Merge remote-tracking branch 'origin/deform-terrain'

Two related issues remain:
* Terrain self shadowing is common and handled poorly
* Odd, but mathematically correct patterns/stripes in feature boundaries

Neither of these relate directly to deformation.

1 files changed, 24 insertions, 27 deletions

diff --git a/lib/maths.h b/lib/maths.h
index 5886326..63b752a 100644
--- a/lib/maths.h
+++ b/lib/maths.h
@@ -8,17 +8,28 @@
 #include <stdexcept>
 #include <utility>
 
-struct Arc : public std::pair<float, float> {
-	using std::pair<float, float>::pair;
+struct Arc : public std::pair<Angle, Angle> {
+	template<glm::length_t Lc, glm::length_t Le, typename T, glm::qualifier Q>
+		requires(Lc >= 2, Le >= 2)
+	Arc(const glm::vec<Lc, T, Q> & centre, const glm::vec<Le, T, Q> & e0p, const glm::vec<Le, T, Q> & e1p) :
+		Arc {RelativePosition2D {e0p.xy() - centre.xy()}, RelativePosition2D {e1p.xy() - centre.xy()}}
+	{
+	}
 
-	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);
+	Arc(const RelativePosition2D & dir0, const RelativePosition2D & dir1);
+	Arc(const Angle angb, const Angle anga);
 
 	auto
 	operator[](bool i) const
 	{
 		return i ? second : first;
 	}
+
+	[[nodiscard]] constexpr inline float
+	length() const
+	{
+		return second - first;
+	}
 };
 
 constexpr const RelativePosition3D up {0, 0, 1};
@@ -84,9 +95,16 @@ glm::mat4 rotate_pitch(float);
 glm::mat4 rotate_yp(Rotation2D);
 glm::mat4 rotate_ypr(Rotation3D);
 
-float vector_yaw(const Direction3D & diff);
+float vector_yaw(const Direction2D & diff);
 float vector_pitch(const Direction3D & diff);
 
+template<typename T, glm::qualifier Q>
+glm::vec<2, T, Q>
+vector_normal(const glm::vec<2, T, Q> & v)
+{
+	return {-v.y, v.x};
+};
+
 float round_frac(const float & v, const float & frac);
 
 template<typename T>
@@ -111,7 +129,7 @@ template<std::integral T, glm::qualifier Q>
 inline constexpr glm::vec<3, T, Q>
 crossProduct(const glm::vec<3, T, Q> a, const glm::vec<3, T, Q> b)
 {
-	return crossProduct<int64_t, Q>(a, b);
+	return crossProduct<Q>(a, b);
 }
 
 template<std::floating_point T, glm::qualifier Q>
@@ -171,12 +189,6 @@ operator%=(glm::vec<L, T, Q> & p, const glm::mat<L + 1, L + 1, T, Q> & mutation)
 	return p = p % mutation;
 }
 
-constexpr inline float
-arc_length(const Arc & arc)
-{
-	return arc.second - arc.first;
-}
-
 float normalize(float ang);
 
 template<typename T, glm::qualifier Q>
@@ -244,21 +256,6 @@ 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