Box2D  2.3.0
A 2D Physics Engine for Games
b2Collision.h
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1 /*
2 * Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
3 *
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18 
19 #ifndef B2_COLLISION_H
20 #define B2_COLLISION_H
21 
22 #include <Box2D/Common/b2Math.h>
23 #include <limits.h>
24 
28 
29 class b2Shape;
30 class b2CircleShape;
31 class b2EdgeShape;
32 class b2PolygonShape;
33 
34 const uint8 b2_nullFeature = UCHAR_MAX;
35 
39 {
40  enum Type
41  {
42  e_vertex = 0,
43  e_face = 1
44  };
45 
46  uint8 indexA;
47  uint8 indexB;
48  uint8 typeA;
49  uint8 typeB;
50 };
51 
54 {
56  uint32 key;
57 };
58 
70 {
72  float32 normalImpulse;
73  float32 tangentImpulse;
75 };
76 
93 struct b2Manifold
94 {
95  enum Type
96  {
97  e_circles,
98  e_faceA,
99  e_faceB
100  };
101 
105  Type type;
106  int32 pointCount;
107 };
108 
111 {
116  void Initialize(const b2Manifold* manifold,
117  const b2Transform& xfA, float32 radiusA,
118  const b2Transform& xfB, float32 radiusB);
119 
123 };
124 
127 {
132 };
133 
137  const b2Manifold* manifold1, const b2Manifold* manifold2);
138 
141 {
142  b2Vec2 v;
143  b2ContactID id;
144 };
145 
148 {
149  b2Vec2 p1, p2;
150  float32 maxFraction;
151 };
152 
156 {
157  b2Vec2 normal;
158  float32 fraction;
159 };
160 
162 struct b2AABB
163 {
165  bool IsValid() const;
166 
169  {
170  return 0.5f * (lowerBound + upperBound);
171  }
172 
175  {
176  return 0.5f * (upperBound - lowerBound);
177  }
178 
180  float32 GetPerimeter() const
181  {
182  float32 wx = upperBound.x - lowerBound.x;
183  float32 wy = upperBound.y - lowerBound.y;
184  return 2.0f * (wx + wy);
185  }
186 
188  void Combine(const b2AABB& aabb)
189  {
190  lowerBound = b2Min(lowerBound, aabb.lowerBound);
191  upperBound = b2Max(upperBound, aabb.upperBound);
192  }
193 
195  void Combine(const b2AABB& aabb1, const b2AABB& aabb2)
196  {
197  lowerBound = b2Min(aabb1.lowerBound, aabb2.lowerBound);
198  upperBound = b2Max(aabb1.upperBound, aabb2.upperBound);
199  }
200 
202  bool Contains(const b2AABB& aabb) const
203  {
204  bool result = true;
205  result = result && lowerBound.x <= aabb.lowerBound.x;
206  result = result && lowerBound.y <= aabb.lowerBound.y;
207  result = result && aabb.upperBound.x <= upperBound.x;
208  result = result && aabb.upperBound.y <= upperBound.y;
209  return result;
210  }
211 
212  bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input) const;
213 
216 };
217 
219 void b2CollideCircles(b2Manifold* manifold,
220  const b2CircleShape* circleA, const b2Transform& xfA,
221  const b2CircleShape* circleB, const b2Transform& xfB);
222 
225  const b2PolygonShape* polygonA, const b2Transform& xfA,
226  const b2CircleShape* circleB, const b2Transform& xfB);
227 
229 void b2CollidePolygons(b2Manifold* manifold,
230  const b2PolygonShape* polygonA, const b2Transform& xfA,
231  const b2PolygonShape* polygonB, const b2Transform& xfB);
232 
234 void b2CollideEdgeAndCircle(b2Manifold* manifold,
235  const b2EdgeShape* polygonA, const b2Transform& xfA,
236  const b2CircleShape* circleB, const b2Transform& xfB);
237 
239 void b2CollideEdgeAndPolygon(b2Manifold* manifold,
240  const b2EdgeShape* edgeA, const b2Transform& xfA,
241  const b2PolygonShape* circleB, const b2Transform& xfB);
242 
244 int32 b2ClipSegmentToLine(b2ClipVertex vOut[2], const b2ClipVertex vIn[2],
245  const b2Vec2& normal, float32 offset, int32 vertexIndexA);
246 
248 bool b2TestOverlap( const b2Shape* shapeA, int32 indexA,
249  const b2Shape* shapeB, int32 indexB,
250  const b2Transform& xfA, const b2Transform& xfB);
251 
252 // ---------------- Inline Functions ------------------------------------------
253 
254 inline bool b2AABB::IsValid() const
255 {
257  bool valid = d.x >= 0.0f && d.y >= 0.0f;
258  valid = valid && lowerBound.IsValid() && upperBound.IsValid();
259  return valid;
260 }
261 
262 inline bool b2TestOverlap(const b2AABB& a, const b2AABB& b)
263 {
264  b2Vec2 d1, d2;
265  d1 = b.lowerBound - a.upperBound;
266  d2 = a.lowerBound - b.upperBound;
267 
268  if (d1.x > 0.0f || d1.y > 0.0f)
269  return false;
270 
271  if (d2.x > 0.0f || d2.y > 0.0f)
272  return false;
273 
274  return true;
275 }
276 
277 #endif
b2ContactID::key
uint32 key
Used to quickly compare contact ids.
Definition: b2Collision.h:56
b2Vec2
A 2D column vector.
Definition: b2Math.h:54
b2ClipSegmentToLine
int32 b2ClipSegmentToLine(b2ClipVertex vOut[2], const b2ClipVertex vIn[2], const b2Vec2 &normal, float32 offset, int32 vertexIndexA)
Clipping for contact manifolds.
Definition: b2Collision.cpp:201
b2AABB::GetExtents
b2Vec2 GetExtents() const
Get the extents of the AABB (half-widths).
Definition: b2Collision.h:174
b2CollideEdgeAndCircle
void b2CollideEdgeAndCircle(b2Manifold *manifold, const b2EdgeShape *polygonA, const b2Transform &xfA, const b2CircleShape *circleB, const b2Transform &xfB)
Compute the collision manifold between an edge and a circle.
Definition: b2CollideEdge.cpp:27
b2_persistState
@ b2_persistState
point persisted across the update
Definition: b2Collision.h:130
b2EdgeShape
Definition: b2EdgeShape.h:28
b2TestOverlap
bool b2TestOverlap(const b2Shape *shapeA, int32 indexA, const b2Shape *shapeB, int32 indexB, const b2Transform &xfA, const b2Transform &xfB)
Determine if two generic shapes overlap.
Definition: b2Collision.cpp:233
b2CollidePolygons
void b2CollidePolygons(b2Manifold *manifold, const b2PolygonShape *polygonA, const b2Transform &xfA, const b2PolygonShape *polygonB, const b2Transform &xfB)
Compute the collision manifold between two polygons.
Definition: b2CollidePolygon.cpp:116
b2AABB::lowerBound
b2Vec2 lowerBound
the lower vertex
Definition: b2Collision.h:214
b2CollidePolygonAndCircle
void b2CollidePolygonAndCircle(b2Manifold *manifold, const b2PolygonShape *polygonA, const b2Transform &xfA, const b2CircleShape *circleB, const b2Transform &xfB)
Compute the collision manifold between a polygon and a circle.
Definition: b2CollideCircle.cpp:51
b2RayCastInput
Ray-cast input data. The ray extends from p1 to p1 + maxFraction * (p2 - p1).
Definition: b2Collision.h:148
b2Transform
Definition: b2Math.h:351
b2Manifold::points
b2ManifoldPoint points[b2_maxManifoldPoints]
the points of contact
Definition: b2Collision.h:102
b2AABB::GetCenter
b2Vec2 GetCenter() const
Get the center of the AABB.
Definition: b2Collision.h:168
b2WorldManifold::Initialize
void Initialize(const b2Manifold *manifold, const b2Transform &xfA, float32 radiusA, const b2Transform &xfB, float32 radiusB)
Definition: b2Collision.cpp:22
b2Manifold
Definition: b2Collision.h:94
b2Manifold::pointCount
int32 pointCount
the number of manifold points
Definition: b2Collision.h:106
b2PointState
b2PointState
This is used for determining the state of contact points.
Definition: b2Collision.h:127
b2AABB::Contains
bool Contains(const b2AABB &aabb) const
Does this aabb contain the provided AABB.
Definition: b2Collision.h:202
b2GetPointStates
void b2GetPointStates(b2PointState state1[b2_maxManifoldPoints], b2PointState state2[b2_maxManifoldPoints], const b2Manifold *manifold1, const b2Manifold *manifold2)
Definition: b2Collision.cpp:88
b2ManifoldPoint
Definition: b2Collision.h:70
b2WorldManifold
This is used to compute the current state of a contact manifold.
Definition: b2Collision.h:111
b2ClipVertex
Used for computing contact manifolds.
Definition: b2Collision.h:141
b2AABB
An axis aligned bounding box.
Definition: b2Collision.h:163
b2Manifold::localNormal
b2Vec2 localNormal
not use for Type::e_points
Definition: b2Collision.h:103
b2AABB::GetPerimeter
float32 GetPerimeter() const
Get the perimeter length.
Definition: b2Collision.h:180
b2ContactID
Contact ids to facilitate warm starting.
Definition: b2Collision.h:54
b2ManifoldPoint::tangentImpulse
float32 tangentImpulse
the friction impulse
Definition: b2Collision.h:73
b2ContactFeature::indexB
uint8 indexB
Feature index on shapeB.
Definition: b2Collision.h:47
b2_removeState
@ b2_removeState
point was removed in the update
Definition: b2Collision.h:131
b2ManifoldPoint::id
b2ContactID id
uniquely identifies a contact point between two shapes
Definition: b2Collision.h:74
b2ManifoldPoint::localPoint
b2Vec2 localPoint
usage depends on manifold type
Definition: b2Collision.h:71
b2AABB::upperBound
b2Vec2 upperBound
the upper vertex
Definition: b2Collision.h:215
b2PolygonShape
Definition: b2PolygonShape.h:29
b2AABB::Combine
void Combine(const b2AABB &aabb)
Combine an AABB into this one.
Definition: b2Collision.h:188
b2ContactFeature::typeA
uint8 typeA
The feature type on shapeA.
Definition: b2Collision.h:48
b2WorldManifold::normal
b2Vec2 normal
world vector pointing from A to B
Definition: b2Collision.h:120
b2WorldManifold::separations
float32 separations[b2_maxManifoldPoints]
a negative value indicates overlap, in meters
Definition: b2Collision.h:122
b2ContactFeature::indexA
uint8 indexA
Feature index on shapeA.
Definition: b2Collision.h:46
b2ManifoldPoint::normalImpulse
float32 normalImpulse
the non-penetration impulse
Definition: b2Collision.h:72
b2AABB::IsValid
bool IsValid() const
Verify that the bounds are sorted.
Definition: b2Collision.h:254
b2_addState
@ b2_addState
point was added in the update
Definition: b2Collision.h:129
b2Manifold::localPoint
b2Vec2 localPoint
usage depends on manifold type
Definition: b2Collision.h:104
b2Shape
Definition: b2Shape.h:43
b2AABB::Combine
void Combine(const b2AABB &aabb1, const b2AABB &aabb2)
Combine two AABBs into this one.
Definition: b2Collision.h:195
b2_maxManifoldPoints
#define b2_maxManifoldPoints
Definition: b2Settings.h:50
b2_nullState
@ b2_nullState
point does not exist
Definition: b2Collision.h:128
b2CollideEdgeAndPolygon
void b2CollideEdgeAndPolygon(b2Manifold *manifold, const b2EdgeShape *edgeA, const b2Transform &xfA, const b2PolygonShape *circleB, const b2Transform &xfB)
Compute the collision manifold between an edge and a circle.
Definition: b2CollideEdge.cpp:692
b2RayCastOutput
Definition: b2Collision.h:156
b2CollideCircles
void b2CollideCircles(b2Manifold *manifold, const b2CircleShape *circleA, const b2Transform &xfA, const b2CircleShape *circleB, const b2Transform &xfB)
Compute the collision manifold between two circles.
Definition: b2CollideCircle.cpp:23
b2WorldManifold::points
b2Vec2 points[b2_maxManifoldPoints]
world contact point (point of intersection)
Definition: b2Collision.h:121
b2ContactFeature::typeB
uint8 typeB
The feature type on shapeB.
Definition: b2Collision.h:49
b2CircleShape
A circle shape.
Definition: b2CircleShape.h:26
b2ContactFeature
Definition: b2Collision.h:39
b2Vec2::IsValid
bool IsValid() const
Does this vector contain finite coordinates?
Definition: b2Math.h:129