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Improve reachability search for scanline filling 

Just do a second BFS from the current position, reset the current
scanline reachability.
scene_man
En Yi 2023-07-20 23:25:32 +08:00
parent 7607827420
commit 6e2ccfa875
2 changed files with 100 additions and 75 deletions
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1
scenes/engine/EC/EC.h
View File

@ -147,6 +147,7 @@ typedef enum _WaterRunnerState
BFS_START,
LOWEST_POINT_SEARCH,
LOWEST_POINT_MOVEMENT,
REACHABILITY_SEARCH,
SCANLINE_FILL,
}WaterRunerState_t;

174
scenes/water_flow.c
View File

@ -45,6 +45,84 @@ void free_water_runner(Entity_t* ent, EntityManager_t* ent_manager)
remove_entity(ent_manager, ent->m_id);
}
static void runner_BFS(const TileGrid_t* tilemap, CWaterRunner_t* p_crunner, int32_t* lowest_tile)
{
while (!sc_queue_empty(&p_crunner->bfs_queue))
{
unsigned int curr_idx = sc_queue_peek_first(&p_crunner->bfs_queue);
sc_queue_del_first(&p_crunner->bfs_queue);
unsigned int curr_height = curr_idx / p_crunner->bfs_tilemap.width;
unsigned int curr_low = *lowest_tile / p_crunner->bfs_tilemap.width;
// Possible optimisation to avoid repeated BFS, dunno how possible
bool to_go[4] = {false, false, false, false};
Tile_t* curr_tile = tilemap->tiles + curr_idx;
unsigned int next = curr_idx + p_crunner->bfs_tilemap.width;
Tile_t* next_tile = tilemap->tiles + next;
if (
curr_height > curr_low
&& curr_tile->water_level < tilemap->max_water_level
&& next_tile->water_level < tilemap->max_water_level
)
{
*lowest_tile = curr_idx;
}
if (next < p_crunner->bfs_tilemap.len)
{
to_go[0] = next_tile->solid != SOLID;
}
if (
next_tile->solid == SOLID
|| next_tile->water_level == tilemap->max_water_level
|| curr_tile->water_level == tilemap->max_water_level
)
{
if (curr_idx % p_crunner->bfs_tilemap.width != 0)
{
next = curr_idx - 1;
next_tile = tilemap->tiles + next;
to_go[1] = next_tile->solid != SOLID;
}
next = curr_idx + 1;
if (next % p_crunner->bfs_tilemap.width != 0)
{
next_tile = tilemap->tiles + next;
to_go[2] = next_tile->solid != SOLID;
}
}
if (curr_tile->water_level == tilemap->max_water_level)
{
next = curr_idx - p_crunner->bfs_tilemap.width;
if (next >= 0 && next / p_crunner->bfs_tilemap.width >= p_crunner->start_height)
{
next_tile = tilemap->tiles + next;
to_go[3] = next_tile->solid != SOLID;
}
}
const int8_t offsets[4] = {p_crunner->bfs_tilemap.width, -1, 1, -p_crunner->bfs_tilemap.width};
for (uint8_t i = 0; i < 4; ++i)
{
next = curr_idx + offsets[i];
if (to_go[i] && !p_crunner->visited[next])
{
sc_queue_add_last(&p_crunner->bfs_queue, next);
p_crunner->bfs_tilemap.tilemap[next].from = curr_idx;
p_crunner->visited[next] = true;
p_crunner->bfs_tilemap.tilemap[next].reachable = true;
}
}
}
}
void update_water_runner_system(Scene_t* scene)
{
// The core of the water runner is to:
@ -109,80 +187,7 @@ void update_water_runner_system(Scene_t* scene)
// Want the fallthough
case LOWEST_POINT_SEARCH:
{
while (!sc_queue_empty(&p_crunner->bfs_queue))
{
unsigned int curr_idx = sc_queue_peek_first(&p_crunner->bfs_queue);
sc_queue_del_first(&p_crunner->bfs_queue);
unsigned int curr_height = curr_idx / p_crunner->bfs_tilemap.width;
unsigned int curr_low = lowest_tile / p_crunner->bfs_tilemap.width;
// Possible optimisation to avoid repeated BFS, dunno how possible
bool to_go[4] = {false, false, false, false};
Tile_t* curr_tile = tilemap.tiles + curr_idx;
unsigned int next = curr_idx + p_crunner->bfs_tilemap.width;
Tile_t* next_tile = tilemap.tiles + next;
if (
curr_height > curr_low
&& curr_tile->water_level < tilemap.max_water_level
&& next_tile->water_level < tilemap.max_water_level
)
{
lowest_tile = curr_idx;
}
if (next < p_crunner->bfs_tilemap.len)
{
to_go[0] = next_tile->solid != SOLID;
}
if (
next_tile->solid == SOLID
|| next_tile->water_level == tilemap.max_water_level
|| curr_tile->water_level == tilemap.max_water_level
)
{
if (curr_idx % p_crunner->bfs_tilemap.width != 0)
{
next = curr_idx - 1;
next_tile = tilemap.tiles + next;
to_go[1] = next_tile->solid != SOLID;
}
next = curr_idx + 1;
if (next % p_crunner->bfs_tilemap.width != 0)
{
next_tile = tilemap.tiles + next;
to_go[2] = next_tile->solid != SOLID;
}
}
if (curr_tile->water_level == tilemap.max_water_level)
{
next = curr_idx - p_crunner->bfs_tilemap.width;
if (next >= 0 && next / p_crunner->bfs_tilemap.width >= p_crunner->start_height)
{
next_tile = tilemap.tiles + next;
to_go[3] = next_tile->solid != SOLID;
}
}
const int8_t offsets[4] = {p_crunner->bfs_tilemap.width, -1, 1, -p_crunner->bfs_tilemap.width};
for (uint8_t i = 0; i < 4; ++i)
{
next = curr_idx + offsets[i];
if (to_go[i] && !p_crunner->visited[next])
{
sc_queue_add_last(&p_crunner->bfs_queue, next);
p_crunner->bfs_tilemap.tilemap[next].from = curr_idx;
p_crunner->visited[next] = true;
p_crunner->bfs_tilemap.tilemap[next].reachable = true;
}
}
}
runner_BFS(&tilemap, p_crunner, &lowest_tile);
p_crunner->target_tile = lowest_tile;
if (p_crunner->target_tile == p_crunner->current_tile)
@ -213,11 +218,30 @@ void update_water_runner_system(Scene_t* scene)
p_ct->position.y = (p_crunner->current_tile / tilemap.width) * tilemap.tile_size;
if (p_crunner->current_tile == p_crunner->target_tile)
{
p_crunner->state = SCANLINE_FILL;
p_crunner->state = REACHABILITY_SEARCH;
}
p_crunner->counter = p_crunner->movement_delay;
}
break;
case REACHABILITY_SEARCH:
{
unsigned int start_tile =
(p_crunner->current_tile / p_crunner->bfs_tilemap.width) * p_crunner->bfs_tilemap.width;
for (size_t i = 0; i < p_crunner->bfs_tilemap.width; ++i)
{
p_crunner->bfs_tilemap.tilemap[start_tile + i].reachable = false;
}
memset(p_crunner->visited, 0, p_crunner->bfs_tilemap.len * sizeof(bool));
p_crunner->bfs_tilemap.tilemap[p_crunner->current_tile].reachable = true;
sc_queue_add_last(&p_crunner->bfs_queue, p_crunner->current_tile);
int32_t lowest_tile = p_crunner->current_tile;
runner_BFS(&tilemap, p_crunner, &lowest_tile);
p_crunner->state = SCANLINE_FILL;
}
break;
default:
break;
}