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 cage_opts xlockmore_opts
86 # define DEFAULTS "*cycles: 1 \n" \
88 "*wireframe: False \n"
89 # include "xlockmore.h" /* from the xscreensaver distribution */
90 #else /* !STANDALONE */
91 # include "xlock.h" /* from the xlockmore distribution */
93 #endif /* !STANDALONE */
99 #include "e_textures.h"
101 ModeSpecOpt cage_opts =
102 {0, NULL, 0, NULL, NULL};
105 ModStruct cage_description =
106 {"cage", "init_cage", "draw_cage", "release_cage",
107 "draw_cage", "change_cage", NULL, &cage_opts,
108 1000, 1, 1, 1, 1.0, 4, "",
109 "Shows the Impossible Cage, an Escher-like GL scene", 0, NULL};
113 #define Scale4Window 0.3
114 #define Scale4Iconic 0.4
116 #define sqr(A) ((A)*(A))
122 /*************************************************************************/
127 int AreObjectsDefined[1];
128 GLXContext *glx_context;
131 static float front_shininess[] =
133 static float front_specular[] =
134 {0.7, 0.7, 0.7, 1.0};
135 static float ambient[] =
136 {0.0, 0.0, 0.0, 1.0};
137 static float diffuse[] =
138 {1.0, 1.0, 1.0, 1.0};
139 static float position0[] =
140 {1.0, 1.0, 1.0, 0.0};
141 static float position1[] =
142 {-1.0, -1.0, 1.0, 0.0};
143 static float lmodel_ambient[] =
144 {0.5, 0.5, 0.5, 1.0};
145 static float lmodel_twoside[] =
148 static float MaterialWhite[] =
149 {0.7, 0.7, 0.7, 1.0};
151 static cagestruct *cage = NULL;
152 static GLuint objects;
154 #define ObjWoodPlank 0
156 #define PlankWidth 3.0
157 #define PlankHeight 0.35
158 #define PlankThickness 0.15
161 draw_woodplank(cagestruct * cp)
163 if (!cp->AreObjectsDefined[ObjWoodPlank]) {
164 glNewList(objects + ObjWoodPlank, GL_COMPILE_AND_EXECUTE);
168 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
170 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
172 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
174 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
175 glNormal3f(0, 0, -1);
177 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
179 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
181 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
183 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
186 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
188 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
190 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
192 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
193 glNormal3f(0, -1, 0);
195 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
197 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
199 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
201 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
204 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
206 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
208 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
210 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
211 glNormal3f(-1, 0, 0);
213 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
215 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
217 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
219 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
222 cp->AreObjectsDefined[ObjWoodPlank] = 1;
224 (void) printf("WoodPlank drawn SLOWLY\n");
227 glCallList(objects + ObjWoodPlank);
229 (void) printf("WoodPlank drawn quickly\n");
235 draw_impossiblecage(cagestruct * cp)
238 glRotatef(90, 0, 1, 0);
239 glTranslatef(0.0, PlankHeight - PlankWidth, -PlankThickness - PlankWidth);
243 glRotatef(90, 0, 0, 1);
244 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - PlankThickness);
248 glRotatef(90, 0, 1, 0);
249 glTranslatef(0.0, PlankWidth - PlankHeight, -PlankThickness - PlankWidth);
253 glTranslatef(0.0, PlankWidth - PlankHeight, 3 * PlankThickness - PlankWidth);
257 glRotatef(90, 0, 0, 1);
258 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - PlankThickness);
262 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - 3 * PlankThickness);
266 glTranslatef(0.0, PlankHeight - PlankWidth, 3 * PlankThickness - PlankWidth);
270 glRotatef(90, 0, 0, 1);
271 glTranslatef(0.0, PlankHeight - PlankWidth, PlankThickness - PlankWidth);
275 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - 3 * PlankThickness);
279 glRotatef(90, 0, 1, 0);
280 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth + PlankThickness);
284 glRotatef(90, 0, 0, 1);
285 glTranslatef(0.0, PlankWidth - PlankHeight, PlankThickness - PlankWidth);
289 glRotatef(90, 0, 1, 0);
290 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth + PlankThickness);
296 reshape(ModeInfo * mi, int width, int height)
298 cagestruct *cp = &cage[MI_SCREEN(mi)];
300 glViewport(0, 0, cp->WindW = (GLint) width, cp->WindH = (GLint) height);
301 glMatrixMode(GL_PROJECTION);
303 glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 15.0);
304 glMatrixMode(GL_MODELVIEW);
308 } else if (width >= 512) {
315 cp->AreObjectsDefined[ObjWoodPlank] = 0;
322 glClearColor(0.0, 0.0, 0.0, 1.0);
324 glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
325 glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
326 glLightfv(GL_LIGHT0, GL_POSITION, position0);
327 glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);
328 glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse);
329 glLightfv(GL_LIGHT1, GL_POSITION, position1);
330 glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
331 glLightModelfv(GL_LIGHT_MODEL_TWO_SIDE, lmodel_twoside);
332 glEnable(GL_LIGHTING);
335 glEnable(GL_NORMALIZE);
340 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
341 glShadeModel(GL_FLAT);
342 glDisable(GL_DEPTH_TEST);
343 glEnable(GL_TEXTURE_2D);
344 glEnable(GL_CULL_FACE);
346 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
347 gluBuild2DMipmaps(GL_TEXTURE_2D, 3, WoodTextureWidth, WoodTextureHeight,
348 GL_RGB, GL_UNSIGNED_BYTE, WoodTextureData);
349 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
350 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
351 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
352 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
353 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
355 glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, front_shininess);
356 glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, front_specular);
360 init_cage(ModeInfo * mi)
362 int screen = MI_SCREEN(mi);
366 if ((cage = (cagestruct *) calloc(MI_NUM_SCREENS(mi),
367 sizeof (cagestruct))) == NULL)
371 cp->step = NRAND(90);
373 if ((cp->glx_context = init_GL(mi)) != NULL) {
375 reshape(mi, MI_WIDTH(mi), MI_HEIGHT(mi));
376 glDrawBuffer(GL_BACK);
377 if (!glIsList(objects))
378 objects = glGenLists(1);
386 draw_cage(ModeInfo * mi)
388 cagestruct *cp = &cage[MI_SCREEN(mi)];
390 Display *display = MI_DISPLAY(mi);
391 Window window = MI_WINDOW(mi);
393 MI_IS_DRAWN(mi) = True;
395 if (!cp->glx_context)
398 glXMakeCurrent(display, window, *(cp->glx_context));
400 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
404 glTranslatef(0.0, 0.0, -10.0);
406 if (!MI_IS_ICONIC(mi)) {
407 glScalef(Scale4Window * cp->WindH / cp->WindW, Scale4Window, Scale4Window);
409 glScalef(Scale4Iconic * cp->WindH / cp->WindW, Scale4Iconic, Scale4Iconic);
413 glRotatef(cp->step * 100, 0, 0, 1);
414 glRotatef(25 + cos(cp->step * 5) * 6, 1, 0, 0);
415 glRotatef(204.5 - sin(cp->step * 5) * 8, 0, 1, 0);
416 draw_impossiblecage(cp);
422 glXSwapBuffers(display, window);
428 change_cage(ModeInfo * mi)
430 cagestruct *cp = &cage[MI_SCREEN(mi)];
432 if (!cp->glx_context)
435 glXMakeCurrent(MI_DISPLAY(mi), MI_WINDOW(mi), *(cp->glx_context));
440 release_cage(ModeInfo * mi)
443 (void) free((void *) cage);
446 if (glIsList(objects)) {
447 glDeleteLists(objects, 1);