Merge remote-tracking branch 'origin/terrain'

8 files changed, 153 insertions, 159 deletions

diff --git a/lib/geometricPlane.cpp b/lib/geometricPlane.cpp
index ea4f02d..567f98a 100644
--- a/lib/geometricPlane.cpp
+++ b/lib/geometricPlane.cpp
@@ -4,10 +4,10 @@
 #include <glm/gtx/intersect.hpp>
 
 GeometricPlane::PlaneRelation
-GeometricPlane::getRelation(glm::vec3 p) const
+GeometricPlane::getRelation(Position3D p) const
 {
 	const auto d = glm::dot(normal, p - origin);
-	return d < 0.f ? PlaneRelation::Below : d > 0.f ? PlaneRelation::Above : PlaneRelation::On;
+	return d < 0.F ? PlaneRelation::Below : d > 0.F ? PlaneRelation::Above : PlaneRelation::On;
 }
 
 bool
diff --git a/lib/geometricPlane.h b/lib/geometricPlane.h
index dc8df50..c74beff 100644
--- a/lib/geometricPlane.h
+++ b/lib/geometricPlane.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "config/types.h"
 #include <glm/vec3.hpp>
 #include <optional>
 
@@ -9,14 +10,15 @@ class GeometricPlane {
 public:
 	struct DistAndPosition {
 		float dist;
-		glm::vec3 position;
+		Position3D position;
 	};
 	enum class PlaneRelation { Above, Below, On };
 
-	glm::vec3 origin, normal;
+	Position3D origin;
+	Normal3D normal;
 
-	PlaneRelation getRelation(glm::vec3 point) const;
-	std::optional<DistAndPosition> getRayIntersectPosition(const Ray &) const;
+	[[nodiscard]] PlaneRelation getRelation(Position3D point) const;
+	[[nodiscard]] std::optional<DistAndPosition> getRayIntersectPosition(const Ray &) const;
 
 	static bool isIntersect(PlaneRelation a, PlaneRelation b);
 };
diff --git a/lib/location.cpp b/lib/location.cpp
index 732dd6d..ff7cfa6 100644
--- a/lib/location.cpp
+++ b/lib/location.cpp
@@ -3,7 +3,7 @@
 #include <glm/gtx/transform.hpp>
 
 glm::mat4
-Location::getTransform() const
+Location::getRotationTransform() const
 {
-	return glm::translate(pos) * rotate_ypr(rot);
+	return rotate_ypr(rot);
 }
diff --git a/lib/location.h b/lib/location.h
index 078f5d3..8570fc2 100644
--- a/lib/location.h
+++ b/lib/location.h
@@ -1,14 +1,16 @@
 #pragma once
 
+#include "config/types.h"
 #include <glm/mat4x4.hpp>
-#include <glm/vec3.hpp>
 
 class Location {
 public:
-	explicit Location(glm::vec3 pos = {}, glm::vec3 rot = {}) : pos {pos}, rot {rot} { }
+#ifndef __cpp_aggregate_paren_init
+	explicit Location(GlobalPosition3D pos = {}, Rotation3D rot = {}) : pos {pos}, rot {rot} { }
+#endif
 
-	glm::mat4 getTransform() const;
+	[[nodiscard]] glm::mat4 getRotationTransform() const;
 
-	glm::vec3 pos;
-	glm::vec3 rot;
+	GlobalPosition3D pos;
+	Rotation3D rot;
 };
diff --git a/lib/maths.cpp b/lib/maths.cpp
index 7594b59..68662fc 100644
--- a/lib/maths.cpp
+++ b/lib/maths.cpp
@@ -3,30 +3,29 @@
 #include <glm/glm.hpp>
 #include <glm/gtx/rotate_vector.hpp>
 #include <glm/gtx/transform.hpp>
-#include <stdexcept>
 
 glm::mat4
-flat_orientation(const glm::vec3 & diff)
+flat_orientation(const Direction3D & diff)
 {
 	static const auto oneeighty {glm::rotate(pi, up)};
-	const auto flatdiff {glm::normalize(!!diff)};
+	const auto flatdiff {glm::normalize(diff.xy() || 0.F)};
 	auto e {glm::orientation(flatdiff, north)};
 	// Handle if diff is exactly opposite to north
 	return (std::isnan(e[0][0])) ? oneeighty : e;
 }
 
 // Helper to lookup into a matrix given an xy vector coordinate
-template<typename M>
+template<typename M, typename I>
 inline auto &
-operator^(M & m, glm::ivec2 xy)
+operator^(M & m, glm::vec<2, I> xy)
 {
 	return m[xy.x][xy.y];
 }
 
 // Create a matrix for the angle, given the targets into the matrix
-template<typename M>
+template<typename M, typename I>
 inline auto
-rotation(typename M::value_type a, glm::ivec2 c1, glm::ivec2 s1, glm::ivec2 c2, glm::ivec2 ms2)
+rotation(typename M::value_type a, glm::vec<2, I> c1, glm::vec<2, I> s1, glm::vec<2, I> c2, glm::vec<2, I> ms2)
 {
 	M m(1);
 	sincosf(a, m ^ s1, m ^ c1);
@@ -39,51 +38,51 @@ rotation(typename M::value_type a, glm::ivec2 c1, glm::ivec2 s1, glm::ivec2 c2,
 glm::mat2
 rotate_flat(float a)
 {
-	return rotation<glm::mat2>(a, {0, 0}, {0, 1}, {1, 1}, {1, 0});
+	return rotation<glm::mat2, glm::length_t>(a, {0, 0}, {0, 1}, {1, 1}, {1, 0});
 }
 
 // Create a yaw transformation matrix
 glm::mat4
 rotate_yaw(float a)
 {
-	return rotation<glm::mat4>(a, {0, 0}, {1, 0}, {1, 1}, {0, 1});
+	return rotation<glm::mat4, glm::length_t>(a, {0, 0}, {1, 0}, {1, 1}, {0, 1});
 }
 
 // Create a roll transformation matrix
 glm::mat4
 rotate_roll(float a)
 {
-	return rotation<glm::mat4>(a, {0, 0}, {2, 0}, {2, 2}, {0, 2});
+	return rotation<glm::mat4, glm::length_t>(a, {0, 0}, {2, 0}, {2, 2}, {0, 2});
 }
 
 // Create a pitch transformation matrix
 glm::mat4
 rotate_pitch(float a)
 {
-	return rotation<glm::mat4>(a, {1, 1}, {1, 2}, {2, 2}, {2, 1});
+	return rotation<glm::mat4, glm::length_t>(a, {1, 1}, {1, 2}, {2, 2}, {2, 1});
 }
 
 // Create a combined yaw, pitch, roll transformation matrix
 glm::mat4
-rotate_ypr(glm::vec3 a)
+rotate_ypr(Rotation3D a)
 {
 	return rotate_yaw(a.y) * rotate_pitch(a.x) * rotate_roll(a.z);
 }
 
 glm::mat4
-rotate_yp(glm::vec2 a)
+rotate_yp(Rotation2D a)
 {
 	return rotate_yaw(a.y) * rotate_pitch(a.x);
 }
 
 float
-vector_yaw(const glm::vec3 & diff)
+vector_yaw(const Direction3D & diff)
 {
 	return std::atan2(diff.x, diff.y);
 }
 
 float
-vector_pitch(const glm::vec3 & diff)
+vector_pitch(const Direction3D & diff)
 {
 	return std::atan(diff.z);
 }
@@ -106,77 +105,6 @@ normalize(float ang)
 	return ang;
 }
 
-Arc::Arc(const glm::vec3 & centre3, const glm::vec3 & e0p, const glm::vec3 & e1p) :
-	Arc([&]() -> Arc {
-		const auto diffa = e0p - centre3;
-		const auto diffb = e1p - centre3;
-		const auto anga = vector_yaw(diffa);
-		const auto angb = [&diffb, &anga]() {
-			const auto angb = vector_yaw(diffb);
-			return (angb < anga) ? angb + two_pi : angb;
-		}();
-		return {anga, angb};
-	}())
-{
-}
-
-std::pair<glm::vec2, bool>
-find_arc_centre(glm::vec2 as, float entrys, glm::vec2 bs, float entrye)
-{
-	if (as == bs) {
-		return {as, false};
-	}
-	return find_arc_centre(as, sincosf(entrys + half_pi), bs, sincosf(entrye - half_pi));
-}
-
-std::pair<glm::vec2, bool>
-find_arc_centre(glm::vec2 as, glm::vec2 ad, glm::vec2 bs, glm::vec2 bd)
-{
-	const auto det = bd.x * ad.y - bd.y * ad.x;
-	if (det != 0) { // near parallel line will yield noisy results
-		const auto d = bs - as;
-		const auto u = (d.y * bd.x - d.x * bd.y) / det;
-		return {as + ad * u, u < 0};
-	}
-	throw std::runtime_error("no intersection");
-}
-
-std::pair<float, float>
-find_arcs_radius(glm::vec2 start, float entrys, glm::vec2 end, float entrye)
-{
-	const auto getrad = [&](float leftOrRight) {
-		return find_arcs_radius(start, sincosf(entrys + leftOrRight), end, sincosf(entrye + leftOrRight));
-	};
-	return {getrad(-half_pi), getrad(half_pi)};
-}
-
-float
-find_arcs_radius(glm::vec2 start, glm::vec2 ad, glm::vec2 end, glm::vec2 bd)
-{
-	// Short name functions for big forula
-	auto sqrt = [](float v) {
-		return std::sqrt(v);
-	};
-
-	// Calculates path across both arcs along the normals... pythagorean theorem... for some known radius r
-	// (2r)^2 = ((m + (X*r)) - (o + (Z*r)))^2 + ((n + (Y*r)) - (p + (W*r)))^2
-	// According to symbolabs.com equation tool, that solves for r to give:
-	// r=(-2 m X+2 X o+2 m Z-2 o Z-2 n Y+2 Y p+2 n W-2 p W-sqrt((2 m X-2 X o-2 m Z+2 o Z+2 n Y-2 Y p-2 n W+2 p W)^(2)-4
-	// (X^(2)-2 X Z+Z^(2)+Y^(2)-2 Y W+W^(2)-4) (m^(2)-2 m o+o^(2)+n^(2)-2 n p+p^(2))))/(2 (X^(2)-2 X Z+Z^(2)+Y^(2)-2 Y
-	// W+W^(2)-4))
-
-	// These exist cos limitations of online formula rearrangement, and I'm OK with that.
-	const auto &m {start.x}, &n {start.y}, &o {end.x}, &p {end.y};
-	const auto &X {ad.x}, &Y {ad.y}, &Z {bd.x}, &W {bd.y};
-
-	return (2 * m * X - 2 * X * o - 2 * m * Z + 2 * o * Z + 2 * n * Y - 2 * Y * p - 2 * n * W + 2 * p * W
-				   - sqrt(sq(-2 * m * X + 2 * X * o + 2 * m * Z - 2 * o * Z - 2 * n * Y + 2 * Y * p + 2 * n * W
-								  - 2 * p * W)
-						   - (4 * (sq(X) - 2 * X * Z + sq(Z) + sq(Y) - 2 * Y * W + sq(W) - 4)
-								   * (sq(m) - 2 * m * o + sq(o) + sq(n) - 2 * n * p + sq(p)))))
-			/ (2 * (sq(X) - 2 * X * Z + sq(Z) + sq(Y) - 2 * Y * W + sq(W) - 4));
-}
-
 float
 operator"" _mph(const long double v)
 {
diff --git a/lib/maths.h b/lib/maths.h
index b95b706..c1bf61a 100644
--- a/lib/maths.h
+++ b/lib/maths.h
@@ -1,36 +1,38 @@
 #pragma once
 
+#include "config/types.h"
 #include <cmath>
 #include <glm/glm.hpp>
 #include <glm/gtc/constants.hpp>
 #include <numeric>
+#include <stdexcept>
 #include <utility>
 
 struct Arc : public std::pair<float, float> {
 	using std::pair<float, float>::pair;
 
-	Arc(const glm::vec3 & centre3, const glm::vec3 & e0p, const glm::vec3 & e1p);
+	template<typename T, glm::qualifier Q>
+	Arc(const glm::vec<3, T, Q> & centre3, const glm::vec<3, T, Q> & e0p, const glm::vec<3, T, Q> & e1p);
 
-	float
-	operator[](unsigned int i) const
+	auto
+	operator[](bool i) const
 	{
 		return i ? second : first;
 	}
 };
 
-constexpr const glm::vec3 origin {0, 0, 0};
-constexpr const glm::vec3 up {0, 0, 1};
-constexpr const glm::vec3 down {0, 0, -1};
-constexpr const glm::vec3 north {0, 1, 0};
-constexpr const glm::vec3 south {0, -1, 0};
-constexpr const glm::vec3 east {1, 0, 0};
-constexpr const glm::vec3 west {-1, 0, 0};
+constexpr const RelativePosition3D up {0, 0, 1};
+constexpr const RelativePosition3D down {0, 0, -1};
+constexpr const RelativePosition3D north {0, 1, 0};
+constexpr const RelativePosition3D south {0, -1, 0};
+constexpr const RelativePosition3D east {1, 0, 0};
+constexpr const RelativePosition3D west {-1, 0, 0};
 constexpr auto half_pi {glm::half_pi<float>()};
 constexpr auto quarter_pi {half_pi / 2};
 constexpr auto pi {glm::pi<float>()};
 constexpr auto two_pi {glm::two_pi<float>()};
 
-glm::mat4 flat_orientation(const glm::vec3 & diff);
+glm::mat4 flat_orientation(const Rotation3D & diff);
 
 // C++ wrapper for C's sincosf, but with references, not pointers
 inline auto
@@ -39,10 +41,10 @@ sincosf(float a, float & s, float & c)
 	return sincosf(a, &s, &c);
 }
 
-inline glm::vec2
+inline Rotation2D
 sincosf(float a)
 {
-	glm::vec2 sc;
+	Rotation2D sc;
 	sincosf(a, sc.x, sc.y);
 	return sc;
 }
@@ -51,11 +53,11 @@ glm::mat2 rotate_flat(float);
 glm::mat4 rotate_roll(float);
 glm::mat4 rotate_yaw(float);
 glm::mat4 rotate_pitch(float);
-glm::mat4 rotate_yp(glm::vec2);
-glm::mat4 rotate_ypr(glm::vec3);
+glm::mat4 rotate_yp(Rotation2D);
+glm::mat4 rotate_ypr(Rotation3D);
 
-float vector_yaw(const glm::vec3 & diff);
-float vector_pitch(const glm::vec3 & diff);
+float vector_yaw(const Direction3D & diff);
+float vector_pitch(const Direction3D & diff);
 
 float round_frac(const float & v, const float & frac);
 
@@ -66,6 +68,17 @@ sq(T v)
 	return v * v;
 }
 
+template<std::integral T, glm::qualifier Q>
+inline constexpr glm::vec<3, T, Q>
+crossInt(const glm::vec<3, T, Q> a, const glm::vec<3, T, Q> b)
+{
+	return {
+			(a.y * b.z) - (a.z * b.y),
+			(a.z * b.x) - (a.x * b.z),
+			(a.x * b.y) - (a.y * b.x),
+	};
+}
+
 template<typename R = float, typename Ta, typename Tb>
 inline constexpr auto
 ratio(Ta a, Tb b)
@@ -87,30 +100,6 @@ perspective_divide(glm::vec<4, T, Q> v)
 	return v / v.w;
 }
 
-constexpr inline glm::vec2
-operator!(const glm::vec3 & v)
-{
-	return {v.x, v.y};
-}
-
-constexpr inline glm::vec3
-operator^(const glm::vec2 & v, float z)
-{
-	return {v.x, v.y, z};
-}
-
-constexpr inline glm::vec4
-operator^(const glm::vec3 & v, float w)
-{
-	return {v.x, v.y, v.z, w};
-}
-
-constexpr inline glm::vec3
-operator!(const glm::vec2 & v)
-{
-	return v ^ 0.F;
-}
-
 template<glm::length_t L1, glm::length_t L2, typename T, glm::qualifier Q>
 inline constexpr glm::vec<L1 + L2, T, Q>
 operator||(const glm::vec<L1, T, Q> v1, const glm::vec<L2, T, Q> v2)
@@ -125,15 +114,17 @@ operator||(const glm::vec<L, T, Q> v1, const T v2)
 	return {v1, v2};
 }
 
-inline glm::vec3
-operator%(const glm::vec3 & p, const glm::mat4 & mutation)
+template<glm::length_t L, typename T, glm::qualifier Q>
+inline constexpr glm::vec<L, T, Q>
+operator%(const glm::vec<L, T, Q> & p, const glm::mat<L + 1, L + 1, T, Q> & mutation)
 {
-	const auto p2 = mutation * (p ^ 1);
+	const auto p2 = mutation * (p || T(1));
 	return p2 / p2.w;
 }
 
-inline glm::vec3
-operator%=(glm::vec3 & p, const glm::mat4 & mutation)
+template<glm::length_t L, typename T, glm::qualifier Q>
+inline constexpr glm::vec<L, T, Q>
+operator%=(glm::vec<L, T, Q> & p, const glm::mat<L + 1, L + 1, T, Q> & mutation)
 {
 	return p = p % mutation;
 }
@@ -146,10 +137,63 @@ arc_length(const Arc & arc)
 
 float normalize(float ang);
 
-std::pair<glm::vec2, bool> find_arc_centre(glm::vec2 start, float entrys, glm::vec2 end, float entrye);
-std::pair<glm::vec2, bool> find_arc_centre(glm::vec2 start, glm::vec2 ad, glm::vec2 end, glm::vec2 bd);
-std::pair<float, float> find_arcs_radius(glm::vec2 start, float entrys, glm::vec2 end, float entrye);
-float find_arcs_radius(glm::vec2 start, glm::vec2 ad, glm::vec2 end, glm::vec2 bd);
+template<typename T, glm::qualifier Q>
+std::pair<glm::vec<2, T, Q>, bool>
+find_arc_centre(glm::vec<2, T, Q> start, Rotation2D startDir, glm::vec<2, T, Q> end, Rotation2D endDir)
+{
+	const auto det = endDir.x * startDir.y - endDir.y * startDir.x;
+	if (det != 0) { // near parallel line will yield noisy results
+		const auto d = end - start;
+		const auto u = (d.y * endDir.x - d.x * endDir.y) / det;
+		return {start + startDir * u, u < 0};
+	}
+	throw std::runtime_error("no intersection");
+}
+
+template<typename T, glm::qualifier Q>
+std::pair<glm::vec<2, T, Q>, bool>
+find_arc_centre(glm::vec<2, T, Q> start, Angle entrys, glm::vec<2, T, Q> end, Angle entrye)
+{
+	if (start == end) {
+		return {start, false};
+	}
+	return find_arc_centre(start, sincosf(entrys + half_pi), end, sincosf(entrye - half_pi));
+}
+
+template<typename T, glm::qualifier Q>
+Angle
+find_arcs_radius(glm::vec<2, T, Q> start, Rotation2D ad, glm::vec<2, T, Q> end, Rotation2D bd)
+{
+	using std::sqrt;
+
+	// Calculates path across both arcs along the normals... pythagorean theorem... for some known radius r
+	// (2r)^2 = ((m + (X*r)) - (o + (Z*r)))^2 + ((n + (Y*r)) - (p + (W*r)))^2
+	// According to symbolabs.com equation tool, that solves for r to give:
+	// r=(-2 m X+2 X o+2 m Z-2 o Z-2 n Y+2 Y p+2 n W-2 p W-sqrt((2 m X-2 X o-2 m Z+2 o Z+2 n Y-2 Y p-2 n W+2 p W)^(2)-4
+	// (X^(2)-2 X Z+Z^(2)+Y^(2)-2 Y W+W^(2)-4) (m^(2)-2 m o+o^(2)+n^(2)-2 n p+p^(2))))/(2 (X^(2)-2 X Z+Z^(2)+Y^(2)-2 Y
+	// W+W^(2)-4))
+
+	// These exist cos limitations of online formula rearrangement, and I'm OK with that.
+	const auto &m {start.x}, &n {start.y}, &o {end.x}, &p {end.y};
+	const auto &X {ad.x}, &Y {ad.y}, &Z {bd.x}, &W {bd.y};
+
+	return (2 * m * X - 2 * X * o - 2 * m * Z + 2 * o * Z + 2 * n * Y - 2 * Y * p - 2 * n * W + 2 * p * W
+				   - sqrt(sq(-2 * m * X + 2 * X * o + 2 * m * Z - 2 * o * Z - 2 * n * Y + 2 * Y * p + 2 * n * W
+								  - 2 * p * W)
+						   - (4 * (sq(X) - 2 * X * Z + sq(Z) + sq(Y) - 2 * Y * W + sq(W) - 4)
+								   * (sq(m) - 2 * m * o + sq(o) + sq(n) - 2 * n * p + sq(p)))))
+			/ (2 * (sq(X) - 2 * X * Z + sq(Z) + sq(Y) - 2 * Y * W + sq(W) - 4));
+}
+
+template<typename T, glm::qualifier Q>
+std::pair<Angle, Angle>
+find_arcs_radius(glm::vec<2, T, Q> start, Angle entrys, glm::vec<2, T, Q> end, Angle entrye)
+{
+	const auto getrad = [&](auto leftOrRight) {
+		return find_arcs_radius(start, sincosf(entrys + leftOrRight), end, sincosf(entrye + leftOrRight));
+	};
+	return {getrad(-half_pi), getrad(half_pi)};
+}
 
 template<typename T>
 auto
@@ -158,6 +202,21 @@ midpoint(const std::pair<T, T> & v)
 	return std::midpoint(v.first, v.second);
 }
 
+template<typename T, glm::qualifier Q>
+Arc::Arc(const glm::vec<3, T, Q> & centre3, const glm::vec<3, T, Q> & e0p, const glm::vec<3, T, Q> & e1p) :
+	Arc([&]() -> Arc {
+		const auto diffa = e0p - centre3;
+		const auto diffb = e1p - centre3;
+		const auto anga = vector_yaw(diffa);
+		const auto angb = [&diffb, &anga]() {
+			const auto angb = vector_yaw(diffb);
+			return (angb < anga) ? angb + two_pi : angb;
+		}();
+		return {anga, angb};
+	}())
+{
+}
+
 // Conversions
 template<typename T>
 inline constexpr auto
diff --git a/lib/ray.cpp b/lib/ray.cpp
index c4e0d8c..9fb3648 100644
--- a/lib/ray.cpp
+++ b/lib/ray.cpp
@@ -2,13 +2,13 @@
 #include <algorithm>
 
 Ray
-Ray::fromPoints(glm::vec3 start, glm::vec3 p)
+Ray::fromPoints(Position3D start, Position3D p)
 {
 	return {start, glm::normalize(p - start)};
 }
 
 float
-Ray::distanceToLine(const glm::vec3 & p1, const glm::vec3 & e1) const
+Ray::distanceToLine(const Position3D & p1, const Position3D & e1) const
 {
 	// https://en.wikipedia.org/wiki/Skew_lines
 	const auto diff = p1 - e1;
@@ -25,10 +25,10 @@ Ray::distanceToLine(const glm::vec3 & p1, const glm::vec3 & e1) const
 }
 
 bool
-Ray::passesCloseToEdges(const std::span<const glm::vec3> positions, float distance) const
+Ray::passesCloseToEdges(const std::span<const Position3D> positions, float distance) const
 {
 	return std::adjacent_find(positions.begin(), positions.end(),
-				   [this, distance](const glm::vec3 & a, const glm::vec3 & b) {
+				   [this, distance](const Position3D & a, const Position3D & b) {
 					   return distanceToLine(a, b) <= distance;
 				   })
 			!= positions.end();
diff --git a/lib/ray.h b/lib/ray.h
index 9bf47af..bc70c74 100644
--- a/lib/ray.h
+++ b/lib/ray.h
@@ -1,17 +1,20 @@
 #pragma once
 
+#include "config/types.h"
 #include <glm/glm.hpp>
 #include <span>
 
 class Ray {
 public:
-	Ray(glm::vec3 start, glm::vec3 direction) : start {start}, direction {direction} { }
+#ifndef __cpp_aggregate_paren_init
+	Ray(Position3D start, Direction3D direction) : start {start}, direction {direction} { }
+#endif
 
-	static Ray fromPoints(glm::vec3, glm::vec3);
+	static Ray fromPoints(Position3D, Position3D);
 
-	glm::vec3 start;
-	glm::vec3 direction;
+	Position3D start;
+	Direction3D direction;
 
-	float distanceToLine(const glm::vec3 & a, const glm::vec3 & b) const;
-	bool passesCloseToEdges(const std::span<const glm::vec3> positions, float distance) const;
+	[[nodiscard]] float distanceToLine(const Position3D & a, const Position3D & b) const;
+	[[nodiscard]] bool passesCloseToEdges(const std::span<const Position3D> positions, float distance) const;
 };