ref: 704890390d7754861f5a097c6abfe0e1ef4f8d41
parent: 88accd3ea54dc381c7ff6cf914ead23ad07c8774
author: Simon Tatham <anakin@pobox.com>
date: Fri Apr 6 08:34:34 EDT 2012
Error checking in Pattern, which was until now the only remaining game that _ought_ to have it but did not. I've tried to implement it before and found that the most obvious approach was so effective as to constitute a spoiler, so this is a deliberately weakened approach which in a bit of play-testing seems to be a more sensible balance. It won't necessarily tell you at the very instant you put a foot wrong, but it will at least ensure that (my usual minimum standard) once you've filled in the whole grid you will either have seen a victory flash, or an error indicator showing you why not. [originally from svn r9445]
--- a/pattern.c
+++ b/pattern.c
@@ -19,6 +19,7 @@
COL_UNKNOWN,
COL_GRID,
COL_CURSOR,
+ COL_ERROR,
NCOLOURS
};
@@ -828,7 +829,7 @@
int started;
int w, h;
int tilesize;
- unsigned char *visible;
+ unsigned char *visible, *numcolours;
int cur_x, cur_y;
};
@@ -1038,6 +1039,165 @@
}
/* ----------------------------------------------------------------------
+ * Error-checking during gameplay.
+ */
+
+/*
+ * The difficulty in error-checking Pattern is to make the error check
+ * _weak_ enough. The most obvious way would be to check each row and
+ * column by calling (a modified form of) do_row() to recursively
+ * analyse the row contents against the clue set and see if the
+ * GRID_UNKNOWNs could be filled in in any way that would end up
+ * correct. However, this turns out to be such a strong error check as
+ * to constitute a spoiler in many situations: you make a typo while
+ * trying to fill in one row, and not only does the row light up to
+ * indicate an error, but several columns crossed by the move also
+ * light up and draw your attention to deductions you hadn't even
+ * noticed you could make.
+ *
+ * So instead I restrict error-checking to 'complete runs' within a
+ * row, by which I mean contiguous sequences of GRID_FULL bounded at
+ * both ends by either GRID_EMPTY or the ends of the row. We identify
+ * all the complete runs in a row, and verify that _those_ are
+ * consistent with the row's clue list. Sequences of complete runs
+ * separated by solid GRID_EMPTY are required to match contiguous
+ * sequences in the clue list, whereas if there's at least one
+ * GRID_UNKNOWN between any two complete runs then those two need not
+ * be contiguous in the clue list.
+ *
+ * To simplify the edge cases, I pretend that the clue list for the
+ * row is extended with a 0 at each end, and I also pretend that the
+ * grid data for the row is extended with a GRID_EMPTY and a
+ * zero-length run at each end. This permits the contiguity checker to
+ * handle the fiddly end effects (e.g. if the first contiguous
+ * sequence of complete runs in the grid matches _something_ in the
+ * clue list but not at the beginning, this is allowable iff there's a
+ * GRID_UNKNOWN before the first one) with minimal faff, since the end
+ * effects just drop out as special cases of the normal inter-run
+ * handling (in this code the above case is not 'at the end of the
+ * clue list' at all, but between the implicit initial zero run and
+ * the first nonzero one).
+ *
+ * We must also be a little careful about how we search for a
+ * contiguous sequence of runs. In the clue list (1 1 2 1 2 3),
+ * suppose we see a GRID_UNKNOWN and then a length-1 run. We search
+ * for 1 in the clue list and find it at the very beginning. But now
+ * suppose we find a length-2 run with no GRID_UNKNOWN before it. We
+ * can't naively look at the next clue from the 1 we found, because
+ * that'll be the second 1 and won't match. Instead, we must backtrack
+ * by observing that the 2 we've just found must be contiguous with
+ * the 1 we've already seen, so we search for the sequence (1 2) and
+ * find it starting at the second 1. Now if we see a 3, we must
+ * rethink again and search for (1 2 3).
+ */
+
+struct errcheck_state {+ /*
+ * rowdata and rowlen point at the clue data for this row in the
+ * game state.
+ */
+ int *rowdata;
+ int rowlen;
+ /*
+ * rowpos indicates the lowest position where it would be valid to
+ * see our next run length. It might be equal to rowlen,
+ * indicating that the next run would have to be the terminating 0.
+ */
+ int rowpos;
+ /*
+ * ncontig indicates how many runs we've seen in a contiguous
+ * block. This is taken into account when searching for the next
+ * run we find, unless ncontig is zeroed out first by encountering
+ * a GRID_UNKNOWN.
+ */
+ int ncontig;
+};
+
+static int errcheck_found_run(struct errcheck_state *es, int r)
+{+/* Macro to handle the pretence that rowdata has a 0 at each end */
+#define ROWDATA(k) ((k)<0 || (k)>=es->rowlen ? 0 : es->rowdata[(k)])
+
+ /*
+ * See if we can find this new run length at a position where it
+ * also matches the last 'ncontig' runs we've seen.
+ */
+ int i, newpos;
+ for (newpos = es->rowpos; newpos <= es->rowlen; newpos++) {+
+ if (ROWDATA(newpos) != r)
+ goto notfound;
+
+ for (i = 1; i <= es->ncontig; i++)
+ if (ROWDATA(newpos - i) != ROWDATA(es->rowpos - i))
+ goto notfound;
+
+ es->rowpos = newpos+1;
+ es->ncontig++;
+ return TRUE;
+
+ notfound:;
+ }
+
+ return FALSE;
+
+#undef ROWDATA
+}
+
+static int check_errors(game_state *state, int i)
+{+ int start, step, end, j;
+ int val, runlen;
+ struct errcheck_state aes, *es = &aes;
+
+ es->rowlen = state->rowlen[i];
+ es->rowdata = state->rowdata + state->rowsize * i;
+ /* Pretend that we've already encountered the initial zero run */
+ es->ncontig = 1;
+ es->rowpos = 0;
+
+ if (i < state->w) {+ start = i;
+ step = state->w;
+ end = start + step * state->h;
+ } else {+ start = (i - state->w) * state->w;
+ step = 1;
+ end = start + step * state->w;
+ }
+
+ runlen = -1;
+ for (j = start - step; j <= end; j += step) {+ if (j < start || j == end)
+ val = GRID_EMPTY;
+ else
+ val = state->grid[j];
+
+ if (val == GRID_UNKNOWN) {+ runlen = -1;
+ es->ncontig = 0;
+ } else if (val == GRID_FULL) {+ if (runlen >= 0)
+ runlen++;
+ } else if (val == GRID_EMPTY) {+ if (runlen > 0) {+ if (!errcheck_found_run(es, runlen))
+ return TRUE; /* error! */
+ }
+ runlen = 0;
+ }
+ }
+
+ /* Signal end-of-row by sending errcheck_found_run the terminating
+ * zero run, which will be marked as contiguous with the previous
+ * run if and only if there hasn't been a GRID_UNKNOWN before. */
+ if (!errcheck_found_run(es, 0))
+ return TRUE; /* error at the last minute! */
+
+ return FALSE; /* no error */
+}
+
+/* ----------------------------------------------------------------------
* Drawing routines.
*/
@@ -1075,6 +1235,9 @@
ret[COL_CURSOR * 3 + 0] = 1.0F;
ret[COL_CURSOR * 3 + 1] = 0.25F;
ret[COL_CURSOR * 3 + 2] = 0.25F;
+ ret[COL_ERROR * 3 + 0] = 1.0F;
+ ret[COL_ERROR * 3 + 1] = 0.0F;
+ ret[COL_ERROR * 3 + 2] = 0.0F;
*ncolours = NCOLOURS;
return ret;
@@ -1090,6 +1253,8 @@
ds->visible = snewn(ds->w * ds->h, unsigned char);
ds->tilesize = 0; /* not decided yet */
memset(ds->visible, 255, ds->w * ds->h);
+ ds->numcolours = snewn(ds->w + ds->h, unsigned char);
+ memset(ds->numcolours, 255, ds->w + ds->h);
ds->cur_x = ds->cur_y = 0;
return ds;
@@ -1131,46 +1296,62 @@
TILE_SIZE, TILE_SIZE);
}
+/*
+ * Draw the numbers for a single row or column.
+ */
static void draw_numbers(drawing *dr, game_drawstate *ds, game_state *state,
- int colour)
+ int i, int erase, int colour)
{- int i, j;
+ int rowlen = state->rowlen[i];
+ int *rowdata = state->rowdata + state->rowsize * i;
+ int nfit;
+ int j;
+ if (erase) {+ if (i < state->w) {+ draw_rect(dr, TOCOORD(state->w, i), 0,
+ TILE_SIZE, BORDER + TLBORDER(state->w) * TILE_SIZE,
+ COL_BACKGROUND);
+ } else {+ draw_rect(dr, 0, TOCOORD(state->h, i - state->w),
+ BORDER + TLBORDER(state->h) * TILE_SIZE, TILE_SIZE,
+ COL_BACKGROUND);
+ }
+ }
+
/*
- * Draw the numbers.
+ * Normally I space the numbers out by the same distance as the
+ * tile size. However, if there are more numbers than available
+ * spaces, I have to squash them up a bit.
*/
- for (i = 0; i < state->w + state->h; i++) {- int rowlen = state->rowlen[i];
- int *rowdata = state->rowdata + state->rowsize * i;
- int nfit;
+ nfit = max(rowlen, TLBORDER(state->h))-1;
+ assert(nfit > 0);
- /*
- * Normally I space the numbers out by the same
- * distance as the tile size. However, if there are
- * more numbers than available spaces, I have to squash
- * them up a bit.
- */
- nfit = max(rowlen, TLBORDER(state->h))-1;
- assert(nfit > 0);
+ for (j = 0; j < rowlen; j++) {+ int x, y;
+ char str[80];
- for (j = 0; j < rowlen; j++) {- int x, y;
- char str[80];
+ if (i < state->w) {+ x = TOCOORD(state->w, i);
+ y = BORDER + TILE_SIZE * (TLBORDER(state->h)-1);
+ y -= ((rowlen-j-1)*TILE_SIZE) * (TLBORDER(state->h)-1) / nfit;
+ } else {+ y = TOCOORD(state->h, i - state->w);
+ x = BORDER + TILE_SIZE * (TLBORDER(state->w)-1);
+ x -= ((rowlen-j-1)*TILE_SIZE) * (TLBORDER(state->h)-1) / nfit;
+ }
- if (i < state->w) {- x = TOCOORD(state->w, i);
- y = BORDER + TILE_SIZE * (TLBORDER(state->h)-1);
- y -= ((rowlen-j-1)*TILE_SIZE) * (TLBORDER(state->h)-1) / nfit;
- } else {- y = TOCOORD(state->h, i - state->w);
- x = BORDER + TILE_SIZE * (TLBORDER(state->w)-1);
- x -= ((rowlen-j-1)*TILE_SIZE) * (TLBORDER(state->h)-1) / nfit;
- }
+ sprintf(str, "%d", rowdata[j]);
+ draw_text(dr, x+TILE_SIZE/2, y+TILE_SIZE/2, FONT_VARIABLE,
+ TILE_SIZE/2, ALIGN_HCENTRE | ALIGN_VCENTRE, colour, str);
+ }
- sprintf(str, "%d", rowdata[j]);
- draw_text(dr, x+TILE_SIZE/2, y+TILE_SIZE/2, FONT_VARIABLE,
- TILE_SIZE/2, ALIGN_HCENTRE | ALIGN_VCENTRE, colour, str);
- }
+ if (i < state->w) {+ draw_update(dr, TOCOORD(state->w, i), 0,
+ TILE_SIZE, BORDER + TLBORDER(state->w) * TILE_SIZE);
+ } else {+ draw_update(dr, 0, TOCOORD(state->h, i - state->w),
+ BORDER + TLBORDER(state->h) * TILE_SIZE, TILE_SIZE);
}
}
@@ -1191,11 +1372,6 @@
*/
draw_rect(dr, 0, 0, SIZE(ds->w), SIZE(ds->h), COL_BACKGROUND);
- /*
- * Draw the numbers.
- */
- draw_numbers(dr, ds, state, COL_TEXT);
-
/*
* Draw the grid outline.
*/
@@ -1265,6 +1441,18 @@
}
}
ds->cur_x = cx; ds->cur_y = cy;
+
+ /*
+ * Redraw any numbers which have changed their colour due to error
+ * indication.
+ */
+ for (i = 0; i < state->w + state->h; i++) {+ int colour = check_errors(state, i) ? COL_ERROR : COL_TEXT;
+ if (ds->numcolours[i] != colour) {+ draw_numbers(dr, ds, state, i, TRUE, colour);
+ ds->numcolours[i] = colour;
+ }
+ }
}
static float game_anim_length(game_state *oldstate,
@@ -1308,7 +1496,7 @@
{int w = state->w, h = state->h;
int ink = print_mono_colour(dr, 0);
- int x, y;
+ int x, y, i;
/* Ick: fake up `ds->tilesize' for macro expansion purposes */
game_drawstate ads, *ds = &ads;
@@ -1338,7 +1526,8 @@
/*
* Clues.
*/
- draw_numbers(dr, ds, state, ink);
+ for (i = 0; i < state->w + state->h; i++)
+ draw_numbers(dr, ds, state, i, FALSE, ink);
/*
* Solution.