1 /* -*- Mode: C; tab-width: 4 -*- */
2 /* cage --- the Impossible Cage, an Escher like scene. */
5 static const char sccsid[] = "@(#)cage.c 5.01 2001/03/01 xlockmore";
9 * Permission to use, copy, modify, and distribute this software and its
10 * documentation for any purpose and without fee is hereby granted,
11 * provided that the above copyright notice appear in all copies and that
12 * both that copyright notice and this permission notice appear in
13 * supporting documentation.
15 * This file is provided AS IS with no warranties of any kind. The author
16 * shall have no liability with respect to the infringement of copyrights,
17 * trade secrets or any patents by this file or any part thereof. In no
18 * event will the author be liable for any lost revenue or profits or
19 * other special, indirect and consequential damages.
21 * The RotateAroundU() routine was adapted from the book
22 * "Computer Graphics Principles and Practice
23 * Foley - vanDam - Feiner - Hughes
24 * Second Edition" Pag. 227, exercise 5.15.
26 * This mode shows some interesting scenes that are impossible OR very
27 * wierd to build in the real universe. Much of the scenes are inspirated
28 * on Mauritz Cornelis Escher's works which derivated the mode's name.
29 * M.C. Escher (1898-1972) was a dutch artist and many people prefer to
30 * say he was a mathematician.
32 * Thanks goes to Brian Paul for making it possible and inexpensive to use
35 * Since I'm not a native English speaker, my apologies for any grammatical
38 * My e-mail address is
39 * mfvianna@centroin.com.br
41 * Marcelo F. Vianna (Jun-01-1997)
44 * 05-Apr-2002: Removed all gllist uses (fix some bug with nvidia driver)
45 * 01-Mar-2001: Added FPS stuff E.Lassauge <lassauge@mail.dotcom.fr>
46 * 01-Nov-2000: Allocation checks
47 * 01-Jan-1998: Mode separated from escher and renamed
48 * 08-Jun-1997: New scene implemented: "Impossible Cage" based in a M.C.
49 * Escher's painting with the same name (quite similar). The
50 * first GL mode 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-1997: Speed ups in Moebius Strip using GL_CULL_FACE.
57 * 03-Jun-1997: 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).
67 * Texture mapping is only available on RGBA contexts, Mono and color index
68 * visuals DO NOT support texture mapping in OpenGL.
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
75 * In real OpenGL, PseudoColor DO NOT support texture map (as far as I know).
80 # define PROGCLASS "Cage"
81 # define HACK_INIT init_cage
82 # define HACK_DRAW draw_cage
83 # define HACK_RESHAPE reshape
84 # define cage_opts xlockmore_opts
85 # define DEFAULTS "*delay: 25000 \n" \
86 "*showFPS: False \n" \
87 "*wireframe: False \n"
88 # include "xlockmore.h" /* from the xscreensaver distribution */
89 #else /* !STANDALONE */
90 # include "xlock.h" /* from the xlockmore distribution */
92 #endif /* !STANDALONE */
98 #include "e_textures.h"
100 ModeSpecOpt cage_opts =
101 {0, (XrmOptionDescRec *) NULL, 0, (argtype *) NULL, (OptionStruct *) NULL};
104 ModStruct cage_description =
105 {"cage", "init_cage", "draw_cage", "release_cage",
106 "draw_cage", "change_cage", (char *) NULL, &cage_opts,
107 25000, 1, 1, 1, 1.0, 4, "",
108 "Shows the Impossible Cage, an Escher-like GL scene", 0, NULL};
112 #define Scale4Window 0.3
113 #define Scale4Iconic 0.4
115 #define sqr(A) ((A)*(A))
121 #define ObjWoodPlank 0
124 /*************************************************************************/
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 = (cagestruct *) NULL;
154 #define PlankWidth 3.0
155 #define PlankHeight 0.35
156 #define PlankThickness 0.15
159 draw_woodplank(cagestruct * cp, int wire)
161 glBegin(wire ? GL_LINES : GL_QUADS);
164 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
166 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
168 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
170 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
171 glNormal3f(0, 0, -1);
173 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
175 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
177 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
179 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
182 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
184 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
186 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
188 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
189 glNormal3f(0, -1, 0);
191 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
193 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
195 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
197 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
200 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
202 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
204 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
206 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
207 glNormal3f(-1, 0, 0);
209 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
211 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
213 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
215 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
222 draw_impossiblecage(cagestruct * cp, int wire)
225 glRotatef(90, 0, 1, 0);
226 glTranslatef(0.0, PlankHeight - PlankWidth, -PlankThickness - PlankWidth);
227 if (!draw_woodplank(cp, wire))
231 glRotatef(90, 0, 0, 1);
232 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - PlankThickness);
233 if (!draw_woodplank(cp, wire))
237 glRotatef(90, 0, 1, 0);
238 glTranslatef(0.0, PlankWidth - PlankHeight, -PlankThickness - PlankWidth);
239 if (!draw_woodplank(cp, wire))
243 glTranslatef(0.0, PlankWidth - PlankHeight, 3 * PlankThickness - PlankWidth);
244 if (!draw_woodplank(cp, wire))
248 glRotatef(90, 0, 0, 1);
249 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - PlankThickness);
250 if (!draw_woodplank(cp, wire))
254 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - 3 * PlankThickness);
255 if (!draw_woodplank(cp, wire))
259 glTranslatef(0.0, PlankHeight - PlankWidth, 3 * PlankThickness - PlankWidth);
260 if (!draw_woodplank(cp, wire))
264 glRotatef(90, 0, 0, 1);
265 glTranslatef(0.0, PlankHeight - PlankWidth, PlankThickness - PlankWidth);
266 if (!draw_woodplank(cp, wire))
270 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - 3 * PlankThickness);
271 if (!draw_woodplank(cp, wire))
275 glRotatef(90, 0, 1, 0);
276 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth + PlankThickness);
277 if (!draw_woodplank(cp, wire))
281 glRotatef(90, 0, 0, 1);
282 glTranslatef(0.0, PlankWidth - PlankHeight, PlankThickness - PlankWidth);
283 if (!draw_woodplank(cp, wire))
287 glRotatef(90, 0, 1, 0);
288 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth + PlankThickness);
289 if (!draw_woodplank(cp, wire))
296 reshape(ModeInfo * mi, int width, int height)
298 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);
317 glClearColor(0.0, 0.0, 0.0, 1.0);
319 if (MI_IS_WIREFRAME(mi))
322 glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
323 glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
324 glLightfv(GL_LIGHT0, GL_POSITION, position0);
325 glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);
326 glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse);
327 glLightfv(GL_LIGHT1, GL_POSITION, position1);
328 glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
329 glLightModelfv(GL_LIGHT_MODEL_TWO_SIDE, lmodel_twoside);
330 glEnable(GL_LIGHTING);
333 glEnable(GL_NORMALIZE);
338 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
339 glShadeModel(GL_FLAT);
340 glDisable(GL_DEPTH_TEST);
341 glEnable(GL_TEXTURE_2D);
342 glEnable(GL_CULL_FACE);
344 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
350 status = gluBuild2DMipmaps(GL_TEXTURE_2D, 3,
351 WoodTextureWidth, WoodTextureHeight,
352 GL_RGB, GL_UNSIGNED_BYTE, WoodTextureData);
355 const char *s = (char *) gluErrorString (status);
356 fprintf (stderr, "%s: error mipmapping texture: %s\n",
357 progname, (s ? s : "(unknown)"));
360 check_gl_error("mipmapping");
362 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
363 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
364 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
365 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
366 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
368 glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, front_shininess);
369 glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, front_specular);
373 release_cage(ModeInfo * mi)
378 for (screen = 0; screen < MI_NUM_SCREENS(mi); screen++) {
379 cagestruct *cp = &cage[screen];
381 if (cp->glx_context) {
382 cp->glx_context = (GLXContext *) NULL;
385 (void) free((void *) cage);
386 cage = (cagestruct *) NULL;
392 init_cage(ModeInfo * mi)
397 if ((cage = (cagestruct *) calloc(MI_NUM_SCREENS(mi),
398 sizeof (cagestruct))) == NULL)
401 cp = &cage[MI_SCREEN(mi)];
403 cp->step = NRAND(90);
404 if ((cp->glx_context = init_GL(mi)) != NULL) {
406 reshape(mi, MI_WIDTH(mi), MI_HEIGHT(mi));
407 glDrawBuffer(GL_BACK);
415 draw_cage(ModeInfo * mi)
417 Display *display = MI_DISPLAY(mi);
418 Window window = MI_WINDOW(mi);
423 cp = &cage[MI_SCREEN(mi)];
425 MI_IS_DRAWN(mi) = True;
426 if (!cp->glx_context)
429 glXMakeCurrent(display, window, *(cp->glx_context));
431 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
435 glTranslatef(0.0, 0.0, -10.0);
437 if (!MI_IS_ICONIC(mi)) {
438 glScalef(Scale4Window * cp->WindH / cp->WindW, Scale4Window, Scale4Window);
440 glScalef(Scale4Iconic * cp->WindH / cp->WindW, Scale4Iconic, Scale4Iconic);
444 glRotatef(cp->step * 100, 0, 0, 1);
445 glRotatef(25 + cos(cp->step * 5) * 6, 1, 0, 0);
446 glRotatef(204.5 - sin(cp->step * 5) * 8, 0, 1, 0);
447 if (!draw_impossiblecage(cp, MI_IS_WIREFRAME(mi))) {
453 if (MI_IS_FPS(mi)) do_fps (mi);
456 glXSwapBuffers(display, window);
462 change_cage(ModeInfo * mi)
464 cagestruct *cp = &cage[MI_SCREEN(mi)];
466 if (!cp->glx_context)
469 glXMakeCurrent(MI_DISPLAY(mi), MI_WINDOW(mi), *(cp->glx_context));