+/*
+ * sixteen.c: `16-puzzle', a sliding-tiles jigsaw which differs
+ * from the 15-puzzle in that you toroidally rotate a row or column
+ * at a time.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <math.h>
+
+#include "puzzles.h"
+
+const char *const game_name = "Sixteen";
+
+#define TILE_SIZE 48
+#define BORDER TILE_SIZE /* big border to fill with arrows */
+#define HIGHLIGHT_WIDTH (TILE_SIZE / 20)
+#define COORD(x) ( (x) * TILE_SIZE + BORDER )
+#define FROMCOORD(x) ( ((x) - BORDER + 2*TILE_SIZE) / TILE_SIZE - 2 )
+
+#define ANIM_TIME 0.1F
+#define FLASH_FRAME 0.1F
+
+#define X(state, i) ( (i) % (state)->w )
+#define Y(state, i) ( (i) / (state)->w )
+#define C(state, x, y) ( (y) * (state)->w + (x) )
+
+enum {
+ COL_BACKGROUND,
+ COL_TEXT,
+ COL_HIGHLIGHT,
+ COL_LOWLIGHT,
+ NCOLOURS
+};
+
+struct game_params {
+ int w, h;
+};
+
+struct game_state {
+ int w, h, n;
+ int *tiles;
+ int completed;
+};
+
+game_params *default_params(void)
+{
+ game_params *ret = snew(game_params);
+
+ ret->w = ret->h = 4;
+
+ return ret;
+}
+
+int game_fetch_preset(int i, char **name, game_params **params)
+{
+ game_params *ret;
+ int w, h;
+ char buf[80];
+
+ switch (i) {
+ case 0: w = 3, h = 3; break;
+ case 1: w = 4, h = 3; break;
+ case 2: w = 4, h = 4; break;
+ case 3: w = 5, h = 4; break;
+ case 4: w = 5, h = 5; break;
+ default: return FALSE;
+ }
+
+ sprintf(buf, "%dx%d", w, h);
+ *name = dupstr(buf);
+ *params = ret = snew(game_params);
+ ret->w = w;
+ ret->h = h;
+ return TRUE;
+}
+
+void free_params(game_params *params)
+{
+ sfree(params);
+}
+
+game_params *dup_params(game_params *params)
+{
+ game_params *ret = snew(game_params);
+ *ret = *params; /* structure copy */
+ return ret;
+}
+
+int perm_parity(int *perm, int n)
+{
+ int i, j, ret;
+
+ ret = 0;
+
+ for (i = 0; i < n-1; i++)
+ for (j = i+1; j < n; j++)
+ if (perm[i] > perm[j])
+ ret = !ret;
+
+ return ret;
+}
+
+char *new_game_seed(game_params *params)
+{
+ int stop, n, i, x;
+ int x1, x2, p1, p2;
+ int *tiles, *used;
+ char *ret;
+ int retlen;
+
+ n = params->w * params->h;
+
+ tiles = snewn(n, int);
+ used = snewn(n, int);
+
+ for (i = 0; i < n; i++) {
+ tiles[i] = -1;
+ used[i] = FALSE;
+ }
+
+ /*
+ * If both dimensions are odd, there is a parity constraint.
+ */
+ if (params->w & params->h & 1)
+ stop = 2;
+ else
+ stop = 0;
+
+ /*
+ * Place everything except (possibly) the last two tiles.
+ */
+ for (x = 0, i = n; i > stop; i--) {
+ int k = i > 1 ? rand_upto(i) : 0;
+ int j;
+
+ for (j = 0; j < n; j++)
+ if (!used[j] && (k-- == 0))
+ break;
+
+ assert(j < n && !used[j]);
+ used[j] = TRUE;
+
+ while (tiles[x] >= 0)
+ x++;
+ assert(x < n);
+ tiles[x] = j;
+ }
+
+ if (stop) {
+ /*
+ * Find the last two locations, and the last two pieces.
+ */
+ while (tiles[x] >= 0)
+ x++;
+ assert(x < n);
+ x1 = x;
+ x++;
+ while (tiles[x] >= 0)
+ x++;
+ assert(x < n);
+ x2 = x;
+
+ for (i = 0; i < n; i++)
+ if (!used[i])
+ break;
+ p1 = i;
+ for (i = p1+1; i < n; i++)
+ if (!used[i])
+ break;
+ p2 = i;
+
+ /*
+ * Try the last two tiles one way round. If that fails, swap
+ * them.
+ */
+ tiles[x1] = p1;
+ tiles[x2] = p2;
+ if (perm_parity(tiles, n) != 0) {
+ tiles[x1] = p2;
+ tiles[x2] = p1;
+ assert(perm_parity(tiles, n) == 0);
+ }
+ }
+
+ /*
+ * Now construct the game seed, by describing the tile array as
+ * a simple sequence of comma-separated integers.
+ */
+ ret = NULL;
+ retlen = 0;
+ for (i = 0; i < n; i++) {
+ char buf[80];
+ int k;
+
+ k = sprintf(buf, "%d,", tiles[i]+1);
+
+ ret = sresize(ret, retlen + k + 1, char);
+ strcpy(ret + retlen, buf);
+ retlen += k;
+ }
+ ret[retlen-1] = '\0'; /* delete last comma */
+
+ sfree(tiles);
+ sfree(used);
+
+ return ret;
+}
+
+game_state *new_game(game_params *params, char *seed)
+{
+ game_state *state = snew(game_state);
+ int i;
+ char *p;
+
+ state->w = params->w;
+ state->h = params->h;
+ state->n = params->w * params->h;
+ state->tiles = snewn(state->n, int);
+
+ p = seed;
+ i = 0;
+ for (i = 0; i < state->n; i++) {
+ assert(*p);
+ state->tiles[i] = atoi(p);
+ while (*p && *p != ',')
+ p++;
+ if (*p) p++; /* eat comma */
+ }
+ assert(!*p);
+
+ state->completed = FALSE;
+
+ return state;
+}
+
+game_state *dup_game(game_state *state)
+{
+ game_state *ret = snew(game_state);
+
+ ret->w = state->w;
+ ret->h = state->h;
+ ret->n = state->n;
+ ret->tiles = snewn(state->w * state->h, int);
+ memcpy(ret->tiles, state->tiles, state->w * state->h * sizeof(int));
+ ret->completed = state->completed;
+
+ return ret;
+}
+
+void free_game(game_state *state)
+{
+ sfree(state);
+}
+
+game_state *make_move(game_state *from, int x, int y, int button)
+{
+ int cx, cy;
+ int dx, dy, tx, ty, n;
+ game_state *ret;
+
+ if (button != LEFT_BUTTON)
+ return NULL;
+
+ cx = FROMCOORD(x);
+ cy = FROMCOORD(y);
+ if (cx == -1 && cy >= 0 && cy < from->h)
+ n = from->w, dx = +1, dy = 0;
+ else if (cx == from->w && cy >= 0 && cy < from->h)
+ n = from->w, dx = -1, dy = 0;
+ else if (cy == -1 && cx >= 0 && cx < from->w)
+ n = from->h, dy = +1, dx = 0;
+ else if (cy == from->h && cx >= 0 && cx < from->w)
+ n = from->h, dy = -1, dx = 0;
+ else
+ return NULL; /* invalid click location */
+
+ ret = dup_game(from);
+
+ do {
+ cx += dx;
+ cy += dy;
+ tx = (cx + dx + from->w) % from->w;
+ ty = (cy + dy + from->h) % from->h;
+ ret->tiles[C(ret, cx, cy)] = from->tiles[C(from, tx, ty)];
+ } while (--n > 0);
+
+ /*
+ * See if the game has been completed.
+ */
+ if (!ret->completed) {
+ ret->completed = TRUE;
+ for (n = 0; n < ret->n; n++)
+ if (ret->tiles[n] != n+1)
+ ret->completed = FALSE;
+ }
+
+ return ret;
+}
+
+/* ----------------------------------------------------------------------
+ * Drawing routines.
+ */
+
+struct game_drawstate {
+ int started;
+ int w, h, bgcolour;
+ int *tiles;
+};
+
+void game_size(game_params *params, int *x, int *y)
+{
+ *x = TILE_SIZE * params->w + 2 * BORDER;
+ *y = TILE_SIZE * params->h + 2 * BORDER;
+}
+
+float *game_colours(frontend *fe, game_state *state, int *ncolours)
+{
+ float *ret = snewn(3 * NCOLOURS, float);
+ int i;
+ float max;
+
+ frontend_default_colour(fe, &ret[COL_BACKGROUND * 3]);
+
+ /*
+ * Drop the background colour so that the highlight is
+ * noticeably brighter than it while still being under 1.
+ */
+ max = ret[COL_BACKGROUND*3];
+ for (i = 1; i < 3; i++)
+ if (ret[COL_BACKGROUND*3+i] > max)
+ max = ret[COL_BACKGROUND*3+i];
+ if (max * 1.2F > 1.0F) {
+ for (i = 0; i < 3; i++)
+ ret[COL_BACKGROUND*3+i] /= (max * 1.2F);
+ }
+
+ for (i = 0; i < 3; i++) {
+ ret[COL_HIGHLIGHT * 3 + i] = ret[COL_BACKGROUND * 3 + i] * 1.2F;
+ ret[COL_LOWLIGHT * 3 + i] = ret[COL_BACKGROUND * 3 + i] * 0.8F;
+ ret[COL_TEXT * 3 + i] = 0.0;
+ }
+
+ *ncolours = NCOLOURS;
+ return ret;
+}
+
+game_drawstate *game_new_drawstate(game_state *state)
+{
+ struct game_drawstate *ds = snew(struct game_drawstate);
+ int i;
+
+ ds->started = FALSE;
+ ds->w = state->w;
+ ds->h = state->h;
+ ds->bgcolour = COL_BACKGROUND;
+ ds->tiles = snewn(ds->w*ds->h, int);
+ for (i = 0; i < ds->w*ds->h; i++)
+ ds->tiles[i] = -1;
+
+ return ds;
+}
+
+void game_free_drawstate(game_drawstate *ds)
+{
+ sfree(ds->tiles);
+ sfree(ds);
+}
+
+static void draw_tile(frontend *fe, game_state *state, int x, int y,
+ int tile, int flash_colour)
+{
+ if (tile == 0) {
+ draw_rect(fe, x, y, TILE_SIZE, TILE_SIZE,
+ flash_colour);
+ } else {
+ int coords[6];
+ char str[40];
+
+ coords[0] = x + TILE_SIZE - 1;
+ coords[1] = y + TILE_SIZE - 1;
+ coords[2] = x + TILE_SIZE - 1;
+ coords[3] = y;
+ coords[4] = x;
+ coords[5] = y + TILE_SIZE - 1;
+ draw_polygon(fe, coords, 3, TRUE, COL_LOWLIGHT);
+ draw_polygon(fe, coords, 3, FALSE, COL_LOWLIGHT);
+
+ coords[0] = x;
+ coords[1] = y;
+ draw_polygon(fe, coords, 3, TRUE, COL_HIGHLIGHT);
+ draw_polygon(fe, coords, 3, FALSE, COL_HIGHLIGHT);
+
+ draw_rect(fe, x + HIGHLIGHT_WIDTH, y + HIGHLIGHT_WIDTH,
+ TILE_SIZE - 2*HIGHLIGHT_WIDTH, TILE_SIZE - 2*HIGHLIGHT_WIDTH,
+ flash_colour);
+
+ sprintf(str, "%d", tile);
+ draw_text(fe, x + TILE_SIZE/2, y + TILE_SIZE/2,
+ FONT_VARIABLE, TILE_SIZE/3, ALIGN_VCENTRE | ALIGN_HCENTRE,
+ COL_TEXT, str);
+ }
+ draw_update(fe, x, y, TILE_SIZE, TILE_SIZE);
+}
+
+static void draw_arrow(frontend *fe, int x, int y, int xdx, int xdy)
+{
+ int coords[14];
+ int ydy = -xdx, ydx = xdy;
+
+#define POINT(n, xx, yy) ( \
+ coords[2*(n)+0] = x + (xx)*xdx + (yy)*ydx, \
+ coords[2*(n)+1] = y + (xx)*xdy + (yy)*ydy)
+
+ POINT(0, TILE_SIZE / 2, 3 * TILE_SIZE / 4); /* top of arrow */
+ POINT(1, 3 * TILE_SIZE / 4, TILE_SIZE / 2); /* right corner */
+ POINT(2, 5 * TILE_SIZE / 8, TILE_SIZE / 2); /* right concave */
+ POINT(3, 5 * TILE_SIZE / 8, TILE_SIZE / 4); /* bottom right */
+ POINT(4, 3 * TILE_SIZE / 8, TILE_SIZE / 4); /* bottom left */
+ POINT(5, 3 * TILE_SIZE / 8, TILE_SIZE / 2); /* left concave */
+ POINT(6, TILE_SIZE / 4, TILE_SIZE / 2); /* left corner */
+
+ draw_polygon(fe, coords, 7, TRUE, COL_LOWLIGHT);
+ draw_polygon(fe, coords, 7, FALSE, COL_TEXT);
+}
+
+void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
+ game_state *state, float animtime, float flashtime)
+{
+ int i, pass, bgcolour;
+
+ if (flashtime > 0) {
+ int frame = (int)(flashtime / FLASH_FRAME);
+ bgcolour = (frame % 2 ? COL_LOWLIGHT : COL_HIGHLIGHT);
+ } else
+ bgcolour = COL_BACKGROUND;
+
+ if (!ds->started) {
+ int coords[6];
+
+ draw_rect(fe, 0, 0,
+ TILE_SIZE * state->w + 2 * BORDER,
+ TILE_SIZE * state->h + 2 * BORDER, COL_BACKGROUND);
+ draw_update(fe, 0, 0,
+ TILE_SIZE * state->w + 2 * BORDER,
+ TILE_SIZE * state->h + 2 * BORDER);
+
+ /*
+ * Recessed area containing the whole puzzle.
+ */
+ coords[0] = COORD(state->w) + HIGHLIGHT_WIDTH - 1;
+ coords[1] = COORD(state->h) + HIGHLIGHT_WIDTH - 1;
+ coords[2] = COORD(state->w) + HIGHLIGHT_WIDTH - 1;
+ coords[3] = COORD(0) - HIGHLIGHT_WIDTH;
+ coords[4] = COORD(0) - HIGHLIGHT_WIDTH;
+ coords[5] = COORD(state->h) + HIGHLIGHT_WIDTH - 1;
+ draw_polygon(fe, coords, 3, TRUE, COL_HIGHLIGHT);
+ draw_polygon(fe, coords, 3, FALSE, COL_HIGHLIGHT);
+
+ coords[1] = COORD(0) - HIGHLIGHT_WIDTH;
+ coords[0] = COORD(0) - HIGHLIGHT_WIDTH;
+ draw_polygon(fe, coords, 3, TRUE, COL_LOWLIGHT);
+ draw_polygon(fe, coords, 3, FALSE, COL_LOWLIGHT);
+
+ /*
+ * Arrows for making moves.
+ */
+ for (i = 0; i < state->w; i++) {
+ draw_arrow(fe, COORD(i), COORD(0), +1, 0);
+ draw_arrow(fe, COORD(i+1), COORD(state->h), -1, 0);
+ }
+ for (i = 0; i < state->h; i++) {
+ draw_arrow(fe, COORD(state->w), COORD(i), 0, +1);
+ draw_arrow(fe, COORD(0), COORD(i+1), 0, -1);
+ }
+
+ ds->started = TRUE;
+ }
+
+ /*
+ * Now draw each tile. We do this in two passes to make
+ * animation easy.
+ */
+
+ clip(fe, COORD(0), COORD(0), TILE_SIZE*state->w, TILE_SIZE*state->h);
+
+ for (pass = 0; pass < 2; pass++) {
+ for (i = 0; i < state->n; i++) {
+ int t, t0;
+ /*
+ * Figure out what should be displayed at this
+ * location. It's either a simple tile, or it's a
+ * transition between two tiles (in which case we say
+ * -1 because it must always be drawn).
+ */
+
+ if (oldstate && oldstate->tiles[i] != state->tiles[i])
+ t = -1;
+ else
+ t = state->tiles[i];
+
+ t0 = t;
+
+ if (ds->bgcolour != bgcolour || /* always redraw when flashing */
+ ds->tiles[i] != t || ds->tiles[i] == -1 || t == -1) {
+ int x, y, x2, y2;
+
+ /*
+ * Figure out what to _actually_ draw, and where to
+ * draw it.
+ */
+ if (t == -1) {
+ int x0, y0, x1, y1, dx, dy;
+ int j;
+
+ /*
+ * On the first pass, just blank the tile.
+ */
+ if (pass == 0) {
+ x = COORD(X(state, i));
+ y = COORD(Y(state, i));
+ x2 = y2 = -1;
+ t = 0;
+ } else {
+ float c;
+
+ t = state->tiles[i];
+
+ /*
+ * FIXME: must be prepared to draw a double
+ * tile in some situations.
+ */
+
+ /*
+ * Find the coordinates of this tile in the old and
+ * new states.
+ */
+ x1 = COORD(X(state, i));
+ y1 = COORD(Y(state, i));
+ for (j = 0; j < oldstate->n; j++)
+ if (oldstate->tiles[j] == state->tiles[i])
+ break;
+ assert(j < oldstate->n);
+ x0 = COORD(X(state, j));
+ y0 = COORD(Y(state, j));
+
+ dx = (x1 - x0);
+ if (abs(dx) > TILE_SIZE) {
+ dx = (dx < 0 ? dx + TILE_SIZE * state->w :
+ dx - TILE_SIZE * state->w);
+ assert(abs(dx) == TILE_SIZE);
+ }
+ dy = (y1 - y0);
+ if (abs(dy) > TILE_SIZE) {
+ dy = (dy < 0 ? dy + TILE_SIZE * state->h :
+ dy - TILE_SIZE * state->h);
+ assert(abs(dy) == TILE_SIZE);
+ }
+
+ c = (animtime / ANIM_TIME);
+ if (c < 0.0F) c = 0.0F;
+ if (c > 1.0F) c = 1.0F;
+
+ x = x0 + (int)(c * dx);
+ y = y0 + (int)(c * dy);
+ x2 = x1 - dx + (int)(c * dx);
+ y2 = y1 - dy + (int)(c * dy);
+ }
+
+ } else {
+ if (pass == 0)
+ continue;
+ x = COORD(X(state, i));
+ y = COORD(Y(state, i));
+ x2 = y2 = -1;
+ }
+
+ draw_tile(fe, state, x, y, t, bgcolour);
+ if (x2 != -1 || y2 != -1)
+ draw_tile(fe, state, x2, y2, t, bgcolour);
+ }
+ ds->tiles[i] = t0;
+ }
+ }
+
+ unclip(fe);
+
+ ds->bgcolour = bgcolour;
+}
+
+float game_anim_length(game_state *oldstate, game_state *newstate)
+{
+ return ANIM_TIME;
+}
+
+float game_flash_length(game_state *oldstate, game_state *newstate)
+{
+ if (!oldstate->completed && newstate->completed)
+ return 2 * FLASH_FRAME;
+ else
+ return 0.0F;
+}