2 files changed, 672 insertions, 0 deletions

@@ -0,0 +1,427 @@
+/*
+ * Copyright (C) 2006, Greg McIntyre
+ * All rights reserved. See the file named COPYING in the distribution
+ * for more details.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#define __USE_ISOC99 1
+#include <math.h>
+#include <float.h>
+#include <assert.h>
+#include "fov.h"
+
+/*
++---++---++---++---+
+|   ||   ||   ||   |
+|   ||   ||   ||   |
+|   ||   ||   ||   |
++---++---++---++---+    2
++---++---++---+#####
+|   ||   ||   |#####
+|   ||   ||   |#####
+|   ||   ||   |#####
++---++---++---+#####X 1 <-- y
++---++---++---++---+
+|   ||   ||   ||   |
+| @ ||   ||   ||   |       <-- srcy centre     -> dy = 0.5 = y - 0.5
+|   ||   ||   ||   |
++---++---++---++---+    0
+0       1       2       3       4
+    ^                       ^
+    |                       |
+ srcx                   x            -> dx = 3.5 = x + 0.5
+centre
+
+Slope from @ to X.
+
++---++---++---++---+
+|   ||   ||   ||   |
+|   ||   ||   ||   |
+|   ||   ||   ||   |
++---++---++---++---+ 2
++---++---++---++---+
+|   ||   ||   ||   |
+|   ||   ||   ||   |
+|   ||   ||   ||   |
++---++---++---+X---+ 1   <-- y
++---++---++---+#####
+|   ||   ||   |#####
+| @ ||   ||   |#####      <-- srcy centre     -> dy = 0.5 = y - 0.5
+|   ||   ||   |#####
++---++---++---+##### 0
+0       1       2       3
+    ^                       ^
+    |                       |
+ srcx                   x            -> dx = 2.5 = x - 0.5
+centre
+
+Slope from @ to X
+*/
+
+
+/* Types ---------------------------------------------------------- */
+
+/** \cond INTERNAL */
+typedef struct {
+    /*@observer@*/ fov_settings_type *settings;
+    /*@observer@*/ void *map;
+    /*@observer@*/ void *source;
+    int source_x;
+    int source_y;
+    unsigned radius;
+} fov_private_data_type;
+/** \endcond */
+
+/* Options -------------------------------------------------------- */
+
+void fov_settings_init(fov_settings_type *settings) { 
+    settings->shape = FOV_SHAPE_CIRCLE_PRECALCULATE;
+    settings->corner_peek = FOV_CORNER_NOPEEK;
+    settings->opaque_apply = FOV_OPAQUE_APPLY;
+    settings->opaque = NULL;
+    settings->apply = NULL;
+    settings->heights = NULL;
+    settings->numheights = 0;
+}
+
+void fov_settings_set_shape(fov_settings_type *settings,
+                            fov_shape_type value) { 
+    settings->shape = value;
+}
+
+void fov_settings_set_corner_peek(fov_settings_type *settings,
+                           fov_corner_peek_type value) {
+    settings->corner_peek = value;
+}
+
+void fov_settings_set_opaque_apply(fov_settings_type *settings,
+                                   fov_opaque_apply_type value) {
+    settings->opaque_apply = value;
+}
+
+void fov_settings_set_opacity_test_function(fov_settings_type *settings,
+                                            bool (*f)(void *map,
+                                                      int x, int y)) {
+    settings->opaque = f;
+}
+
+void fov_settings_set_apply_lighting_function(fov_settings_type *settings,
+                                              void (*f)(void *map,
+                                                        int x, int y,
+                                                        int dx, int dy,
+                                                        void *src)) {
+    settings->apply = f;
+}
+
+/* Circular FOV --------------------------------------------------- */
+
+/*@null@*/ static unsigned *precalculate_heights(unsigned maxdist) {
+    unsigned i;
+    unsigned *result = (unsigned *)malloc((maxdist+2)*sizeof(unsigned));
+    if (result) {
+        for (i = 0; i <= maxdist; ++i) {
+            result[i] = (unsigned)sqrtf((float)(maxdist*maxdist - i*i));
+        }
+        result[maxdist+1] = 0;
+    }
+    return result;
+}
+
+static unsigned height(fov_settings_type *settings, int x,
+                unsigned maxdist) {
+    unsigned **newheights;
+
+    if (maxdist > settings->numheights) {
+        newheights = (unsigned **)calloc((size_t)maxdist, sizeof(unsigned*));
+        if (newheights != NULL) {
+            if (settings->heights != NULL && settings->numheights > 0) {
+                /* Copy the pointers to the heights arrays we've already
+                 * calculated. Once copied out, we can free the old
+                 * array of pointers. */
+                memcpy(newheights, settings->heights,
+                       settings->numheights*sizeof(unsigned*));
+                free(settings->heights);
+            }
+            settings->heights = newheights;
+            settings->numheights = maxdist;
+        }
+    }
+    if (settings->heights) {
+        if (settings->heights[maxdist-1] == NULL) {
+            settings->heights[maxdist-1] = precalculate_heights(maxdist);
+        }
+        if (settings->heights[maxdist-1] != NULL) {
+            return settings->heights[maxdist-1][abs(x)];
+        }
+    }
+    return 0;
+}
+
+void fov_settings_free(fov_settings_type *settings) {
+    unsigned i;
+    if (settings != NULL) {
+        if (settings->heights != NULL && settings->numheights > 0) {
+            /*@+forloopexec@*/
+            for (i = 0; i < settings->numheights; ++i) {
+                unsigned *h = settings->heights[i];
+                if (h != NULL) {
+                    free(h);
+                }
+                settings->heights[i] = NULL;
+            }
+            /*@=forloopexec@*/
+            free(settings->heights);
+            settings->heights = NULL;
+            settings->numheights = 0;
+        }
+    }
+}
+
+/* Slope ---------------------------------------------------------- */
+
+static float fov_slope(float dx, float dy) {
+    if (dx <= -FLT_EPSILON || dx >= FLT_EPSILON) {
+        return dy/dx;
+    } else {
+        return 0.0;
+    }
+}
+
+/* Octants -------------------------------------------------------- */
+
+#define FOV_DEFINE_OCTANT(signx, signy, rx, ry, nx, ny, nf, apply_edge, apply_diag)             \
+    static void fov_octant_##nx##ny##nf(                                                        \
+                                        fov_private_data_type *data,                            \
+                                        int dx,                                                 \
+                                        float start_slope,                                      \
+                                        float end_slope) {                                      \
+        int x, y, dy, dy0, dy1;                                                                 \
+        unsigned h;                                                                             \
+        int prev_blocked = -1;                                                                  \
+        float end_slope_next;                                                                   \
+        fov_settings_type *settings = data->settings;                                           \
+                                                                                                \
+        if (dx == 0) {                                                                          \
+            fov_octant_##nx##ny##nf(data, dx+1, start_slope, end_slope);                        \
+            return;                                                                             \
+        } else if ((unsigned)dx > data->radius) {                                               \
+            return;                                                                             \
+        }                                                                                       \
+                                                                                                \
+        dy0 = (int)(0.5f + ((float)dx)*start_slope);                                            \
+        dy1 = (int)(0.5f + ((float)dx)*end_slope);                                              \
+                                                                                                \
+        rx = data->source_##rx signx dx;                                                        \
+        ry = data->source_##ry signy dy0;                                                       \
+                                                                                                \
+        if (!apply_diag && dy1 == dx) {                                                         \
+            /* We do diagonal lines on every second octant, so they don't get done twice. */    \
+            --dy1;                                                                              \
+        }                                                                                       \
+                                                                                                \
+        switch (settings->shape) {                                                              \
+        case FOV_SHAPE_CIRCLE_PRECALCULATE:                                                     \
+            h = height(settings, dx, data->radius);                                             \
+            break;                                                                              \
+        case FOV_SHAPE_CIRCLE:                                                                  \
+            h = (unsigned)sqrtf((float)(data->radius*data->radius - dx*dx));                    \
+            break;                                                                              \
+        case FOV_SHAPE_OCTAGON:                                                                 \
+            h = (data->radius - dx)<<1;                                                         \
+            break;                                                                              \
+        default:                                                                                \
+            h = data->radius;                                                                   \
+            break;                                                                              \
+        };                                                                                      \
+        if ((unsigned)dy1 > h) {                                                                \
+            if (h == 0) {                                                                       \
+                return;                                                                         \
+            }                                                                                   \
+            dy1 = (int)h;                                                                       \
+        }                                                                                       \
+                                                                                                \
+        /*fprintf(stderr, "(%2d) = [%2d .. %2d] (%f .. %f), h=%d,edge=%d\n",                    \
+                dx, dy0, dy1, ((float)dx)*start_slope,                                          \
+                0.5f + ((float)dx)*end_slope, h, apply_edge);*/                                 \
+                                                                                                \
+        for (dy = dy0; dy <= dy1; ++dy) {                                                       \
+            ry = data->source_##ry signy dy;                                                    \
+                                                                                                \
+            if (settings->opaque(data->map, x, y)) {                                            \
+                if (settings->opaque_apply == FOV_OPAQUE_APPLY && (apply_edge || dy > 0)) {     \
+                    settings->apply(data->map, x, y, x - data->source_x, y - data->source_y, data->source);         \
+                }                                                                               \
+                if (prev_blocked == 0) {                                                        \
+                    end_slope_next = fov_slope((float)dx + 0.5f, (float)dy - 0.5f);             \
+                    fov_octant_##nx##ny##nf(data, dx+1, start_slope, end_slope_next);           \
+                }                                                                               \
+                prev_blocked = 1;                                                               \
+            } else {                                                                            \
+                if (apply_edge || dy > 0) {                                                     \
+                    settings->apply(data->map, x, y, x - data->source_x, y - data->source_y, data->source);         \
+                }                                                                               \
+                if (prev_blocked == 1) {                                                        \
+                    start_slope = fov_slope((float)dx - 0.5f, (float)dy - 0.5f);                \
+                }                                                                               \
+                prev_blocked = 0;                                                               \
+            }                                                                                   \
+        }                                                                                       \
+                                                                                                \
+        if (prev_blocked == 0) {                                                                \
+            fov_octant_##nx##ny##nf(data, dx+1, start_slope, end_slope);                        \
+        }                                                                                       \
+    }
+
+FOV_DEFINE_OCTANT(+,+,x,y,p,p,n,true,true)
+FOV_DEFINE_OCTANT(+,+,y,x,p,p,y,true,false)
+FOV_DEFINE_OCTANT(+,-,x,y,p,m,n,false,true)
+FOV_DEFINE_OCTANT(+,-,y,x,p,m,y,false,false)
+FOV_DEFINE_OCTANT(-,+,x,y,m,p,n,true,true)
+FOV_DEFINE_OCTANT(-,+,y,x,m,p,y,true,false)
+FOV_DEFINE_OCTANT(-,-,x,y,m,m,n,false,true)
+FOV_DEFINE_OCTANT(-,-,y,x,m,m,y,false,false)
+
+
+/* Circle --------------------------------------------------------- */
+
+static void _fov_circle(fov_private_data_type *data) {
+    /*
+     * Octants are defined by (x,y,r) where:
+     *  x = [p]ositive or [n]egative x increment
+     *  y = [p]ositive or [n]egative y increment
+     *  r = [y]es or [n]o for reflecting on axis x = y
+     *
+     *   \pmy|ppy/
+     *    \  |  /
+     *     \ | /
+     *   mpn\|/ppn
+     *   ----@----
+     *   mmn/|\pmn
+     *     / | \
+     *    /  |  \
+     *   /mmy|mpy\
+     */
+    fov_octant_ppn(data, 1, (float)0.0f, (float)1.0f);
+    fov_octant_ppy(data, 1, (float)0.0f, (float)1.0f);
+    fov_octant_pmn(data, 1, (float)0.0f, (float)1.0f);
+    fov_octant_pmy(data, 1, (float)0.0f, (float)1.0f);
+    fov_octant_mpn(data, 1, (float)0.0f, (float)1.0f);
+    fov_octant_mpy(data, 1, (float)0.0f, (float)1.0f);
+    fov_octant_mmn(data, 1, (float)0.0f, (float)1.0f);
+    fov_octant_mmy(data, 1, (float)0.0f, (float)1.0f);
+}
+
+void fov_circle(fov_settings_type *settings,
+                void *map,
+                void *source,
+                int source_x,
+                int source_y,
+                unsigned radius) {
+    fov_private_data_type data;
+
+    data.settings = settings;
+    data.map = map;
+    data.source = source;
+    data.source_x = source_x;
+    data.source_y = source_y;
+    data.radius = radius;
+
+    _fov_circle(&data);
+}
+
+/**
+ * Limit x to the range [a, b].
+ */
+static float betweenf(float x, float a, float b) {
+    if (x - a < FLT_EPSILON) { /* x < a */
+        return a;
+    } else if (x - b > FLT_EPSILON) { /* x > b */
+        return b;
+    } else {
+        return x;
+    }
+}
+
+#define BEAM_DIRECTION(d, p1, p2, p3, p4, p5, p6, p7, p8)   \
+    if (direction == d) {                                   \
+        end_slope = betweenf(a, 0.0f, 1.0f);                \
+        fov_octant_##p1(&data, 1, 0.0f, end_slope);         \
+        fov_octant_##p2(&data, 1, 0.0f, end_slope);         \
+        if (a - 1.0f > FLT_EPSILON) { /* a > 1.0f */        \
+            start_slope = betweenf(2.0f - a, 0.0f, 1.0f);   \
+            fov_octant_##p3(&data, 1, start_slope, 1.0f);   \
+            fov_octant_##p4(&data, 1, start_slope, 1.0f);   \
+        }                                                   \
+        if (a - 2.0f > FLT_EPSILON) { /* a > 2.0f */        \
+            end_slope = betweenf(a - 2.0f, 0.0f, 1.0f);     \
+            fov_octant_##p5(&data, 1, 0.0f, end_slope);     \
+            fov_octant_##p6(&data, 1, 0.0f, end_slope);     \
+        }                                                   \
+        if (a - 3.0f > FLT_EPSILON) { /* a > 3.0f */        \
+            start_slope = betweenf(4.0f - a, 0.0f, 1.0f);   \
+            fov_octant_##p7(&data, 1, start_slope, 1.0f);   \
+            fov_octant_##p8(&data, 1, start_slope, 1.0f);   \
+        }                                                   \
+    }
+
+#define BEAM_DIRECTION_DIAG(d, p1, p2, p3, p4, p5, p6, p7, p8)  \
+    if (direction == d) {                                       \
+        start_slope = betweenf(1.0f - a, 0.0f, 1.0f);           \
+        fov_octant_##p1(&data, 1, start_slope, 1.0f);           \
+        fov_octant_##p2(&data, 1, start_slope, 1.0f);           \
+        if (a - 1.0f > FLT_EPSILON) { /* a > 1.0f */            \
+            end_slope = betweenf(a - 1.0f, 0.0f, 1.0f);         \
+            fov_octant_##p3(&data, 1, 0.0f, end_slope);         \
+            fov_octant_##p4(&data, 1, 0.0f, end_slope);         \
+        }                                                       \
+        if (a - 2.0f > FLT_EPSILON) { /* a > 2.0f */            \
+            start_slope = betweenf(3.0f - a, 0.0f, 1.0f);       \
+            fov_octant_##p5(&data, 1, start_slope, 1.0f);       \
+            fov_octant_##p6(&data, 1, start_slope, 1.0f);       \
+        }                                                       \
+        if (a - 3.0f > FLT_EPSILON) { /* a > 3.0f */            \
+            end_slope = betweenf(a - 3.0f, 0.0f, 1.0f);         \
+            fov_octant_##p7(&data, 1, 0.0f, end_slope);         \
+            fov_octant_##p8(&data, 1, 0.0f, end_slope);         \
+        }                                                       \
+    }
+
+void fov_beam(fov_settings_type *settings, void *map, void *source,
+              int source_x, int source_y, unsigned radius,
+              fov_direction_type direction, float angle) {
+
+    fov_private_data_type data;
+    float start_slope, end_slope, a;
+
+    data.settings = settings;
+    data.map = map;
+    data.source = source;
+    data.source_x = source_x;
+    data.source_y = source_y;
+    data.radius = radius;
+
+    if (angle <= 0.0f) {
+        return;
+    } else if (angle >= 360.0f) {
+        _fov_circle(&data);
+        return;
+    }
+
+    /* Calculate the angle as a percentage of 45 degrees, halved (for
+     * each side of the centre of the beam). e.g. angle = 180.0f means
+     * half the beam is 90.0 which is 2x45, so the result is 2.0.
+     */
+    a = angle/90.0f;
+
+    BEAM_DIRECTION(FOV_EAST, ppn, pmn, ppy, mpy, pmy, mmy, mpn, mmn);
+    BEAM_DIRECTION(FOV_WEST, mpn, mmn, pmy, mmy, ppy, mpy, ppn, pmn);
+    BEAM_DIRECTION(FOV_NORTH, mpy, mmy, mmn, pmn, mpn, ppn, pmy, ppy);
+    BEAM_DIRECTION(FOV_SOUTH, pmy, ppy, mpn, ppn, mmn, pmn, mmy, mpy);
+    BEAM_DIRECTION_DIAG(FOV_NORTHEAST, pmn, mpy, mmy, ppn, mmn, ppy, mpn, pmy);
+    BEAM_DIRECTION_DIAG(FOV_NORTHWEST, mmn, mmy, mpn, mpy, pmy, pmn, ppy, ppn);
+    BEAM_DIRECTION_DIAG(FOV_SOUTHEAST, ppn, ppy, pmy, pmn, mpn, mpy, mmn, mmy);
+    BEAM_DIRECTION_DIAG(FOV_SOUTHWEST, pmy, mpn, ppy, mmn, ppn, mmy, pmn, mpy);
+}
@@ -0,0 +1,245 @@
+/*
+ * Copyright (C) 2006-2007, Greg McIntyre. All rights reserved. See the file
+ * named COPYING in the distribution for more details.
+ */
+
+/**
+ * \mainpage Field of View Library
+ * 
+ * \section about About
+ * 
+ * This is a C library which implements a course-grained lighting
+ * algorithm suitable for tile-based games such as roguelikes.
+ * 
+ * \section copyright Copyright
+ * 
+ * \verbinclude COPYING
+ * 
+ * \section thanks Thanks
+ * 
+ * Thanks to Bj&ouml;rn Bergstr&ouml;m
+ * <bjorn.bergstrom@hyperisland.se> for the algorithm.
+ * 
+ */
+
+/**
+ * \file fov.h
+ * Field-of-view algorithm for dynamically casting light/shadow on a
+ * low resolution 2D raster.
+ */
+#ifndef LIBFOV_HEADER
+#define LIBFOV_HEADER
+
+#include <stdbool.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Eight-way directions. */
+typedef enum {
+    FOV_EAST = 0,
+    FOV_NORTHEAST,
+    FOV_NORTH,
+    FOV_NORTHWEST,
+    FOV_WEST,
+    FOV_SOUTHWEST,
+    FOV_SOUTH,
+    FOV_SOUTHEAST
+} fov_direction_type;
+
+/** Values for the shape setting. */
+typedef enum {
+    FOV_SHAPE_CIRCLE_PRECALCULATE,
+    FOV_SHAPE_SQUARE,
+    FOV_SHAPE_CIRCLE,
+    FOV_SHAPE_OCTAGON
+} fov_shape_type;
+
+/** Values for the corner peek setting. */
+typedef enum {
+    FOV_CORNER_NOPEEK,
+    FOV_CORNER_PEEK
+} fov_corner_peek_type;
+
+/** Values for the opaque apply setting. */
+typedef enum {
+    FOV_OPAQUE_APPLY,
+    FOV_OPAQUE_NOAPPLY
+} fov_opaque_apply_type;
+
+/** @cond INTERNAL */
+typedef /*@null@*/ unsigned *height_array_t;
+/** @endcond */
+
+typedef struct {
+    /** Opacity test callback. */
+    /*@null@*/ bool (*opaque)(void *map, int x, int y);
+
+    /** Lighting callback to set lighting on a map tile. */
+    /*@null@*/ void (*apply)(void *map, int x, int y, int dx, int dy, void *src);
+
+    /** Shape setting. */
+    fov_shape_type shape;
+
+    /** Whether to peek around corners. */
+    fov_corner_peek_type corner_peek;
+
+    /** Whether to call apply on opaque tiles. */
+    fov_opaque_apply_type opaque_apply;
+
+    /** \cond INTERNAL */
+
+    /** Pre-calculated data. \internal */
+    /*@null@*/ height_array_t *heights;
+
+    /** Size of pre-calculated data. \internal */
+    unsigned numheights;
+
+    /** \endcond */
+} fov_settings_type;
+
+/** The opposite direction to that given. */
+#define fov_direction_opposite(direction) ((fov_direction_type)(((direction)+4)&0x7))
+
+/**
+ * Set all the default options. You must call this option when you
+ * create a new settings data structure.
+ *
+ * These settings are the defaults used:
+ *
+ * - shape: FOV_SHAPE_CIRCLE_PRECALCULATE
+ * - corner_peek: FOV_CORNER_NOPEEK
+ * - opaque_apply: FOV_OPAQUE_APPLY
+ *
+ * Callbacks still need to be set up after calling this function.
+ *
+ * \param settings Pointer to data structure containing settings.
+ */
+void fov_settings_init(fov_settings_type *settings);
+
+/**
+ * Set the shape of the field of view.
+ *
+ * \param settings Pointer to data structure containing settings.
+ * \param value One of the following values, where R is the radius:
+ *
+ * - FOV_SHAPE_CIRCLE_PRECALCULATE \b (default): Limit the FOV to a
+ * circle with radius R by precalculating, which consumes more memory
+ * at the rate of 4*(R+2) bytes per R used in calls to fov_circle. 
+ * Each radius is only calculated once so that it can be used again. 
+ * Use fov_free() to free this precalculated data's memory.
+ *
+ * - FOV_SHAPE_CIRCLE: Limit the FOV to a circle with radius R by
+ * calculating on-the-fly.
+ *
+ * - FOV_SHAPE_OCTOGON: Limit the FOV to an octogon with maximum radius R.
+ *
+ * - FOV_SHAPE_SQUARE: Limit the FOV to an R*R square.
+ */
+void fov_settings_set_shape(fov_settings_type *settings, fov_shape_type value);
+
+/**
+ * <em>NOT YET IMPLEMENTED</em>.
+ *
+ * Set whether sources will peek around corners.
+ *
+ * \param settings Pointer to data structure containing settings.
+ * \param value One of the following values:
+ *
+ * - FOV_CORNER_PEEK \b (default): Renders:
+\verbatim
+  ........
+  ........
+  ........
+  ..@#    
+  ...#    
+\endverbatim
+ * - FOV_CORNER_NOPEEK: Renders:
+\verbatim
+  ......
+  .....
+  ....
+  ..@#
+  ...#
+\endverbatim
+ */
+void fov_settings_set_corner_peek(fov_settings_type *settings, fov_corner_peek_type value);
+
+/**
+ * Whether to call the apply callback on opaque tiles.
+ *
+ * \param settings Pointer to data structure containing settings.
+ * \param value One of the following values:
+ *
+ * - FOV_OPAQUE_APPLY \b (default): Call apply callback on opaque tiles.
+ * - FOV_OPAQUE_NOAPPLY: Do not call the apply callback on opaque tiles.
+ */
+void fov_settings_set_opaque_apply(fov_settings_type *settings, fov_opaque_apply_type value);
+
+/**
+ * Set the function used to test whether a map tile is opaque.
+ *
+ * \param settings Pointer to data structure containing settings.
+ * \param f The function called to test whether a map tile is opaque.
+ */
+void fov_settings_set_opacity_test_function(fov_settings_type *settings, bool (*f)(void *map, int x, int y));
+
+/**
+ * Set the function used to apply lighting to a map tile.
+ *
+ * \param settings Pointer to data structure containing settings.
+ * \param f The function called to apply lighting to a map tile.
+ */
+void fov_settings_set_apply_lighting_function(fov_settings_type *settings, void (*f)(void *map, int x, int y, int dx, int dy, void *src));
+
+/**
+ * Free any memory that may have been cached in the settings
+ * structure.
+ *
+ * \param settings Pointer to data structure containing settings.
+ */
+void fov_settings_free(fov_settings_type *settings);
+
+/**
+ * Calculate a full circle field of view from a source at (x,y).
+ *
+ * \param settings Pointer to data structure containing settings.
+ * \param map Pointer to map data structure to be passed to callbacks.
+ * \param source Pointer to data structure holding source of light.
+ * \param source_x x-axis coordinate from which to start.
+ * \param source_y y-axis coordinate from which to start.
+ * \param radius Euclidean distance from (x,y) after which to stop.
+ */
+void fov_circle(fov_settings_type *settings, void *map, void *source,
+                int source_x, int source_y, unsigned radius
+);
+
+/**
+ * Calculate a field of view from source at (x,y), pointing
+ * in the given direction and with the given angle. The larger
+ * the angle, the wider, "less focused" the beam. Each side of the
+ * line pointing in the direction from the source will be half the
+ * angle given such that the angle specified will be represented on
+ * the raster.
+ *
+ * \param settings Pointer to data structure containing settings.
+ * \param map Pointer to map data structure to be passed to callbacks.
+ * \param source Pointer to data structure holding source of light.
+ * \param source_x x-axis coordinate from which to start.
+ * \param source_y y-axis coordinate from which to start.
+ * \param radius Euclidean distance from (x,y) after which to stop.
+ * \param direction One of eight directions the beam of light can point.
+ * \param angle The angle at the base of the beam of light, in degrees.
+ */
+void fov_beam(fov_settings_type *settings, void *map, void *source,
+              int source_x, int source_y, unsigned radius,
+              fov_direction_type direction, float angle
+);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif