los.cpp

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/*
 * Crossfire -- cooperative multi-player graphical RPG and adventure game
 *
 * Copyright (c) 1999-2014 Mark Wedel and the Crossfire Development Team
 * Copyright (c) 1992 Frank Tore Johansen
 *
 * Crossfire is free software and comes with ABSOLUTELY NO WARRANTY. You are
 * welcome to redistribute it under certain conditions. For details, please
 * see COPYING and LICENSE.
 *
 * The authors can be reached via e-mail at <crossfire@metalforge.org>.
 */

#include "global.h"

#include <math.h>
#include <stdlib.h>
#include <string.h>

#define SPACE_BLOCK 0.5

#define XRAY_RADIUS         2

#define SEE_IN_DARK_LEVELS  2

#define LOS_BLOCKED         100
#define LOS_NO_DARKNESS     0
#define LOS_MARKED          -1

struct blocks {
    int x[4], y[4];
    int index;
};

static blocks block[MAP_CLIENT_X][MAP_CLIENT_Y];

static void expand_lighted_sight(object *op);

static void set_block(int x, int y, int bx, int by) {
    int index = block[x][y].index, i;

    /* Due to flipping, we may get duplicates - better safe than sorry.
     */
    for (i = 0; i < index; i++) {
        if (block[x][y].x[i] == bx
        && block[x][y].y[i] == by)
            return;
    }

    block[x][y].x[index] = bx;
    block[x][y].y[index] = by;
    block[x][y].index++;
#ifdef LOS_DEBUG
    LOG(llevDebug, "setblock: added %d %d -> %d %d (%d)\n", x, y, bx, by, block[x][y].index);
#endif
}

void init_block(void) {
    int x, y, dx, dy, i;
    static const int block_x[3] = {
        -1, -1, 0
    }, block_y[3] = {
        -1, 0, -1
    };

    for (x = 0; x < MAP_CLIENT_X; x++)
        for (y = 0; y < MAP_CLIENT_Y; y++) {
            block[x][y].index = 0;
        }

    /* The table should be symmetric, so only do the upper left
     * quadrant - makes the processing easier.
     */
    for (x = 1; x <= MAP_CLIENT_X/2; x++) {
        for (y = 1; y <= MAP_CLIENT_Y/2; y++) {
            /* center space never blocks */
            if (x == MAP_CLIENT_X/2 && y == MAP_CLIENT_Y/2)
                continue;

            for (i = 0; i < 3; i++) {
                dx = x+block_x[i];
                dy = y+block_y[i];

                /* If its a straight line, its blocked */
                if ((dx == x && x == MAP_CLIENT_X/2)
                || (dy == y && y == MAP_CLIENT_Y/2)) {
                    /* For simplicity, we mirror the coordinates to block the other
                    * quadrants.
                    */
                    set_block(x, y, dx, dy);
                    if (x == MAP_CLIENT_X/2) {
                        set_block(x, MAP_CLIENT_Y-y-1, dx, MAP_CLIENT_Y-dy-1);
                    } else if (y == MAP_CLIENT_Y/2) {
                        set_block(MAP_CLIENT_X-x-1, y, MAP_CLIENT_X-dx-1, dy);
                    }
                } else {
                    float d1, s, l;

                    /* We use the algorihm that found out how close the point
                     * (x,y) is to the line from dx,dy to the center of the viewable
                     * area.  l is the distance from x,y to the line.
                     * r is more a curiosity - it lets us know what direction (left/right)
                     * the line is off
                     */

                    d1 = (float)(pow(MAP_CLIENT_X/2-dx, 2)+pow(MAP_CLIENT_Y/2-dy, 2));
                    s = (float)((dy-y)*(MAP_CLIENT_X/2-dx)-(dx-x)*(MAP_CLIENT_Y/2-dy))/d1;
                    l = FABS(sqrt(d1)*s);

                    if (l <= SPACE_BLOCK) {
                        /* For simplicity, we mirror the coordinates to block the other
                        * quadrants.
                        */
                        set_block(x, y, dx, dy);
                        set_block(MAP_CLIENT_X-x-1, y, MAP_CLIENT_X-dx-1, dy);
                        set_block(x, MAP_CLIENT_Y-y-1, dx, MAP_CLIENT_Y-dy-1);
                        set_block(MAP_CLIENT_X-x-1, MAP_CLIENT_Y-y-1, MAP_CLIENT_X-dx-1, MAP_CLIENT_Y-dy-1);
                    }
                }
            }
        }
    }
}

static void set_wall(player *pl, int x, int y) {
    // Get this outside the loop -- now we can recycle x and y in the loop
    // Trying less dereferencing for better efficiency
    // Equivalent to &(block[x][y]), but faster.
    const blocks * const at = block[x] + y;
    /*
     * Assume the mapsize will not change mid-drawing. This seemed to work in my testing
     * Neila Hawkins 2019-12-03
     */
    const int map_sock_x = (MAP_CLIENT_X-pl->socket->mapx)>>1,
              map_sock_y = (MAP_CLIENT_Y-pl->socket->mapy)>>1;
    for (int i = 0; i < at->index; i++) {
        int dx = at->x[i], dy = at->y[i];

        /* x, y are the values as adjusted to be in the
        * socket look structure. Since the values are copied,
        * we can safely store this in the x and y passed to the function,
        * since they were only needed to find the element of the blocks array.
        */
        x = dx-map_sock_x;
        y = dy-map_sock_y;

        if (x < 0 || x >= pl->socket->mapx
        || y < 0 || y >= pl->socket->mapy
        /* If already set to LOS_BLOCKED, we probably hit this space through recursion already. */
        || pl->blocked_los[x][y] == LOS_BLOCKED)
            continue;
        /* we need to adjust to the fact that the socket
         * code wants the los to start from the 0,0
         * and not be relative to middle of los array.
         */
        pl->blocked_los[x][y] = LOS_BLOCKED;
        set_wall(pl, dx, dy);
    }
}

static void check_wall(object *op, int x, int y) {
    int ax, ay;

    if (!block[x][y].index)
        return;

    /* ax, ay are coordinates as indexed into the look window */
    ax = x-(MAP_CLIENT_X-op->contr->socket->mapx)/2;
    ay = y-(MAP_CLIENT_Y-op->contr->socket->mapy)/2;

    /* If the converted coordinates are outside the viewable
     * area for the client, return now.
     */
    if (ax < 0 || ay < 0 || ax >= op->contr->socket->mapx || ay >= op->contr->socket->mapy)
        return;

    /* If this space is already blocked, prune the processing - presumably
     * whatever has set this space to be blocked has done the work and already
     * done the dependency chain.
     */
    if (op->contr->blocked_los[ax][ay] == LOS_BLOCKED)
        return;


    if (get_map_flags(op->map, NULL, op->x+x-MAP_CLIENT_X/2, op->y+y-MAP_CLIENT_Y/2, NULL, NULL)&(P_BLOCKSVIEW|P_OUT_OF_MAP))
        set_wall(op->contr, x, y);
}

void clear_los(player *pl) {
    /* This is safer than using the socket->mapx, mapy because
     * we index the blocked_los as a 2 way array, so clearing
     * the first z spaces may not not cover the spaces we are
     * actually going to use
     */
    (void)memset((void *)pl->blocked_los, LOS_NO_DARKNESS,
        MAP_CLIENT_X*MAP_CLIENT_Y);
}

static void expand_sight(object *op) {
    int i, x, y, dx, dy;

    for (x = 1; x < op->contr->socket->mapx-1; x++) { /* loop over inner squares */
        for (y = 1; y < op->contr->socket->mapy-1; y++) {
            if (op->contr->blocked_los[x][y] == LOS_NO_DARKNESS) {
                /* If the space does not block view, process surrounding spaces */
                if (!(get_map_flags(op->map, NULL,
                    op->x-op->contr->socket->mapx/2+x,
                    op->y-op->contr->socket->mapy/2+y,
                    NULL, NULL)&(P_BLOCKSVIEW|P_OUT_OF_MAP))) {
                    /* mark all directions around space */
                    for (i = 1; i <= 8; i += 1) {
                        dx = x+freearr_x[i];
                        dy = y+freearr_y[i];

                        /* Mark any space that is blocked (or has a darkness value) */
                        if (op->contr->blocked_los[dx][dy] > LOS_NO_DARKNESS)
                            op->contr->blocked_los[dx][dy] = LOS_MARKED;
                    }
                }
            }
        }
    }

    if (MAP_DARKNESS(op->map) > 0) /* player is on a dark map */
        expand_lighted_sight(op);


    /* clear mark squares, or fix up invalid spaces. The grant vision
     * code in expand_lighted_sight() can result in negative numbers */
    for (x = 0; x < op->contr->socket->mapx; x++) {
        for (y = 0; y < op->contr->socket->mapy; y++) {
            /* If space was marked above, or the space has an invalid
             * darkness (too bright), then set the space to visible */
            if (op->contr->blocked_los[x][y] <= LOS_MARKED) {
                op->contr->blocked_los[x][y] = LOS_NO_DARKNESS;
            }
        }
    }
}

int has_carried_lights(const object *op) {
    /* op may glow! */
    if (op->glow_radius > 0)
        return 1;

    return 0;
}

static void expand_lighted_sight(object *op) {
    int x, y, darklevel, ax, ay, basex, basey, mflags, light_radius, dark_change;
    mapstruct *m = op->map;
    int16_t nx, ny;

    darklevel = MAP_DARKNESS(m);

    /* If the player can see in the dark (infravision), lower the darklevel for the player */
    if (QUERY_FLAG(op, FLAG_SEE_IN_DARK)) {
        darklevel -= SEE_IN_DARK_LEVELS;
    }

    /* add light, by finding all (non-null) nearby light sources, then
     * mark those squares specially. If the darklevel<1, there is no
     * reason to do this, so we skip this function
     */
    if (darklevel < 1)
        return;

    /* Do a sanity check.  If not valid, some code below may do odd
     * things.
     */
    if (darklevel > MAX_DARKNESS) {
        LOG(llevError, "Map darkness for %s on %s is too high (%d)\n", op->name, op->map->path, darklevel);
        darklevel = MAX_DARKNESS;
    }

    /* First, limit player furthest (unlighted) vision */
    for (x = 0; x < op->contr->socket->mapx; x++)
        for (y = 0; y < op->contr->socket->mapy; y++)
            if (op->contr->blocked_los[x][y] != LOS_BLOCKED)
                op->contr->blocked_los[x][y] = MAX_LIGHT_RADII;

    /* the spaces[] darkness value contains the information we need.
     * Only process the area of interest.
     * the basex, basey values represent the position in the op->contr->blocked_los
     * array.  Its easier to just increment them here (and start with the right
     * value) than to recalculate them down below.
     */
    for (x = (op->x-op->contr->socket->mapx/2-MAX_LIGHT_RADII), basex = -MAX_LIGHT_RADII;
            x <= (op->x+op->contr->socket->mapx/2+MAX_LIGHT_RADII); x++, basex++) {
        for (y = (op->y-op->contr->socket->mapy/2-MAX_LIGHT_RADII), basey = -MAX_LIGHT_RADII;
                y <= (op->y+op->contr->socket->mapy/2+MAX_LIGHT_RADII); y++, basey++) {
            m = op->map;
            nx = x;
            ny = y;

            mflags = get_map_flags(m, &m, nx, ny, &nx, &ny);

            if (mflags&P_OUT_OF_MAP)
                continue;

            /* This space is providing light, so we need to brighten up the
            * spaces around here.
            */
            light_radius = GET_MAP_LIGHT(m, nx, ny);

            if (light_radius == 0)
                continue;

            for (ax = basex-light_radius; ax <= basex+light_radius; ax++) {
                /* Check if space is within view */
                if (ax < 0 || ax >= op->contr->socket->mapx)
                    continue;

                for (ay = basey-light_radius; ay <= basey+light_radius; ay++) {
                    /* Check if space is within view */
                    if (ay < 0 || ay >= op->contr->socket->mapy)
                        continue;

                    /* If the space is fully blocked, do nothing. */
                    if (op->contr->blocked_los[ax][ay] == LOS_BLOCKED)
                        continue;

                    /* Brighten the space.  The further the light is away from the
                     * source (basex-x), the less effect it has.  Though light used
                     * to dim in a square manner, it now dims in a circular manner
                     * using the the pythagorean theorem. glow_radius still
                     * represents the radius
                     */
                    int x1 = basex-ax;
                    int y1 = basey-ay;

                    if (light_radius > 0)
                        op->contr->blocked_los[ax][ay] -= MAX((light_radius-ihypot(x1, y1)), 0);
                    if (light_radius < 0)
                        op->contr->blocked_los[ax][ay] -= MIN((light_radius+ihypot(x1, y1)), 0);
                } /* for ay */
            } /* for ax */
        } /* for y */
    } /* for x */

    /* Outdoor should never really be completely pitch black dark like
     * a dungeon, so let the player at least see a little around themselves
     */
    if (op->map->outdoor && darklevel > (MAX_DARKNESS-3)) {

        /* Update player space */
        if (op->contr->blocked_los[op->contr->socket->mapx/2][op->contr->socket->mapy/2] > (MAX_DARKNESS-3))
            op->contr->blocked_los[op->contr->socket->mapx/2][op->contr->socket->mapy/2] = MAX_DARKNESS-3;

        /* Update spaces around player */
        for (x = -1; x <= 1; x++) {
            for (y = -1; y <= 1; y++) {
                if (op->contr->blocked_los[x+op->contr->socket->mapx/2][y+op->contr->socket->mapy/2] > (MAX_DARKNESS-2))
                    op->contr->blocked_los[x+op->contr->socket->mapx/2][y+op->contr->socket->mapy/2] = MAX_DARKNESS-2;
            }
        }
    }

    /* grant some vision to the player, based on the darklevel
     * Note this might lighten spaces to be < 0, which is fixed up in expand_sight()
     */
    for (x = darklevel-MAX_DARKNESS; x < MAX_DARKNESS+1-darklevel; x++) {
        for (y = darklevel-MAX_DARKNESS; y < MAX_DARKNESS+1-darklevel; y++) {
            if (!(op->contr->blocked_los[x+op->contr->socket->mapx/2][y+op->contr->socket->mapy/2] == LOS_BLOCKED)) {
                dark_change = MAX(0, (MAX_DARKNESS + 1) - darklevel - MAX(abs(x), abs(y)));
                op->contr->blocked_los[x+op->contr->socket->mapx/2][y+op->contr->socket->mapy/2] -= dark_change;
            }
        }
    }
}

static void blinded_sight(player *pl) {
    int x, y;

    for (x = 0; x < pl->socket->mapx; x++)
        for (y = 0; y <  pl->socket->mapy; y++)
            pl->blocked_los[x][y] = LOS_BLOCKED;

    pl->blocked_los[pl->socket->mapx/2][pl->socket->mapy/2] = LOS_NO_DARKNESS;
}

void update_los(object *op) {
    int mapx, mapy, dx, dy, x, y;

    if (QUERY_FLAG(op, FLAG_REMOVED))
        return;

    /* Set the LOS array to all visible */
    clear_los(op->contr);
    if (QUERY_FLAG(op, FLAG_WIZ) /* || XRAYS(op) */) {
        return;
    }

    /* Locally save mapx/mapy to save some dereferences */
    mapx = op->contr->socket->mapx;
    mapy = op->contr->socket->mapy;

    /* For larger maps, this is more efficient than the old way which
     * used the chaining of the block array.  Since many space views could
     * be blocked by different spaces in front, this mean that a lot of spaces
     * could be examined multiple times, as each path would be looked at.
     */
    for (x = (MAP_CLIENT_X-mapx)/2+1; x < (MAP_CLIENT_X+mapx)/2-1; x++)
        for (y = (MAP_CLIENT_Y-mapy)/2+1; y < (MAP_CLIENT_Y+mapy)/2-1; y++)
            check_wall(op, x, y);

    /* do the los of the player. 3 (potential) cases */
    if (QUERY_FLAG(op, FLAG_BLIND)) { /* player is blind */
        blinded_sight(op->contr);
    }
    else {
        expand_sight(op);
    }

    if (QUERY_FLAG(op, FLAG_XRAYS)) {
        dx = mapx / 2;
        dy = mapy / 2;

        for (x = -XRAY_RADIUS; x <= XRAY_RADIUS; x++)
            for (y = -XRAY_RADIUS; y <= XRAY_RADIUS; y++)
                op->contr->blocked_los[dx+x][dy+y] = LOS_NO_DARKNESS;
    }
}

void update_all_map_los(mapstruct *map) {
    player *pl;

    for (pl = first_player; pl != NULL; pl = pl->next) {
        if (pl->ob->map == map)
            pl->do_los = 1;
    }
}

void update_all_los(const mapstruct *map, int x, int y) {
    player *pl;

    for (pl = first_player; pl != NULL; pl = pl->next) {
        /* Player should not have a null map, but do this
         * check as a safety
         */
        if (!pl->ob->map)
            continue;

        /* Same map is simple case - see if pl is close enough.
         * Note in all cases, we did the check for same map first,
         * and then see if the player is close enough and update
         * los if that is the case.  If the player is on the
         * corresponding map, but not close enough, then the
         * player can't be on another map that may be closer,
         * so by setting it up this way, we trim processing
         * some.
         */
        if (pl->ob->map == map) {
            if ((abs(pl->ob->x-x) <= pl->socket->mapx/2)
            && (abs(pl->ob->y-y) <= pl->socket->mapy/2))
                pl->do_los = 1;
        }
        /* Now we check to see if player is on adjacent
         * maps to the one that changed and also within
         * view.  The tile_maps[] could be null, but in that
         * case it should never match the pl->ob->map, so
         * we want ever try to dereference any of the data in it.
         */

        /* The logic for 0 and 3 is to see how far the player is
         * from the edge of the map (height/width) - pl->ob->(x,y)
         * and to add current position on this map - that gives a
         * distance.
         * For 1 and 2, we check to see how far the given
         * coordinate (x,y) is from the corresponding edge,
         * and then add the players location, which gives
         * a distance.
         */
        else if (pl->ob->map == map->tile_map[0]) {
            if ((abs(pl->ob->x-x) <= pl->socket->mapx/2)
            && (abs(y+MAP_HEIGHT(map->tile_map[0])-pl->ob->y) <= pl->socket->mapy/2))
                pl->do_los = 1;
        } else if (pl->ob->map == map->tile_map[2]) {
            if ((abs(pl->ob->x-x) <= pl->socket->mapx/2)
            && (abs(pl->ob->y+MAP_HEIGHT(map)-y) <= pl->socket->mapy/2))
                pl->do_los = 1;
        } else if (pl->ob->map == map->tile_map[1]) {
            if ((abs(pl->ob->x+MAP_WIDTH(map)-x) <= pl->socket->mapx/2)
            && (abs(pl->ob->y-y) <= pl->socket->mapy/2))
                pl->do_los = 1;
        } else if (pl->ob->map == map->tile_map[3]) {
            if ((abs(x+MAP_WIDTH(map->tile_map[3])-pl->ob->x) <= pl->socket->mapx/2)
            && (abs(pl->ob->y-y) <= pl->socket->mapy/2))
                pl->do_los = 1;
        }
    }
}

void print_los(object *op) {
    int x, y;
    char buf[MAP_CLIENT_X*2+20], buf2[10];

    snprintf(buf, sizeof(buf), "[fixed]   ");
    for (x = 0; x < op->contr->socket->mapx; x++) {
        snprintf(buf2, sizeof(buf2), "%2d", x);
        strncat(buf, buf2, sizeof(buf)-strlen(buf)-1);
    }
    draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_COMMAND, MSG_TYPE_COMMAND_DEBUG, buf);
    for (y = 0; y < op->contr->socket->mapy; y++) {
        snprintf(buf, sizeof(buf), "[fixed]%2d:", y);
        for (x = 0; x < op->contr->socket->mapx; x++) {
            snprintf(buf2, sizeof(buf2), " %1d", op->contr->blocked_los[x][y] == LOS_BLOCKED ? 1 : 0);
            strncat(buf, buf2, sizeof(buf)-strlen(buf)-1);
        }
        draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_COMMAND, MSG_TYPE_COMMAND_DEBUG, buf);
    }
}

void make_sure_seen(const object *op) {
    player *pl;

    for (pl = first_player; pl; pl = pl->next)
        if (pl->ob->map == op->map
        && pl->ob->y-pl->socket->mapy/2 <= op->y
        && pl->ob->y+pl->socket->mapy/2 >= op->y
        && pl->ob->x-pl->socket->mapx/2 <= op->x
        && pl->ob->x+pl->socket->mapx/2 >= op->x)
            pl->blocked_los[pl->socket->mapx/2+op->x-pl->ob->x][pl->socket->mapy/2+op->y-pl->ob->y] = LOS_NO_DARKNESS;
}

void make_sure_not_seen(const object *op) {
    player *pl;

    for (pl = first_player; pl; pl = pl->next)
        if (pl->ob->map == op->map
        && pl->ob->y-pl->socket->mapy/2 <= op->y
        && pl->ob->y+pl->socket->mapy/2 >= op->y
        && pl->ob->x-pl->socket->mapx/2 <= op->x
        && pl->ob->x+pl->socket->mapx/2 >= op->x)
            pl->do_los = 1;
}