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 "*cycles: 1 \n" \
89 "*showFPS: False \n" \
90 "*wireframe: False \n"
91 # include "xlockmore.h" /* from the xscreensaver distribution */
92 #else /* !STANDALONE */
93 # include "xlock.h" /* from the xlockmore distribution */
95 #endif /* !STANDALONE */
101 #include "e_textures.h"
103 ModeSpecOpt cage_opts =
104 {0, NULL, 0, NULL, NULL};
107 ModStruct cage_description =
108 {"cage", "init_cage", "draw_cage", "release_cage",
109 "draw_cage", "change_cage", NULL, &cage_opts,
110 1000, 1, 1, 1, 1.0, 4, "",
111 "Shows the Impossible Cage, an Escher-like GL scene", 0, NULL};
115 #define Scale4Window 0.3
116 #define Scale4Iconic 0.4
118 #define sqr(A) ((A)*(A))
124 /*************************************************************************/
129 int AreObjectsDefined[1];
130 GLXContext *glx_context;
133 static float front_shininess[] =
135 static float front_specular[] =
136 {0.7, 0.7, 0.7, 1.0};
137 static float ambient[] =
138 {0.0, 0.0, 0.0, 1.0};
139 static float diffuse[] =
140 {1.0, 1.0, 1.0, 1.0};
141 static float position0[] =
142 {1.0, 1.0, 1.0, 0.0};
143 static float position1[] =
144 {-1.0, -1.0, 1.0, 0.0};
145 static float lmodel_ambient[] =
146 {0.5, 0.5, 0.5, 1.0};
147 static float lmodel_twoside[] =
150 static float MaterialWhite[] =
151 {0.7, 0.7, 0.7, 1.0};
153 static cagestruct *cage = NULL;
154 static GLuint objects;
156 #define ObjWoodPlank 0
158 #define PlankWidth 3.0
159 #define PlankHeight 0.35
160 #define PlankThickness 0.15
163 draw_woodplank(cagestruct * cp)
165 if (!cp->AreObjectsDefined[ObjWoodPlank]) {
166 glNewList(objects + ObjWoodPlank, GL_COMPILE_AND_EXECUTE);
170 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
172 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
174 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
176 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
177 glNormal3f(0, 0, -1);
179 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
181 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
183 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
185 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
188 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
190 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
192 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
194 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
195 glNormal3f(0, -1, 0);
197 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
199 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
201 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
203 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
206 glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
208 glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
210 glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
212 glVertex3f(PlankWidth, PlankHeight, PlankThickness);
213 glNormal3f(-1, 0, 0);
215 glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
217 glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
219 glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
221 glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
224 cp->AreObjectsDefined[ObjWoodPlank] = 1;
226 (void) printf("WoodPlank drawn SLOWLY\n");
229 glCallList(objects + ObjWoodPlank);
231 (void) printf("WoodPlank drawn quickly\n");
237 draw_impossiblecage(cagestruct * cp)
240 glRotatef(90, 0, 1, 0);
241 glTranslatef(0.0, PlankHeight - PlankWidth, -PlankThickness - PlankWidth);
245 glRotatef(90, 0, 0, 1);
246 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - PlankThickness);
250 glRotatef(90, 0, 1, 0);
251 glTranslatef(0.0, PlankWidth - PlankHeight, -PlankThickness - PlankWidth);
255 glTranslatef(0.0, PlankWidth - PlankHeight, 3 * PlankThickness - PlankWidth);
259 glRotatef(90, 0, 0, 1);
260 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - PlankThickness);
264 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - 3 * PlankThickness);
268 glTranslatef(0.0, PlankHeight - PlankWidth, 3 * PlankThickness - PlankWidth);
272 glRotatef(90, 0, 0, 1);
273 glTranslatef(0.0, PlankHeight - PlankWidth, PlankThickness - PlankWidth);
277 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - 3 * PlankThickness);
281 glRotatef(90, 0, 1, 0);
282 glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth + PlankThickness);
286 glRotatef(90, 0, 0, 1);
287 glTranslatef(0.0, PlankWidth - PlankHeight, PlankThickness - PlankWidth);
291 glRotatef(90, 0, 1, 0);
292 glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth + PlankThickness);
298 reshape_cage(ModeInfo * mi, int width, int height)
300 cagestruct *cp = &cage[MI_SCREEN(mi)];
302 glViewport(0, 0, cp->WindW = (GLint) width, cp->WindH = (GLint) height);
303 glMatrixMode(GL_PROJECTION);
305 glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 15.0);
306 glMatrixMode(GL_MODELVIEW);
310 } else if (width >= 512) {
317 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);
349 gluBuild2DMipmaps(GL_TEXTURE_2D, 3, WoodTextureWidth, WoodTextureHeight,
350 GL_RGB, GL_UNSIGNED_BYTE, WoodTextureData);
351 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
352 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
353 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
354 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
355 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
357 glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, front_shininess);
358 glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, front_specular);
362 init_cage(ModeInfo * mi)
364 int screen = MI_SCREEN(mi);
368 if ((cage = (cagestruct *) calloc(MI_NUM_SCREENS(mi),
369 sizeof (cagestruct))) == NULL)
373 cp->step = NRAND(90);
375 if ((cp->glx_context = init_GL(mi)) != NULL) {
377 reshape_cage(mi, MI_WIDTH(mi), MI_HEIGHT(mi));
378 glDrawBuffer(GL_BACK);
379 if (!glIsList(objects))
380 objects = glGenLists(1);
388 draw_cage(ModeInfo * mi)
390 cagestruct *cp = &cage[MI_SCREEN(mi)];
392 Display *display = MI_DISPLAY(mi);
393 Window window = MI_WINDOW(mi);
395 MI_IS_DRAWN(mi) = True;
397 if (!cp->glx_context)
400 glXMakeCurrent(display, window, *(cp->glx_context));
402 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
406 glTranslatef(0.0, 0.0, -10.0);
408 if (!MI_IS_ICONIC(mi)) {
409 glScalef(Scale4Window * cp->WindH / cp->WindW, Scale4Window, Scale4Window);
411 glScalef(Scale4Iconic * cp->WindH / cp->WindW, Scale4Iconic, Scale4Iconic);
415 glRotatef(cp->step * 100, 0, 0, 1);
416 glRotatef(25 + cos(cp->step * 5) * 6, 1, 0, 0);
417 glRotatef(204.5 - sin(cp->step * 5) * 8, 0, 1, 0);
418 draw_impossiblecage(cp);
422 if (mi->fps_p) do_fps (mi);
425 glXSwapBuffers(display, window);
431 change_cage(ModeInfo * mi)
433 cagestruct *cp = &cage[MI_SCREEN(mi)];
435 if (!cp->glx_context)
438 glXMakeCurrent(MI_DISPLAY(mi), MI_WINDOW(mi), *(cp->glx_context));
443 release_cage(ModeInfo * mi)
446 (void) free((void *) cage);
449 if (glIsList(objects)) {
450 glDeleteLists(objects, 1);