optimize chunk intersection tests a little

diff --git a/src/chunk.cpp b/src/chunk.cpp
index f43f8fd524582525a08d0f915e1e7d9d02db752e..e61a3a70ba0260a2600f8498fb4c24996c1c89d3 100644 (file)
--- a/src/chunk.cpp
+++ b/src/chunk.cpp
@@ -56,24 +56,14 @@ void Chunk::Draw() {
 bool Chunk::Intersection(
        const Ray &ray,
        const glm::mat4 &M,
-       int *blkid,
-       float *dist,
-       glm::vec3 *normal) const {
-       { // rough check
-               if (!blank::Intersection(ray, Bounds(), M)) {
-                       return false;
-               }
-       }
-
-       if (!blkid && !dist && !normal) {
-               return true;
-       }
-
+       int &blkid,
+       float &dist,
+       glm::vec3 &normal
+) const {
        // TODO: should be possible to heavily optimize this
        int id = 0;
-       int closest_id = -1;
-       float closest_dist = std::numeric_limits<float>::infinity();
-       glm::vec3 closest_normal(0, 1, 0);
+       blkid = -1;
+       dist = std::numeric_limits<float>::infinity();
        for (int z = 0; z < Depth(); ++z) {
                for (int y = 0; y < Height(); ++y) {
                        for (int x = 0; x < Width(); ++x, ++id) {
@@ -83,30 +73,22 @@ bool Chunk::Intersection(
                                float cur_dist;
                                glm::vec3 cur_norm;
                                if (Type(blocks[id]).shape->Intersects(ray, M * ToTransform(id), cur_dist, cur_norm)) {
-                                       if (cur_dist < closest_dist) {
-                                               closest_id = id;
-                                               closest_dist = cur_dist;
-                                               closest_normal = cur_norm;
+                                       if (cur_dist < dist) {
+                                               blkid = id;
+                                               dist = cur_dist;
+                                               normal = cur_norm;
                                        }
                                }
                        }
                }
        }
 
-       if (closest_id < 0) {
+       if (blkid < 0) {
                return false;
+       } else {
+               normal = glm::vec3(BlockAt(blkid).Transform() * glm::vec4(normal, 0.0f));
+               return true;
        }
-
-       if (blkid) {
-               *blkid = closest_id;
-       }
-       if (dist) {
-               *dist = closest_dist;
-       }
-       if (normal) {
-               *normal = glm::vec3(BlockAt(closest_id).Transform() * glm::vec4(closest_normal, 0.0f));
-       }
-       return true;
 }
 
 void Chunk::Position(const Pos &pos) {

diff --git a/src/chunk.hpp b/src/chunk.hpp
index 255d73b163f70ff25db4bade6f1b9a087a767aee..19f5c07ea31f453b0b10573342c8bebe7f44dc04 100644 (file)
--- a/src/chunk.hpp
+++ b/src/chunk.hpp
@@ -74,12 +74,20 @@ public:
 
        const BlockType &Type(const Block &b) const { return *types->Get(b.type); }
 
+       bool Intersection(
+               const Ray &ray,
+               const glm::mat4 &M,
+               float &dist
+       ) const {
+               return blank::Intersection(ray, Bounds(), M, &dist);
+       }
+
        bool Intersection(
                const Ray &,
                const glm::mat4 &M,
-               int *blkid = nullptr,
-               float *dist = nullptr,
-               glm::vec3 *normal = nullptr) const;
+               int &blkid,
+               float &dist,
+               glm::vec3 &normal) const;
 
        void Position(const Pos &);
        const Pos &Position() const { return position; }

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;