/* grids.c */
-extern bool los(POSITION y1, POSITION x1, POSITION y2, POSITION x2);
extern void update_local_illumination(POSITION y, POSITION x);
extern bool player_can_see_bold(POSITION y, POSITION x);
extern bool cave_valid_bold(POSITION y, POSITION x);
return (n);
}
+/*!
+ * @brief LOS(Line Of Sight / 視線が通っているか)の判定を行う。
+ * @param y1 始点のy座標
+ * @param x1 始点のx座標
+ * @param y2 終点のy座標
+ * @param x2 終点のx座標
+ * @return LOSが通っているならTRUEを返す。
+ * @details
+ * A simple, fast, integer-based line-of-sight algorithm. By Joseph Hall,\n
+ * 4116 Brewster Drive, Raleigh NC 27606. Email to jnh@ecemwl.ncsu.edu.\n
+ *\n
+ * Returns TRUE if a line of sight can be traced from (x1,y1) to (x2,y2).\n
+ *\n
+ * The LOS begins at the center of the tile (x1,y1) and ends at the center of\n
+ * the tile (x2,y2). If los() is to return TRUE, all of the tiles this line\n
+ * passes through must be floor tiles, except for (x1,y1) and (x2,y2).\n
+ *\n
+ * We assume that the "mathematical corner" of a non-floor tile does not\n
+ * block line of sight.\n
+ *\n
+ * Because this function uses (short) ints for all calculations, overflow may\n
+ * occur if dx and dy exceed 90.\n
+ *\n
+ * Once all the degenerate cases are eliminated, the values "qx", "qy", and\n
+ * "m" are multiplied by a scale factor "f1 = abs(dx * dy * 2)", so that\n
+ * we can use integer arithmetic.\n
+ *\n
+ * We travel from start to finish along the longer axis, starting at the border\n
+ * between the first and second tiles, where the y offset = .5 * slope, taking\n
+ * into account the scale factor. See below.\n
+ *\n
+ * Also note that this function and the "move towards target" code do NOT\n
+ * share the same properties. Thus, you can see someone, target them, and\n
+ * then fire a bolt at them, but the bolt may hit a wall, not them. However\n,
+ * by clever choice of target locations, you can sometimes throw a "curve".\n
+ *\n
+ * Note that "line of sight" is not "reflexive" in all cases.\n
+ *\n
+ * Use the "projectable()" routine to test "spell/missile line of sight".\n
+ *\n
+ * Use the "update_view()" function to determine player line-of-sight.\n
+ */
+bool los(POSITION y1, POSITION x1, POSITION y2, POSITION x2)
+{
+ /* Delta */
+ POSITION dx, dy;
+
+ /* Absolute */
+ POSITION ax, ay;
+
+ /* Signs */
+ POSITION sx, sy;
+
+ /* Fractions */
+ POSITION qx, qy;
+
+ /* Scanners */
+ POSITION tx, ty;
+
+ /* Scale factors */
+ POSITION f1, f2;
+
+ /* Slope, or 1/Slope, of LOS */
+ POSITION m;
+
+
+ /* Extract the offset */
+ dy = y2 - y1;
+ dx = x2 - x1;
+
+ /* Extract the absolute offset */
+ ay = ABS(dy);
+ ax = ABS(dx);
+
+
+ /* Handle adjacent (or identical) grids */
+ if ((ax < 2) && (ay < 2)) return TRUE;
+
+
+ /* Paranoia -- require "safe" origin */
+ /* if (!in_bounds(y1, x1)) return FALSE; */
+ /* if (!in_bounds(y2, x2)) return FALSE; */
+
+
+ /* Directly South/North */
+ if (!dx)
+ {
+ /* South -- check for walls */
+ if (dy > 0)
+ {
+ for (ty = y1 + 1; ty < y2; ty++)
+ {
+ if (!cave_los_bold(ty, x1)) return FALSE;
+ }
+ }
+
+ /* North -- check for walls */
+ else
+ {
+ for (ty = y1 - 1; ty > y2; ty--)
+ {
+ if (!cave_los_bold(ty, x1)) return FALSE;
+ }
+ }
+
+ /* Assume los */
+ return TRUE;
+ }
+
+ /* Directly East/West */
+ if (!dy)
+ {
+ /* East -- check for walls */
+ if (dx > 0)
+ {
+ for (tx = x1 + 1; tx < x2; tx++)
+ {
+ if (!cave_los_bold(y1, tx)) return FALSE;
+ }
+ }
+
+ /* West -- check for walls */
+ else
+ {
+ for (tx = x1 - 1; tx > x2; tx--)
+ {
+ if (!cave_los_bold(y1, tx)) return FALSE;
+ }
+ }
+
+ /* Assume los */
+ return TRUE;
+ }
+
+
+ /* Extract some signs */
+ sx = (dx < 0) ? -1 : 1;
+ sy = (dy < 0) ? -1 : 1;
+
+
+ /* Vertical "knights" */
+ if (ax == 1)
+ {
+ if (ay == 2)
+ {
+ if (cave_los_bold(y1 + sy, x1)) return TRUE;
+ }
+ }
+
+ /* Horizontal "knights" */
+ else if (ay == 1)
+ {
+ if (ax == 2)
+ {
+ if (cave_los_bold(y1, x1 + sx)) return TRUE;
+ }
+ }
+
+
+ /* Calculate scale factor div 2 */
+ f2 = (ax * ay);
+
+ /* Calculate scale factor */
+ f1 = f2 << 1;
+
+
+ /* Travel horizontally */
+ if (ax >= ay)
+ {
+ /* Let m = dy / dx * 2 * (dy * dx) = 2 * dy * dy */
+ qy = ay * ay;
+ m = qy << 1;
+
+ tx = x1 + sx;
+
+ /* Consider the special case where slope == 1. */
+ if (qy == f2)
+ {
+ ty = y1 + sy;
+ qy -= f1;
+ }
+ else
+ {
+ ty = y1;
+ }
+
+ /* Note (below) the case (qy == f2), where */
+ /* the LOS exactly meets the corner of a tile. */
+ while (x2 - tx)
+ {
+ if (!cave_los_bold(ty, tx)) return FALSE;
+
+ qy += m;
+
+ if (qy < f2)
+ {
+ tx += sx;
+ }
+ else if (qy > f2)
+ {
+ ty += sy;
+ if (!cave_los_bold(ty, tx)) return FALSE;
+ qy -= f1;
+ tx += sx;
+ }
+ else
+ {
+ ty += sy;
+ qy -= f1;
+ tx += sx;
+ }
+ }
+ }
+
+ /* Travel vertically */
+ else
+ {
+ /* Let m = dx / dy * 2 * (dx * dy) = 2 * dx * dx */
+ qx = ax * ax;
+ m = qx << 1;
+
+ ty = y1 + sy;
+
+ if (qx == f2)
+ {
+ tx = x1 + sx;
+ qx -= f1;
+ }
+ else
+ {
+ tx = x1;
+ }
+
+ /* Note (below) the case (qx == f2), where */
+ /* the LOS exactly meets the corner of a tile. */
+ while (y2 - ty)
+ {
+ if (!cave_los_bold(ty, tx)) return FALSE;
+
+ qx += m;
+
+ if (qx < f2)
+ {
+ ty += sy;
+ }
+ else if (qx > f2)
+ {
+ tx += sx;
+ if (!cave_los_bold(ty, tx)) return FALSE;
+ qx -= f1;
+ ty += sy;
+ }
+ else
+ {
+ tx += sx;
+ qx -= f1;
+ ty += sy;
+ }
+ }
+ }
+
+ /* Assume los */
+ return TRUE;
+}
+
/*
* Determine if a bolt spell cast from (y1,x1) to (y2,x2) will arrive
* at the final destination, assuming no monster gets in the way.
extern sint project_path(u16b *gp, POSITION range, POSITION y1, POSITION x1, POSITION y2, POSITION x2, BIT_FLAGS flg);
extern POSITION distance(POSITION y1, POSITION x1, POSITION y2, POSITION x2);
+extern bool los(POSITION y1, POSITION x1, POSITION y2, POSITION x2);
+
extern bool projectable(POSITION y1, POSITION x1, POSITION y2, POSITION x2);
extern void scatter(POSITION *yp, POSITION *xp, POSITION y, POSITION x, POSITION d, BIT_FLAGS mode);
extern void mmove2(POSITION *y, POSITION *x, POSITION y1, POSITION x1, POSITION y2, POSITION x2);
return FALSE;
}
-/*!
- * @brief LOS(Line Of Sight / 視線が通っているか)の判定を行う。
- * @param y1 始点のy座標
- * @param x1 始点のx座標
- * @param y2 終点のy座標
- * @param x2 終点のx座標
- * @return LOSが通っているならTRUEを返す。
- * @details
- * A simple, fast, integer-based line-of-sight algorithm. By Joseph Hall,\n
- * 4116 Brewster Drive, Raleigh NC 27606. Email to jnh@ecemwl.ncsu.edu.\n
- *\n
- * Returns TRUE if a line of sight can be traced from (x1,y1) to (x2,y2).\n
- *\n
- * The LOS begins at the center of the tile (x1,y1) and ends at the center of\n
- * the tile (x2,y2). If los() is to return TRUE, all of the tiles this line\n
- * passes through must be floor tiles, except for (x1,y1) and (x2,y2).\n
- *\n
- * We assume that the "mathematical corner" of a non-floor tile does not\n
- * block line of sight.\n
- *\n
- * Because this function uses (short) ints for all calculations, overflow may\n
- * occur if dx and dy exceed 90.\n
- *\n
- * Once all the degenerate cases are eliminated, the values "qx", "qy", and\n
- * "m" are multiplied by a scale factor "f1 = abs(dx * dy * 2)", so that\n
- * we can use integer arithmetic.\n
- *\n
- * We travel from start to finish along the longer axis, starting at the border\n
- * between the first and second tiles, where the y offset = .5 * slope, taking\n
- * into account the scale factor. See below.\n
- *\n
- * Also note that this function and the "move towards target" code do NOT\n
- * share the same properties. Thus, you can see someone, target them, and\n
- * then fire a bolt at them, but the bolt may hit a wall, not them. However\n,
- * by clever choice of target locations, you can sometimes throw a "curve".\n
- *\n
- * Note that "line of sight" is not "reflexive" in all cases.\n
- *\n
- * Use the "projectable()" routine to test "spell/missile line of sight".\n
- *\n
- * Use the "update_view()" function to determine player line-of-sight.\n
- */
-bool los(POSITION y1, POSITION x1, POSITION y2, POSITION x2)
-{
- /* Delta */
- POSITION dx, dy;
-
- /* Absolute */
- POSITION ax, ay;
-
- /* Signs */
- POSITION sx, sy;
-
- /* Fractions */
- POSITION qx, qy;
-
- /* Scanners */
- POSITION tx, ty;
-
- /* Scale factors */
- POSITION f1, f2;
-
- /* Slope, or 1/Slope, of LOS */
- POSITION m;
-
-
- /* Extract the offset */
- dy = y2 - y1;
- dx = x2 - x1;
-
- /* Extract the absolute offset */
- ay = ABS(dy);
- ax = ABS(dx);
-
-
- /* Handle adjacent (or identical) grids */
- if ((ax < 2) && (ay < 2)) return TRUE;
-
-
- /* Paranoia -- require "safe" origin */
- /* if (!in_bounds(y1, x1)) return FALSE; */
- /* if (!in_bounds(y2, x2)) return FALSE; */
-
-
- /* Directly South/North */
- if (!dx)
- {
- /* South -- check for walls */
- if (dy > 0)
- {
- for (ty = y1 + 1; ty < y2; ty++)
- {
- if (!cave_los_bold(ty, x1)) return FALSE;
- }
- }
-
- /* North -- check for walls */
- else
- {
- for (ty = y1 - 1; ty > y2; ty--)
- {
- if (!cave_los_bold(ty, x1)) return FALSE;
- }
- }
-
- /* Assume los */
- return TRUE;
- }
-
- /* Directly East/West */
- if (!dy)
- {
- /* East -- check for walls */
- if (dx > 0)
- {
- for (tx = x1 + 1; tx < x2; tx++)
- {
- if (!cave_los_bold(y1, tx)) return FALSE;
- }
- }
-
- /* West -- check for walls */
- else
- {
- for (tx = x1 - 1; tx > x2; tx--)
- {
- if (!cave_los_bold(y1, tx)) return FALSE;
- }
- }
-
- /* Assume los */
- return TRUE;
- }
-
-
- /* Extract some signs */
- sx = (dx < 0) ? -1 : 1;
- sy = (dy < 0) ? -1 : 1;
-
-
- /* Vertical "knights" */
- if (ax == 1)
- {
- if (ay == 2)
- {
- if (cave_los_bold(y1 + sy, x1)) return TRUE;
- }
- }
-
- /* Horizontal "knights" */
- else if (ay == 1)
- {
- if (ax == 2)
- {
- if (cave_los_bold(y1, x1 + sx)) return TRUE;
- }
- }
-
-
- /* Calculate scale factor div 2 */
- f2 = (ax * ay);
-
- /* Calculate scale factor */
- f1 = f2 << 1;
-
-
- /* Travel horizontally */
- if (ax >= ay)
- {
- /* Let m = dy / dx * 2 * (dy * dx) = 2 * dy * dy */
- qy = ay * ay;
- m = qy << 1;
-
- tx = x1 + sx;
-
- /* Consider the special case where slope == 1. */
- if (qy == f2)
- {
- ty = y1 + sy;
- qy -= f1;
- }
- else
- {
- ty = y1;
- }
-
- /* Note (below) the case (qy == f2), where */
- /* the LOS exactly meets the corner of a tile. */
- while (x2 - tx)
- {
- if (!cave_los_bold(ty, tx)) return FALSE;
-
- qy += m;
-
- if (qy < f2)
- {
- tx += sx;
- }
- else if (qy > f2)
- {
- ty += sy;
- if (!cave_los_bold(ty, tx)) return FALSE;
- qy -= f1;
- tx += sx;
- }
- else
- {
- ty += sy;
- qy -= f1;
- tx += sx;
- }
- }
- }
-
- /* Travel vertically */
- else
- {
- /* Let m = dx / dy * 2 * (dx * dy) = 2 * dx * dx */
- qx = ax * ax;
- m = qx << 1;
-
- ty = y1 + sy;
-
- if (qx == f2)
- {
- tx = x1 + sx;
- qx -= f1;
- }
- else
- {
- tx = x1;
- }
-
- /* Note (below) the case (qx == f2), where */
- /* the LOS exactly meets the corner of a tile. */
- while (y2 - ty)
- {
- if (!cave_los_bold(ty, tx)) return FALSE;
-
- qx += m;
-
- if (qx < f2)
- {
- ty += sy;
- }
- else if (qx > f2)
- {
- tx += sx;
- if (!cave_los_bold(ty, tx)) return FALSE;
- qx -= f1;
- ty += sy;
- }
- else
- {
- tx += sx;
- qx -= f1;
- ty += sy;
- }
- }
- }
-
- /* Assume los */
- return TRUE;
-}
-
#define COMPLEX_WALL_ILLUMINATION /*!< 照明状態を壁により影響を受ける、より複雑な判定に切り替えるマクロ */
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