mirror of https://github.com/axmolengine/axmol.git
135 lines
3.9 KiB
C++
135 lines
3.9 KiB
C++
// MIT License
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// Copyright (c) 2019 Erin Catto
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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#ifndef B2_MOUSE_JOINT_H
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#define B2_MOUSE_JOINT_H
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#include "b2_api.h"
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#include "b2_joint.h"
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/// Mouse joint definition. This requires a world target point,
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/// tuning parameters, and the time step.
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struct B2_API b2MouseJointDef : public b2JointDef
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{
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b2MouseJointDef()
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{
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type = e_mouseJoint;
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target.Set(0.0f, 0.0f);
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maxForce = 0.0f;
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stiffness = 0.0f;
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damping = 0.0f;
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}
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/// The initial world target point. This is assumed
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/// to coincide with the body anchor initially.
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b2Vec2 target;
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/// The maximum constraint force that can be exerted
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/// to move the candidate body. Usually you will express
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/// as some multiple of the weight (multiplier * mass * gravity).
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float maxForce;
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/// The linear stiffness in N/m
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float stiffness;
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/// The linear damping in N*s/m
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float damping;
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};
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/// A mouse joint is used to make a point on a body track a
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/// specified world point. This a soft constraint with a maximum
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/// force. This allows the constraint to stretch and without
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/// applying huge forces.
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/// NOTE: this joint is not documented in the manual because it was
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/// developed to be used in the testbed. If you want to learn how to
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/// use the mouse joint, look at the testbed.
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class B2_API b2MouseJoint : public b2Joint
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{
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public:
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/// Implements b2Joint.
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b2Vec2 GetAnchorA() const override;
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/// Implements b2Joint.
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b2Vec2 GetAnchorB() const override;
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/// Implements b2Joint.
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b2Vec2 GetReactionForce(float inv_dt) const override;
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/// Implements b2Joint.
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float GetReactionTorque(float inv_dt) const override;
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/// Use this to update the target point.
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void SetTarget(const b2Vec2& target);
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const b2Vec2& GetTarget() const;
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/// Set/get the maximum force in Newtons.
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void SetMaxForce(float force);
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float GetMaxForce() const;
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/// Set/get the linear stiffness in N/m
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void SetStiffness(float stiffness) { m_stiffness = stiffness; }
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float GetStiffness() const { return m_stiffness; }
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/// Set/get linear damping in N*s/m
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void SetDamping(float damping) { m_damping = damping; }
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float GetDamping() const { return m_damping; }
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/// The mouse joint does not support dumping.
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void Dump() override { b2Log("Mouse joint dumping is not supported.\n"); }
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/// Implement b2Joint::ShiftOrigin
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void ShiftOrigin(const b2Vec2& newOrigin) override;
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protected:
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friend class b2Joint;
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b2MouseJoint(const b2MouseJointDef* def);
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void InitVelocityConstraints(const b2SolverData& data) override;
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void SolveVelocityConstraints(const b2SolverData& data) override;
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bool SolvePositionConstraints(const b2SolverData& data) override;
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b2Vec2 m_localAnchorB;
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b2Vec2 m_targetA;
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float m_stiffness;
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float m_damping;
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float m_beta;
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// Solver shared
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b2Vec2 m_impulse;
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float m_maxForce;
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float m_gamma;
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// Solver temp
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int32 m_indexA;
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int32 m_indexB;
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b2Vec2 m_rB;
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b2Vec2 m_localCenterB;
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float m_invMassB;
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float m_invIB;
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b2Mat22 m_mass;
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b2Vec2 m_C;
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};
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#endif
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