Rename Box2D folder to box2d

src/libraries/box2d/b2_distance_joint.h

@@ -0,0 +1,140 @@
+// MIT License
+
+// Copyright (c) 2019 Erin Catto
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#ifndef B2_DISTANCE_JOINT_H
+#define B2_DISTANCE_JOINT_H
+
+#include "b2_joint.h"
+
+/// Distance joint definition. This requires defining an anchor point on both
+/// bodies and the non-zero length of the distance joint. The definition uses local anchor points
+/// so that the initial configuration can violate the constraint
+/// slightly. This helps when saving and loading a game.
+/// @warning Do not use a zero or short length.
+struct b2DistanceJointDef : public b2JointDef
+{
+	b2DistanceJointDef()
+	{
+		type = e_distanceJoint;
+		localAnchorA.Set(0.0f, 0.0f);
+		localAnchorB.Set(0.0f, 0.0f);
+		length = 1.0f;
+		stiffness = 0.0f;
+		damping = 0.0f;
+	}
+
+	/// Initialize the bodies, anchors, and length using the world
+	/// anchors.
+	void Initialize(b2Body* bodyA, b2Body* bodyB,
+					const b2Vec2& anchorA, const b2Vec2& anchorB);
+
+	/// The local anchor point relative to bodyA's origin.
+	b2Vec2 localAnchorA;
+
+	/// The local anchor point relative to bodyB's origin.
+	b2Vec2 localAnchorB;
+
+	/// The natural length between the anchor points.
+	float length;
+
+	/// The linear stiffness in N/m. A value of 0 disables softness.
+	float stiffness;
+
+	/// The linear damping in N*s/m.
+	float damping;
+};
+
+/// A distance joint constrains two points on two bodies to remain at a fixed
+/// distance from each other. You can view this as a massless, rigid rod.
+class b2DistanceJoint : public b2Joint
+{
+public:
+
+	b2Vec2 GetAnchorA() const override;
+	b2Vec2 GetAnchorB() const override;
+
+	/// Get the reaction force given the inverse time step.
+	/// Unit is N.
+	b2Vec2 GetReactionForce(float inv_dt) const override;
+
+	/// Get the reaction torque given the inverse time step.
+	/// Unit is N*m. This is always zero for a distance joint.
+	float GetReactionTorque(float inv_dt) const override;
+
+	/// The local anchor point relative to bodyA's origin.
+	const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }
+
+	/// The local anchor point relative to bodyB's origin.
+	const b2Vec2& GetLocalAnchorB() const  { return m_localAnchorB; }
+
+	/// Set/get the natural length.
+	/// Manipulating the length can lead to non-physical behavior when the frequency is zero.
+	void SetLength(float length) { m_length = length; }
+	float GetLength() const { return m_length; }
+
+	/// Set/get the linear stiffness in N/m
+	void SetStiffness(float stiffness) { m_stiffness = stiffness; }
+	float GetStiffness() const { return m_stiffness; }
+
+	/// Set/get linear damping in N*s/m
+	void SetDamping(float damping) { m_damping = damping; }
+	float GetDamping() const { return m_damping; }
+
+	/// Dump joint to dmLog
+	void Dump() override;
+
+protected:
+
+	friend class b2Joint;
+	b2DistanceJoint(const b2DistanceJointDef* data);
+
+	void InitVelocityConstraints(const b2SolverData& data) override;
+	void SolveVelocityConstraints(const b2SolverData& data) override;
+	bool SolvePositionConstraints(const b2SolverData& data) override;
+
+	float m_stiffness;
+	float m_damping;
+	float m_bias;
+
+	// Solver shared
+	b2Vec2 m_localAnchorA;
+	b2Vec2 m_localAnchorB;
+	float m_gamma;
+	float m_impulse;
+	float m_length;
+
+	// Solver temp
+	int32 m_indexA;
+	int32 m_indexB;
+	b2Vec2 m_u;
+	b2Vec2 m_rA;
+	b2Vec2 m_rB;
+	b2Vec2 m_localCenterA;
+	b2Vec2 m_localCenterB;
+	float m_invMassA;
+	float m_invMassB;
+	float m_invIA;
+	float m_invIB;
+	float m_mass;
+};
+
+#endif