From ba3ac11b4154669693c73b8de1c84ceb2b585bb6 Mon Sep 17 00:00:00 2001
From: MihailRis <mexaruc@gmail.com>
Date: Tue, 8 Oct 2024 16:26:26 +0300
Subject: [PATCH] optimize lines generation

---
 src/maths/util.hpp                     | 36 ++++++++++++++++++++++++--
 src/world/generator/WorldGenerator.cpp | 10 +------
 2 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/src/maths/util.hpp b/src/maths/util.hpp
index ddedb855..a5302980 100644
--- a/src/maths/util.hpp
+++ b/src/maths/util.hpp
@@ -69,14 +69,28 @@ namespace util {
             rand();
         }
     };
-    
+
+    /// @return integer square of distance between two points
+    /// @note glm::distance2 does not support integer vectors
+    inline int distance2(const glm::ivec3& a, const glm::ivec3& b) {
+        return (b.x - a.x) * (b.x - a.x) +
+            (b.y - a.y) * (b.y - a.y) +
+            (b.z - a.z) * (b.z - a.z);
+    }
+
+    /// @return integer square of vector length
+    /// @note glm::length2 does not support integer vectors
+    inline int length2(const glm::ivec3& a) {
+        return a.x * a.x + a.y * a.y + a.z * a.z;
+    }
+
     /// @brief Find nearest point on segment to given
     /// @param a segment point A
     /// @param b segment point B
     /// @param point given point (may be anywhere)
     /// @return nearest point on the segment to given point 
     inline glm::vec3 closest_point_on_segment(
-        glm::vec3 a, glm::vec3 b, const glm::vec3& point
+        const glm::vec3& a, const glm::vec3& b, const glm::vec3& point
     ) {
         auto vec = b - a;
         float da = glm::distance2(point, a);
@@ -86,4 +100,22 @@ namespace util {
         t = std::min(1.0f, std::max(0.0f, t));
         return a + vec * t;
     }
+
+    /// @brief Find nearest point on segment to given
+    /// @param a segment point A
+    /// @param b segment point B
+    /// @param point given point (may be anywhere)
+    /// @note this overload is actually faster (comment out method to compare)
+    /// @return nearest point on the segment to given point 
+    inline glm::ivec3 closest_point_on_segment(
+        const glm::ivec3& a, const glm::ivec3& b, const glm::ivec3& point
+    ) {
+        auto vec = b - a;
+        float da = distance2(point, a);
+        float db = distance2(point, b);
+        float len = length2(vec);
+        float t = (((da - db) / len) * 0.5f + 0.5f);
+        t = std::min(1.0f, std::max(0.0f, t));
+        return a + glm::ivec3(glm::vec3(vec) * t);
+    }
 }
diff --git a/src/world/generator/WorldGenerator.cpp b/src/world/generator/WorldGenerator.cpp
index f1157343..301049b7 100644
--- a/src/world/generator/WorldGenerator.cpp
+++ b/src/world/generator/WorldGenerator.cpp
@@ -305,14 +305,6 @@ void WorldGenerator::update(int centerX, int centerY, int loadDistance) {
     surroundMap.setCenter(centerX, centerY);
 }
 
-/// @return integer square of distance between two points
-/// @note glm::distance2 does not support integer vectors
-static inline int distance2(const glm::ivec3& a, const glm::ivec3& b) {
-    return (b.x - a.x) * (b.x - a.x) +
-           (b.y - a.y) * (b.y - a.y) +
-           (b.z - a.z) * (b.z - a.z);
-}
-
 void WorldGenerator::generate(voxel* voxels, int chunkX, int chunkZ) {
     surroundMap.completeAt(chunkX, chunkZ);
 
@@ -414,7 +406,7 @@ void WorldGenerator::generate(voxel* voxels, int chunkX, int chunkZ) {
                     glm::ivec3 point {gx, y, gz};
                     glm::ivec3 closest = util::closest_point_on_segment(
                         a, b, point);
-                    if (distance2(closest, point) <= radius*radius) {
+                    if (util::distance2(closest, point) <= radius*radius) {
                         voxels[vox_index(x, y, z)] = {line.block, {}};
                     }
                 }