#define D 0x08
#define LOCKED 0x10
#define ACTIVE 0x20
+#define RLOOP (R << 6)
+#define ULOOP (U << 6)
+#define LLOOP (L << 6)
+#define DLOOP (D << 6)
+#define LOOP(dir) ((dir) << 6)
/* Rotations: Anticlockwise, Clockwise, Flip, general rotate */
#define A(x) ( (((x) & 0x07) << 1) | (((x) & 0x08) >> 3) )
COL_ENDPOINT,
COL_POWERED,
COL_BARRIER,
+ COL_LOOP,
NCOLOURS
};
sfree(perimeter);
}
+static int *compute_loops_inner(int w, int h, int wrapping,
+ const unsigned char *tiles,
+ const unsigned char *barriers);
+
static char *new_game_desc(const game_params *params, random_state *rs,
char **aux, int interactive)
{
* connectedness. However, that would take more effort, and
* it's easier to simply make sure every grid is _obviously_
* not solved.)
+ *
+ * We also require that our shuffle produces no loops in the
+ * initial grid state, because it's a bit rude to light up a 'HEY,
+ * YOU DID SOMETHING WRONG!' indicator when the user hasn't even
+ * had a chance to do _anything_ yet. This also is possible just
+ * by retrying the whole shuffle on failure, because it's clear
+ * that at least one non-solved shuffle with no loops must exist.
+ * (Proof: take the _solved_ state of the puzzle, and rotate one
+ * endpoint.)
*/
while (1) {
- int mismatches;
+ int mismatches, prev_loopsquares, this_loopsquares, i;
+ int *loops;
+ shuffle:
for (y = 0; y < h; y++) {
for (x = 0; x < w; x++) {
int orig = index(params, tiles, x, y);
}
}
+ /*
+ * Check for loops, and try to fix them by reshuffling just
+ * the squares involved.
+ */
+ prev_loopsquares = w*h+1;
+ while (1) {
+ loops = compute_loops_inner(w, h, params->wrapping, tiles, NULL);
+ this_loopsquares = 0;
+ for (i = 0; i < w*h; i++) {
+ if (loops[i]) {
+ int orig = tiles[i];
+ int rot = random_upto(rs, 4);
+ tiles[i] = ROT(orig, rot);
+ this_loopsquares++;
+ }
+ }
+ sfree(loops);
+ if (this_loopsquares > prev_loopsquares) {
+ /*
+ * We're increasing rather than reducing the number of
+ * loops. Give up and go back to the full shuffle.
+ */
+ goto shuffle;
+ }
+ if (this_loopsquares == 0)
+ break;
+ prev_loopsquares = this_loopsquares;
+ }
+
mismatches = 0;
/*
* I can't even be bothered to check for mismatches across
mismatches++;
}
- if (mismatches > 0)
- break;
+ if (mismatches == 0)
+ continue;
+
+ /* OK. */
+ break;
}
/*
return active;
}
+static int *compute_loops_inner(int w, int h, int wrapping,
+ const unsigned char *tiles,
+ const unsigned char *barriers)
+{
+ int *loops, *dsf;
+ int x, y;
+
+ /*
+ * The loop-detecting algorithm I use here is not quite the same
+ * one as I've used in Slant and Loopy. Those two puzzles use a
+ * very similar algorithm which works by finding connected
+ * components, not of the graph _vertices_, but of the pieces of
+ * space in between them. You divide the plane into maximal areas
+ * that can't be intersected by a grid edge (faces in Loopy,
+ * diamond shapes centred on a grid edge in Slant); you form a dsf
+ * over those areas, and unify any pair _not_ separated by a graph
+ * edge; then you've identified the connected components of the
+ * space, and can now immediately tell whether an edge is part of
+ * a loop or not by checking whether the pieces of space on either
+ * side of it are in the same component.
+ *
+ * In Net, this doesn't work reliably, because of the toroidal
+ * wrapping mode. A torus has non-trivial homology, which is to
+ * say, there can exist a closed loop on its surface which is not
+ * the boundary of any proper subset of the torus's area. For
+ * example, consider the 'loop' consisting of a straight vertical
+ * line going off the top of the grid and coming back on the
+ * bottom to join up with itself. This certainly wants to be
+ * marked as a loop, but it won't be detected as one by the above
+ * algorithm, because all the area of the grid is still connected
+ * via the left- and right-hand edges, so the two sides of the
+ * loop _are_ in the same equivalence class.
+ *
+ * The replacement algorithm I use here is also dsf-based, but the
+ * dsf is now over _sides of edges_. That is to say, on a general
+ * graph, you would have two dsf elements per edge of the graph.
+ * The unification rule is: for each vertex, iterate round the
+ * edges leaving that vertex in cyclic order, and dsf-unify the
+ * _near sides_ of each pair of adjacent edges. The effect of this
+ * is to trace round the outside edge of each connected component
+ * of the graph (this time of the actual graph, not the space
+ * between), so that the outline of each component becomes its own
+ * equivalence class. And now, just as before, an edge is part of
+ * a loop iff its two sides are not in the same component.
+ *
+ * This correctly detects even homologically nontrivial loops on a
+ * torus, because a torus is still _orientable_ - there's no way
+ * that a loop can join back up with itself with the two sides
+ * swapped. It would stop working, however, on a Mobius strip or a
+ * Klein bottle - so if I ever implement either of those modes for
+ * Net, I'll have to revisit this algorithm yet again and probably
+ * replace it with a completely general and much more fiddly
+ * approach such as Tarjan's bridge-finding algorithm (which is
+ * linear-time, but looks to me as if it's going to take more
+ * effort to get it working, especially when the graph is
+ * represented so unlike an ordinary graph).
+ *
+ * In Net, the algorithm as I describe it above has to be fiddled
+ * with just a little, to deal with the fact that there are two
+ * kinds of 'vertex' in the graph - one set at face-centres, and
+ * another set at edge-midpoints where two wires either do or do
+ * not join. Since those two vertex classes have very different
+ * representations in the Net data structure, separate code is
+ * needed for them.
+ */
+
+ /* Four potential edges per grid cell; one dsf node for each side
+ * of each one makes 8 per cell. */
+ dsf = snew_dsf(w*h*8);
+
+ /* Encode the dsf nodes. We imagine going round anticlockwise, so
+ * BEFORE(dir) indicates the clockwise side of an edge, e.g. the
+ * underside of R or the right-hand side of U. AFTER is the other
+ * side. */
+#define BEFORE(dir) ((dir)==R?7:(dir)==U?1:(dir)==L?3:5)
+#define AFTER(dir) ((dir)==R?0:(dir)==U?2:(dir)==L?4:6)
+
+#if 0
+ printf("--- begin\n");
+#endif
+ for (y = 0; y < h; y++) {
+ for (x = 0; x < w; x++) {
+ int tile = tiles[y*w+x];
+ int dir;
+ for (dir = 1; dir < 0x10; dir <<= 1) {
+ /*
+ * To unify dsf nodes around a face-centre vertex,
+ * it's easiest to do it _unconditionally_ - e.g. just
+ * unify the top side of R with the right side of U
+ * regardless of whether there's an edge in either
+ * place. Later we'll also unify the top and bottom
+ * sides of any nonexistent edge, which will e.g.
+ * complete a connection BEFORE(U) - AFTER(R) -
+ * BEFORE(R) - AFTER(D) in the absence of an R edge.
+ *
+ * This is a safe optimisation because these extra dsf
+ * nodes unified into our equivalence class can't get
+ * out of control - they are never unified with
+ * anything _else_ elsewhere in the algorithm.
+ */
+#if 0
+ printf("tile centre %d,%d: merge %d,%d\n",
+ x, y,
+ (y*w+x)*8+AFTER(C(dir)),
+ (y*w+x)*8+BEFORE(dir));
+#endif
+ dsf_merge(dsf,
+ (y*w+x)*8+AFTER(C(dir)),
+ (y*w+x)*8+BEFORE(dir));
+
+ if (tile & dir) {
+ int x1, y1;
+
+ OFFSETWH(x1, y1, x, y, dir, w, h);
+
+ /*
+ * If the tile does have an edge going out in this
+ * direction, we must check whether it joins up
+ * (without being blocked by a barrier) to an edge
+ * in the next cell along. If so, we unify around
+ * the edge-centre vertex by joining each side of
+ * this edge to the appropriate side of the next
+ * cell's edge; otherwise, the edge is a stub (the
+ * only one reaching the edge-centre vertex) and
+ * so we join its own two sides together.
+ */
+ if ((barriers && barriers[y*w+x] & dir) ||
+ !(tiles[y1*w+x1] & F(dir))) {
+#if 0
+ printf("tile edge stub %d,%d -> %c: merge %d,%d\n",
+ x, y, (dir==L?'L':dir==U?'U':dir==R?'R':'D'),
+ (y*w+x)*8+BEFORE(dir),
+ (y*w+x)*8+AFTER(dir));
+#endif
+ dsf_merge(dsf,
+ (y*w+x)*8+BEFORE(dir),
+ (y*w+x)*8+AFTER(dir));
+ } else {
+#if 0
+ printf("tile edge conn %d,%d -> %c: merge %d,%d\n",
+ x, y, (dir==L?'L':dir==U?'U':dir==R?'R':'D'),
+ (y*w+x)*8+BEFORE(dir),
+ (y*w+x)*8+AFTER(F(dir)));
+#endif
+ dsf_merge(dsf,
+ (y*w+x)*8+BEFORE(dir),
+ (y1*w+x1)*8+AFTER(F(dir)));
+#if 0
+ printf("tile edge conn %d,%d -> %c: merge %d,%d\n",
+ x, y, (dir==L?'L':dir==U?'U':dir==R?'R':'D'),
+ (y*w+x)*8+AFTER(dir),
+ (y*w+x)*8+BEFORE(F(dir)));
+#endif
+ dsf_merge(dsf,
+ (y*w+x)*8+AFTER(dir),
+ (y1*w+x1)*8+BEFORE(F(dir)));
+ }
+ } else {
+ /*
+ * As discussed above, if this edge doesn't even
+ * exist, we unify its two sides anyway to
+ * complete the unification of whatever edges do
+ * exist in this cell.
+ */
+#if 0
+ printf("tile edge missing %d,%d -> %c: merge %d,%d\n",
+ x, y, (dir==L?'L':dir==U?'U':dir==R?'R':'D'),
+ (y*w+x)*8+BEFORE(dir),
+ (y*w+x)*8+AFTER(dir));
+#endif
+ dsf_merge(dsf,
+ (y*w+x)*8+BEFORE(dir),
+ (y*w+x)*8+AFTER(dir));
+ }
+ }
+ }
+ }
+
+#if 0
+ printf("--- end\n");
+#endif
+ loops = snewn(w*h, int);
+
+ /*
+ * Now we've done the loop detection and can read off the output
+ * flags trivially: any piece of connection whose two sides are
+ * not in the same dsf class is part of a loop.
+ */
+ for (y = 0; y < h; y++) {
+ for (x = 0; x < w; x++) {
+ int dir;
+ int tile = tiles[y*w+x];
+ int flags = 0;
+ for (dir = 1; dir < 0x10; dir <<= 1) {
+ if ((tile & dir) &&
+ (dsf_canonify(dsf, (y*w+x)*8+BEFORE(dir)) !=
+ dsf_canonify(dsf, (y*w+x)*8+AFTER(dir)))) {
+ flags |= LOOP(dir);
+ }
+ }
+ loops[y*w+x] = flags;
+ }
+ }
+
+ sfree(dsf);
+ return loops;
+}
+
+static int *compute_loops(const game_state *state)
+{
+ return compute_loops_inner(state->width, state->height, state->wrapping,
+ state->tiles, state->barriers);
+}
+
struct game_ui {
int org_x, org_y; /* origin */
int cx, cy; /* source tile (game coordinates) */
int width, height;
int org_x, org_y;
int tilesize;
- unsigned char *visible;
+ int *visible;
};
/* ----------------------------------------------------------------------
static game_drawstate *game_new_drawstate(drawing *dr, const game_state *state)
{
game_drawstate *ds = snew(game_drawstate);
+ int i;
ds->started = FALSE;
ds->width = state->width;
ds->height = state->height;
ds->org_x = ds->org_y = -1;
- ds->visible = snewn(state->width * state->height, unsigned char);
+ ds->visible = snewn(state->width * state->height, int);
ds->tilesize = 0; /* undecided yet */
- memset(ds->visible, 0xFF, state->width * state->height);
+ for (i = 0; i < state->width * state->height; i++)
+ ds->visible[i] = -1;
return ds;
}
ret[COL_BARRIER * 3 + 1] = 0.0F;
ret[COL_BARRIER * 3 + 2] = 0.0F;
+ /*
+ * Highlighted loops are red as well.
+ */
+ ret[COL_LOOP * 3 + 0] = 1.0F;
+ ret[COL_LOOP * 3 + 1] = 0.0F;
+ ret[COL_LOOP * 3 + 2] = 0.0F;
+
/*
* Unpowered endpoints are blue.
*/
ey = (TILE_SIZE - TILE_BORDER - 1.0F) / 2.0F * Y(dir);
MATMUL(tx, ty, matrix, ex, ey);
draw_line(dr, bx+(int)cx, by+(int)cy,
- bx+(int)(cx+tx), by+(int)(cy+ty), col);
+ bx+(int)(cx+tx), by+(int)(cy+ty),
+ (tile & LOOP(dir)) ? COL_LOOP : col);
}
}
+ /* If we've drawn any loop-highlighted arms, make sure the centre
+ * point is loop-coloured rather than a later arm overwriting it. */
+ if (tile & (RLOOP | ULOOP | LLOOP | DLOOP))
+ draw_rect(dr, bx+(int)cx, by+(int)cy, 1, 1, COL_LOOP);
/*
* Draw the box in the middle. We do this in blue if the tile
*/
draw_rect_coords(dr, px-vx, py-vy, px+lx+vx, py+ly+vy, COL_WIRE);
draw_rect_coords(dr, px, py, px+lx, py+ly,
- (tile & ACTIVE) ? COL_POWERED : COL_WIRE);
+ ((tile & LOOP(dir)) ? COL_LOOP :
+ (tile & ACTIVE) ? COL_POWERED :
+ COL_WIRE));
} else {
/*
* The other tile extends into our border, but isn't
{
int x, y, tx, ty, frame, last_rotate_dir, moved_origin = FALSE;
unsigned char *active;
+ int *loops;
float angle = 0.0;
/*
* Draw any tile which differs from the way it was last drawn.
*/
active = compute_active(state, ui->cx, ui->cy);
+ loops = compute_loops(state);
for (x = 0; x < ds->width; x++)
for (y = 0; y < ds->height; y++) {
- unsigned char c = tile(state, GX(x), GY(y)) |
- index(state, active, GX(x), GY(y));
+ int c = tile(state, GX(x), GY(y)) |
+ index(state, active, GX(x), GY(y)) |
+ index(state, loops, GX(x), GY(y));
int is_src = GX(x) == ui->cx && GY(y) == ui->cy;
int is_anim = GX(x) == tx && GY(y) == ty;
int is_cursor = ui->cur_visible &&
if (moved_origin ||
index(state, ds->visible, x, y) != c ||
- index(state, ds->visible, x, y) == 0xFF ||
+ index(state, ds->visible, x, y) == -1 ||
is_src || is_anim || is_cursor) {
draw_tile(dr, state, ds, x, y, c,
is_src, (is_anim ? angle : 0.0F), is_cursor);
if (is_src || is_anim || is_cursor)
- index(state, ds->visible, x, y) = 0xFF;
+ index(state, ds->visible, x, y) = -1;
else
index(state, ds->visible, x, y) = c;
}
}
sfree(active);
+ sfree(loops);
}
static float game_anim_length(const game_state *oldstate,
~ian / sgt-puzzles.git / blobdiff