From a8b3118e8305fd1c668ea25e07157b625c9747ff Mon Sep 17 00:00:00 2001
From: Joursoir <chat@joursoir.net>
Date: Sat, 10 Apr 2021 17:29:02 +0000
Subject: add glm headers

---
 src/include/glm/gtx/quaternion.inl | 159 +++++++++++++++++++++++++++++++++++++
 1 file changed, 159 insertions(+)
 create mode 100644 src/include/glm/gtx/quaternion.inl

(limited to 'src/include/glm/gtx/quaternion.inl')

diff --git a/src/include/glm/gtx/quaternion.inl b/src/include/glm/gtx/quaternion.inl
new file mode 100644
index 0000000..34aed89
--- /dev/null
+++ b/src/include/glm/gtx/quaternion.inl
@@ -0,0 +1,159 @@
+/// @ref gtx_quaternion
+
+#include <limits>
+#include "../gtc/constants.hpp"
+
+namespace glm
+{
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER GLM_CONSTEXPR qua<T, Q> quat_identity()
+	{
+		return qua<T, Q>(static_cast<T>(1), static_cast<T>(0), static_cast<T>(0), static_cast<T>(0));
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER vec<3, T, Q> cross(vec<3, T, Q> const& v, qua<T, Q> const& q)
+	{
+		return inverse(q) * v;
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER vec<3, T, Q> cross(qua<T, Q> const& q, vec<3, T, Q> const& v)
+	{
+		return q * v;
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER qua<T, Q> squad
+	(
+		qua<T, Q> const& q1,
+		qua<T, Q> const& q2,
+		qua<T, Q> const& s1,
+		qua<T, Q> const& s2,
+		T const& h)
+	{
+		return mix(mix(q1, q2, h), mix(s1, s2, h), static_cast<T>(2) * (static_cast<T>(1) - h) * h);
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER qua<T, Q> intermediate
+	(
+		qua<T, Q> const& prev,
+		qua<T, Q> const& curr,
+		qua<T, Q> const& next
+	)
+	{
+		qua<T, Q> invQuat = inverse(curr);
+		return exp((log(next * invQuat) + log(prev * invQuat)) / static_cast<T>(-4)) * curr;
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER vec<3, T, Q> rotate(qua<T, Q> const& q, vec<3, T, Q> const& v)
+	{
+		return q * v;
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER vec<4, T, Q> rotate(qua<T, Q> const& q, vec<4, T, Q> const& v)
+	{
+		return q * v;
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER T extractRealComponent(qua<T, Q> const& q)
+	{
+		T w = static_cast<T>(1) - q.x * q.x - q.y * q.y - q.z * q.z;
+		if(w < T(0))
+			return T(0);
+		else
+			return -sqrt(w);
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER GLM_CONSTEXPR T length2(qua<T, Q> const& q)
+	{
+		return q.x * q.x + q.y * q.y + q.z * q.z + q.w * q.w;
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER qua<T, Q> shortMix(qua<T, Q> const& x, qua<T, Q> const& y, T const& a)
+	{
+		if(a <= static_cast<T>(0)) return x;
+		if(a >= static_cast<T>(1)) return y;
+
+		T fCos = dot(x, y);
+		qua<T, Q> y2(y); //BUG!!! qua<T> y2;
+		if(fCos < static_cast<T>(0))
+		{
+			y2 = -y;
+			fCos = -fCos;
+		}
+
+		//if(fCos > 1.0f) // problem
+		T k0, k1;
+		if(fCos > (static_cast<T>(1) - epsilon<T>()))
+		{
+			k0 = static_cast<T>(1) - a;
+			k1 = static_cast<T>(0) + a; //BUG!!! 1.0f + a;
+		}
+		else
+		{
+			T fSin = sqrt(T(1) - fCos * fCos);
+			T fAngle = atan(fSin, fCos);
+			T fOneOverSin = static_cast<T>(1) / fSin;
+			k0 = sin((static_cast<T>(1) - a) * fAngle) * fOneOverSin;
+			k1 = sin((static_cast<T>(0) + a) * fAngle) * fOneOverSin;
+		}
+
+		return qua<T, Q>(
+			k0 * x.w + k1 * y2.w,
+			k0 * x.x + k1 * y2.x,
+			k0 * x.y + k1 * y2.y,
+			k0 * x.z + k1 * y2.z);
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER qua<T, Q> fastMix(qua<T, Q> const& x, qua<T, Q> const& y, T const& a)
+	{
+		return glm::normalize(x * (static_cast<T>(1) - a) + (y * a));
+	}
+
+	template<typename T, qualifier Q>
+	GLM_FUNC_QUALIFIER qua<T, Q> rotation(vec<3, T, Q> const& orig, vec<3, T, Q> const& dest)
+	{
+		T cosTheta = dot(orig, dest);
+		vec<3, T, Q> rotationAxis;
+
+		if(cosTheta >= static_cast<T>(1) - epsilon<T>()) {
+			// orig and dest point in the same direction
+			return quat_identity<T,Q>();
+		}
+
+		if(cosTheta < static_cast<T>(-1) + epsilon<T>())
+		{
+			// special case when vectors in opposite directions :
+			// there is no "ideal" rotation axis
+			// So guess one; any will do as long as it's perpendicular to start
+			// This implementation favors a rotation around the Up axis (Y),
+			// since it's often what you want to do.
+			rotationAxis = cross(vec<3, T, Q>(0, 0, 1), orig);
+			if(length2(rotationAxis) < epsilon<T>()) // bad luck, they were parallel, try again!
+				rotationAxis = cross(vec<3, T, Q>(1, 0, 0), orig);
+
+			rotationAxis = normalize(rotationAxis);
+			return angleAxis(pi<T>(), rotationAxis);
+		}
+
+		// Implementation from Stan Melax's Game Programming Gems 1 article
+		rotationAxis = cross(orig, dest);
+
+		T s = sqrt((T(1) + cosTheta) * static_cast<T>(2));
+		T invs = static_cast<T>(1) / s;
+
+		return qua<T, Q>(
+			s * static_cast<T>(0.5f),
+			rotationAxis.x * invs,
+			rotationAxis.y * invs,
+			rotationAxis.z * invs);
+	}
+}//namespace glm
-- 
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