X-Git-Url: https://git.distorted.org.uk/~mdw/sgt/puzzles/blobdiff_plain/937a9efffe3be5ecb6c6b9fb6596644d05aed3d9..055b9cd27af52f30534c77af067a98e5ca9c4461:/pegs.c

diff --git a/pegs.c b/pegs.c
index 2a03902..d1addd1 100644
--- a/pegs.c
+++ b/pegs.c
@@ -530,9 +530,7 @@ static char *new_game_desc(game_params *params, random_state *rs,
 		  case TYPE_OCTAGON:
 		    cx = abs(x - w/2);
 		    cy = abs(y - h/2);
-		    if (cx == 0 && cy == 0)
-			v = GRID_HOLE;
-		    else if (cx + cy > 1 + max(w,h)/2)
+		    if (cx + cy > 1 + max(w,h)/2)
 			v = GRID_OBST;
 		    else
 			v = GRID_PEG;
@@ -540,6 +538,107 @@ static char *new_game_desc(game_params *params, random_state *rs,
 		}
 		grid[y*w+x] = v;
 	    }
+
+	if (params->type == TYPE_OCTAGON) {
+	    /*
+	     * The octagonal (European) solitaire layout is
+	     * actually _insoluble_ with the starting hole at the
+	     * centre. Here's a proof:
+	     * 
+	     * Colour the squares of the board diagonally in
+	     * stripes of three different colours, which I'll call
+	     * A, B and C. So the board looks like this:
+	     * 
+	     *     A B C
+	     *   A B C A B
+	     * A B C A B C A
+	     * B C A B C A B
+	     * C A B C A B C
+	     *   B C A B C
+	     *     A B C
+	     * 
+	     * Suppose we keep running track of the number of pegs
+	     * occuping each colour of square. This colouring has
+	     * the property that any valid move whatsoever changes
+	     * all three of those counts by one (two of them go
+	     * down and one goes up), which means that the _parity_
+	     * of every count flips on every move.
+	     * 
+	     * If the centre square starts off unoccupied, then
+	     * there are twelve pegs on each colour and all three
+	     * counts start off even; therefore, after 35 moves all
+	     * three counts would have to be odd, which isn't
+	     * possible if there's only one peg left. []
+	     * 
+	     * This proof works just as well if the starting hole
+	     * is _any_ of the thirteen positions labelled B. Also,
+	     * we can stripe the board in the opposite direction
+	     * and rule out any square labelled B in that colouring
+	     * as well. This leaves:
+	     * 
+	     *     Y n Y
+	     *   n n Y n n
+	     * Y n n Y n n Y
+	     * n Y Y n Y Y n
+	     * Y n n Y n n Y
+	     *   n n Y n n
+	     *     Y n Y
+	     * 
+	     * where the ns are squares we've proved insoluble, and
+	     * the Ys are the ones remaining.
+	     * 
+	     * That doesn't prove all those starting positions to
+	     * be soluble, of course; they're merely the ones we
+	     * _haven't_ proved to be impossible. Nevertheless, it
+	     * turns out that they are all soluble, so when the
+	     * user requests an Octagon board the simplest thing is
+	     * to pick one of these at random.
+	     * 
+	     * Rather than picking equiprobably from those twelve
+	     * positions, we'll pick equiprobably from the three
+	     * equivalence classes
+	     */
+	    switch (random_upto(rs, 3)) {
+	      case 0:
+		/* Remove a random corner piece. */
+		{
+		    int dx, dy;
+
+		    dx = random_upto(rs, 2) * 2 - 1;   /* +1 or -1 */
+		    dy = random_upto(rs, 2) * 2 - 1;   /* +1 or -1 */
+		    if (random_upto(rs, 2))
+			dy *= 3;
+		    else
+			dx *= 3;
+		    grid[(3+dy)*w+(3+dx)] = GRID_HOLE;
+		}
+		break;
+	      case 1:
+		/* Remove a random piece two from the centre. */
+		{
+		    int dx, dy;
+		    dx = 2 * (random_upto(rs, 2) * 2 - 1);
+		    if (random_upto(rs, 2))
+			dy = 0;
+		    else
+			dy = dx, dx = 0;
+		    grid[(3+dy)*w+(3+dx)] = GRID_HOLE;
+		}
+		break;
+	      default /* case 2 */:
+		/* Remove a random piece one from the centre. */
+		{
+		    int dx, dy;
+		    dx = random_upto(rs, 2) * 2 - 1;
+		    if (random_upto(rs, 2))
+			dy = 0;
+		    else
+			dy = dx, dx = 0;
+		    grid[(3+dy)*w+(3+dx)] = GRID_HOLE;
+		}
+		break;
+	    }
+	}
     }
 
     /*
@@ -569,7 +668,7 @@ static char *validate_desc(game_params *params, char *desc)
     return NULL;
 }
 
-static game_state *new_game(midend_data *me, game_params *params, char *desc)
+static game_state *new_game(midend *me, game_params *params, char *desc)
 {
     int w = params->w, h = params->h;
     game_state *state = snew(game_state);
@@ -770,7 +869,7 @@ static game_state *execute_move(game_state *state, char *move)
     int sx, sy, tx, ty;
     game_state *ret;
 
-    if (sscanf(move, "%d,%d-%d,%d", &sx, &sy, &tx, &ty)) {
+    if (sscanf(move, "%d,%d-%d,%d", &sx, &sy, &tx, &ty) == 4) {
 	int mx, my, dx, dy;
 
 	if (sx < 0 || sx >= w || sy < 0 || sy >= h)
@@ -830,19 +929,18 @@ static void game_compute_size(game_params *params, int tilesize,
     *y = TILESIZE * params->h + 2 * BORDER;
 }
 
-static void game_set_size(game_drawstate *ds, game_params *params,
-			  int tilesize)
+static void game_set_size(drawing *dr, game_drawstate *ds,
+			  game_params *params, int tilesize)
 {
     ds->tilesize = tilesize;
 
     assert(TILESIZE > 0);
 
-    if (ds->drag_background)
-	blitter_free(ds->drag_background);
-    ds->drag_background = blitter_new(TILESIZE, TILESIZE);
+    assert(!ds->drag_background);      /* set_size is never called twice */
+    ds->drag_background = blitter_new(dr, TILESIZE, TILESIZE);
 }
 
-static float *game_colours(frontend *fe, game_state *state, int *ncolours)
+static float *game_colours(frontend *fe, int *ncolours)
 {
     float *ret = snewn(3 * NCOLOURS, float);
 
@@ -856,7 +954,7 @@ static float *game_colours(frontend *fe, game_state *state, int *ncolours)
     return ret;
 }
 
-static game_drawstate *game_new_drawstate(game_state *state)
+static game_drawstate *game_new_drawstate(drawing *dr, game_state *state)
 {
     int w = state->w, h = state->h;
     struct game_drawstate *ds = snew(struct game_drawstate);
@@ -879,33 +977,33 @@ static game_drawstate *game_new_drawstate(game_state *state)
     return ds;
 }
 
-static void game_free_drawstate(game_drawstate *ds)
+static void game_free_drawstate(drawing *dr, game_drawstate *ds)
 {
     if (ds->drag_background)
-	blitter_free(ds->drag_background);
+	blitter_free(dr, ds->drag_background);
     sfree(ds->grid);
     sfree(ds);
 }
 
-static void draw_tile(frontend *fe, game_drawstate *ds,
+static void draw_tile(drawing *dr, game_drawstate *ds,
 		      int x, int y, int v, int bgcolour)
 {
     if (bgcolour >= 0) {
-	draw_rect(fe, x, y, TILESIZE, TILESIZE, bgcolour);
+	draw_rect(dr, x, y, TILESIZE, TILESIZE, bgcolour);
     }
 
     if (v == GRID_HOLE) {
-	draw_circle(fe, x+TILESIZE/2, y+TILESIZE/2, TILESIZE/4,
+	draw_circle(dr, x+TILESIZE/2, y+TILESIZE/2, TILESIZE/4,
 		    COL_LOWLIGHT, COL_LOWLIGHT);
     } else if (v == GRID_PEG) {
-	draw_circle(fe, x+TILESIZE/2, y+TILESIZE/2, TILESIZE/3,
+	draw_circle(dr, x+TILESIZE/2, y+TILESIZE/2, TILESIZE/3,
 		    COL_PEG, COL_PEG);
     }
 
-    draw_update(fe, x, y, TILESIZE, TILESIZE);
+    draw_update(dr, x, y, TILESIZE, TILESIZE);
 }
 
-static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
+static void game_redraw(drawing *dr, game_drawstate *ds, game_state *oldstate,
 			game_state *state, int dir, game_ui *ui,
 			float animtime, float flashtime)
 {
@@ -924,13 +1022,13 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
      */
     if (ds->dragging) {
 	assert(ds->drag_background);
-        blitter_load(fe, ds->drag_background, ds->dragx, ds->dragy);
-        draw_update(fe, ds->dragx, ds->dragy, TILESIZE, TILESIZE);
+        blitter_load(dr, ds->drag_background, ds->dragx, ds->dragy);
+        draw_update(dr, ds->dragx, ds->dragy, TILESIZE, TILESIZE);
 	ds->dragging = FALSE;
     }
 
     if (!ds->started) {
-	draw_rect(fe, 0, 0,
+	draw_rect(dr, 0, 0,
 		  TILESIZE * state->w + 2 * BORDER,
 		  TILESIZE * state->h + 2 * BORDER, COL_BACKGROUND);
 
@@ -951,10 +1049,10 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 		    coords[3] = COORD(y+1) + HIGHLIGHT_WIDTH - 1;
 		    coords[4] = COORD(x) - HIGHLIGHT_WIDTH;
 		    coords[5] = COORD(y) - HIGHLIGHT_WIDTH;
-		    draw_polygon(fe, coords, 3, COL_HIGHLIGHT, COL_HIGHLIGHT);
+		    draw_polygon(dr, coords, 3, COL_HIGHLIGHT, COL_HIGHLIGHT);
 		    coords[4] = COORD(x+1) + HIGHLIGHT_WIDTH - 1;
 		    coords[5] = COORD(y+1) + HIGHLIGHT_WIDTH - 1;
-		    draw_polygon(fe, coords, 3, COL_LOWLIGHT, COL_LOWLIGHT);
+		    draw_polygon(dr, coords, 3, COL_LOWLIGHT, COL_LOWLIGHT);
 		}
 	for (y = 0; y < h; y++)
 	    for (x = 0; x < w; x++)
@@ -963,11 +1061,11 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 		     * Second pass: draw everything but the two
 		     * diagonal corners.
 		     */
-		    draw_rect(fe, COORD(x) - HIGHLIGHT_WIDTH,
+		    draw_rect(dr, COORD(x) - HIGHLIGHT_WIDTH,
 			      COORD(y) - HIGHLIGHT_WIDTH,
 			      TILESIZE + HIGHLIGHT_WIDTH,
 			      TILESIZE + HIGHLIGHT_WIDTH, COL_HIGHLIGHT);
-		    draw_rect(fe, COORD(x),
+		    draw_rect(dr, COORD(x),
 			      COORD(y),
 			      TILESIZE + HIGHLIGHT_WIDTH,
 			      TILESIZE + HIGHLIGHT_WIDTH, COL_LOWLIGHT);
@@ -995,7 +1093,7 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 			    coords[5] = coords[3] - HIGHLIGHT_WIDTH * (dx-sn*dy);
 			    coords[6] = coords[0] + HIGHLIGHT_WIDTH * (dy+sn*dx);
 			    coords[7] = coords[1] + HIGHLIGHT_WIDTH * (dx+sn*dy);
-			    draw_polygon(fe, coords, 4, c, c);
+			    draw_polygon(dr, coords, 4, c, c);
 			}
 		    }
 		}
@@ -1006,7 +1104,7 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 		     * Second pass: draw everything but the two
 		     * diagonal corners.
 		     */
-		    draw_rect(fe, COORD(x),
+		    draw_rect(dr, COORD(x),
 			      COORD(y),
 			      TILESIZE,
 			      TILESIZE, COL_BACKGROUND);
@@ -1014,7 +1112,7 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 
 	ds->started = TRUE;
 
-	draw_update(fe, 0, 0,
+	draw_update(dr, 0, 0,
 		    TILESIZE * state->w + 2 * BORDER,
 		    TILESIZE * state->h + 2 * BORDER);
     }
@@ -1037,7 +1135,7 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 	    if (v != GRID_OBST &&
                 (bgcolour != ds->bgcolour || /* always redraw when flashing */
                  v != ds->grid[y*w+x])) {
-		draw_tile(fe, ds, COORD(x), COORD(y), v, bgcolour);
+		draw_tile(dr, ds, COORD(x), COORD(y), v, bgcolour);
 	    }
 	}
 
@@ -1048,8 +1146,8 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 	ds->dragging = TRUE;
 	ds->dragx = ui->dx - TILESIZE/2;
 	ds->dragy = ui->dy - TILESIZE/2;
-	blitter_save(fe, ds->drag_background, ds->dragx, ds->dragy);
-	draw_tile(fe, ds, ds->dragx, ds->dragy, GRID_PEG, -1);
+	blitter_save(dr, ds->drag_background, ds->dragx, ds->dragy);
+	draw_tile(dr, ds, ds->dragx, ds->dragy, GRID_PEG, -1);
     }
 
     ds->bgcolour = bgcolour;
@@ -1070,14 +1168,17 @@ static float game_flash_length(game_state *oldstate, game_state *newstate,
         return 0.0F;
 }
 
-static int game_wants_statusbar(void)
+static int game_timing_state(game_state *state, game_ui *ui)
 {
-    return FALSE;
+    return TRUE;
 }
 
-static int game_timing_state(game_state *state)
+static void game_print_size(game_params *params, float *x, float *y)
+{
+}
+
+static void game_print(drawing *dr, game_state *state, int tilesize)
 {
-    return TRUE;
 }
 
 #ifdef COMBINED
@@ -1085,7 +1186,7 @@ static int game_timing_state(game_state *state)
 #endif
 
 const struct game thegame = {
-    "Pegs", "games.pegs",
+    "Pegs", "games.pegs", "pegs",
     default_params,
     game_fetch_preset,
     decode_params,
@@ -1115,7 +1216,8 @@ const struct game thegame = {
     game_redraw,
     game_anim_length,
     game_flash_length,
-    game_wants_statusbar,
+    FALSE, FALSE, game_print_size, game_print,
+    FALSE,			       /* wants_statusbar */
     FALSE, game_timing_state,
-    0,				       /* mouse_priorities */
+    0,				       /* flags */
 };