2 * queens - solves n queens problem, displays
3 * i make no claims that this is an optimal solution to the problem,
7 * version 1.0 - May 10, 2002
9 * Copyright (C) 2002 Blair Tennessy (tennessy@cs.ubc.ca)
11 * Permission to use, copy, modify, distribute, and sell this software and its
12 * documentation for any purpose is hereby granted without fee, provided that
13 * the above copyright notice appear in all copies and that both that
14 * copyright notice and this permission notice appear in supporting
15 * documentation. No representations are made about the suitability of this
16 * software for any purpose. It is provided "as is" without express or
21 #define DEFAULTS "*delay: 20000 \n" \
22 "*showFPS: False \n" \
23 "*wireframe: False \n" \
25 # define refresh_queens 0
26 # include "xlockmore.h"
34 #include "gltrackball.h"
37 #define countof(x) (sizeof((x))/sizeof((*x)))
39 static XrmOptionDescRec opts[] = {
40 {"+rotate", ".queens.rotate", XrmoptionNoArg, "false" },
41 {"-rotate", ".queens.rotate", XrmoptionNoArg, "true" },
42 {"+flat", ".queens.flat", XrmoptionNoArg, "false" },
43 {"-flat", ".queens.flat", XrmoptionNoArg, "true" },
46 static int rotate, wire, clearbits, flat;
48 static argtype vars[] = {
49 {&rotate, "rotate", "Rotate", "True", t_Bool},
50 {&flat, "flat", "Flat", "False", t_Bool},
53 ENTRYPOINT ModeSpecOpt queens_opts = {countof(opts), opts, countof(vars), vars, NULL};
56 ModStruct queens_description =
57 {"queens", "init_queens", "draw_queens", "release_queens",
58 "draw_queens", "init_queens", NULL, &queens_opts,
59 1000, 1, 2, 1, 4, 1.0, "",
71 GLXContext *glx_context;
73 trackball_state *trackball;
77 int board[MAXBOARD][MAXBOARD];
78 int steps, colorset, BOARDSIZE;
83 static Queenscreen *qss = NULL;
85 /* definition of white/black colors */
86 static const GLfloat colors[COLORSETS][2][3] =
88 {{0.43, 0.54, 0.76}, {0.8, 0.8, 0.8}},
89 {{0.5, 0.7, 0.9}, {0.2, 0.3, 0.6}},
90 {{0.53725490196, 0.360784313725, 0.521568627451}, {0.6, 0.6, 0.6}},
91 {{0.15, 0.77, 0.54}, {0.5, 0.5, 0.5}},
92 {{0.9, 0.45, 0.0}, {0.5, 0.5, 0.5}},
96 queens_handle_event (ModeInfo *mi, XEvent *event)
98 Queenscreen *qs = &qss[MI_SCREEN(mi)];
100 if (event->xany.type == ButtonPress &&
101 event->xbutton.button == Button1)
103 qs->button_down_p = True;
104 gltrackball_start (qs->trackball,
105 event->xbutton.x, event->xbutton.y,
106 MI_WIDTH (mi), MI_HEIGHT (mi));
109 else if (event->xany.type == ButtonRelease &&
110 event->xbutton.button == Button1)
112 qs->button_down_p = False;
115 else if (event->xany.type == ButtonPress &&
116 (event->xbutton.button == Button4 ||
117 event->xbutton.button == Button5))
119 gltrackball_mousewheel (qs->trackball, event->xbutton.button, 5,
120 !event->xbutton.state);
123 else if (event->xany.type == MotionNotify &&
126 gltrackball_track (qs->trackball,
127 event->xmotion.x, event->xmotion.y,
128 MI_WIDTH (mi), MI_HEIGHT (mi));
137 /* returns true if placing a queen on column c causes a conflict */
138 static int conflictsCols(Queenscreen *qs, int c)
142 for(i = 0; i < qs->BOARDSIZE; ++i)
149 /* returns true if placing a queen on (r,c) causes a diagonal conflict */
150 static int conflictsDiag(Queenscreen *qs, int r, int c)
155 int n = r < c ? r : c;
156 for(i = 0; i < qs->BOARDSIZE-abs(r-c); ++i)
157 if(qs->board[r-n+i][c-n+i])
161 n = r < qs->BOARDSIZE - (c+1) ? r : qs->BOARDSIZE - (c+1);
162 for(i = 0; i < qs->BOARDSIZE-abs(qs->BOARDSIZE - (1+r+c)); ++i)
163 if(qs->board[r-n+i][c+n-i])
169 /* returns true if placing a queen at (r,c) causes a conflict */
170 static int conflicts(Queenscreen *qs, int r, int c)
172 return !conflictsCols(qs, c) ? conflictsDiag(qs, r, c) : 1;
176 static void blank(Queenscreen *qs)
180 for(i = 0; i < MAXBOARD; ++i)
181 for(j = 0; j < MAXBOARD; ++j)
182 qs->board[i][j] = NONE;
185 /* recursively determine solution */
186 static int findSolution(Queenscreen *qs, int row, int col)
188 if(row == qs->BOARDSIZE)
191 while(col < qs->BOARDSIZE) {
192 if(!conflicts(qs, row, col)) {
193 qs->board[row][col] = 1;
195 if(findSolution(qs, row+1, 0))
198 qs->board[row][col] = 0;
207 /** driver for finding solution */
208 static void go(Queenscreen *qs) { while(!findSolution(qs, 0, random()%qs->BOARDSIZE)); }
210 /* lighting variables */
211 static const GLfloat front_shininess[] = {60.0};
212 static const GLfloat front_specular[] = {0.4, 0.4, 0.4, 1.0};
213 static const GLfloat ambient[] = {0.3, 0.3, 0.3, 1.0};
214 static const GLfloat diffuse[] = {0.8, 0.8, 0.8, 1.0};
216 /* configure lighting */
217 static void setup_lights(Queenscreen *qs)
220 /* setup twoside lighting */
221 glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
222 glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
223 glLightfv(GL_LIGHT0, GL_POSITION, qs->position);
224 glEnable(GL_LIGHTING);
227 /* setup material properties */
228 glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, front_shininess);
229 glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, front_specular);
231 glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
234 #define checkImageWidth 8
235 #define checkImageHeight 8
236 /*static GLubyte checkImage[checkImageWidth][checkImageHeight][3];*/
238 /* return alpha value for fading */
239 static GLfloat findAlpha(Queenscreen *qs)
241 return qs->steps < 128 ? qs->steps/128.0 : qs->steps < 1024-128 ?1.0:(1024-qs->steps)/128.0;
245 static void drawPieces(Queenscreen *qs)
249 for(i = 0; i < qs->BOARDSIZE; ++i) {
250 for(j = 0; j < qs->BOARDSIZE; ++j) {
251 if(qs->board[i][j]) {
252 glColor3fv(colors[qs->colorset][i%2]);
256 glTranslatef(1.0, 0.0, 0.0);
259 glTranslatef(-1.0*qs->BOARDSIZE, 0.0, 1.0);
263 /** reflectionboard */
264 static void draw_reflections(Queenscreen *qs)
268 glEnable(GL_STENCIL_TEST);
269 glStencilFunc(GL_ALWAYS, 1, 1);
270 glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
271 glColorMask(0,0,0,0);
272 glDisable(GL_CULL_FACE);
274 glDisable(GL_DEPTH_TEST);
277 /* only draw white squares */
278 for(i = 0; i < qs->BOARDSIZE; ++i) {
279 for(j = (qs->BOARDSIZE+i) % 2; j < qs->BOARDSIZE; j += 2) {
280 glVertex3f(i, 0.0, j + 1.0);
281 glVertex3f(i + 1.0, 0.0, j + 1.0);
282 glVertex3f(i + 1.0, 0.0, j);
283 glVertex3f(i, 0.0, j);
287 glEnable(GL_DEPTH_TEST);
289 glColorMask(1, 1, 1, 1);
290 glStencilFunc(GL_EQUAL, 1, 1);
291 glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
294 glScalef(1.0, -1.0, 1.0);
295 glTranslatef(0.5, 0.001, 0.5);
296 glLightfv(GL_LIGHT0, GL_POSITION, qs->position);
299 glDisable(GL_STENCIL_TEST);
302 glLightfv(GL_LIGHT0, GL_POSITION, qs->position);
304 glEnable(GL_CULL_FACE);
306 glColorMask(1,1,1,1);
310 static void drawBoard(Queenscreen *qs)
316 for(i = 0; i < qs->BOARDSIZE; ++i)
317 for(j = 0; j < qs->BOARDSIZE; ++j) {
318 int par = (i-j+qs->BOARDSIZE)%2;
319 glColor4f(colors[qs->colorset][par][0],
320 colors[qs->colorset][par][1],
321 colors[qs->colorset][par][2],
323 glNormal3f(0.0, 1.0, 0.0);
324 glVertex3f(i, 0.0, j + 1.0);
325 glVertex3f(i + 1.0, 0.0, j + 1.0);
326 glVertex3f(i + 1.0, 0.0, j);
327 glVertex3f(i, 0.0, j);
333 static void display(Queenscreen *qs)
337 glMatrixMode(GL_MODELVIEW);
340 /* setup light attenuation */
341 glEnable(GL_COLOR_MATERIAL);
342 glLightf(GL_LIGHT0, GL_CONSTANT_ATTENUATION, 0.8/(0.01+findAlpha(qs)));
343 glLightf(GL_LIGHT0, GL_LINEAR_ATTENUATION, 0.06);
345 /** setup perspective */
346 glTranslatef(0.0, 0.0, -1.5*qs->BOARDSIZE);
347 glRotatef(30.0, 1.0, 0.0, 0.0);
348 gltrackball_rotate (qs->trackball);
349 glRotatef(qs->theta*100, 0.0, 1.0, 0.0);
350 glTranslatef(-0.5*qs->BOARDSIZE, 0.0, -0.5*qs->BOARDSIZE);
352 /* find light positions */
353 qs->position[0] = qs->BOARDSIZE/2.0 + qs->BOARDSIZE/1.4*-sin(qs->theta*100*M_PI/180.0);
354 qs->position[2] = qs->BOARDSIZE/2.0 + qs->BOARDSIZE/1.4*cos(qs->theta*100*M_PI/180.0);
355 qs->position[1] = 6.0;
358 glEnable(GL_LIGHTING);
359 glLightfv(GL_LIGHT0, GL_POSITION, qs->position);
363 /* draw reflections */
365 draw_reflections(qs);
372 glLightf(GL_LIGHT0, GL_LINEAR_ATTENUATION, 0.1);
374 glTranslatef(0.5, 0.0, 0.5);
378 if(!qs->button_down_p)
381 /* zero out board, find new solution of size MINBOARD <= i <= MAXBOARD */
382 if(++qs->steps == 1024) {
385 qs->BOARDSIZE = MINBOARD + (random() % (MAXBOARD - MINBOARD + 1));
386 qs->colorset = (qs->colorset+1)%COLORSETS;
391 static const GLfloat spidermodel[][3] =
411 #define EPSILON 0.001
413 /** draws cylindermodel */
414 static void draw_model(int chunks, const GLfloat model[][3], int r)
417 GLUquadricObj *quadric = gluNewQuadric();
419 glRotatef(-90.0, 1.0, 0.0, 0.0);
421 for(i = 0; i < chunks; ++i) {
422 if(model[i][0] > EPSILON || model[i][1] > EPSILON)
423 gluCylinder(quadric, model[i][0], model[i][1], model[i][2], r, 1);
424 glTranslatef(0.0, 0.0, model[i][2]);
430 ENTRYPOINT void reshape_queens(ModeInfo *mi, int width, int height)
432 GLfloat h = (GLfloat) height / (GLfloat) width;
433 glViewport(0,0, width, height);
434 glMatrixMode(GL_PROJECTION);
436 gluPerspective(45, 1/h, 2.0, 30.0);
437 glMatrixMode(GL_MODELVIEW);
440 ENTRYPOINT void init_queens(ModeInfo *mi)
442 int screen = MI_SCREEN(mi);
444 wire = MI_IS_WIREFRAME(mi);
447 !(qss = (Queenscreen *) calloc(MI_NUM_SCREENS(mi), sizeof(Queenscreen))))
451 qs->window = MI_WINDOW(mi);
452 qs->trackball = gltrackball_init ();
454 qs->BOARDSIZE = 8; /* 8 cuz its classic */
456 if((qs->glx_context = init_GL(mi)))
457 reshape_queens(mi, MI_WIDTH(mi), MI_HEIGHT(mi));
461 glClearColor(0.0, 0.0, 0.0, 0.0);
462 glNewList(QUEEN, GL_COMPILE);
463 draw_model(countof(spidermodel), spidermodel, 24);
467 glShadeModel(GL_FLAT);
469 clearbits = GL_COLOR_BUFFER_BIT;
471 glColorMaterial(GL_FRONT, GL_DIFFUSE);
472 glEnable(GL_COLOR_MATERIAL);
476 glEnable(GL_DEPTH_TEST);
477 clearbits |= GL_DEPTH_BUFFER_BIT;
478 clearbits |= GL_STENCIL_BUFFER_BIT;
479 glEnable(GL_CULL_FACE);
483 glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
485 /* find a solution */
489 ENTRYPOINT void draw_queens(ModeInfo *mi)
491 Queenscreen *qs = &qss[MI_SCREEN(mi)];
492 Window w = MI_WINDOW(mi);
493 Display *disp = MI_DISPLAY(mi);
498 glXMakeCurrent(disp, w, *(qs->glx_context));
502 if(mi->fps_p) do_fps(mi);
504 glXSwapBuffers(disp, w);
507 ENTRYPOINT void release_queens(ModeInfo *mi)
516 XSCREENSAVER_MODULE ("Queens", queens)