1 /* -*- Mode: C; tab-width: 4 -*- */
2 /* cage --- the Impossible Cage, an Escher like scene. */
4 #if !defined( lint ) && !defined( SABER )
5 static const char sccsid[] = "@(#)cage.c 4.07 98/01/04 xlockmore";
12 * Permission to use, copy, modify, and distribute this software and its
13 * documentation for any purpose and without fee is hereby granted,
14 * provided that the above copyright notice appear in all copies and that
15 * both that copyright notice and this permission notice appear in
16 * supporting documentation.
18 * This file is provided AS IS with no warranties of any kind. The author
19 * shall have no liability with respect to the infringement of copyrights,
20 * trade secrets or any patents by this file or any part thereof. In no
21 * event will the author be liable for any lost revenue or profits or
22 * other special, indirect and consequential damages.
24 * The RotateAroundU() routine was adapted from the book
25 * "Computer Graphics Principles and Practice
26 * Foley - vanDam - Feiner - Hughes
27 * Second Edition" Pag. 227, exercise 5.15.
29 * This mode shows some interesting scenes that are impossible OR very
30 * wierd to build in the real universe. Much of the scenes are inspirated
31 * on Mauritz Cornelis Escher's works which derivated the mode's name.
32 * M.C. Escher (1898-1972) was a dutch artist and many people prefer to
33 * say he was a mathematician.
35 * Thanks goes to Brian Paul for making it possible and inexpensive to use
38 * Since I'm not a native English speaker, my apologies for any grammatical
41 * My e-mail address is
44 * Marcelo F. Vianna (Jun-01-1997)
47 * 01-Jan-98: Mode separated from escher and renamed
48 * 08-Jun-97: New scene implemented: "Impossible Cage" based in a M.C. Escher's
49 * painting with the same name (quite similar). The first GL mode
50 * to use texture mapping.
51 * The "Impossible Cage" scene doesn't use DEPTH BUFFER, the
52 * wood planks are drawn consistently using GL_CULL_FACE, and
53 * the painter's algorithm is used to sort the planks.
55 * 07-Jun-97: Speed ups in Moebius Strip using GL_CULL_FACE.
57 * 03-Jun-97: Initial Release (Only one scene: "Moebius Strip")
58 * The Moebius Strip scene was inspirated in a M.C. Escher's
59 * painting named Moebius Strip II in wich ants walk across a
60 * Moebius Strip path, sometimes meeting each other and sometimes
61 * being in "opposite faces" (note that the moebius strip has
62 * only one face and one edge).
68 * Texture mapping is only available on RGBA contexts, Mono and color index
69 * visuals DO NOT support texture mapping in OpenGL.
71 * BUT Mesa do implements RGBA contexts in pseudo color visuals, so texture
72 * mapping shuld work on PseudoColor, DirectColor, TrueColor using Mesa. Mono
73 * is not officially supported for both OpenGL and Mesa, but seems to not crash
76 * In real OpenGL, PseudoColor DO NOT support texture map (as far as I know).
79 #include <X11/Intrinsic.h>
82 # define PROGCLASS "Cage"
83 # define HACK_INIT init_cage
84 # define HACK_DRAW draw_cage
85 # define HACK_RESHAPE reshape_cage
86 # define cage_opts xlockmore_opts
87 # define DEFAULTS "*delay: 25000 \n" \
88 "*showFPS: False \n" \
89 "*wireframe: False \n"
90 # include "xlockmore.h" /* from the xscreensaver distribution */
91 #else /* !STANDALONE */
92 # include "xlock.h" /* from the xlockmore distribution */
94 #endif /* !STANDALONE */
100 #include "e_textures.h"
102 ModeSpecOpt cage_opts =
103 {0, NULL, 0, NULL, NULL};
106 ModStruct cage_description =
107 {"cage", "init_cage", "draw_cage", "release_cage",
108 "draw_cage", "change_cage", NULL, &cage_opts,
109 1000, 1, 1, 1, 1.0, 4, "",
110 "Shows the Impossible Cage, an Escher-like GL scene", 0, NULL};
114 #define Scale4Window 0.3
115 #define Scale4Iconic 0.4
117 #define sqr(A) ((A)*(A))
123 /*************************************************************************/
128 int AreObjectsDefined[1];
129 GLXContext *glx_context;
132 static float front_shininess[] =
134 static float front_specular[] =
135 {0.7, 0.7, 0.7, 1.0};
136 static float ambient[] =
137 {0.0, 0.0, 0.0, 1.0};
138 static float diffuse[] =
139 {1.0, 1.0, 1.0, 1.0};
140 static float position0[] =
141 {1.0, 1.0, 1.0, 0.0};
142 static float position1[] =
143 {-1.0, -1.0, 1.0, 0.0};
144 static float lmodel_ambient[] =
145 {0.5, 0.5, 0.5, 1.0};
146 static float lmodel_twoside[] =
149 static float MaterialWhite[] =
150 {0.7, 0.7, 0.7, 1.0};
152 static cagestruct *cage = NULL;
153 static GLuint objects;
155 #define ObjWoodPlank 0
157 #define PlankWidth 3.0
158 #define PlankHeight 0.35
159 #define PlankThickness 0.15
162 draw_woodplank(cagestruct * cp)
164 if (!cp->AreObjectsDefined[ObjWoodPlank]) {
165 glNewList(objects + ObjWoodPlank, GL_COMPILE_AND_EXECUTE);
169 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
171 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
173 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
175 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
176 glNormal3f(0, 0, -1);
178 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
180 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
182 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
184 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
187 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
189 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
191 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
193 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
194 glNormal3f(0, -1, 0);
196 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
198 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
200 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
202 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
205 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
207 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
209 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
211 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
212 glNormal3f(-1, 0, 0);
214 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
216 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
218 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
220 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
223 cp->AreObjectsDefined[ObjWoodPlank] = 1;
225 (void) printf("WoodPlank drawn SLOWLY\n");
228 glCallList(objects + ObjWoodPlank);
230 (void) printf("WoodPlank drawn quickly\n");
236 draw_impossiblecage(cagestruct * cp)
239 glRotatef(90, 0, 1, 0);
240 glTranslatef(0.0, PlankHeight - PlankWidth, -PlankThickness - PlankWidth);
244 glRotatef(90, 0, 0, 1);
245 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - PlankThickness);
249 glRotatef(90, 0, 1, 0);
250 glTranslatef(0.0, PlankWidth - PlankHeight, -PlankThickness - PlankWidth);
254 glTranslatef(0.0, PlankWidth - PlankHeight, 3 * PlankThickness - PlankWidth);
258 glRotatef(90, 0, 0, 1);
259 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - PlankThickness);
263 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - 3 * PlankThickness);
267 glTranslatef(0.0, PlankHeight - PlankWidth, 3 * PlankThickness - PlankWidth);
271 glRotatef(90, 0, 0, 1);
272 glTranslatef(0.0, PlankHeight - PlankWidth, PlankThickness - PlankWidth);
276 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - 3 * PlankThickness);
280 glRotatef(90, 0, 1, 0);
281 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth + PlankThickness);
285 glRotatef(90, 0, 0, 1);
286 glTranslatef(0.0, PlankWidth - PlankHeight, PlankThickness - PlankWidth);
290 glRotatef(90, 0, 1, 0);
291 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth + PlankThickness);
297 reshape_cage(ModeInfo * mi, int width, int height)
299 cagestruct *cp = &cage[MI_SCREEN(mi)];
301 glViewport(0, 0, cp->WindW = (GLint) width, cp->WindH = (GLint) height);
302 glMatrixMode(GL_PROJECTION);
304 glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 15.0);
305 glMatrixMode(GL_MODELVIEW);
309 } else if (width >= 512) {
316 cp->AreObjectsDefined[ObjWoodPlank] = 0;
324 glClearColor(0.0, 0.0, 0.0, 1.0);
326 glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
327 glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
328 glLightfv(GL_LIGHT0, GL_POSITION, position0);
329 glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);
330 glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse);
331 glLightfv(GL_LIGHT1, GL_POSITION, position1);
332 glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
333 glLightModelfv(GL_LIGHT_MODEL_TWO_SIDE, lmodel_twoside);
334 glEnable(GL_LIGHTING);
337 glEnable(GL_NORMALIZE);
342 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
343 glShadeModel(GL_FLAT);
344 glDisable(GL_DEPTH_TEST);
345 glEnable(GL_TEXTURE_2D);
346 glEnable(GL_CULL_FACE);
348 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
351 status = gluBuild2DMipmaps(GL_TEXTURE_2D, 3,
352 WoodTextureWidth, WoodTextureHeight,
353 GL_RGB, GL_UNSIGNED_BYTE, WoodTextureData);
356 const char *s = gluErrorString (status);
357 fprintf (stderr, "%s: error mipmapping texture: %s\n",
358 progname, (s ? s : "(unknown)"));
361 check_gl_error("mipmapping");
363 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
364 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
365 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
366 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
367 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
369 glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, front_shininess);
370 glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, front_specular);
374 init_cage(ModeInfo * mi)
376 int screen = MI_SCREEN(mi);
380 if ((cage = (cagestruct *) calloc(MI_NUM_SCREENS(mi),
381 sizeof (cagestruct))) == NULL)
385 cp->step = NRAND(90);
387 if ((cp->glx_context = init_GL(mi)) != NULL) {
389 reshape_cage(mi, MI_WIDTH(mi), MI_HEIGHT(mi));
390 glDrawBuffer(GL_BACK);
391 if (!glIsList(objects))
392 objects = glGenLists(1);
400 draw_cage(ModeInfo * mi)
402 cagestruct *cp = &cage[MI_SCREEN(mi)];
404 Display *display = MI_DISPLAY(mi);
405 Window window = MI_WINDOW(mi);
407 MI_IS_DRAWN(mi) = True;
409 if (!cp->glx_context)
412 glXMakeCurrent(display, window, *(cp->glx_context));
414 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
418 glTranslatef(0.0, 0.0, -10.0);
420 if (!MI_IS_ICONIC(mi)) {
421 glScalef(Scale4Window * cp->WindH / cp->WindW, Scale4Window, Scale4Window);
423 glScalef(Scale4Iconic * cp->WindH / cp->WindW, Scale4Iconic, Scale4Iconic);
427 glRotatef(cp->step * 100, 0, 0, 1);
428 glRotatef(25 + cos(cp->step * 5) * 6, 1, 0, 0);
429 glRotatef(204.5 - sin(cp->step * 5) * 8, 0, 1, 0);
430 draw_impossiblecage(cp);
434 if (mi->fps_p) do_fps (mi);
437 glXSwapBuffers(display, window);
443 change_cage(ModeInfo * mi)
445 cagestruct *cp = &cage[MI_SCREEN(mi)];
447 if (!cp->glx_context)
450 glXMakeCurrent(MI_DISPLAY(mi), MI_WINDOW(mi), *(cp->glx_context));
455 release_cage(ModeInfo * mi)
458 (void) free((void *) cage);
461 if (glIsList(objects)) {
462 glDeleteLists(objects, 1);