From c86f000881bb0160b3f3076b18ee05056b7961cd Mon Sep 17 00:00:00 2001
From: Woeful_Wolf <54476280+WoefulWolf@users.noreply.github.com>
Date: Thu, 1 Feb 2024 22:34:42 +0200
Subject: [PATCH] Moved closest_line_seg_line_seg to common/systems/src/phys.rs
 and renamed to closest_points_ls3

---
 common/systems/src/phys.rs    | 37 ++++++++++++++++++++++++
 voxygen/src/session/target.rs | 53 ++---------------------------------
 2 files changed, 39 insertions(+), 51 deletions(-)

diff --git a/common/systems/src/phys.rs b/common/systems/src/phys.rs
index f12a5738e0..acc93766cd 100644
--- a/common/systems/src/phys.rs
+++ b/common/systems/src/phys.rs
@@ -2200,6 +2200,43 @@ fn closest_points(n: LineSegment2<f32>, m: LineSegment2<f32>) -> (Vec2<f32>, Vec
     }
 }
 
+// Get closest point between 2 3D line segments https://math.stackexchange.com/a/4289668
+pub fn closest_points_ls3(n: LineSegment3<f32>, m: LineSegment3<f32>) -> (Vec3<f32>, Vec3<f32>) {
+    let p1 = n.start;
+    let p2 = n.end;
+    let p3 = m.start;
+    let p4 = m.end;
+
+    let d1 = p2 - p1;
+    let d2 = p4 - p3;
+    let d21 = p3 - p1;
+
+    let v22 = d2.dot(d2);
+    let v11 = d1.dot(d1);
+    let v21 = d2.dot(d1);
+    let v21_1 = d21.dot(d1);
+    let v21_2 = d21.dot(d2);
+
+    let denom = v21 * v21 - v22 * v11;
+
+    let (s, t) = if denom == 0.0 {
+        let s = 0.0;
+        let t = (v11 * s - v21_1) / v21;
+        (s, t)
+    } else {
+        let s = (v21_2 * v21 - v22 * v21_1) / denom;
+        let t = (-v21_1 * v21 + v11 * v21_2) / denom;
+        (s, t)
+    };
+
+    let (s, t) = (s.clamp(0.0, 1.0), t.clamp(0.0, 1.0));
+
+    let p_a = p1 + s * d1;
+    let p_b = p3 + t * d2;
+
+    (p_a, p_b)
+}
+
 /// Find pushback vector and collision_distance we assume between this
 /// colliders assuming that only one of them is capsule prism.
 fn capsule2cylinder(c0: ColliderContext, c1: ColliderContext) -> (Vec2<f32>, f32) {
diff --git a/voxygen/src/session/target.rs b/voxygen/src/session/target.rs
index 70fd3c015a..2cde3bfbac 100644
--- a/voxygen/src/session/target.rs
+++ b/voxygen/src/session/target.rs
@@ -13,6 +13,7 @@ use common::{
     vol::ReadVol,
 };
 use common_base::span;
+use common_systems::phys::closest_points_ls3;
 
 #[derive(Clone, Copy, Debug)]
 pub struct Target<T> {
@@ -305,12 +306,7 @@ pub(super) fn ray_entities(
                             start: world_p0,
                             end: world_p1,
                         };
-                        closest_line_seg_line_seg(
-                            seg_ray.start,
-                            seg_ray.end,
-                            seg_capsule.start,
-                            seg_capsule.end,
-                        )
+                        closest_points_ls3(seg_ray, seg_capsule)
                     } else {
                         let nearest = seg_ray.projected_point(world_p0);
                         (nearest, world_p0)
@@ -338,48 +334,3 @@ pub(super) fn ray_entities(
 
     entity
 }
-
-// Get closest point between 2 line segments https://math.stackexchange.com/a/4289668
-fn closest_line_seg_line_seg(
-    p1: Vec3<f32>,
-    p2: Vec3<f32>,
-    p3: Vec3<f32>,
-    p4: Vec3<f32>,
-) -> (Vec3<f32>, Vec3<f32>) {
-    let p1 = Vec3::new(p1.x as f64, p1.y as f64, p1.z as f64);
-    let p2 = Vec3::new(p2.x as f64, p2.y as f64, p2.z as f64);
-    let p3 = Vec3::new(p3.x as f64, p3.y as f64, p3.z as f64);
-    let p4 = Vec3::new(p4.x as f64, p4.y as f64, p4.z as f64);
-
-    let d1 = p2 - p1;
-    let d2 = p4 - p3;
-    let d21 = p3 - p1;
-
-    let v22 = d2.dot(d2);
-    let v11 = d1.dot(d1);
-    let v21 = d2.dot(d1);
-    let v21_1 = d21.dot(d1);
-    let v21_2 = d21.dot(d2);
-
-    let denom = v21 * v21 - v22 * v11;
-
-    let (s, t) = if denom == 0.0 {
-        let s = 0.0;
-        let t = (v11 * s - v21_1) / v21;
-        (s, t)
-    } else {
-        let s = (v21_2 * v21 - v22 * v21_1) / denom;
-        let t = (-v21_1 * v21 + v11 * v21_2) / denom;
-        (s, t)
-    };
-
-    let (s, t) = (s.clamp(0.0, 1.0), t.clamp(0.0, 1.0));
-
-    let p_a = p1 + s * d1;
-    let p_b = p3 + t * d2;
-
-    (
-        Vec3::new(p_a.x as f32, p_a.y as f32, p_a.z as f32),
-        Vec3::new(p_b.x as f32, p_b.y as f32, p_b.z as f32),
-    )
-}