git.maemo.org Git - blok/blob - Box2D/Source/Dynamics/Contacts/b2CircleContact.cpp

   1 /*
   2 * Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
   3 *
   4 * This software is provided 'as-is', without any express or implied
   5 * warranty.  In no event will the authors be held liable for any damages
   6 * arising from the use of this software.
   7 * Permission is granted to anyone to use this software for any purpose,
   8 * including commercial applications, and to alter it and redistribute it
   9 * freely, subject to the following restrictions:
  10 * 1. The origin of this software must not be misrepresented; you must not
  11 * claim that you wrote the original software. If you use this software
  12 * in a product, an acknowledgment in the product documentation would be
  13 * appreciated but is not required.
  14 * 2. Altered source versions must be plainly marked as such, and must not be
  15 * misrepresented as being the original software.
  16 * 3. This notice may not be removed or altered from any source distribution.
  17 */
  18
  19 #include "b2CircleContact.h"
  20 #include "../b2Body.h"
  21 #include "../b2WorldCallbacks.h"
  22 #include "../../Common/b2BlockAllocator.h"
  23
  24 #include <new>
  25 #include <string.h>
  26
  27 b2Contact* b2CircleContact::Create(b2Shape* shape1, b2Shape* shape2, b2BlockAllocator* allocator)
  28 {
  29         void* mem = allocator->Allocate(sizeof(b2CircleContact));
  30         return new (mem) b2CircleContact(shape1, shape2);
  31 }
  32
  33 void b2CircleContact::Destroy(b2Contact* contact, b2BlockAllocator* allocator)
  34 {
  35         ((b2CircleContact*)contact)->~b2CircleContact();
  36         allocator->Free(contact, sizeof(b2CircleContact));
  37 }
  38
  39 b2CircleContact::b2CircleContact(b2Shape* s1, b2Shape* s2)
  40 : b2Contact(s1, s2)
  41 {
  42         b2Assert(m_shape1->GetType() == e_circleShape);
  43         b2Assert(m_shape2->GetType() == e_circleShape);
  44         m_manifold.pointCount = 0;
  45         m_manifold.points[0].normalImpulse = 0.0f;
  46         m_manifold.points[0].tangentImpulse = 0.0f;
  47 }
  48
  49 void b2CircleContact::Evaluate(b2ContactListener* listener)
  50 {
  51         b2Body* b1 = m_shape1->GetBody();
  52         b2Body* b2 = m_shape2->GetBody();
  53
  54         b2Manifold m0;
  55         memcpy(&m0, &m_manifold, sizeof(b2Manifold));
  56
  57         b2CollideCircles(&m_manifold, (b2CircleShape*)m_shape1, b1->GetXForm(), (b2CircleShape*)m_shape2, b2->GetXForm());
  58
  59         b2ContactPoint cp;
  60         cp.shape1 = m_shape1;
  61         cp.shape2 = m_shape2;
  62         cp.friction = m_friction;
  63         cp.restitution = m_restitution;
  64
  65         if (m_manifold.pointCount > 0)
  66         {
  67                 m_manifoldCount = 1;
  68                 b2ManifoldPoint* mp = m_manifold.points + 0;
  69
  70                 if (m0.pointCount == 0)
  71                 {
  72                         mp->normalImpulse = 0.0f;
  73                         mp->tangentImpulse = 0.0f;
  74
  75                         if (listener)
  76                         {
  77                                 cp.position = b1->GetWorldPoint(mp->localPoint1);
  78                                 b2Vec2 v1 = b1->GetLinearVelocityFromLocalPoint(mp->localPoint1);
  79                                 b2Vec2 v2 = b2->GetLinearVelocityFromLocalPoint(mp->localPoint2);
  80                                 cp.velocity = v2 - v1;
  81                                 cp.normal = m_manifold.normal;
  82                                 cp.separation = mp->separation;
  83                                 cp.id = mp->id;
  84                                 listener->Add(&cp);
  85                         }
  86                 }
  87                 else
  88                 {
  89                         b2ManifoldPoint* mp0 = m0.points + 0;
  90                         mp->normalImpulse = mp0->normalImpulse;
  91                         mp->tangentImpulse = mp0->tangentImpulse;
  92
  93                         if (listener)
  94                         {
  95                                 cp.position = b1->GetWorldPoint(mp->localPoint1);
  96                                 b2Vec2 v1 = b1->GetLinearVelocityFromLocalPoint(mp->localPoint1);
  97                                 b2Vec2 v2 = b2->GetLinearVelocityFromLocalPoint(mp->localPoint2);
  98                                 cp.velocity = v2 - v1;
  99                                 cp.normal = m_manifold.normal;
 100                                 cp.separation = mp->separation;
 101                                 cp.id = mp->id;
 102                                 listener->Persist(&cp);
 103                         }
 104                 }
 105         }
 106         else
 107         {
 108                 m_manifoldCount = 0;
 109                 if (m0.pointCount > 0 && listener)
 110                 {
 111                         b2ManifoldPoint* mp0 = m0.points + 0;
 112                         cp.position = b1->GetWorldPoint(mp0->localPoint1);
 113                         b2Vec2 v1 = b1->GetLinearVelocityFromLocalPoint(mp0->localPoint1);
 114                         b2Vec2 v2 = b2->GetLinearVelocityFromLocalPoint(mp0->localPoint2);
 115                         cp.velocity = v2 - v1;
 116                         cp.normal = m0.normal;
 117                         cp.separation = mp0->separation;
 118                         cp.id = mp0->id;
 119                         listener->Remove(&cp);
 120                 }
 121         }
 122 }