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 release_stairs 0
63 # include "xlockmore.h" /* from the xscreensaver distribution */
64 #else /* !STANDALONE */
65 # include "xlock.h" /* from the xlockmore distribution */
67 #endif /* !STANDALONE */
72 #include "e_textures.h"
74 #include "ximage-loader.h"
75 #include "images/gen/wood_png.h"
79 #include "gltrackball.h"
81 ENTRYPOINT ModeSpecOpt stairs_opts =
82 {0, NULL, 0, NULL, NULL};
85 ModStruct stairs_description =
86 {"stairs", "init_stairs", "draw_stairs", NULL,
87 "draw_stairs", "change_stairs", "free_stairs", &stairs_opts,
88 1000, 1, 1, 1, 4, 1.0, "",
89 "Shows Infinite Stairs, an Escher-like scene", 0, NULL};
93 #define Scale4Window 0.3
94 #define Scale4Iconic 0.4
96 #define sqr(A) ((A)*(A))
102 /*************************************************************************/
108 int AreObjectsDefined[1];
111 GLXContext *glx_context;
112 trackball_state *trackball;
117 static const float front_shininess[] = {60.0};
118 static const float front_specular[] = {0.7, 0.7, 0.7, 1.0};
119 static const float ambient[] = {0.0, 0.0, 0.0, 1.0};
120 static const float diffuse[] = {1.0, 1.0, 1.0, 1.0};
121 static const float position0[] = {1.0, 1.0, 1.0, 0.0};
122 static const float position1[] = {-1.0, -1.0, 1.0, 0.0};
123 static const float lmodel_ambient[] = {0.5, 0.5, 0.5, 1.0};
124 static const float lmodel_twoside[] = {GL_TRUE};
126 static const float MaterialYellow[] = {0.7, 0.7, 0.0, 1.0};
127 static const float MaterialWhite[] = {0.7, 0.7, 0.7, 1.0};
129 static const float ball_positions[] = {
151 #define NPOSITIONS ((sizeof ball_positions) / (sizeof ball_positions[0]) / 3)
152 #define SPHERE_TICKS 32
154 static stairsstruct *stairs = NULL;
157 draw_block(GLfloat width, GLfloat height, GLfloat thickness)
164 glVertex3f(-width, -height, thickness);
166 glVertex3f(width, -height, thickness);
168 glVertex3f(width, height, thickness);
170 glVertex3f(-width, height, thickness);
172 glNormal3f(0, 0, -1);
174 glVertex3f(-width, height, -thickness);
176 glVertex3f(width, height, -thickness);
178 glVertex3f(width, -height, -thickness);
180 glVertex3f(-width, -height, -thickness);
184 glVertex3f(-width, height, thickness);
186 glVertex3f(width, height, thickness);
188 glVertex3f(width, height, -thickness);
190 glVertex3f(-width, height, -thickness);
192 glNormal3f(0, -1, 0);
194 glVertex3f(-width, -height, -thickness);
196 glVertex3f(width, -height, -thickness);
198 glVertex3f(width, -height, thickness);
200 glVertex3f(-width, -height, thickness);
204 glVertex3f(width, -height, thickness);
206 glVertex3f(width, -height, -thickness);
208 glVertex3f(width, height, -thickness);
210 glVertex3f(width, height, thickness);
212 glNormal3f(-1, 0, 0);
214 glVertex3f(-width, height, thickness);
216 glVertex3f(-width, height, -thickness);
218 glVertex3f(-width, -height, -thickness);
220 glVertex3f(-width, -height, thickness);
227 draw_stairs_internal(ModeInfo * mi)
231 mi->polygon_count = 0;
235 glTranslatef(-3.0, 0.1, 2.0);
236 for (X = 0; X < 2; X++) {
237 mi->polygon_count += draw_block(0.5, 2.7 + 0.1 * X, 0.5);
238 glTranslatef(0.0, 0.1, -1.0);
241 glTranslatef(-3.0, 0.0, 3.0);
244 for (X = 0; X < 6; X++) {
245 mi->polygon_count += draw_block(0.5, 2.6 - 0.1 * X, 0.5);
246 glTranslatef(1.0, -0.1, 0.0);
248 glTranslatef(-1.0, -0.9, -1.0);
249 for (X = 0; X < 5; X++) {
250 mi->polygon_count += draw_block(0.5, 3.0 - 0.1 * X, 0.5);
251 glTranslatef(0.0, 0.0, -1.0);
253 glTranslatef(-1.0, -1.1, 1.0);
254 for (X = 0; X < 3; X++) {
255 mi->polygon_count += draw_block(0.5, 3.5 - 0.1 * X, 0.5);
256 glTranslatef(-1.0, -0.1, 0.0);
263 /*#define DEBUG_PATH*/
266 draw_sphere(int pos, int tick)
268 int pos2 = (pos+1) % NPOSITIONS;
269 GLfloat x1 = ball_positions[pos*3];
270 GLfloat y1 = ball_positions[pos*3+1];
271 GLfloat z1 = ball_positions[pos*3+2];
272 GLfloat x2 = ball_positions[pos2*3];
273 GLfloat y2 = ball_positions[pos2*3+1];
274 GLfloat z2 = ball_positions[pos2*3+2];
275 GLfloat frac = tick / (GLfloat) SPHERE_TICKS;
276 GLfloat x = x1 + (x2 - x1) * frac;
277 GLfloat y = y1 + (y2 - y1) * frac + (2 * sin (M_PI * frac));
278 GLfloat z = z1 + (z2 - z1) * frac;
286 glVertex3f(x, y-7.5, z);
287 glVertex3f(x, y, z); glVertex3f(x, y, z-0.6);
288 glVertex3f(x, y, z); glVertex3f(x, y, z+0.6);
289 glVertex3f(x, y, z); glVertex3f(x+0.6, y, z);
290 glVertex3f(x, y, z); glVertex3f(x-0.6, y, z);
294 # else /* !DEBUG_PATH */
296 glTranslatef(x, y, z);
298 glScalef (0.5, 0.5, 0.5);
300 /* make ball a little smaller on the gap to obscure distance */
301 if (pos == NPOSITIONS-1)
302 glScalef (0.95, 0.95, 0.95);
304 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialYellow);
305 glDisable (GL_TEXTURE_2D);
306 glShadeModel(GL_SMOOTH);
308 polys += unit_sphere (32, 32, False);
309 glShadeModel(GL_FLAT);
310 glEnable (GL_TEXTURE_2D);
311 #endif /* !DEBUG_PATH */
320 reshape_stairs (ModeInfo * mi, int width, int height)
322 stairsstruct *sp = &stairs[MI_SCREEN(mi)];
325 if (width > height * 5) { /* tiny window: show middle */
330 glViewport(0, y, sp->WindW = (GLint) width, sp->WindH = (GLint) height);
331 glMatrixMode(GL_PROJECTION);
333 glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 15.0);
334 glMatrixMode(GL_MODELVIEW);
338 } else if (width >= 512) {
348 stairs_handle_event (ModeInfo *mi, XEvent *event)
350 stairsstruct *sp = &stairs[MI_SCREEN(mi)];
352 if (gltrackball_event_handler (event, sp->trackball,
353 MI_WIDTH (mi), MI_HEIGHT (mi),
356 else if (event->xany.type == KeyPress)
360 XLookupString (&event->xkey, &c, 1, &keysym, 0);
361 if (c == ' ' || c == '\t')
363 gltrackball_reset (sp->trackball, 0, 0);
377 glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
378 glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
379 glLightfv(GL_LIGHT0, GL_POSITION, position0);
380 glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);
381 glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse);
382 glLightfv(GL_LIGHT1, GL_POSITION, position1);
383 glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
384 glLightModelfv(GL_LIGHT_MODEL_TWO_SIDE, lmodel_twoside);
385 glEnable(GL_LIGHTING);
388 glEnable(GL_NORMALIZE);
391 glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
392 glShadeModel(GL_FLAT);
393 glEnable(GL_DEPTH_TEST);
394 glEnable(GL_TEXTURE_2D);
395 glEnable(GL_CULL_FACE);
397 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
401 status = gluBuild2DMipmaps(GL_TEXTURE_2D, 3,
402 WoodTextureWidth, WoodTextureHeight,
403 GL_RGB, GL_UNSIGNED_BYTE, WoodTextureData);
406 const char *s = (char *) gluErrorString (status);
407 fprintf (stderr, "%s: error mipmapping %dx%d texture: %s\n",
408 progname, WoodTextureWidth, WoodTextureHeight,
409 (s ? s : "(unknown)"));
412 check_gl_error("mipmapping");
415 XImage *img = image_data_to_ximage (mi->dpy, mi->xgwa.visual,
416 wood_png, sizeof(wood_png));
417 glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA,
418 img->width, img->height, 0,
419 GL_RGBA, GL_UNSIGNED_BYTE, img->data);
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);
436 init_stairs (ModeInfo * mi)
438 int screen = MI_SCREEN(mi);
441 MI_INIT (mi, stairs);
442 sp = &stairs[screen];
446 sp->sphere_position = NRAND(NPOSITIONS);
449 if ((sp->glx_context = init_GL(mi)) != NULL) {
451 reshape_stairs(mi, MI_WIDTH(mi), MI_HEIGHT(mi));
452 glDrawBuffer(GL_BACK);
453 if (!glIsList(sp->objects))
454 sp->objects = glGenLists(1);
460 sp->trackball = gltrackball_init (False);
464 draw_stairs (ModeInfo * mi)
466 stairsstruct *sp = &stairs[MI_SCREEN(mi)];
467 GLfloat rot = current_device_rotation();
469 Display *display = MI_DISPLAY(mi);
470 Window window = MI_WINDOW(mi);
472 if (!sp->glx_context)
475 glXMakeCurrent(display, window, *(sp->glx_context));
477 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
481 glRotatef(rot, 0, 0, 1);
483 glTranslatef(0.0, 0.0, -10.0);
485 if (!MI_IS_ICONIC(mi)) {
486 glScalef(Scale4Window * sp->WindH / sp->WindW, Scale4Window, Scale4Window);
488 glScalef(Scale4Iconic * sp->WindH / sp->WindW, Scale4Iconic, Scale4Iconic);
491 # ifdef HAVE_MOBILE /* Keep it the same relative size when rotated. */
493 GLfloat h = MI_HEIGHT(mi) / (GLfloat) MI_WIDTH(mi);
494 if (rot != 0 && rot != 180 && rot != -180)
495 glScalef (1/h, 1/h, 1/h);
499 gltrackball_rotate (sp->trackball);
501 glTranslatef(0, 0.5, 0);
502 glRotatef(44.5, 1, 0, 0);
503 glRotatef(50, 0, 1, 0);
506 if ((LRAND() % 500) == 0)
507 sp->rotating = (LRAND() & 1) ? 1 : -1;
511 glRotatef(sp->rotating * sp->step, 0, 1, 0);
512 if (sp->step >= 360) {
518 if (!sp->button_down_p)
523 draw_stairs_internal(mi);
530 glDisable(GL_LIGHTING);
531 glDisable(GL_TEXTURE_2D);
532 glBegin (GL_LINE_LOOP);
533 # endif /* DEBUG_PATH */
534 for (i = 0; i < NPOSITIONS; i ++)
535 for (j = 0; j < SPHERE_TICKS; j++)
536 mi->polygon_count += draw_sphere(i, j);
539 glEnable(GL_LIGHTING);
540 glEnable(GL_TEXTURE_2D);
541 # endif /* DEBUG_PATH */
544 mi->polygon_count += draw_sphere(sp->sphere_position, sp->sphere_tick);
547 if (sp->button_down_p)
549 else if (++sp->sphere_tick >= SPHERE_TICKS)
552 if (++sp->sphere_position >= NPOSITIONS)
553 sp->sphere_position = 0;
558 if (mi->fps_p) do_fps (mi);
561 glXSwapBuffers(display, window);
566 change_stairs (ModeInfo * mi)
568 stairsstruct *sp = &stairs[MI_SCREEN(mi)];
570 if (!sp->glx_context)
573 glXMakeCurrent(MI_DISPLAY(mi), MI_WINDOW(mi), *(sp->glx_context));
576 #endif /* !STANDALONE */
579 free_stairs (ModeInfo * mi)
581 stairsstruct *sp = &stairs[MI_SCREEN(mi)];
582 if (glIsList(sp->objects)) {
583 glDeleteLists(sp->objects, 1);
587 XSCREENSAVER_MODULE ("Stairs", stairs)