b2Body.cpp
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上传日期:2022-01-07
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- /*
- * Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
- *
- * 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.
- */
- #include <Box2D/Dynamics/b2Body.h>
- #include <Box2D/Dynamics/b2Fixture.h>
- #include <Box2D/Dynamics/b2World.h>
- #include <Box2D/Dynamics/Contacts/b2Contact.h>
- #include <Box2D/Dynamics/Joints/b2Joint.h>
- b2Body::b2Body(const b2BodyDef* bd, b2World* world)
- {
- b2Assert(bd->position.IsValid());
- b2Assert(bd->linearVelocity.IsValid());
- b2Assert(b2IsValid(bd->angle));
- b2Assert(b2IsValid(bd->angularVelocity));
- b2Assert(b2IsValid(bd->inertiaScale) && bd->inertiaScale >= 0.0f);
- b2Assert(b2IsValid(bd->angularDamping) && bd->angularDamping >= 0.0f);
- b2Assert(b2IsValid(bd->linearDamping) && bd->linearDamping >= 0.0f);
- m_flags = 0;
- if (bd->bullet)
- {
- m_flags |= e_bulletFlag;
- }
- if (bd->fixedRotation)
- {
- m_flags |= e_fixedRotationFlag;
- }
- if (bd->allowSleep)
- {
- m_flags |= e_autoSleepFlag;
- }
- if (bd->awake)
- {
- m_flags |= e_awakeFlag;
- }
- if (bd->active)
- {
- m_flags |= e_activeFlag;
- }
- m_world = world;
- m_xf.position = bd->position;
- m_xf.R.Set(bd->angle);
- m_sweep.localCenter.SetZero();
- m_sweep.a0 = m_sweep.a = bd->angle;
- m_sweep.c0 = m_sweep.c = b2Mul(m_xf, m_sweep.localCenter);
- m_jointList = NULL;
- m_contactList = NULL;
- m_prev = NULL;
- m_next = NULL;
- m_linearVelocity = bd->linearVelocity;
- m_angularVelocity = bd->angularVelocity;
- m_linearDamping = bd->linearDamping;
- m_angularDamping = bd->angularDamping;
- m_force.SetZero();
- m_torque = 0.0f;
- m_sleepTime = 0.0f;
- m_type = bd->type;
- if (m_type == b2_dynamicBody)
- {
- m_mass = 1.0f;
- m_invMass = 1.0f;
- }
- else
- {
- m_mass = 0.0f;
- m_invMass = 0.0f;
- }
- m_I = 0.0f;
- m_invI = 0.0f;
- m_userData = bd->userData;
- m_fixtureList = NULL;
- m_fixtureCount = 0;
- }
- b2Body::~b2Body()
- {
- // shapes and joints are destroyed in b2World::Destroy
- }
- void b2Body::SetType(b2BodyType type)
- {
- if (m_type == type)
- {
- return;
- }
- m_type = type;
- ResetMassData();
- if (m_type == b2_staticBody)
- {
- m_linearVelocity.SetZero();
- m_angularVelocity = 0.0f;
- }
- SetAwake(true);
- m_force.SetZero();
- m_torque = 0.0f;
- // Since the body type changed, we need to flag contacts for filtering.
- for (b2ContactEdge* ce = m_contactList; ce; ce = ce->next)
- {
- ce->contact->FlagForFiltering();
- }
- }
- b2Fixture* b2Body::CreateFixture(const b2FixtureDef* def)
- {
- b2Assert(m_world->IsLocked() == false);
- if (m_world->IsLocked() == true)
- {
- return NULL;
- }
- b2BlockAllocator* allocator = &m_world->m_blockAllocator;
- void* memory = allocator->Allocate(sizeof(b2Fixture));
- b2Fixture* fixture = new (memory) b2Fixture;
- fixture->Create(allocator, this, def);
- if (m_flags & e_activeFlag)
- {
- b2BroadPhase* broadPhase = &m_world->m_contactManager.m_broadPhase;
- fixture->CreateProxy(broadPhase, m_xf);
- }
- fixture->m_next = m_fixtureList;
- m_fixtureList = fixture;
- ++m_fixtureCount;
- fixture->m_body = this;
- // Adjust mass properties if needed.
- if (fixture->m_density > 0.0f)
- {
- ResetMassData();
- }
- // Let the world know we have a new fixture. This will cause new contacts
- // to be created at the beginning of the next time step.
- m_world->m_flags |= b2World::e_newFixture;
- return fixture;
- }
- b2Fixture* b2Body::CreateFixture(const b2Shape* shape, float32 density)
- {
- b2FixtureDef def;
- def.shape = shape;
- def.density = density;
- return CreateFixture(&def);
- }
- void b2Body::DestroyFixture(b2Fixture* fixture)
- {
- b2Assert(m_world->IsLocked() == false);
- if (m_world->IsLocked() == true)
- {
- return;
- }
- b2Assert(fixture->m_body == this);
- // Remove the fixture from this body's singly linked list.
- b2Assert(m_fixtureCount > 0);
- b2Fixture** node = &m_fixtureList;
- bool found = false;
- while (*node != NULL)
- {
- if (*node == fixture)
- {
- *node = fixture->m_next;
- found = true;
- break;
- }
- node = &(*node)->m_next;
- }
- // You tried to remove a shape that is not attached to this body.
- b2Assert(found);
- // Destroy any contacts associated with the fixture.
- b2ContactEdge* edge = m_contactList;
- while (edge)
- {
- b2Contact* c = edge->contact;
- edge = edge->next;
- b2Fixture* fixtureA = c->GetFixtureA();
- b2Fixture* fixtureB = c->GetFixtureB();
- if (fixture == fixtureA || fixture == fixtureB)
- {
- // This destroys the contact and removes it from
- // this body's contact list.
- m_world->m_contactManager.Destroy(c);
- }
- }
- b2BlockAllocator* allocator = &m_world->m_blockAllocator;
- if (m_flags & e_activeFlag)
- {
- b2Assert(fixture->m_proxyId != b2BroadPhase::e_nullProxy);
- b2BroadPhase* broadPhase = &m_world->m_contactManager.m_broadPhase;
- fixture->DestroyProxy(broadPhase);
- }
- else
- {
- b2Assert(fixture->m_proxyId == b2BroadPhase::e_nullProxy);
- }
- fixture->Destroy(allocator);
- fixture->m_body = NULL;
- fixture->m_next = NULL;
- fixture->~b2Fixture();
- allocator->Free(fixture, sizeof(b2Fixture));
- --m_fixtureCount;
- // Reset the mass data.
- ResetMassData();
- }
- void b2Body::ResetMassData()
- {
- // Compute mass data from shapes. Each shape has its own density.
- m_mass = 0.0f;
- m_invMass = 0.0f;
- m_I = 0.0f;
- m_invI = 0.0f;
- m_sweep.localCenter.SetZero();
- // Static and kinematic bodies have zero mass.
- if (m_type == b2_staticBody || m_type == b2_kinematicBody)
- {
- m_sweep.c0 = m_sweep.c = m_xf.position;
- return;
- }
- b2Assert(m_type == b2_dynamicBody);
- // Accumulate mass over all fixtures.
- b2Vec2 center = b2Vec2_zero;
- for (b2Fixture* f = m_fixtureList; f; f = f->m_next)
- {
- if (f->m_density == 0.0f)
- {
- continue;
- }
- b2MassData massData;
- f->GetMassData(&massData);
- m_mass += massData.mass;
- center += massData.mass * massData.center;
- m_I += massData.I;
- }
- // Compute center of mass.
- if (m_mass > 0.0f)
- {
- m_invMass = 1.0f / m_mass;
- center *= m_invMass;
- }
- else
- {
- // Force all dynamic bodies to have a positive mass.
- m_mass = 1.0f;
- m_invMass = 1.0f;
- }
- if (m_I > 0.0f && (m_flags & e_fixedRotationFlag) == 0)
- {
- // Center the inertia about the center of mass.
- m_I -= m_mass * b2Dot(center, center);
- b2Assert(m_I > 0.0f);
- m_invI = 1.0f / m_I;
- }
- else
- {
- m_I = 0.0f;
- m_invI = 0.0f;
- }
- // Move center of mass.
- b2Vec2 oldCenter = m_sweep.c;
- m_sweep.localCenter = center;
- m_sweep.c0 = m_sweep.c = b2Mul(m_xf, m_sweep.localCenter);
- // Update center of mass velocity.
- m_linearVelocity += b2Cross(m_angularVelocity, m_sweep.c - oldCenter);
- }
- void b2Body::SetMassData(const b2MassData* massData)
- {
- b2Assert(m_world->IsLocked() == false);
- if (m_world->IsLocked() == true)
- {
- return;
- }
- if (m_type != b2_dynamicBody)
- {
- return;
- }
- m_invMass = 0.0f;
- m_I = 0.0f;
- m_invI = 0.0f;
- m_mass = massData->mass;
- if (m_mass <= 0.0f)
- {
- m_mass = 1.0f;
- }
- m_invMass = 1.0f / m_mass;
- if (massData->I > 0.0f && (m_flags & b2Body::e_fixedRotationFlag) == 0)
- {
- m_I = massData->I - m_mass * b2Dot(massData->center, massData->center);
- b2Assert(m_I > 0.0f);
- m_invI = 1.0f / m_I;
- }
- // Move center of mass.
- b2Vec2 oldCenter = m_sweep.c;
- m_sweep.localCenter = massData->center;
- m_sweep.c0 = m_sweep.c = b2Mul(m_xf, m_sweep.localCenter);
- // Update center of mass velocity.
- m_linearVelocity += b2Cross(m_angularVelocity, m_sweep.c - oldCenter);
- }
- bool b2Body::ShouldCollide(const b2Body* other) const
- {
- // At least one body should be dynamic.
- if (m_type != b2_dynamicBody && other->m_type != b2_dynamicBody)
- {
- return false;
- }
- // Does a joint prevent collision?
- for (b2JointEdge* jn = m_jointList; jn; jn = jn->next)
- {
- if (jn->other == other)
- {
- if (jn->joint->m_collideConnected == false)
- {
- return false;
- }
- }
- }
- return true;
- }
- void b2Body::SetTransform(const b2Vec2& position, float32 angle)
- {
- b2Assert(m_world->IsLocked() == false);
- if (m_world->IsLocked() == true)
- {
- return;
- }
- m_xf.R.Set(angle);
- m_xf.position = position;
- m_sweep.c0 = m_sweep.c = b2Mul(m_xf, m_sweep.localCenter);
- m_sweep.a0 = m_sweep.a = angle;
- b2BroadPhase* broadPhase = &m_world->m_contactManager.m_broadPhase;
- for (b2Fixture* f = m_fixtureList; f; f = f->m_next)
- {
- f->Synchronize(broadPhase, m_xf, m_xf);
- }
- m_world->m_contactManager.FindNewContacts();
- }
- void b2Body::SynchronizeFixtures()
- {
- b2Transform xf1;
- xf1.R.Set(m_sweep.a0);
- xf1.position = m_sweep.c0 - b2Mul(xf1.R, m_sweep.localCenter);
- b2BroadPhase* broadPhase = &m_world->m_contactManager.m_broadPhase;
- for (b2Fixture* f = m_fixtureList; f; f = f->m_next)
- {
- f->Synchronize(broadPhase, xf1, m_xf);
- }
- }
- void b2Body::SetActive(bool flag)
- {
- if (flag == IsActive())
- {
- return;
- }
- if (flag)
- {
- m_flags |= e_activeFlag;
- // Create all proxies.
- b2BroadPhase* broadPhase = &m_world->m_contactManager.m_broadPhase;
- for (b2Fixture* f = m_fixtureList; f; f = f->m_next)
- {
- f->CreateProxy(broadPhase, m_xf);
- }
- // Contacts are created the next time step.
- }
- else
- {
- m_flags &= ~e_activeFlag;
- // Destroy all proxies.
- b2BroadPhase* broadPhase = &m_world->m_contactManager.m_broadPhase;
- for (b2Fixture* f = m_fixtureList; f; f = f->m_next)
- {
- f->DestroyProxy(broadPhase);
- }
- // Destroy the attached contacts.
- b2ContactEdge* ce = m_contactList;
- while (ce)
- {
- b2ContactEdge* ce0 = ce;
- ce = ce->next;
- m_world->m_contactManager.Destroy(ce0->contact);
- }
- m_contactList = NULL;
- }
- }