1 /* -*- Mode: C; tab-width: 4 -*- */
2 /* stairs --- Infinite Stairs, and Escher-like scene. */
5 static const char sccsid[] = "@(#)stairs.c 4.07 97/11/24 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 * This mode shows some interesting scenes that are impossible OR very
22 * weird to build in the real universe. Much of the scenes are inspirated
23 * on Mauritz Cornelis stairs's works which derivated the mode's name.
24 * M.C. Escher (1898-1972) was a dutch artist and many people prefer to
25 * say he was a mathematician.
27 * Thanks goes to Brian Paul for making it possible and inexpensive to use
30 * Since I'm not a native English speaker, my apologies for any grammatical
33 * My e-mail address is
36 * Marcelo F. Vianna (Jun-01-1997)
39 * 07-Jan-98: This would be a scene for the escher mode, but now escher mode
40 * was splitted in different modes for each scene. This is the
41 * initial release and is not working yet.
47 * Texture mapping is only available on RGBA contexts, Mono and color index
48 * visuals DO NOT support texture mapping in OpenGL.
50 * BUT Mesa do implements RGBA contexts in pseudo color visuals, so texture
51 * mapping shuld work on PseudoColor, DirectColor, TrueColor using Mesa. Mono
52 * is not officially supported for both OpenGL and Mesa, but seems to not crash
55 * In real OpenGL, PseudoColor DO NOT support texture map (as far as I know).
59 # define DEFAULTS "*delay: 20000 \n" \
62 # define refresh_stairs 0
63 # define release_stairs 0
64 # include "xlockmore.h" /* from the xscreensaver distribution */
65 #else /* !STANDALONE */
66 # include "xlock.h" /* from the xlockmore distribution */
68 #endif /* !STANDALONE */
73 #include "e_textures.h"
75 #include "xpm-ximage.h"
76 #include "../images/wood.xpm"
80 #include "gltrackball.h"
82 ENTRYPOINT ModeSpecOpt stairs_opts =
83 {0, NULL, 0, NULL, NULL};
86 ModStruct stairs_description =
87 {"stairs", "init_stairs", "draw_stairs", NULL,
88 "draw_stairs", "change_stairs", NULL, &stairs_opts,
89 1000, 1, 1, 1, 4, 1.0, "",
90 "Shows Infinite Stairs, an Escher-like scene", 0, NULL};
94 #define Scale4Window 0.3
95 #define Scale4Iconic 0.4
97 #define sqr(A) ((A)*(A))
103 /*************************************************************************/
109 int AreObjectsDefined[1];
112 GLXContext *glx_context;
113 trackball_state *trackball;
118 static const float front_shininess[] = {60.0};
119 static const float front_specular[] = {0.7, 0.7, 0.7, 1.0};
120 static const float ambient[] = {0.0, 0.0, 0.0, 1.0};
121 static const float diffuse[] = {1.0, 1.0, 1.0, 1.0};
122 static const float position0[] = {1.0, 1.0, 1.0, 0.0};
123 static const float position1[] = {-1.0, -1.0, 1.0, 0.0};
124 static const float lmodel_ambient[] = {0.5, 0.5, 0.5, 1.0};
125 static const float lmodel_twoside[] = {GL_TRUE};
127 static const float MaterialYellow[] = {0.7, 0.7, 0.0, 1.0};
128 static const float MaterialWhite[] = {0.7, 0.7, 0.7, 1.0};
130 static const float ball_positions[] = {
152 #define NPOSITIONS ((sizeof ball_positions) / (sizeof ball_positions[0]) / 3)
153 #define SPHERE_TICKS 32
155 static stairsstruct *stairs = NULL;
158 draw_block(GLfloat width, GLfloat height, GLfloat thickness)
165 glVertex3f(-width, -height, thickness);
167 glVertex3f(width, -height, thickness);
169 glVertex3f(width, height, thickness);
171 glVertex3f(-width, height, thickness);
173 glNormal3f(0, 0, -1);
175 glVertex3f(-width, height, -thickness);
177 glVertex3f(width, height, -thickness);
179 glVertex3f(width, -height, -thickness);
181 glVertex3f(-width, -height, -thickness);
185 glVertex3f(-width, height, thickness);
187 glVertex3f(width, height, thickness);
189 glVertex3f(width, height, -thickness);
191 glVertex3f(-width, height, -thickness);
193 glNormal3f(0, -1, 0);
195 glVertex3f(-width, -height, -thickness);
197 glVertex3f(width, -height, -thickness);
199 glVertex3f(width, -height, thickness);
201 glVertex3f(-width, -height, thickness);
205 glVertex3f(width, -height, thickness);
207 glVertex3f(width, -height, -thickness);
209 glVertex3f(width, height, -thickness);
211 glVertex3f(width, height, thickness);
213 glNormal3f(-1, 0, 0);
215 glVertex3f(-width, height, thickness);
217 glVertex3f(-width, height, -thickness);
219 glVertex3f(-width, -height, -thickness);
221 glVertex3f(-width, -height, thickness);
228 draw_stairs_internal(ModeInfo * mi)
232 mi->polygon_count = 0;
236 glTranslatef(-3.0, 0.1, 2.0);
237 for (X = 0; X < 2; X++) {
238 mi->polygon_count += draw_block(0.5, 2.7 + 0.1 * X, 0.5);
239 glTranslatef(0.0, 0.1, -1.0);
242 glTranslatef(-3.0, 0.0, 3.0);
245 for (X = 0; X < 6; X++) {
246 mi->polygon_count += draw_block(0.5, 2.6 - 0.1 * X, 0.5);
247 glTranslatef(1.0, -0.1, 0.0);
249 glTranslatef(-1.0, -0.9, -1.0);
250 for (X = 0; X < 5; X++) {
251 mi->polygon_count += draw_block(0.5, 3.0 - 0.1 * X, 0.5);
252 glTranslatef(0.0, 0.0, -1.0);
254 glTranslatef(-1.0, -1.1, 1.0);
255 for (X = 0; X < 3; X++) {
256 mi->polygon_count += draw_block(0.5, 3.5 - 0.1 * X, 0.5);
257 glTranslatef(-1.0, -0.1, 0.0);
264 /*#define DEBUG_PATH*/
267 draw_sphere(int pos, int tick)
269 int pos2 = (pos+1) % NPOSITIONS;
270 GLfloat x1 = ball_positions[pos*3];
271 GLfloat y1 = ball_positions[pos*3+1];
272 GLfloat z1 = ball_positions[pos*3+2];
273 GLfloat x2 = ball_positions[pos2*3];
274 GLfloat y2 = ball_positions[pos2*3+1];
275 GLfloat z2 = ball_positions[pos2*3+2];
276 GLfloat frac = tick / (GLfloat) SPHERE_TICKS;
277 GLfloat x = x1 + (x2 - x1) * frac;
278 GLfloat y = y1 + (y2 - y1) * frac + (2 * sin (M_PI * frac));
279 GLfloat z = z1 + (z2 - z1) * frac;
287 glVertex3f(x, y-7.5, z);
288 glVertex3f(x, y, z); glVertex3f(x, y, z-0.6);
289 glVertex3f(x, y, z); glVertex3f(x, y, z+0.6);
290 glVertex3f(x, y, z); glVertex3f(x+0.6, y, z);
291 glVertex3f(x, y, z); glVertex3f(x-0.6, y, z);
295 # else /* !DEBUG_PATH */
297 glTranslatef(x, y, z);
299 glScalef (0.5, 0.5, 0.5);
301 /* make ball a little smaller on the gap to obscure distance */
302 if (pos == NPOSITIONS-1)
303 glScalef (0.95, 0.95, 0.95);
305 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialYellow);
306 glDisable (GL_TEXTURE_2D);
307 glShadeModel(GL_SMOOTH);
309 polys += unit_sphere (32, 32, False);
310 glShadeModel(GL_FLAT);
311 glEnable (GL_TEXTURE_2D);
312 #endif /* !DEBUG_PATH */
321 reshape_stairs (ModeInfo * mi, int width, int height)
323 stairsstruct *sp = &stairs[MI_SCREEN(mi)];
325 glViewport(0, 0, sp->WindW = (GLint) width, sp->WindH = (GLint) height);
326 glMatrixMode(GL_PROJECTION);
328 glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 15.0);
329 glMatrixMode(GL_MODELVIEW);
333 } else if (width >= 512) {
343 stairs_handle_event (ModeInfo *mi, XEvent *event)
345 stairsstruct *sp = &stairs[MI_SCREEN(mi)];
347 if (gltrackball_event_handler (event, sp->trackball,
348 MI_WIDTH (mi), MI_HEIGHT (mi),
351 else if (event->xany.type == KeyPress)
355 XLookupString (&event->xkey, &c, 1, &keysym, 0);
356 if (c == ' ' || c == '\t')
358 gltrackball_reset (sp->trackball, 0, 0);
372 glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
373 glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
374 glLightfv(GL_LIGHT0, GL_POSITION, position0);
375 glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);
376 glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse);
377 glLightfv(GL_LIGHT1, GL_POSITION, position1);
378 glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
379 glLightModelfv(GL_LIGHT_MODEL_TWO_SIDE, lmodel_twoside);
380 glEnable(GL_LIGHTING);
383 glEnable(GL_NORMALIZE);
386 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
387 glShadeModel(GL_FLAT);
388 glEnable(GL_DEPTH_TEST);
389 glEnable(GL_TEXTURE_2D);
390 glEnable(GL_CULL_FACE);
392 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
396 status = gluBuild2DMipmaps(GL_TEXTURE_2D, 3,
397 WoodTextureWidth, WoodTextureHeight,
398 GL_RGB, GL_UNSIGNED_BYTE, WoodTextureData);
401 const char *s = (char *) gluErrorString (status);
402 fprintf (stderr, "%s: error mipmapping %dx%d texture: %s\n",
403 progname, WoodTextureWidth, WoodTextureHeight,
404 (s ? s : "(unknown)"));
407 check_gl_error("mipmapping");
410 XImage *img = xpm_to_ximage (mi->dpy,
414 glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA,
415 img->width, img->height, 0,
417 /* GL_UNSIGNED_BYTE, */
418 GL_UNSIGNED_INT_8_8_8_8_REV,
420 check_gl_error("texture");
425 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
426 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
427 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
428 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
429 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
431 glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, front_shininess);
432 glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, front_specular);
435 static void free_stairs (ModeInfo * mi);
438 init_stairs (ModeInfo * mi)
440 int screen = MI_SCREEN(mi);
443 MI_INIT (mi, stairs, free_stairs);
444 sp = &stairs[screen];
448 sp->sphere_position = NRAND(NPOSITIONS);
451 if ((sp->glx_context = init_GL(mi)) != NULL) {
453 reshape_stairs(mi, MI_WIDTH(mi), MI_HEIGHT(mi));
454 glDrawBuffer(GL_BACK);
455 if (!glIsList(sp->objects))
456 sp->objects = glGenLists(1);
462 sp->trackball = gltrackball_init (False);
466 draw_stairs (ModeInfo * mi)
468 stairsstruct *sp = &stairs[MI_SCREEN(mi)];
469 GLfloat rot = current_device_rotation();
471 Display *display = MI_DISPLAY(mi);
472 Window window = MI_WINDOW(mi);
474 if (!sp->glx_context)
477 glXMakeCurrent(display, window, *(sp->glx_context));
479 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
483 glRotatef(rot, 0, 0, 1);
485 glTranslatef(0.0, 0.0, -10.0);
487 if (!MI_IS_ICONIC(mi)) {
488 glScalef(Scale4Window * sp->WindH / sp->WindW, Scale4Window, Scale4Window);
490 glScalef(Scale4Iconic * sp->WindH / sp->WindW, Scale4Iconic, Scale4Iconic);
493 # ifdef HAVE_MOBILE /* Keep it the same relative size when rotated. */
495 GLfloat h = MI_HEIGHT(mi) / (GLfloat) MI_WIDTH(mi);
496 if (rot != 0 && rot != 180 && rot != -180)
497 glScalef (1/h, 1/h, 1/h);
501 gltrackball_rotate (sp->trackball);
503 glTranslatef(0, 0.5, 0);
504 glRotatef(44.5, 1, 0, 0);
505 glRotatef(50, 0, 1, 0);
508 if ((LRAND() % 500) == 0)
509 sp->rotating = (LRAND() & 1) ? 1 : -1;
513 glRotatef(sp->rotating * sp->step, 0, 1, 0);
514 if (sp->step >= 360) {
520 if (!sp->button_down_p)
525 draw_stairs_internal(mi);
532 glDisable(GL_LIGHTING);
533 glDisable(GL_TEXTURE_2D);
534 glBegin (GL_LINE_LOOP);
535 # endif /* DEBUG_PATH */
536 for (i = 0; i < NPOSITIONS; i ++)
537 for (j = 0; j < SPHERE_TICKS; j++)
538 mi->polygon_count += draw_sphere(i, j);
541 glEnable(GL_LIGHTING);
542 glEnable(GL_TEXTURE_2D);
543 # endif /* DEBUG_PATH */
546 mi->polygon_count += draw_sphere(sp->sphere_position, sp->sphere_tick);
549 if (sp->button_down_p)
551 else if (++sp->sphere_tick >= SPHERE_TICKS)
554 if (++sp->sphere_position >= NPOSITIONS)
555 sp->sphere_position = 0;
560 if (mi->fps_p) do_fps (mi);
563 glXSwapBuffers(display, window);
568 change_stairs (ModeInfo * mi)
570 stairsstruct *sp = &stairs[MI_SCREEN(mi)];
572 if (!sp->glx_context)
575 glXMakeCurrent(MI_DISPLAY(mi), MI_WINDOW(mi), *(sp->glx_context));
578 #endif /* !STANDALONE */
581 free_stairs (ModeInfo * mi)
583 stairsstruct *sp = &stairs[MI_SCREEN(mi)];
584 if (glIsList(sp->objects)) {
585 glDeleteLists(sp->objects, 1);
589 XSCREENSAVER_MODULE ("Stairs", stairs)