补充某些必要的文件

This commit is contained in:
SmallMain
2022-06-25 11:52:00 +08:00
parent 4ecc470f86
commit 03533b046c
2869 changed files with 1345388 additions and 2 deletions

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/*
* 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 <string.h>
b2ChainShape::~b2ChainShape()
{
Clear();
}
void b2ChainShape::Clear()
{
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);
for (int32 i = 1; i < count; ++i)
{
b2Vec2 v1 = vertices[i-1];
b2Vec2 v2 = vertices[i];
// If the code crashes here, it means your vertices are too close together.
b2Assert(b2DistanceSquared(v1, v2) > b2_linearSlop * b2_linearSlop);
}
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);
for (int32 i = 1; i < count; ++i)
{
// If the code crashes here, it means your vertices are too close together.
b2Assert(b2DistanceSquared(vertices[i-1], vertices[i]) > b2_linearSlop * b2_linearSlop);
}
m_count = count;
m_vertices = (b2Vec2*)b2Alloc(count * sizeof(b2Vec2));
memcpy(m_vertices, vertices, m_count * sizeof(b2Vec2));
m_hasPrevVertex = false;
m_hasNextVertex = false;
m_prevVertex.SetZero();
m_nextVertex.SetZero();
}
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;
}

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/*
* 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();
/// Clear all data.
void Clear();
/// 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;
/// 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 = false;
m_hasNextVertex = false;
}
#endif

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/*
* 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
* 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/b2CircleShape.h>
#include <new>
b2Shape* b2CircleShape::Clone(b2BlockAllocator* allocator) const
{
void* mem = allocator->Allocate(sizeof(b2CircleShape));
b2CircleShape* clone = new (mem) b2CircleShape;
*clone = *this;
return clone;
}
int32 b2CircleShape::GetChildCount() const
{
return 1;
}
bool b2CircleShape::TestPoint(const b2Transform& transform, const b2Vec2& p) const
{
b2Vec2 center = transform.p + b2Mul(transform.q, m_p);
b2Vec2 d = p - center;
return b2Dot(d, d) <= m_radius * m_radius;
}
// Collision Detection in Interactive 3D Environments by Gino van den Bergen
// From Section 3.1.2
// x = s + a * r
// norm(x) = radius
bool b2CircleShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
const b2Transform& transform, int32 childIndex) const
{
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;
// Solve quadratic equation.
b2Vec2 r = input.p2 - input.p1;
float32 c = b2Dot(s, r);
float32 rr = b2Dot(r, r);
float32 sigma = c * c - rr * b;
// Check for negative discriminant and short segment.
if (sigma < 0.0f || rr < b2_epsilon)
{
return false;
}
// Find the point of intersection of the line with the circle.
float32 a = -(c + b2Sqrt(sigma));
// Is the intersection point on the segment?
if (0.0f <= a && a <= input.maxFraction * rr)
{
a /= rr;
output->fraction = a;
output->normal = s + a * r;
output->normal.Normalize();
return true;
}
return false;
}
void b2CircleShape::ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const
{
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);
}
void b2CircleShape::ComputeMass(b2MassData* massData, float32 density) const
{
massData->mass = density * b2_pi * m_radius * m_radius;
massData->center = m_p;
// inertia about the local origin
massData->I = massData->mass * (0.5f * m_radius * m_radius + b2Dot(m_p, m_p));
}

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/*
* 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
* 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_CIRCLE_SHAPE_H
#define B2_CIRCLE_SHAPE_H
#include <Box2D/Collision/Shapes/b2Shape.h>
/// A circle shape.
class b2CircleShape : public b2Shape
{
public:
b2CircleShape();
/// 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, 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;
/// 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 1; }
/// Get a vertex by index. Used by b2Distance.
const b2Vec2& GetVertex(int32 index) const;
/// Position
b2Vec2 m_p;
};
inline b2CircleShape::b2CircleShape()
{
m_type = e_circle;
m_radius = 0.0f;
m_p.SetZero();
}
inline int32 b2CircleShape::GetSupport(const b2Vec2 &d) const
{
B2_NOT_USED(d);
return 0;
}
inline const b2Vec2& b2CircleShape::GetSupportVertex(const b2Vec2 &d) const
{
B2_NOT_USED(d);
return m_p;
}
inline const b2Vec2& b2CircleShape::GetVertex(int32 index) const
{
B2_NOT_USED(index);
b2Assert(index == 0);
return m_p;
}
#endif

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/*
* 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>
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 = -b2Mul(xf.q, normal);
}
else
{
output->normal = b2Mul(xf.q, 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;
}

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/*
* 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_vertex0.x = 0.0f;
m_vertex0.y = 0.0f;
m_vertex3.x = 0.0f;
m_vertex3.y = 0.0f;
m_hasVertex0 = false;
m_hasVertex3 = false;
}
#endif

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/*
* 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
* 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/b2PolygonShape.h>
#include <new>
b2Shape* b2PolygonShape::Clone(b2BlockAllocator* allocator) const
{
void* mem = allocator->Allocate(sizeof(b2PolygonShape));
b2PolygonShape* clone = new (mem) b2PolygonShape;
*clone = *this;
return clone;
}
void b2PolygonShape::SetAsBox(float32 hx, float32 hy)
{
m_count = 4;
m_vertices[0].Set(-hx, -hy);
m_vertices[1].Set( hx, -hy);
m_vertices[2].Set( hx, hy);
m_vertices[3].Set(-hx, hy);
m_normals[0].Set(0.0f, -1.0f);
m_normals[1].Set(1.0f, 0.0f);
m_normals[2].Set(0.0f, 1.0f);
m_normals[3].Set(-1.0f, 0.0f);
m_centroid.SetZero();
}
void b2PolygonShape::SetAsBox(float32 hx, float32 hy, const b2Vec2& center, float32 angle)
{
m_count = 4;
m_vertices[0].Set(-hx, -hy);
m_vertices[1].Set( hx, -hy);
m_vertices[2].Set( hx, hy);
m_vertices[3].Set(-hx, hy);
m_normals[0].Set(0.0f, -1.0f);
m_normals[1].Set(1.0f, 0.0f);
m_normals[2].Set(0.0f, 1.0f);
m_normals[3].Set(-1.0f, 0.0f);
m_centroid = center;
b2Transform xf;
xf.p = center;
xf.q.Set(angle);
// Transform vertices and normals.
for (int32 i = 0; i < m_count; ++i)
{
m_vertices[i] = b2Mul(xf, m_vertices[i]);
m_normals[i] = b2Mul(xf.q, m_normals[i]);
}
}
int32 b2PolygonShape::GetChildCount() const
{
return 1;
}
static b2Vec2 ComputeCentroid(const b2Vec2* vs, int32 count)
{
b2Assert(count >= 3);
b2Vec2 c; c.Set(0.0f, 0.0f);
float32 area = 0.0f;
// 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);
#if 0
// This code would put the reference point inside the polygon.
for (int32 i = 0; i < count; ++i)
{
pRef += vs[i];
}
pRef *= 1.0f / count;
#endif
const float32 inv3 = 1.0f / 3.0f;
for (int32 i = 0; i < count; ++i)
{
// Triangle vertices.
b2Vec2 p1 = pRef;
b2Vec2 p2 = vs[i];
b2Vec2 p3 = i + 1 < count ? vs[i+1] : vs[0];
b2Vec2 e1 = p2 - p1;
b2Vec2 e2 = p3 - p1;
float32 D = b2Cross(e1, e2);
float32 triangleArea = 0.5f * D;
area += triangleArea;
// Area weighted centroid
c += triangleArea * inv3 * (p1 + p2 + p3);
}
// Centroid
b2Assert(area > b2_epsilon);
c *= 1.0f / area;
return c;
}
void b2PolygonShape::Set(const b2Vec2* vertices, int32 count)
{
b2Assert(3 <= count && count <= b2_maxPolygonVertices);
if (count < 3)
{
SetAsBox(1.0f, 1.0f);
return;
}
int32 n = b2Min(count, b2_maxPolygonVertices);
// Perform welding and copy vertices into local buffer.
b2Vec2 ps[b2_maxPolygonVertices];
int32 tempCount = 0;
for (int32 i = 0; i < n; ++i)
{
b2Vec2 v = vertices[i];
bool unique = true;
for (int32 j = 0; j < tempCount; ++j)
{
if (b2DistanceSquared(v, ps[j]) < 0.5f * b2_linearSlop)
{
unique = false;
break;
}
}
if (unique)
{
ps[tempCount++] = v;
}
}
n = tempCount;
if (n < 3)
{
// Polygon is degenerate.
b2Assert(false);
SetAsBox(1.0f, 1.0f);
return;
}
// Create the convex hull using the Gift wrapping algorithm
// http://en.wikipedia.org/wiki/Gift_wrapping_algorithm
// Find the right most point on the hull
int32 i0 = 0;
float32 x0 = ps[0].x;
for (int32 i = 1; i < n; ++i)
{
float32 x = ps[i].x;
if (x > x0 || (x == x0 && ps[i].y < ps[i0].y))
{
i0 = i;
x0 = x;
}
}
int32 hull[b2_maxPolygonVertices];
int32 m = 0;
int32 ih = i0;
for (;;)
{
hull[m] = ih;
int32 ie = 0;
for (int32 j = 1; j < n; ++j)
{
if (ie == ih)
{
ie = j;
continue;
}
b2Vec2 r = ps[ie] - ps[hull[m]];
b2Vec2 v = ps[j] - ps[hull[m]];
float32 c = b2Cross(r, v);
if (c < 0.0f)
{
ie = j;
}
// Collinearity check
if (c == 0.0f && v.LengthSquared() > r.LengthSquared())
{
ie = j;
}
}
++m;
ih = ie;
if (ie == i0)
{
break;
}
}
if (m < 3)
{
// Polygon is degenerate.
b2Assert(false);
SetAsBox(1.0f, 1.0f);
return;
}
m_count = m;
// Copy vertices.
for (int32 i = 0; i < m; ++i)
{
m_vertices[i] = ps[hull[i]];
}
// Compute normals. Ensure the edges have non-zero length.
for (int32 i = 0; i < m; ++i)
{
int32 i1 = i;
int32 i2 = i + 1 < m ? i + 1 : 0;
b2Vec2 edge = m_vertices[i2] - m_vertices[i1];
b2Assert(edge.LengthSquared() > b2_epsilon * b2_epsilon);
m_normals[i] = b2Cross(edge, 1.0f);
m_normals[i].Normalize();
}
// Compute the polygon centroid.
m_centroid = ComputeCentroid(m_vertices, m);
}
bool b2PolygonShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
{
b2Vec2 pLocal = b2MulT(xf.q, p - xf.p);
for (int32 i = 0; i < m_count; ++i)
{
float32 dot = b2Dot(m_normals[i], pLocal - m_vertices[i]);
if (dot > 0.0f)
{
return false;
}
}
return true;
}
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.q, input.p1 - xf.p);
b2Vec2 p2 = b2MulT(xf.q, input.p2 - xf.p);
b2Vec2 d = p2 - p1;
float32 lower = 0.0f, upper = input.maxFraction;
int32 index = -1;
for (int32 i = 0; i < m_count; ++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)
{
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, int32 childIndex) const
{
B2_NOT_USED(childIndex);
b2Vec2 lower = b2Mul(xf, m_vertices[0]);
b2Vec2 upper = lower;
for (int32 i = 1; i < m_count; ++i)
{
b2Vec2 v = b2Mul(xf, m_vertices[i]);
lower = b2Min(lower, v);
upper = b2Max(upper, v);
}
b2Vec2 r(m_radius, m_radius);
aabb->lowerBound = lower - r;
aabb->upperBound = upper + r;
}
void b2PolygonShape::ComputeMass(b2MassData* massData, float32 density) const
{
// Polygon mass, centroid, and inertia.
// Let rho be the polygon density in mass per unit area.
// Then:
// mass = rho * int(dA)
// centroid.x = (1/mass) * rho * int(x * dA)
// centroid.y = (1/mass) * rho * int(y * dA)
// I = rho * int((x*x + y*y) * dA)
//
// We can compute these integrals by summing all the integrals
// for each triangle of the polygon. To evaluate the integral
// for a single triangle, we make a change of variables to
// the (u,v) coordinates of the triangle:
// x = x0 + e1x * u + e2x * v
// y = y0 + e1y * u + e2y * v
// where 0 <= u && 0 <= v && u + v <= 1.
//
// We integrate u from [0,1-v] and then v from [0,1].
// We also need to use the Jacobian of the transformation:
// D = cross(e1, e2)
//
// Simplification: triangle centroid = (1/3) * (p1 + p2 + p3)
//
// The rest of the derivation is handled by computer algebra.
b2Assert(m_count >= 3);
b2Vec2 center; center.Set(0.0f, 0.0f);
float32 area = 0.0f;
float32 I = 0.0f;
// s is the reference point for forming triangles.
// It's location doesn't change the result (except for rounding error).
b2Vec2 s(0.0f, 0.0f);
// This code would put the reference point inside the polygon.
for (int32 i = 0; i < m_count; ++i)
{
s += m_vertices[i];
}
s *= 1.0f / m_count;
const float32 k_inv3 = 1.0f / 3.0f;
for (int32 i = 0; i < m_count; ++i)
{
// Triangle vertices.
b2Vec2 e1 = m_vertices[i] - s;
b2Vec2 e2 = i + 1 < m_count ? m_vertices[i+1] - s : m_vertices[0] - s;
float32 D = b2Cross(e1, e2);
float32 triangleArea = 0.5f * D;
area += triangleArea;
// Area weighted centroid
center += triangleArea * k_inv3 * (e1 + e2);
float32 ex1 = e1.x, ey1 = e1.y;
float32 ex2 = e2.x, ey2 = e2.y;
float32 intx2 = ex1*ex1 + ex2*ex1 + ex2*ex2;
float32 inty2 = ey1*ey1 + ey2*ey1 + ey2*ey2;
I += (0.25f * k_inv3 * D) * (intx2 + inty2);
}
// Total mass
massData->mass = density * area;
// Center of mass
b2Assert(area > b2_epsilon);
center *= 1.0f / area;
massData->center = center + s;
// 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));
}
bool b2PolygonShape::Validate() const
{
for (int32 i = 0; i < m_count; ++i)
{
int32 i1 = i;
int32 i2 = i < m_count - 1 ? i1 + 1 : 0;
b2Vec2 p = m_vertices[i1];
b2Vec2 e = m_vertices[i2] - p;
for (int32 j = 0; j < m_count; ++j)
{
if (j == i1 || j == i2)
{
continue;
}
b2Vec2 v = m_vertices[j] - p;
float32 c = b2Cross(e, v);
if (c < 0.0f)
{
return false;
}
}
}
return true;
}

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/*
* 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
* 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_POLYGON_SHAPE_H
#define B2_POLYGON_SHAPE_H
#include <Box2D/Collision/Shapes/b2Shape.h>
/// 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:
b2PolygonShape();
/// Implement b2Shape.
b2Shape* Clone(b2BlockAllocator* allocator) const;
/// @see b2Shape::GetChildCount
int32 GetChildCount() const;
/// Create a convex hull from the given array of local points.
/// The count must be in the range [3, b2_maxPolygonVertices].
/// @warning the points may be re-ordered, even if they form a convex polygon
/// @warning collinear points are handled but not removed. Collinear points
/// may lead to poor stacking behavior.
void Set(const b2Vec2* points, int32 count);
/// Build vertices to represent an axis-aligned box centered on the local origin.
/// @param hx the half-width.
/// @param hy the half-height.
void SetAsBox(float32 hx, float32 hy);
/// Build vertices to represent an oriented box.
/// @param hx the half-width.
/// @param hy the half-height.
/// @param center the center of the box in local coordinates.
/// @param angle the rotation of the box in local coordinates.
void SetAsBox(float32 hx, float32 hy, const b2Vec2& center, float32 angle);
/// @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;
/// Get the vertex count.
int32 GetVertexCount() const { return m_count; }
/// Get a vertex by index.
const b2Vec2& GetVertex(int32 index) const;
/// Validate convexity. This is a very time consuming operation.
/// @returns true if valid
bool Validate() const;
b2Vec2 m_centroid;
b2Vec2 m_vertices[b2_maxPolygonVertices];
b2Vec2 m_normals[b2_maxPolygonVertices];
int32 m_count;
};
inline b2PolygonShape::b2PolygonShape()
{
m_type = e_polygon;
m_radius = b2_polygonRadius;
m_count = 0;
m_centroid.SetZero();
}
inline const b2Vec2& b2PolygonShape::GetVertex(int32 index) const
{
b2Assert(0 <= index && index < m_count);
return m_vertices[index];
}
#endif

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/*
* 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
* 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_SHAPE_H
#define B2_SHAPE_H
#include <Box2D/Common/b2BlockAllocator.h>
#include <Box2D/Common/b2Math.h>
#include <Box2D/Collision/b2Collision.h>
/// This holds the mass data computed for a shape.
struct b2MassData
{
/// The mass of the shape, usually in kilograms.
float32 mass;
/// The position of the shape's centroid relative to the shape's origin.
b2Vec2 center;
/// The rotational inertia of the shape about the local origin.
float32 I;
};
/// 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. Shapes may encapsulate a one or more child shapes.
class b2Shape
{
public:
enum Type
{
e_circle = 0,
e_edge = 1,
e_polygon = 2,
e_chain = 3,
e_typeCount = 4
};
virtual ~b2Shape() {}
/// Clone the concrete shape using the provided allocator.
virtual b2Shape* Clone(b2BlockAllocator* allocator) const = 0;
/// Get the type of this shape. You can use this to down cast to the concrete shape.
/// @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 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.
/// @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 a child shape.
/// @param aabb returns the axis aligned box.
/// @param xf the world transform of the shape.
/// @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.
/// @param massData returns the mass data for this shape.
/// @param density the density in kilograms per meter squared.
virtual void ComputeMass(b2MassData* massData, float32 density) const = 0;
Type m_type;
float32 m_radius;
};
inline b2Shape::Type b2Shape::GetType() const
{
return m_type;
}
#endif