Implement sub-tile collboxes

These will be later used by the pathfinding algorithm.

3 files changed, 63 insertions, 3 deletions

diff --git a/src/terrain/CMakeLists.txt b/src/terrain/CMakeLists.txt
index c74de94..7a0e5bd 100644
--- a/src/terrain/CMakeLists.txt
+++ b/src/terrain/CMakeLists.txt
@@ -1,3 +1,3 @@
 add_library(terrain "src/terrain.c")
 target_include_directories(terrain PUBLIC "inc")
-target_link_libraries(terrain PUBLIC container camera gfx)
+target_link_libraries(terrain PUBLIC container camera gfx util)
diff --git a/src/terrain/inc/terrain.h b/src/terrain/inc/terrain.h
index 508fe25..fbe8af8 100644
--- a/src/terrain/inc/terrain.h
+++ b/src/terrain/inc/terrain.h
@@ -3,6 +3,7 @@
 
 #include <camera.h>
 #include <gfx.h>
+#include <util.h>
 #include <stddef.h>
 
 #ifdef __cplusplus
@@ -25,13 +26,19 @@ enum terrain_type
 
 struct terrain_map
 {
-    enum terrain_type m[MAP_TILES][MAP_TILES];
+    struct terrain_tile
+    {
+       enum terrain_type t;
+       unsigned char bl;
+    } m[MAP_TILES][MAP_TILES];
+
     int nx, ny, last_w, last_h;
 };
 
 void terrain_init(struct terrain_map *map);
 void terrain_update(struct terrain_map *map);
 int terrain_render(const struct terrain_map *map, const struct camera *cam);
+void terrain_block_update(const struct util_rect *dim, bool alive, void *p);
 
 extern struct sprite grass_sprite;
 
diff --git a/src/terrain/src/terrain.c b/src/terrain/src/terrain.c
index 23c4015..8f1924c 100644
--- a/src/terrain/src/terrain.c
+++ b/src/terrain/src/terrain.c
@@ -1,6 +1,7 @@
 #include <terrain.h>
 #include <camera.h>
 #include <gfx.h>
+#include <util.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
@@ -26,6 +27,56 @@ void terrain_update(struct terrain_map *const map)
     }
 }
 
+struct block
+{
+    size_t x0, x1, y0, y1;
+};
+
+void terrain_block_update(const struct util_rect *const dim, const bool alive,
+    void *const p)
+{
+    const struct block b =
+    {
+        .x0 = dim->x / TERRAIN_SZ,
+        .x1 = (dim->x + dim->w) / TERRAIN_SZ,
+        .y0 = dim->y / TERRAIN_SZ,
+        .y1 = (dim->y + dim->h) / TERRAIN_SZ
+    };
+
+    for (size_t x = b.x0; x <= b.x1; x++)
+        for (size_t y = b.y0; y <= b.y1; y++)
+            for (size_t i = 0; i < 2; i++)
+                for (size_t j = 0; j < 2; j++)
+                {
+                    const struct util_rect sub =
+                    {
+                        .x = x * TERRAIN_SZ + i * (TERRAIN_SZ / 2),
+                        .y = y * TERRAIN_SZ + j * (TERRAIN_SZ / 2),
+                        .w = TERRAIN_SZ / 2,
+                        .h = TERRAIN_SZ / 2
+                    };
+
+                    if (util_collision(dim, &sub))
+                    {
+                        const enum
+                        {
+                            NO_SUB = 0,
+                            UPPER_LEFT = 1 << 0,
+                            UPPER_RIGHT = 1 << 1,
+                            LOWER_LEFT = 1 << 2,
+                            LOWER_RIGHT = 1 << 3,
+                            ALL_BLOCKS = UPPER_LEFT | UPPER_RIGHT
+                                | LOWER_LEFT | LOWER_RIGHT
+                        } sub = 1 << (i + j * 2);
+
+                        struct terrain_map *const map = p;
+                        unsigned char *const bl = &map->m[y][x].bl;
+
+                        *bl = alive ? *bl | sub : *bl & ~sub;
+                    }
+                }
+}
+
 int terrain_render(const struct terrain_map *const map,
     const struct camera *const cam)
 {
@@ -54,9 +105,11 @@ int terrain_render(const struct terrain_map *const map,
         for (struct m y = {.i = start_y, .p = remy};
             y.i < ny + start_y; y.i++, y.p += TERRAIN_SZ)
         {
+            const struct terrain_tile *const t = &map->m[y.i][x.i];
+
             sprite_get_or_ret(s, -1);
 
-            switch (map->m[y.i][x.i])
+            switch (t->t)
             {
                 case TERRAIN_TYPE_GRASS:
                     if (sprite_clone(&grass_sprite, s))