optimize chunk intersection tests a little

[blank.git] / src / world.cpp

diff --git a/src/world.cpp b/src/world.cpp
index 5244d152bbe1326e190d2819120c1e54d7b3729f..675c29ffbb97a284737974053ae61c86cc22fa2c 100644 (file)
--- a/src/world.cpp
+++ b/src/world.cpp
@@ -91,6 +91,17 @@ World::World()
 }
 
 
+namespace {
+
+struct Candidate {
+       Chunk *chunk;
+       float dist;
+};
+
+std::vector<Candidate> candidates;
+
+}
+
 bool World::Intersection(
                const Ray &ray,
                const glm::mat4 &M,
@@ -98,18 +109,30 @@ bool World::Intersection(
                int *blkid,
                float *dist,
                glm::vec3 *normal) {
+       candidates.clear();
+
+       for (Chunk &cur_chunk : chunks.Loaded()) {
+               float cur_dist;
+               if (cur_chunk.Intersection(ray, M * cur_chunk.Transform(player.ChunkCoords()), cur_dist)) {
+                       candidates.push_back({ &cur_chunk, cur_dist });
+               }
+       }
+
+       if (candidates.empty()) return false;
+
        Chunk *closest_chunk = nullptr;
-       int closest_blkid = -1;
        float closest_dist = std::numeric_limits<float>::infinity();
+       int closest_blkid = -1;
        glm::vec3 closest_normal;
 
-       for (Chunk &cur_chunk : chunks.Loaded()) {
+       for (Candidate &cand : candidates) {
+               if (cand.dist > closest_dist) continue;
                int cur_blkid;
                float cur_dist;
                glm::vec3 cur_normal;
-               if (cur_chunk.Intersection(ray, M * cur_chunk.Transform(player.ChunkCoords()), &cur_blkid, &cur_dist, &cur_normal)) {
+               if (cand.chunk->Intersection(ray, M * cand.chunk->Transform(player.ChunkCoords()), cur_blkid, cur_dist, cur_normal)) {
                        if (cur_dist < closest_dist) {
-                               closest_chunk = &cur_chunk;
+                               closest_chunk = cand.chunk;
                                closest_blkid = cur_blkid;
                                closest_dist = cur_dist;
                                closest_normal = cur_normal;