20 - 0.05 * sin3, -0.25 + 0.1 * cos3, -0.45);
 346         glEnd();
 347
 348         glEnable(GL_LIGHTING);
 349
 350         ant_step += 0.3;
 351 }
 352
 353 static void
 354 RotateAaroundU(float Ax, float Ay, float Az,
 355                float Ux, float Uy, float Uz,
 356                float *Cx, float *Cy, float *Cz,
 357                float Theta)
 358 {
 359         float       cosO = cos(Theta);
 360         float       sinO = sin(Theta);
 361         float       one_cosO = 1 - cosO;
 362         float       Ux2 = sqr(Ux);
 363         float       Uy2 = sqr(Uy);
 364         float       Uz2 = sqr(Uz);
 365         float       UxUy = Ux * Uy;
 366         float       UxUz = Ux * Uz;
 367         float       UyUz = Uy * Uz;
 368
 369         *Cx = (Ux2 + cosO * (1 - Ux2)) * Ax + (UxUy * one_cosO - Uz * sinO) * Ay + (UxUz * one_cosO + Uy * sinO) * Az;
 370         *Cy = (UxUy * one_cosO + Uz * sinO) * Ax + (Uy2 + cosO * (1 - Uy2)) * Ay + (UyUz * one_cosO - Ux * sinO) * Az;
 371         *Cz = (UxUz * one_cosO - Uy * sinO) * Ax + (UyUz * one_cosO + Ux * sinO) * Ay + (Uz2 + cosO * (1 - Uz2)) * Az;
 372 }
 373
 374 #define MoebiusDivisions 40
 375 #define MoebiusTransversals 4
 376 static void
 377 draw_moebius(ModeInfo * mi)
 378 {
 379         GLfloat     Phi, Theta;
 380         GLfloat     cPhi, sPhi;
 381         escherstruct *ep = &escher[MI_SCREEN(mi)];
 382         int         i, j;
 383
 384         float       Cx, Cy, Cz;
 385
 386         if (!ep->AreObjectsDefined[ObjMoebiusStrip]) {
 387                 glNewList(objects + ObjMoebiusStrip, GL_COMPILE_AND_EXECUTE);
 388
 389                 if (solidmoebius) {
 390                         glBegin(GL_QUAD_STRIP);
 391                         Phi = 0;
 392                         i = 0;
 393                         while (i < (MoebiusDivisions * 2 + 1)) {
 394                                 Theta = Phi / 2;
 395                                 cPhi = cos(Phi);
 396                                 sPhi = sin(Phi);
 397
 398                                 i++;
 399                                 if (i % 2)
 400                                         glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialRed);
 401                                 else
 402                                         glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialGray);
 403
 404                                 RotateAaroundU(cPhi, sPhi, 0, -sPhi, cPhi, 0, &Cx, &Cy, &Cz, Theta);
 405                                 glNormal3f(Cx, Cy, Cz);
 406                                 RotateAaroundU(0, 0, 1, -sPhi, cPhi, 0, &Cx, &Cy, &Cz, Theta);
 407                                 glVertex3f(cPhi * 3 + Cx, sPhi * 3 + Cy, +Cz);
 408                                 glVertex3f(cPhi * 3 - Cx, sPhi * 3 - Cy, -Cz);
 409
 410                                 Phi += Pi / MoebiusDivisions;
 411                         }
 412                         glEnd();
 413                 } else {
 414                         for (j = -MoebiusTransversals; j < MoebiusTransversals; j++) {
 415                                 glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 416                                 glBegin(GL_QUAD_STRIP);
 417                                 Phi = 0;
 418                                 i = 0;
 419                                 while (i < (MoebiusDivisions * 2 + 1)) {
 420                                         Theta = Phi / 2;
 421                                         cPhi = cos(Phi);
 422                                         sPhi = sin(Phi);
 423
 424                                         RotateAaroundU(cPhi, sPhi, 0, -sPhi, cPhi, 0, &Cx, &Cy, &Cz, Theta);
 425                                         glNormal3f(Cx, Cy, Cz);
 426                                         RotateAaroundU(0, 0, 1, -sPhi, cPhi, 0, &Cx, &Cy, &Cz, Theta);
 427                                         j++;
 428                                         if (j == MoebiusTransversals)
 429                                                 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
 430                                         else if (i % 2)
 431                                                 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialRed);
 432                                         else
 433                                                 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialGray);
 434                                         glVertex3f(cPhi * 3 + Cx / MoebiusTransversals * j, sPhi * 3 + Cy / MoebiusTransversals * j, +Cz / MoebiusTransversals * j);
 435                                         j--;
 436                                         if (j == -MoebiusTransversals)
 437                                                 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
 438                                         else if (i % 2)
 439                                                 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialRed);
 440                                         else
 441                                                 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialGray);
 442                                         glVertex3f(cPhi * 3 + Cx / MoebiusTransversals * j, sPhi * 3 + Cy / MoebiusTransversals * j, +Cz / MoebiusTransversals * j);
 443
 444                                         Phi += Pi / MoebiusDivisions;
 445                                         i++;
 446                                 }
 447                                 glEnd();
 448                         }
 449                         glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
 450                 }
 451
 452                 glEndList();
 453                 ep->AreObjectsDefined[ObjMoebiusStrip] = 1;
 454 #ifdef DEBUG_LISTS
 455                 (void) printf("Strip drawn SLOWLY\n");
 456 #endif
 457         } else {
 458                 glCallList(objects + ObjMoebiusStrip);
 459 #ifdef DEBUG_LISTS
 460                 (void) printf("Strip drawn quickly\n");
 461 #endif
 462         }
 463
 464         if (!noants) {
 465                 /* DRAW BLUE ANT */
 466                 glPushMatrix();
 467                 glRotatef(ep->ant_position + 180, 0, 0, 1);
 468                 glTranslatef(3, 0, 0);
 469                 glRotatef(ep->ant_position / 2 + 90, 0, 1, 0);
 470                 glTranslatef(0.28, 0, -0.45);
 471                 draw_escher_ant(ep, MaterialYellow);
 472                 glPopMatrix();
 473
 474                 /* DRAW YELLOW ANT */
 475                 glPushMatrix();
 476                 glRotatef(ep->ant_position, 0, 0, 1);
 477                 glTranslatef(3, 0, 0);
 478                 glRotatef(ep->ant_position / 2, 0, 1, 0);
 479                 glTranslatef(0.28, 0, -0.45);
 480                 draw_escher_ant(ep, MaterialBlue);
 481                 glPopMatrix();
 482
 483                 /* DRAW GREEN ANT */
 484                 glPushMatrix();
 485                 glRotatef(-ep->ant_position, 0, 0, 1);
 486                 glTranslatef(3, 0, 0);
 487                 glRotatef(-ep->ant_position / 2, 0, 1, 0);
 488                 glTranslatef(0.28, 0, 0.45);
 489                 glRotatef(180, 1, 0, 0);
 490                 draw_escher_ant(ep, MaterialGreen);
 491                 glPopMatrix();
 492
 493                 /* DRAW CYAN ANT */
 494                 glPushMatrix();
 495                 glRotatef(-ep->ant_position + 180, 0, 0, 1);
 496                 glTranslatef(3, 0, 0);
 497                 glRotatef(-ep->ant_position / 2 + 90, 0, 1, 0);
 498                 glTranslatef(0.28, 0, 0.45);
 499                 glRotatef(180, 1, 0, 0);
 500                 draw_escher_ant(ep, MaterialCyan);
 501                 glPopMatrix();
 502         }
 503         ep->ant_position += 1;
 504 }
 505 #undef MoebiusDivisions
 506 #undef MoebiusTransversals
 507
 508 static void
 509 draw_woodplank(escherstruct * ep)
 510 {
 511         if (!ep->AreObjectsDefined[ObjWoodPlank]) {
 512                 glNewList(objects + ObjWoodPlank, GL_COMPILE_AND_EXECUTE);
 513                 glBegin(GL_QUADS);
 514                 glNormal3f(0, 0, 1);
 515                 glTexCoord2f(0, 0);
 516                 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
 517                 glTexCoord2f(1, 0);
 518                 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
 519                 glTexCoord2f(1, 1);
 520                 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
 521                 glTexCoord2f(0, 1);
 522                 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
 523                 glNormal3f(0, 0, -1);
 524                 glTexCoord2f(0, 0);
 525                 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
 526                 glTexCoord2f(1, 0);
 527                 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
 528                 glTexCoord2f(1, 1);
 529                 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
 530                 glTexCoord2f(0, 1);
 531                 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
 532                 glNormal3f(0, 1, 0);
 533                 glTexCoord2f(0, 0);
 534                 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
 535                 glTexCoord2f(1, 0);
 536                 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
 537                 glTexCoord2f(1, 1);
 538                 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
 539                 glTexCoord2f(0, 1);
 540                 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
 541                 glNormal3f(0, -1, 0);
 542                 glTexCoord2f(0, 0);
 543                 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
 544                 glTexCoord2f(1, 0);
 545                 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
 546                 glTexCoord2f(1, 1);
 547                 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
 548                 glTexCoord2f(0, 1);
 549                 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
 550                 glNormal3f(1, 0, 0);
 551                 glTexCoord2f(0, 0);
 552                 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
 553                 glTexCoord2f(1, 0);
 554                 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
 555                 glTexCoord2f(1, 1);
 556                 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
 557                 glTexCoord2f(0, 1);
 558                 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
 559                 glNormal3f(-1, 0, 0);
 560                 glTexCoord2f(0, 0);
 561                 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
 562                 glTexCoord2f(1, 0);
 563                 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
 564                 glTexCoord2f(1, 1);
 565                 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
 566                 glTexCoord2f(0, 1);
 567                 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
 568                 glEnd();
 569                 glEndList();
 570                 ep->AreObjectsDefined[ObjWoodPlank] = 1;
 571 #ifdef DEBUG_LISTS
 572                 (void) printf("WoodPlank drawn SLOWLY\n");
 573 #endif
 574         } else {
 575                 glCallList(objects + ObjWoodPlank);
 576 #ifdef DEBUG_LISTS
 577                 (void) printf("WoodPlank drawn quickly\n");
 578 #endif
 579         }
 580 }
 581
 582 static void
 583 draw_impossiblecage(escherstruct * ep)
 584 {
 585         glPushMatrix();
 586         glRotatef(90, 0, 1, 0);
 587         glTranslatef(0.0, PlankHeight - PlankWidth, -PlankThickness - PlankWidth);
 588         draw_woodplank(ep);
 589         glPopMatrix();
 590         glPushMatrix();
 591         glRotatef(90, 0, 0, 1);
 592         glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - PlankThickness);
 593         draw_woodplank(ep);
 594         glPopMatrix();
 595         glPushMatrix();
 596         glRotatef(90, 0, 1, 0);
 597         glTranslatef(0.0, PlankWidth - PlankHeight, -PlankThickness - PlankWidth);
 598         draw_woodplank(ep);
 599         glPopMatrix();
 600         glPushMatrix();
 601         glTranslatef(0.0, PlankWidth - PlankHeight, 3 * PlankThickness - PlankWidth);
 602         draw_woodplank(ep);
 603         glPopMatrix();
 604         glPushMatrix();
 605         glRotatef(90, 0, 0, 1);
 606         glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - PlankThickness);
 607         draw_woodplank(ep);
 608         glPopMatrix();
 609         glPushMatrix();
 610         glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - 3 * PlankThickness);
 611         draw_woodplank(ep);
 612         glPopMatrix();
 613         glPushMatrix();
 614         glTranslatef(0.0, PlankHeight - PlankWidth, 3 * PlankThickness - PlankWidth);
 615         draw_woodplank(ep);
 616         glPopMatrix();
 617         glPushMatrix();
 618         glRotatef(90, 0, 0, 1);
 619         glTranslatef(0.0, PlankHeight - PlankWidth, PlankThickness - PlankWidth);
 620         draw_woodplank(ep);
 621         glPopMatrix();
 622         glPushMatrix();
 623         glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - 3 * PlankThickness);
 624         draw_woodplank(ep);
 625         glPopMatrix();
 626         glPushMatrix();
 627         glRotatef(90, 0, 1, 0);
 628         glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth + PlankThickness);
 629         draw_woodplank(ep);
 630         glPopMatrix();
 631         glPushMatrix();
 632         glRotatef(90, 0, 0, 1);
 633         glTranslatef(0.0, PlankWidth - PlankHeight, PlankThickness - PlankWidth);
 634         draw_woodplank(ep);
 635         glPopMatrix();
 636         glPushMatrix();
 637         glRotatef(90, 0, 1, 0);
 638         glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth + PlankThickness);
 639         draw_woodplank(ep);
 640         glPopMatrix();
 641 }
 642
 643 void
 644 draw_escher(ModeInfo * mi)
 645 {
 646         escherstruct *ep = &escher[MI_SCREEN(mi)];
 647
 648         Display    *display = MI_DISPLAY(mi);
 649         Window      window = MI_WINDOW(mi);
 650
 651         glXMakeCurrent(display, window, ep->glx_context);
 652
 653         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 654
 655         glPushMatrix();
 656
 657         glTranslatef(0.0, 0.0, -10.0);
 658
 659         if (!MI_WIN_IS_ICONIC(mi)) {
 660                 glScalef(Scale4Window * ep->WindH / ep->WindW, Scale4Window, Scale4Window);
 661         } else {
 662                 glScalef(Scale4Iconic * ep->WindH / ep->WindW, Scale4Iconic, Scale4Iconic);
 663         }
 664
 665
 666         switch (ep->scene) {
 667                 case 1:
 668                         glRotatef(ep->step * 100, 1, 0, 0);
 669                         glRotatef(ep->step * 95, 0, 1, 0);
 670                         glRotatef(ep->step * 90, 0, 0, 1);
 671                         draw_moebius(mi);
 672                         break;
 673                 case 2: /* 196 - 213 */
 674                         glRotatef(ep->step * 100, 0, 0, 1);
 675                         glRotatef(25 + cos(ep->step * 5) * 6, 1, 0, 0);
 676                         glRotatef(204.5 - sin(ep->step * 5) * 8, 0, 1, 0);
 677                         draw_impossiblecage(ep);
 678                         break;
 679         }
 680
 681         glPopMatrix();
 682
 683         glFlush();
 684
 685         glXSwapBuffers(display, window);
 686
 687         ep->step += 0.025;
 688 }
 689
 690 static void
 691 reshape(ModeInfo * mi, int width, int height)
 692 {
 693         escherstruct *ep = &escher[MI_SCREEN(mi)];
 694
 695         glViewport(0, 0, ep->WindW = (GLint) width, ep->WindH = (GLint) height);
 696         glMatrixMode(GL_PROJECTION);
 697         glLoadIdentity();
 698         glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 15.0);
 699         glMatrixMode(GL_MODELVIEW);
 700         if (width >= 1024) {
 701                 glLineWidth(3);
 702                 glPointSize(3);
 703         } else if (width >= 512) {
 704                 glLineWidth(2);
 705                 glPointSize(2);
 706         } else {
 707                 glLineWidth(1);
 708                 glPointSize(1);
 709         }
 710         ep->AreObjectsDefined[ObjMoebiusStrip] = 0;
 711         ep->AreObjectsDefined[ObjAntBody] = 0;
 712         ep->AreObjectsDefined[ObjWoodPlank] = 0;
 713 }
 714
 715 static void
 716 pinit(ModeInfo * mi)
 717 {
 718         escherstruct *ep = &escher[MI_SCREEN(mi)];
 719
 720         glClearDepth(1.0);
 721         glClearColor(0.0, 0.0, 0.0, 1.0);
 722
 723         glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
 724         glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
 725         glLightfv(GL_LIGHT0, GL_POSITION, position0);
 726         glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);
 727         glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse);
 728         glLightfv(GL_LIGHT1, GL_POSITION, position1);
 729         glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
 730         glLightModelfv(GL_LIGHT_MODEL_TWO_SIDE, lmodel_twoside);
 731         glEnable(GL_LIGHTING);
 732         glEnable(GL_LIGHT0);
 733         glEnable(GL_LIGHT1);
 734         glEnable(GL_NORMALIZE);
 735         glFrontFace(GL_CCW);
 736         glCullFace(GL_BACK);
 737
 738         switch (ep->scene) {
 739                 case 1:
 740                         glShadeModel(GL_SMOOTH);
 741                         glEnable(GL_DEPTH_TEST);
 742                         glDisable(GL_TEXTURE_2D);
 743                         glDisable(GL_CULL_FACE);
 744                         break;
 745                 case 2:
 746                         glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
 747                         glShadeModel(GL_FLAT);
 748                         glDisable(GL_DEPTH_TEST);
 749                         glEnable(GL_TEXTURE_2D);
 750                         glEnable(GL_CULL_FACE);
 751                         break;
 752         }
 753
 754         glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 755         gluBuild2DMipmaps(GL_TEXTURE_2D, 3, WoodTextureWidth, WoodTextureHeight,
 756                           GL_RGB, GL_UNSIGNED_BYTE, WoodTextureData);
 757         glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 758         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
 759         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
 760         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 761         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 762
 763         glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, front_shininess);
 764         glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, front_specular);
 765 }
 766
 767 void
 768 init_escher(ModeInfo * mi)
 769 {
 770         int         screen = MI_SCREEN(mi);
 771         escherstruct *ep;
 772
 773         if (escher == NULL) {
 774                 if ((escher = (escherstruct *) calloc(MI_NUM_SCREENS(mi),
 775                                              sizeof (escherstruct))) == NULL)
 776                         return;
 777         }
 778         ep = &escher[screen];
 779         ep->step = NRAND(90);
 780         ep->ant_position = NRAND(90);
 781
 782         ep->glx_context = init_GL(mi);
 783
 784         reshape(mi, MI_WIN_WIDTH(mi), MI_WIN_HEIGHT(mi));
 785         ep->scene = MI_BATCHCOUNT(mi);
 786         if (ep->scene <= 0 || ep->scene > NUM_SCENES)
 787                 ep->scene = NRAND(NUM_SCENES) + 1;
 788         glDrawBuffer(GL_BACK);
 789         objects = glGenLists(3);
 790         pinit(mi);
 791
 792 }
 793
 794 void
 795 change_escher(ModeInfo * mi)
 796 {
 797         escherstruct *ep = &escher[MI_SCREEN(mi)];
 798
 799         ep->scene = (ep->scene) % NUM_SCENES + 1;
 800         glXMakeCurrent(MI_DISPLAY(mi), MI_WINDOW(mi), ep->glx_context);
 801         pinit(mi);
 802 }
 803
 804 void
 805 release_escher(ModeInfo * mi)
 806 {
 807         if (escher != NULL) {
 808                 (void) free((void *) escher);
 809                 escher = NULL;
 810         }
 811         glDeleteLists(objects, 3);
 812 }
 813
 814 #endif