b2Rope.h

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/*
* Copyright (c) 2011 Erin Catto http://www.box2d.org
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/

#ifndef B2_ROPE_H
#define B2_ROPE_H

#include <Box2D/Common/b2Math.h>

class b2Draw;

struct b2RopeDef
{
        b2RopeDef()
        {
                vertices = NULL;
                count = 0;
                masses = NULL;
                gravity.SetZero();
                damping = 0.1f;
                k2 = 0.9f;
                k3 = 0.1f;
        }

        b2Vec2* vertices;

        int32 count;

        float32* masses;

        b2Vec2 gravity;

        float32 damping;

        float32 k2;

        float32 k3;
};

class b2Rope
{
public:
        b2Rope();
        ~b2Rope();

        void Initialize(const b2RopeDef* def);

        void Step(float32 timeStep, int32 iterations);

        int32 GetVertexCount() const
        {
                return m_count;
        }

        const b2Vec2* GetVertices() const
        {
                return m_ps;
        }

        void Draw(b2Draw* draw) const;

        void SetAngle(float32 angle);

private:

        void SolveC2();
        void SolveC3();

        int32 m_count;
        b2Vec2* m_ps;
        b2Vec2* m_p0s;
        b2Vec2* m_vs;

        float32* m_ims;

        float32* m_Ls;
        float32* m_as;

        b2Vec2 m_gravity;
        float32 m_damping;

        float32 m_k2;
        float32 m_k3;
};

#endif