Updated to Box2D 2.2, added new joints, some other updates to match the API changes (still plenty more to go though)

--HG--
branch : box2d-update

src/modules/physics/box2d/Box2D/Collision/Shapes/b2ChainShape.cpp

@@ -0,0 +1,171 @@
+/*
+* Copyright (c) 2006-2010 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.
+*/
+
+#include <Box2D/Collision/Shapes/b2ChainShape.h>
+#include <Box2D/Collision/Shapes/b2EdgeShape.h>
+#include <new>
+#include <cstring>
+using namespace std;
+
+b2ChainShape::~b2ChainShape()
+{
+	b2Free(m_vertices);
+	m_vertices = NULL;
+	m_count = 0;
+}
+
+void b2ChainShape::CreateLoop(const b2Vec2* vertices, int32 count)
+{
+	b2Assert(m_vertices == NULL && m_count == 0);
+	b2Assert(count >= 3);
+	m_count = count + 1;
+	m_vertices = (b2Vec2*)b2Alloc(m_count * sizeof(b2Vec2));
+	memcpy(m_vertices, vertices, count * sizeof(b2Vec2));
+	m_vertices[count] = m_vertices[0];
+	m_prevVertex = m_vertices[m_count - 2];
+	m_nextVertex = m_vertices[1];
+	m_hasPrevVertex = true;
+	m_hasNextVertex = true;
+}
+
+void b2ChainShape::CreateChain(const b2Vec2* vertices, int32 count)
+{
+	b2Assert(m_vertices == NULL && m_count == 0);
+	b2Assert(count >= 2);
+	m_count = count;
+	m_vertices = (b2Vec2*)b2Alloc(count * sizeof(b2Vec2));
+	memcpy(m_vertices, vertices, m_count * sizeof(b2Vec2));
+	m_hasPrevVertex = false;
+	m_hasNextVertex = false;
+}
+
+void b2ChainShape::SetPrevVertex(const b2Vec2& prevVertex)
+{
+	m_prevVertex = prevVertex;
+	m_hasPrevVertex = true;
+}
+
+void b2ChainShape::SetNextVertex(const b2Vec2& nextVertex)
+{
+	m_nextVertex = nextVertex;
+	m_hasNextVertex = true;
+}
+
+b2Shape* b2ChainShape::Clone(b2BlockAllocator* allocator) const
+{
+	void* mem = allocator->Allocate(sizeof(b2ChainShape));
+	b2ChainShape* clone = new (mem) b2ChainShape;
+	clone->CreateChain(m_vertices, m_count);
+	clone->m_prevVertex = m_prevVertex;
+	clone->m_nextVertex = m_nextVertex;
+	clone->m_hasPrevVertex = m_hasPrevVertex;
+	clone->m_hasNextVertex = m_hasNextVertex;
+	return clone;
+}
+
+int32 b2ChainShape::GetChildCount() const
+{
+	// edge count = vertex count - 1
+	return m_count - 1;
+}
+
+void b2ChainShape::GetChildEdge(b2EdgeShape* edge, int32 index) const
+{
+	b2Assert(0 <= index && index < m_count - 1);
+	edge->m_type = b2Shape::e_edge;
+	edge->m_radius = m_radius;
+
+	edge->m_vertex1 = m_vertices[index + 0];
+	edge->m_vertex2 = m_vertices[index + 1];
+
+	if (index > 0)
+	{
+		edge->m_vertex0 = m_vertices[index - 1];
+		edge->m_hasVertex0 = true;
+	}
+	else
+	{
+		edge->m_vertex0 = m_prevVertex;
+		edge->m_hasVertex0 = m_hasPrevVertex;
+	}
+
+	if (index < m_count - 2)
+	{
+		edge->m_vertex3 = m_vertices[index + 2];
+		edge->m_hasVertex3 = true;
+	}
+	else
+	{
+		edge->m_vertex3 = m_nextVertex;
+		edge->m_hasVertex3 = m_hasNextVertex;
+	}
+}
+
+bool b2ChainShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
+{
+	B2_NOT_USED(xf);
+	B2_NOT_USED(p);
+	return false;
+}
+
+bool b2ChainShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+							const b2Transform& xf, int32 childIndex) const
+{
+	b2Assert(childIndex < m_count);
+
+	b2EdgeShape edgeShape;
+
+	int32 i1 = childIndex;
+	int32 i2 = childIndex + 1;
+	if (i2 == m_count)
+	{
+		i2 = 0;
+	}
+
+	edgeShape.m_vertex1 = m_vertices[i1];
+	edgeShape.m_vertex2 = m_vertices[i2];
+
+	return edgeShape.RayCast(output, input, xf, 0);
+}
+
+void b2ChainShape::ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) const
+{
+	b2Assert(childIndex < m_count);
+
+	int32 i1 = childIndex;
+	int32 i2 = childIndex + 1;
+	if (i2 == m_count)
+	{
+		i2 = 0;
+	}
+
+	b2Vec2 v1 = b2Mul(xf, m_vertices[i1]);
+	b2Vec2 v2 = b2Mul(xf, m_vertices[i2]);
+
+	aabb->lowerBound = b2Min(v1, v2);
+	aabb->upperBound = b2Max(v1, v2);
+}
+
+void b2ChainShape::ComputeMass(b2MassData* massData, float32 density) const
+{
+	B2_NOT_USED(density);
+
+	massData->mass = 0.0f;
+	massData->center.SetZero();
+	massData->I = 0.0f;
+}

src/modules/physics/box2d/Box2D/Collision/Shapes/b2ChainShape.h

@@ -0,0 +1,117 @@
+/*
+* Copyright (c) 2006-2010 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_CHAIN_SHAPE_H
+#define B2_CHAIN_SHAPE_H
+
+#include <Box2D/Collision/Shapes/b2Shape.h>
+
+class b2EdgeShape;
+
+/// A chain shape is a free form sequence of line segments.
+/// The chain has two-sided collision, so you can use inside and outside collision.
+/// Therefore, you may use any winding order.
+/// Since there may be many vertices, they are allocated using b2Alloc.
+/// Connectivity information is used to create smooth collisions.
+/// WARNING: The chain will not collide properly if there are self-intersections.
+class b2ChainShape : public b2Shape
+{
+public:
+	b2ChainShape();
+
+	/// The destructor frees the vertices using b2Free.
+	~b2ChainShape();
+
+	/// Create a loop. This automatically adjusts connectivity.
+	/// @param vertices an array of vertices, these are copied
+	/// @param count the vertex count
+	void CreateLoop(const b2Vec2* vertices, int32 count);
+
+	/// Create a chain with isolated end vertices.
+	/// @param vertices an array of vertices, these are copied
+	/// @param count the vertex count
+	void CreateChain(const b2Vec2* vertices, int32 count);
+
+	/// Establish connectivity to a vertex that precedes the first vertex.
+	/// Don't call this for loops.
+	void SetPrevVertex(const b2Vec2& prevVertex);
+
+	/// Establish connectivity to a vertex that follows the last vertex.
+	/// Don't call this for loops.
+	void SetNextVertex(const b2Vec2& nextVertex);
+
+	/// Implement b2Shape. Vertices are cloned using b2Alloc.
+	b2Shape* Clone(b2BlockAllocator* allocator) const;
+
+	/// @see b2Shape::GetChildCount
+	int32 GetChildCount() const;
+
+	/// Get a child edge.
+	void GetChildEdge(b2EdgeShape* edge, int32 index) const;
+
+	/// This always return false.
+	/// @see b2Shape::TestPoint
+	bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
+
+	/// Implement b2Shape.
+	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+					const b2Transform& transform, int32 childIndex) const;
+
+	/// @see b2Shape::ComputeAABB
+	void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const;
+
+	/// Chains have zero mass.
+	/// @see b2Shape::ComputeMass
+	void ComputeMass(b2MassData* massData, float32 density) const;
+
+	/// Get the number of vertices.
+	int32 GetVertexCount() const { return m_count; }
+
+	/// Get the vertices (read-only).
+	const b2Vec2& GetVertex(int32 index) const
+	{
+		b2Assert(0 <= index && index < m_count);
+		return m_vertices[index];
+	}
+
+	/// Get the vertices (read-only).
+	const b2Vec2* GetVertices() const { return m_vertices; }
+
+protected:
+
+	/// The vertices. Owned by this class.
+	b2Vec2* m_vertices;
+
+	/// The vertex count.
+	int32 m_count;
+
+	b2Vec2 m_prevVertex, m_nextVertex;
+	bool m_hasPrevVertex, m_hasNextVertex;
+};
+
+inline b2ChainShape::b2ChainShape()
+{
+	m_type = e_chain;
+	m_radius = b2_polygonRadius;
+	m_vertices = NULL;
+	m_count = 0;
+	m_hasPrevVertex = NULL;
+	m_hasNextVertex = NULL;
+}
+
+#endif

src/modules/physics/box2d/Box2D/Collision/Shapes/b2CircleShape.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
+* Copyright (c) 2006-2009 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
@@ -18,6 +18,7 @@
 
 #include <Box2D/Collision/Shapes/b2CircleShape.h>
 #include <new>
+using namespace std;
 
 b2Shape* b2CircleShape::Clone(b2BlockAllocator* allocator) const
 {
@@ -27,9 +28,14 @@ b2Shape* b2CircleShape::Clone(b2BlockAllocator* allocator) const
 	return clone;
 }
 
+int32 b2CircleShape::GetChildCount() const
+{
+	return 1;
+}
+
 bool b2CircleShape::TestPoint(const b2Transform& transform, const b2Vec2& p) const
 {
-	b2Vec2 center = transform.position + b2Mul(transform.R, m_p);
+	b2Vec2 center = transform.p + b2Mul(transform.q, m_p);
 	b2Vec2 d = p - center;
 	return b2Dot(d, d) <= m_radius * m_radius;
 }
@@ -38,9 +44,12 @@ bool b2CircleShape::TestPoint(const b2Transform& transform, const b2Vec2& p) con
 // From Section 3.1.2
 // x = s + a * r
 // norm(x) = radius
-bool b2CircleShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input, const b2Transform& transform) const
+bool b2CircleShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+							const b2Transform& transform, int32 childIndex) const
 {
-	b2Vec2 position = transform.position + b2Mul(transform.R, m_p);
+	B2_NOT_USED(childIndex);
+
+	b2Vec2 position = transform.p + b2Mul(transform.q, m_p);
 	b2Vec2 s = input.p1 - position;
 	float32 b = b2Dot(s, s) - m_radius * m_radius;
 
@@ -72,9 +81,11 @@ bool b2CircleShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input
 	return false;
 }
 
-void b2CircleShape::ComputeAABB(b2AABB* aabb, const b2Transform& transform) const
+void b2CircleShape::ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const
 {
-	b2Vec2 p = transform.position + b2Mul(transform.R, m_p);
+	B2_NOT_USED(childIndex);
+
+	b2Vec2 p = transform.p + b2Mul(transform.q, m_p);
 	aabb->lowerBound.Set(p.x - m_radius, p.y - m_radius);
 	aabb->upperBound.Set(p.x + m_radius, p.y + m_radius);
 }

src/modules/physics/box2d/Box2D/Collision/Shapes/b2CircleShape.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
+* Copyright (c) 2006-2009 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
@@ -30,14 +30,18 @@ public:
 	/// Implement b2Shape.
 	b2Shape* Clone(b2BlockAllocator* allocator) const;
 
+	/// @see b2Shape::GetChildCount
+	int32 GetChildCount() const;
+
 	/// Implement b2Shape.
 	bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
 
 	/// Implement b2Shape.
-	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input, const b2Transform& transform) const;
+	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+				const b2Transform& transform, int32 childIndex) const;
 
 	/// @see b2Shape::ComputeAABB
-	void ComputeAABB(b2AABB* aabb, const b2Transform& transform) const;
+	void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const;
 
 	/// @see b2Shape::ComputeMass
 	void ComputeMass(b2MassData* massData, float32 density) const;

src/modules/physics/box2d/Box2D/Collision/Shapes/b2EdgeShape.cpp

@@ -0,0 +1,139 @@
+/*
+* Copyright (c) 2006-2010 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.
+*/
+
+#include <Box2D/Collision/Shapes/b2EdgeShape.h>
+#include <new>
+using namespace std;
+
+void b2EdgeShape::Set(const b2Vec2& v1, const b2Vec2& v2)
+{
+	m_vertex1 = v1;
+	m_vertex2 = v2;
+	m_hasVertex0 = false;
+	m_hasVertex3 = false;
+}
+
+b2Shape* b2EdgeShape::Clone(b2BlockAllocator* allocator) const
+{
+	void* mem = allocator->Allocate(sizeof(b2EdgeShape));
+	b2EdgeShape* clone = new (mem) b2EdgeShape;
+	*clone = *this;
+	return clone;
+}
+
+int32 b2EdgeShape::GetChildCount() const
+{
+	return 1;
+}
+
+bool b2EdgeShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
+{
+	B2_NOT_USED(xf);
+	B2_NOT_USED(p);
+	return false;
+}
+
+// p = p1 + t * d
+// v = v1 + s * e
+// p1 + t * d = v1 + s * e
+// s * e - t * d = p1 - v1
+bool b2EdgeShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+							const b2Transform& xf, int32 childIndex) const
+{
+	B2_NOT_USED(childIndex);
+
+	// Put the ray into the edge's frame of reference.
+	b2Vec2 p1 = b2MulT(xf.q, input.p1 - xf.p);
+	b2Vec2 p2 = b2MulT(xf.q, input.p2 - xf.p);
+	b2Vec2 d = p2 - p1;
+
+	b2Vec2 v1 = m_vertex1;
+	b2Vec2 v2 = m_vertex2;
+	b2Vec2 e = v2 - v1;
+	b2Vec2 normal(e.y, -e.x);
+	normal.Normalize();
+
+	// q = p1 + t * d
+	// dot(normal, q - v1) = 0
+	// dot(normal, p1 - v1) + t * dot(normal, d) = 0
+	float32 numerator = b2Dot(normal, v1 - p1);
+	float32 denominator = b2Dot(normal, d);
+
+	if (denominator == 0.0f)
+	{
+		return false;
+	}
+
+	float32 t = numerator / denominator;
+	if (t < 0.0f || input.maxFraction < t)
+	{
+		return false;
+	}
+
+	b2Vec2 q = p1 + t * d;
+
+	// q = v1 + s * r
+	// s = dot(q - v1, r) / dot(r, r)
+	b2Vec2 r = v2 - v1;
+	float32 rr = b2Dot(r, r);
+	if (rr == 0.0f)
+	{
+		return false;
+	}
+
+	float32 s = b2Dot(q - v1, r) / rr;
+	if (s < 0.0f || 1.0f < s)
+	{
+		return false;
+	}
+
+	output->fraction = t;
+	if (numerator > 0.0f)
+	{
+		output->normal = -normal;
+	}
+	else
+	{
+		output->normal = normal;
+	}
+	return true;
+}
+
+void b2EdgeShape::ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) const
+{
+	B2_NOT_USED(childIndex);
+
+	b2Vec2 v1 = b2Mul(xf, m_vertex1);
+	b2Vec2 v2 = b2Mul(xf, m_vertex2);
+
+	b2Vec2 lower = b2Min(v1, v2);
+	b2Vec2 upper = b2Max(v1, v2);
+
+	b2Vec2 r(m_radius, m_radius);
+	aabb->lowerBound = lower - r;
+	aabb->upperBound = upper + r;
+}
+
+void b2EdgeShape::ComputeMass(b2MassData* massData, float32 density) const
+{
+	B2_NOT_USED(density);
+
+	massData->mass = 0.0f;
+	massData->center = 0.5f * (m_vertex1 + m_vertex2);
+	massData->I = 0.0f;
+}

src/modules/physics/box2d/Box2D/Collision/Shapes/b2EdgeShape.h

@@ -0,0 +1,70 @@
+/*
+* Copyright (c) 2006-2010 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_EDGE_SHAPE_H
+#define B2_EDGE_SHAPE_H
+
+#include <Box2D/Collision/Shapes/b2Shape.h>
+
+/// A line segment (edge) shape. These can be connected in chains or loops
+/// to other edge shapes. The connectivity information is used to ensure
+/// correct contact normals.
+class b2EdgeShape : public b2Shape
+{
+public:
+	b2EdgeShape();
+
+	/// Set this as an isolated edge.
+	void Set(const b2Vec2& v1, const b2Vec2& v2);
+
+	/// Implement b2Shape.
+	b2Shape* Clone(b2BlockAllocator* allocator) const;
+
+	/// @see b2Shape::GetChildCount
+	int32 GetChildCount() const;
+
+	/// @see b2Shape::TestPoint
+	bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
+
+	/// Implement b2Shape.
+	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+				const b2Transform& transform, int32 childIndex) const;
+
+	/// @see b2Shape::ComputeAABB
+	void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const;
+
+	/// @see b2Shape::ComputeMass
+	void ComputeMass(b2MassData* massData, float32 density) const;
+	
+	/// These are the edge vertices
+	b2Vec2 m_vertex1, m_vertex2;
+
+	/// Optional adjacent vertices. These are used for smooth collision.
+	b2Vec2 m_vertex0, m_vertex3;
+	bool m_hasVertex0, m_hasVertex3;
+};
+
+inline b2EdgeShape::b2EdgeShape()
+{
+	m_type = e_edge;
+	m_radius = b2_polygonRadius;
+	m_hasVertex0 = false;
+	m_hasVertex3 = false;
+}
+
+#endif

src/modules/physics/box2d/Box2D/Collision/Shapes/b2PolygonShape.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
+* Copyright (c) 2006-2009 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
@@ -55,41 +55,29 @@ void b2PolygonShape::SetAsBox(float32 hx, float32 hy, const b2Vec2& center, floa
 	m_centroid = center;
 
 	b2Transform xf;
-	xf.position = center;
-	xf.R.Set(angle);
+	xf.p = center;
+	xf.q.Set(angle);
 
 	// Transform vertices and normals.
 	for (int32 i = 0; i < m_vertexCount; ++i)
 	{
 		m_vertices[i] = b2Mul(xf, m_vertices[i]);
-		m_normals[i] = b2Mul(xf.R, m_normals[i]);
+		m_normals[i] = b2Mul(xf.q, m_normals[i]);
 	}
 }
 
-void b2PolygonShape::SetAsEdge(const b2Vec2& v1, const b2Vec2& v2)
+int32 b2PolygonShape::GetChildCount() const
 {
-	m_vertexCount = 2;
-	m_vertices[0] = v1;
-	m_vertices[1] = v2;
-	m_centroid = 0.5f * (v1 + v2);
-	m_normals[0] = b2Cross(v2 - v1, 1.0f);
-	m_normals[0].Normalize();
-	m_normals[1] = -m_normals[0];
+	return 1;
 }
 
 static b2Vec2 ComputeCentroid(const b2Vec2* vs, int32 count)
 {
-	b2Assert(count >= 2);
+	b2Assert(count >= 3);
 
 	b2Vec2 c; c.Set(0.0f, 0.0f);
 	float32 area = 0.0f;
 
-	if (count == 2)
-	{
-		c = 0.5f * (vs[0] + vs[1]);
-		return c;
-	}
-
 	// pRef is the reference point for forming triangles.
 	// It's location doesn't change the result (except for rounding error).
 	b2Vec2 pRef(0.0f, 0.0f);
@@ -131,7 +119,7 @@ static b2Vec2 ComputeCentroid(const b2Vec2* vs, int32 count)
 
 void b2PolygonShape::Set(const b2Vec2* vertices, int32 count)
 {
-	b2Assert(2 <= count && count <= b2_maxPolygonVertices);
+	b2Assert(3 <= count && count <= b2_maxPolygonVertices);
 	m_vertexCount = count;
 
 	// Copy vertices.
@@ -170,10 +158,10 @@ void b2PolygonShape::Set(const b2Vec2* vertices, int32 count)
 			
 			b2Vec2 r = m_vertices[j] - m_vertices[i1];
 
-			// Your polygon is non-convex (it has an indentation) or
-			// has colinear edges.
+			// If this crashes, your polygon is non-convex, has colinear edges,
+			// or the winding order is wrong.
 			float32 s = b2Cross(edge, r);
-			b2Assert(s > 0.0f);
+			b2Assert(s > 0.0f && "ERROR: Please ensure your polygon is convex and has a CCW winding order");
 		}
 	}
 #endif
@@ -184,7 +172,7 @@ void b2PolygonShape::Set(const b2Vec2* vertices, int32 count)
 
 bool b2PolygonShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
 {
-	b2Vec2 pLocal = b2MulT(xf.R, p - xf.position);
+	b2Vec2 pLocal = b2MulT(xf.q, p - xf.p);
 
 	for (int32 i = 0; i < m_vertexCount; ++i)
 	{
@@ -198,131 +186,82 @@ bool b2PolygonShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
 	return true;
 }
 
-bool b2PolygonShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input, const b2Transform& xf) const
+bool b2PolygonShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+								const b2Transform& xf, int32 childIndex) const
 {
+	B2_NOT_USED(childIndex);
+
 	// Put the ray into the polygon's frame of reference.
-	b2Vec2 p1 = b2MulT(xf.R, input.p1 - xf.position);
-	b2Vec2 p2 = b2MulT(xf.R, input.p2 - xf.position);
+	b2Vec2 p1 = b2MulT(xf.q, input.p1 - xf.p);
+	b2Vec2 p2 = b2MulT(xf.q, input.p2 - xf.p);
 	b2Vec2 d = p2 - p1;
 
-	if (m_vertexCount == 2)
-	{
-		b2Vec2 v1 = m_vertices[0];
-		b2Vec2 v2 = m_vertices[1];
-		b2Vec2 normal = m_normals[0];
+	float32 lower = 0.0f, upper = input.maxFraction;
 
-		// q = p1 + t * d
-		// dot(normal, q - v1) = 0
-		// dot(normal, p1 - v1) + t * dot(normal, d) = 0
-		float32 numerator = b2Dot(normal, v1 - p1);
-		float32 denominator = b2Dot(normal, d);
+	int32 index = -1;
+
+	for (int32 i = 0; i < m_vertexCount; ++i)
+	{
+		// p = p1 + a * d
+		// dot(normal, p - v) = 0
+		// dot(normal, p1 - v) + a * dot(normal, d) = 0
+		float32 numerator = b2Dot(m_normals[i], m_vertices[i] - p1);
+		float32 denominator = b2Dot(m_normals[i], d);
 
 		if (denominator == 0.0f)
-		{
-			return false;
-		}
-	
-		float32 t = numerator / denominator;
-		if (t < 0.0f || 1.0f < t)
-		{
-			return false;
-		}
-
-		b2Vec2 q = p1 + t * d;
-
-		// q = v1 + s * r
-		// s = dot(q - v1, r) / dot(r, r)
-		b2Vec2 r = v2 - v1;
-		float32 rr = b2Dot(r, r);
-		if (rr == 0.0f)
-		{
-			return false;
-		}
-
-		float32 s = b2Dot(q - v1, r) / rr;
-		if (s < 0.0f || 1.0f < s)
-		{
-			return false;
-		}
-
-		output->fraction = t;
-		if (numerator > 0.0f)
-		{
-			output->normal = -normal;
-		}
-		else
-		{
-			output->normal = normal;
-		}
-		return true;
-	}
-	else
-	{
-		float32 lower = 0.0f, upper = input.maxFraction;
-
-		int32 index = -1;
-
-		for (int32 i = 0; i < m_vertexCount; ++i)
-		{
-			// p = p1 + a * d
-			// dot(normal, p - v) = 0
-			// dot(normal, p1 - v) + a * dot(normal, d) = 0
-			float32 numerator = b2Dot(m_normals[i], m_vertices[i] - p1);
-			float32 denominator = b2Dot(m_normals[i], d);
-
-			if (denominator == 0.0f)
-			{	
-				if (numerator < 0.0f)
-				{
-					return false;
-				}
-			}
-			else
-			{
-				// Note: we want this predicate without division:
-				// lower < numerator / denominator, where denominator < 0
-				// Since denominator < 0, we have to flip the inequality:
-				// lower < numerator / denominator <==> denominator * lower > numerator.
-				if (denominator < 0.0f && numerator < lower * denominator)
-				{
-					// Increase lower.
-					// The segment enters this half-space.
-					lower = numerator / denominator;
-					index = i;
-				}
-				else if (denominator > 0.0f && numerator < upper * denominator)
-				{
-					// Decrease upper.
-					// The segment exits this half-space.
-					upper = numerator / denominator;
-				}
-			}
-
-			// The use of epsilon here causes the assert on lower to trip
-			// in some cases. Apparently the use of epsilon was to make edge
-			// shapes work, but now those are handled separately.
-			//if (upper < lower - b2_epsilon)
-			if (upper < lower)
+		{	
+			if (numerator < 0.0f)
 			{
 				return false;
 			}
 		}
-
-		b2Assert(0.0f <= lower && lower <= input.maxFraction);
-
-		if (index >= 0)
+		else
 		{
-			output->fraction = lower;
-			output->normal = b2Mul(xf.R, m_normals[index]);
-			return true;
+			// Note: we want this predicate without division:
+			// lower < numerator / denominator, where denominator < 0
+			// Since denominator < 0, we have to flip the inequality:
+			// lower < numerator / denominator <==> denominator * lower > numerator.
+			if (denominator < 0.0f && numerator < lower * denominator)
+			{
+				// Increase lower.
+				// The segment enters this half-space.
+				lower = numerator / denominator;
+				index = i;
+			}
+			else if (denominator > 0.0f && numerator < upper * denominator)
+			{
+				// Decrease upper.
+				// The segment exits this half-space.
+				upper = numerator / denominator;
+			}
 		}
+
+		// The use of epsilon here causes the assert on lower to trip
+		// in some cases. Apparently the use of epsilon was to make edge
+		// shapes work, but now those are handled separately.
+		//if (upper < lower - b2_epsilon)
+		if (upper < lower)
+		{
+			return false;
+		}
+	}
+
+	b2Assert(0.0f <= lower && lower <= input.maxFraction);
+
+	if (index >= 0)
+	{
+		output->fraction = lower;
+		output->normal = b2Mul(xf.q, m_normals[index]);
+		return true;
 	}
 
 	return false;
 }
 
-void b2PolygonShape::ComputeAABB(b2AABB* aabb, const b2Transform& xf) const
+void b2PolygonShape::ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) const
 {
+	B2_NOT_USED(childIndex);
+
 	b2Vec2 lower = b2Mul(xf, m_vertices[0]);
 	b2Vec2 upper = lower;
 
@@ -364,44 +303,30 @@ void b2PolygonShape::ComputeMass(b2MassData* massData, float32 density) const
 	//
 	// The rest of the derivation is handled by computer algebra.
 
-	b2Assert(m_vertexCount >= 2);
-
-	// A line segment has zero mass.
-	if (m_vertexCount == 2)
-	{
-		massData->center = 0.5f * (m_vertices[0] + m_vertices[1]);
-		massData->mass = 0.0f;
-		massData->I = 0.0f;
-		return;
-	}
+	b2Assert(m_vertexCount >= 3);
 
 	b2Vec2 center; center.Set(0.0f, 0.0f);
 	float32 area = 0.0f;
 	float32 I = 0.0f;
 
-	// pRef is the reference point for forming triangles.
+	// s is the reference point for forming triangles.
 	// It's location doesn't change the result (except for rounding error).
-	b2Vec2 pRef(0.0f, 0.0f);
-#if 0
+	b2Vec2 s(0.0f, 0.0f);
+
 	// This code would put the reference point inside the polygon.
 	for (int32 i = 0; i < m_vertexCount; ++i)
 	{
-		pRef += m_vertices[i];
+		s += m_vertices[i];
 	}
-	pRef *= 1.0f / count;
-#endif
+	s *= 1.0f / m_vertexCount;
 
 	const float32 k_inv3 = 1.0f / 3.0f;
 
 	for (int32 i = 0; i < m_vertexCount; ++i)
 	{
 		// Triangle vertices.
-		b2Vec2 p1 = pRef;
-		b2Vec2 p2 = m_vertices[i];
-		b2Vec2 p3 = i + 1 < m_vertexCount ? m_vertices[i+1] : m_vertices[0];
-
-		b2Vec2 e1 = p2 - p1;
-		b2Vec2 e2 = p3 - p1;
+		b2Vec2 e1 = m_vertices[i] - s;
+		b2Vec2 e2 = i + 1 < m_vertexCount ? m_vertices[i+1] - s : m_vertices[0] - s;
 
 		float32 D = b2Cross(e1, e2);
 
@@ -409,16 +334,15 @@ void b2PolygonShape::ComputeMass(b2MassData* massData, float32 density) const
 		area += triangleArea;
 
 		// Area weighted centroid
-		center += triangleArea * k_inv3 * (p1 + p2 + p3);
+		center += triangleArea * k_inv3 * (e1 + e2);
 
-		float32 px = p1.x, py = p1.y;
 		float32 ex1 = e1.x, ey1 = e1.y;
 		float32 ex2 = e2.x, ey2 = e2.y;
 
-		float32 intx2 = k_inv3 * (0.25f * (ex1*ex1 + ex2*ex1 + ex2*ex2) + (px*ex1 + px*ex2)) + 0.5f*px*px;
-		float32 inty2 = k_inv3 * (0.25f * (ey1*ey1 + ey2*ey1 + ey2*ey2) + (py*ey1 + py*ey2)) + 0.5f*py*py;
+		float32 intx2 = ex1*ex1 + ex2*ex1 + ex2*ex2;
+		float32 inty2 = ey1*ey1 + ey2*ey1 + ey2*ey2;
 
-		I += D * (intx2 + inty2);
+		I += (0.25f * k_inv3 * D) * (intx2 + inty2);
 	}
 
 	// Total mass
@@ -427,8 +351,11 @@ void b2PolygonShape::ComputeMass(b2MassData* massData, float32 density) const
 	// Center of mass
 	b2Assert(area > b2_epsilon);
 	center *= 1.0f / area;
-	massData->center = center;
+	massData->center = center + s;
 
-	// Inertia tensor relative to the local origin.
+	// Inertia tensor relative to the local origin (point s).
 	massData->I = density * I;
+	
+	// Shift to center of mass then to original body origin.
+	massData->I += massData->mass * (b2Dot(massData->center, massData->center) - b2Dot(center, center));
 }

src/modules/physics/box2d/Box2D/Collision/Shapes/b2PolygonShape.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
+* Copyright (c) 2006-2009 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
@@ -23,6 +23,8 @@
 
 /// A convex polygon. It is assumed that the interior of the polygon is to
 /// the left of each edge.
+/// Polygons have a maximum number of vertices equal to b2_maxPolygonVertices.
+/// In most cases you should not need many vertices for a convex polygon.
 class b2PolygonShape : public b2Shape
 {
 public:
@@ -31,8 +33,12 @@ public:
 	/// Implement b2Shape.
 	b2Shape* Clone(b2BlockAllocator* allocator) const;
 
+	/// @see b2Shape::GetChildCount
+	int32 GetChildCount() const;
+
 	/// Copy vertices. This assumes the vertices define a convex polygon.
 	/// It is assumed that the exterior is the the right of each edge.
+	/// The count must be in the range [3, b2_maxPolygonVertices].
 	void Set(const b2Vec2* vertices, int32 vertexCount);
 
 	/// Build vertices to represent an axis-aligned box.
@@ -47,27 +53,19 @@ public:
 	/// @param angle the rotation of the box in local coordinates.
 	void SetAsBox(float32 hx, float32 hy, const b2Vec2& center, float32 angle);
 
-	/// Set this as a single edge.
-	void SetAsEdge(const b2Vec2& v1, const b2Vec2& v2);
-
 	/// @see b2Shape::TestPoint
 	bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
 
 	/// Implement b2Shape.
-	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input, const b2Transform& transform) const;
+	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+					const b2Transform& transform, int32 childIndex) const;
 
 	/// @see b2Shape::ComputeAABB
-	void ComputeAABB(b2AABB* aabb, const b2Transform& transform) const;
+	void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const;
 
 	/// @see b2Shape::ComputeMass
 	void ComputeMass(b2MassData* massData, float32 density) const;
 
-	/// Get the supporting vertex index in the given direction.
-	int32 GetSupport(const b2Vec2& d) const;
-
-	/// Get the supporting vertex in the given direction.
-	const b2Vec2& GetSupportVertex(const b2Vec2& d) const;
-
 	/// Get the vertex count.
 	int32 GetVertexCount() const { return m_vertexCount; }
 
@@ -88,40 +86,6 @@ inline b2PolygonShape::b2PolygonShape()
 	m_centroid.SetZero();
 }
 
-inline int32 b2PolygonShape::GetSupport(const b2Vec2& d) const
-{
-	int32 bestIndex = 0;
-	float32 bestValue = b2Dot(m_vertices[0], d);
-	for (int32 i = 1; i < m_vertexCount; ++i)
-	{
-		float32 value = b2Dot(m_vertices[i], d);
-		if (value > bestValue)
-		{
-			bestIndex = i;
-			bestValue = value;
-		}
-	}
-
-	return bestIndex;
-}
-
-inline const b2Vec2& b2PolygonShape::GetSupportVertex(const b2Vec2& d) const
-{
-	int32 bestIndex = 0;
-	float32 bestValue = b2Dot(m_vertices[0], d);
-	for (int32 i = 1; i < m_vertexCount; ++i)
-	{
-		float32 value = b2Dot(m_vertices[i], d);
-		if (value > bestValue)
-		{
-			bestIndex = i;
-			bestValue = value;
-		}
-	}
-
-	return m_vertices[bestIndex];
-}
-
 inline const b2Vec2& b2PolygonShape::GetVertex(int32 index) const
 {
 	b2Assert(0 <= index && index < m_vertexCount);

src/modules/physics/box2d/Box2D/Collision/Shapes/b2Shape.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
+* Copyright (c) 2006-2009 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
@@ -38,20 +38,20 @@ struct b2MassData
 
 /// A shape is used for collision detection. You can create a shape however you like.
 /// Shapes used for simulation in b2World are created automatically when a b2Fixture
-/// is created.
+/// is created. Shapes may encapsulate a one or more child shapes.
 class b2Shape
 {
 public:
 	
 	enum Type
 	{
-		e_unknown= -1,
 		e_circle = 0,
-		e_polygon = 1,
-		e_typeCount = 2,
+		e_edge = 1,
+		e_polygon = 2,
+		e_chain = 3,
+		e_typeCount = 4
 	};
 
-	b2Shape() { m_type = e_unknown; }
 	virtual ~b2Shape() {}
 
 	/// Clone the concrete shape using the provided allocator.
@@ -61,21 +61,27 @@ public:
 	/// @return the shape type.
 	Type GetType() const;
 
+	/// Get the number of child primitives.
+	virtual int32 GetChildCount() const = 0;
+
 	/// Test a point for containment in this shape. This only works for convex shapes.
 	/// @param xf the shape world transform.
 	/// @param p a point in world coordinates.
 	virtual bool TestPoint(const b2Transform& xf, const b2Vec2& p) const = 0;
 
-	/// Cast a ray against this shape.
+	/// Cast a ray against a child shape.
 	/// @param output the ray-cast results.
 	/// @param input the ray-cast input parameters.
 	/// @param transform the transform to be applied to the shape.
-	virtual bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input, const b2Transform& transform) const = 0;
+	/// @param childIndex the child shape index
+	virtual bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+						const b2Transform& transform, int32 childIndex) const = 0;
 
-	/// Given a transform, compute the associated axis aligned bounding box for this shape.
+	/// Given a transform, compute the associated axis aligned bounding box for a child shape.
 	/// @param aabb returns the axis aligned box.
 	/// @param xf the world transform of the shape.
-	virtual void ComputeAABB(b2AABB* aabb, const b2Transform& xf) const = 0;
+	/// @param childIndex the child shape
+	virtual void ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) const = 0;
 
 	/// Compute the mass properties of this shape using its dimensions and density.
 	/// The inertia tensor is computed about the local origin.