forked from mirrors/principia
156 lines
3.3 KiB
C++
156 lines
3.3 KiB
C++
/*
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* Copyright (c) 2013 Google, Inc.
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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* 3. This notice may not be removed or altered from any source distribution.
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*/
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#include <Box2D/Particle/b2ParticleGroup.h>
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#include <Box2D/Particle/b2ParticleSystem.h>
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b2ParticleGroup::b2ParticleGroup()
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{
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m_system = NULL;
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m_firstIndex = 0;
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m_lastIndex = 0;
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m_groupFlags = 0;
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m_strength = 1.0f;
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m_prev = NULL;
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m_next = NULL;
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m_timestamp = -1;
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m_mass = 0;
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m_inertia = 0;
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m_center = b2Vec2_zero;
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m_linearVelocity = b2Vec2_zero;
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m_angularVelocity = 0;
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m_transform.SetIdentity();
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m_destroyAutomatically = true;
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m_toBeDestroyed = false;
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m_toBeSplit = false;
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m_userData = NULL;
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}
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b2ParticleGroup::~b2ParticleGroup()
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{
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}
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int32 b2ParticleGroup::GetBufferIndex() const
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{
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return m_firstIndex;
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}
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int32 b2ParticleGroup::GetGroupFlags() const
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{
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return m_groupFlags;
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}
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void b2ParticleGroup::SetGroupFlags(int32 flags)
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{
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m_groupFlags = flags;
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}
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float32 b2ParticleGroup::GetMass() const
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{
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UpdateStatistics();
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return m_mass;
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}
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float32 b2ParticleGroup::GetInertia() const
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{
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UpdateStatistics();
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return m_inertia;
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}
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b2Vec2 b2ParticleGroup::GetCenter() const
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{
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UpdateStatistics();
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return m_center;
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}
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b2Vec2 b2ParticleGroup::GetLinearVelocity() const
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{
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UpdateStatistics();
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return m_linearVelocity;
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}
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float32 b2ParticleGroup::GetAngularVelocity() const
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{
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UpdateStatistics();
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return m_angularVelocity;
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}
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const b2Transform& b2ParticleGroup::GetTransform() const
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{
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return m_transform;
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}
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const b2Vec2& b2ParticleGroup::GetPosition() const
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{
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return m_transform.p;
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}
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float32 b2ParticleGroup::GetAngle() const
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{
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return m_transform.q.GetAngle();
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}
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void* b2ParticleGroup::GetUserData() const
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{
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return m_userData;
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}
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void b2ParticleGroup::SetUserData(void* data)
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{
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m_userData = data;
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}
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void b2ParticleGroup::UpdateStatistics() const
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{
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if (m_timestamp != m_system->m_timestamp)
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{
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float32 m = m_system->GetParticleMass();
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m_mass = 0;
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m_center.SetZero();
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m_linearVelocity.SetZero();
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for (int32 i = m_firstIndex; i < m_lastIndex; i++)
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{
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m_mass += m;
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m_center += m * m_system->m_positionBuffer.data[i];
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m_linearVelocity += m * m_system->m_velocityBuffer.data[i];
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}
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if (m_mass > 0)
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{
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m_center *= 1 / m_mass;
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m_linearVelocity *= 1 / m_mass;
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}
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m_inertia = 0;
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m_angularVelocity = 0;
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for (int32 i = m_firstIndex; i < m_lastIndex; i++)
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{
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b2Vec2 p = m_system->m_positionBuffer.data[i] - m_center;
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b2Vec2 v = m_system->m_velocityBuffer.data[i] - m_linearVelocity;
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m_inertia += m * b2Dot(p, p);
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m_angularVelocity += m * b2Cross(p, v);
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}
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if (m_inertia > 0)
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{
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m_angularVelocity *= 1 / m_inertia;
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}
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m_timestamp = m_system->m_timestamp;
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}
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}
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