feat: add cave (#8)

* feat: add cave generate

* fix: incorrect blocks on cave surface

* fix: non-deterministic cave generator

* refactor: move all chunk generation to dedicated generation thread

* refactor: remove inital cave

* feat: add cave parameter adjustment

* refactor: adjust cave probability

src/gameplay/cave_carver.cpp

@@ -0,0 +1,52 @@
+#include "Cubed/gameplay/cave_carver.hpp"
+
+#include "Cubed/constants.hpp"
+
+namespace Cubed {
+CaveCarver::CaveCarver() {}
+
+std::unordered_map<int, CavePath>& CaveCarver::paths() { return m_paths; }
+
+void CaveCarver::init(unsigned world_seed) {
+    m_seed = world_seed;
+    m_sum = 0;
+    m_random.init(m_seed);
+}
+
+void CaveCarver::reload(unsigned world_seed) {
+    m_seed = world_seed;
+    m_paths.clear();
+    init(world_seed);
+}
+
+void CaveCarver::add_path(const glm::vec3& pos) {
+    m_paths.emplace(m_sum, CavePath{m_seed, m_sum, pos});
+    m_sum++;
+}
+
+void CaveCarver::try_to_add_path(const ChunkPos& chunk_pos,
+                                 unsigned chunk_seed) {
+    Random random{chunk_seed};
+    if (random.random_bool(static_cast<double>(m_cave_probability))) {
+        const int CHUNK_MIN_X = chunk_pos.x * CHUNK_SIZE;
+        const int CHUNK_MIN_Z = chunk_pos.z * CHUNK_SIZE;
+        const int CHUNK_MAX_X = CHUNK_MIN_X + SIZE_X - 1;
+        const int CHUNK_MAX_Z = CHUNK_MIN_Z + SIZE_Z - 1;
+        const int CHUNK_MIN_Y = 0;
+        const int CHUNK_MAX_Y = SIZE_Y - 1;
+        int max_y = std::min(CHUNK_MAX_Y, 40);
+        int x = random.random_int(CHUNK_MIN_X, CHUNK_MAX_X);
+        int y = random.random_int(CHUNK_MIN_Y + 1, max_y);
+        int z = random.random_int(CHUNK_MIN_Z, CHUNK_MAX_Z);
+        add_path(glm::vec3{x, y, z});
+    }
+}
+
+void CaveCarver::cleanup_finished_caves() {
+    std::erase_if(m_paths,
+                  [](const auto& kv) { return kv.second.is_finished(); });
+}
+
+int CaveCarver::cave_sum() const { return m_sum; }
+float& CaveCarver::cave_probability() { return m_cave_probability; }
+} // namespace Cubed