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#include <engine/fov.h>
#include <engine/utils.h>
#include <math.h>
#include <stdint.h>
void fov_shadowcast_rec(const void* map, const v2_i32 mapsize,
bool (*visblocking)(const void*), i32* lightmap,
const i32 range, v2_i32 src, const i32 row, f32 start,
const f32 end, const i8 xx, const i8 xy, const i8 yx,
const i8 yy) {
if (start < end) return;
const i32 range_2 = range * range;
f32 new_start = start;
for (i32 i = row; i <= range; i++) {
i32 dx = (-1 * i) - 1;
i32 dy = -1 * i;
bool blocked = false;
while (dx <= 0) {
dx += 1;
const i32 mapx = src.x + dx * xx + dy * xy;
const i32 mapy = src.y + dx * yx + dy * yy;
const f32 slope_l = (((f32)dx) - 0.5f) / (((f32)dy) + 0.5f);
const f32 slope_r = (((f32)dx) + 0.5f) / (((f32)dy) - 0.5f);
if (start < slope_r) continue;
if (end > slope_l) break;
if (dx * dx + dy * dy < range_2) {
/* set as visible */
if (mapx >= 0 && mapx < (long)mapsize.x && mapy >= 0 &&
mapy < (long)mapsize.y) {
// TODO: Calculate proper dist from source
f32 x_2 = (src.x - mapx) * (src.x - mapx);
f32 y_2 = (src.y - mapy) * (src.y - mapy);
lightmap[mapy * mapsize.x + mapx] =
MAX(lightmap[mapy * mapsize.x + mapx],
range - sqrt((f32)(x_2 + y_2)));
}
}
/* sizeof(i32) is the size of enums */
/* -- unless the compiler doesn't follow standard behaviour */
const bool is_blocked = visblocking(
(void*)((u64)map + sizeof(i32) /* ~ enum size */
* (mapsize.x * mapy + mapx) /* index */
));
if (blocked) {
if (!is_blocked) {
new_start = slope_r;
} else {
blocked = false;
start = new_start;
}
} else if (!is_blocked && i < range) {
blocked = true;
fov_shadowcast_rec(map, mapsize, visblocking, lightmap, range, src,
i + 1, start, slope_l, xx, xy, yx, yy);
new_start = slope_r;
}
}
if (blocked) break;
}
}
/* http://www.roguebasin.com/index.php?title=FOV_using_recursive_shadowcasting
*/
void fov_shadowcast(const void* map, const v2_i32 mapsize,
bool (*visblocking)(const void*), i32* lightmap,
const i32 range, const v2_i32 src) {
const i8 m[4][8] = {
{1, 0, 0, -1, -1, 0, 0, 1},
{0, 1, -1, 0, 0, -1, 1, 0},
{0, 1, 1, 0, 0, -1, -1, 0},
{1, 0, 0, 1, -1, 0, 0, -1},
};
for (i32 oct = 0; oct < 8; oct++) {
fov_shadowcast_rec(map, mapsize, visblocking, lightmap, range, src, 1, 1.0,
0.0, m[0][oct], m[1][oct], m[2][oct], m[3][oct]);
}
/* The center is the most lit square */
lightmap[src.y * mapsize.x + src.x] = range;
}
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