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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));
}
/*
* 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 override;
/// @see b2Shape::GetChildCount
int32 GetChildCount() const override;
/// Implement b2Shape.
bool TestPoint(const b2Transform& transform, const b2Vec2& p) const override;
/// Implement b2Shape.
bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
const b2Transform& transform, int32 childIndex) const override;
/// @see b2Shape::ComputeAABB
void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const override;
/// @see b2Shape::ComputeMass
void ComputeMass(b2MassData* massData, float32 density) const override;
/// Position
b2Vec2 m_p;
};
inline b2CircleShape::b2CircleShape()
{
m_type = e_circle;
m_radius = 0.0f;
m_p.SetZero();
}
#endif
/*
* 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;
}
/*
* 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 override;
/// @see b2Shape::GetChildCount
int32 GetChildCount() const override;
/// @see b2Shape::TestPoint
bool TestPoint(const b2Transform& transform, const b2Vec2& p) const override;
/// Implement b2Shape.
bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
const b2Transform& transform, int32 childIndex) const override;
/// @see b2Shape::ComputeAABB
void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const override;
/// @see b2Shape::ComputeMass
void ComputeMass(b2MassData* massData, float32 density) const override;
/// 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
/*
* 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) * (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 (;;)
{
b2Assert(m < b2_maxPolygonVertices);
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;
}
/*
* 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 override;
/// @see b2Shape::GetChildCount
int32 GetChildCount() const override;
/// 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 override;
/// Implement b2Shape.
bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
const b2Transform& transform, int32 childIndex) const override;
/// @see b2Shape::ComputeAABB
void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const override;
/// @see b2Shape::ComputeMass
void ComputeMass(b2MassData* massData, float32 density) const override;
/// 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();
}
#endif
/*
* 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;
/// Radius of a shape. For polygonal shapes this must be b2_polygonRadius. There is no support for
/// making rounded polygons.
float32 m_radius;
};
inline b2Shape::Type b2Shape::GetType() const
{
return m_type;
}
#endif
/*
* 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/b2BroadPhase.h"
b2BroadPhase::b2BroadPhase()
{
m_proxyCount = 0;
m_pairCapacity = 16;
m_pairCount = 0;
m_pairBuffer = (b2Pair*)b2Alloc(m_pairCapacity * sizeof(b2Pair));
m_moveCapacity = 16;
m_moveCount = 0;
m_moveBuffer = (int32*)b2Alloc(m_moveCapacity * sizeof(int32));
}
b2BroadPhase::~b2BroadPhase()
{
b2Free(m_moveBuffer);
b2Free(m_pairBuffer);
}
int32 b2BroadPhase::CreateProxy(const b2AABB& aabb, void* userData)
{
int32 proxyId = m_tree.CreateProxy(aabb, userData);
++m_proxyCount;
BufferMove(proxyId);
return proxyId;
}
void b2BroadPhase::DestroyProxy(int32 proxyId)
{
UnBufferMove(proxyId);
--m_proxyCount;
m_tree.DestroyProxy(proxyId);
}
void b2BroadPhase::MoveProxy(int32 proxyId, const b2AABB& aabb, const b2Vec2& displacement)
{
bool buffer = m_tree.MoveProxy(proxyId, aabb, displacement);
if (buffer)
{
BufferMove(proxyId);
}
}
void b2BroadPhase::TouchProxy(int32 proxyId)
{
BufferMove(proxyId);
}
void b2BroadPhase::BufferMove(int32 proxyId)
{
if (m_moveCount == m_moveCapacity)
{
int32* oldBuffer = m_moveBuffer;
m_moveCapacity *= 2;
m_moveBuffer = (int32*)b2Alloc(m_moveCapacity * sizeof(int32));
memcpy(m_moveBuffer, oldBuffer, m_moveCount * sizeof(int32));
b2Free(oldBuffer);
}
m_moveBuffer[m_moveCount] = proxyId;
++m_moveCount;
}
void b2BroadPhase::UnBufferMove(int32 proxyId)
{
for (int32 i = 0; i < m_moveCount; ++i)
{
if (m_moveBuffer[i] == proxyId)
{
m_moveBuffer[i] = e_nullProxy;
}
}
}
// This is called from b2DynamicTree::Query when we are gathering pairs.
bool b2BroadPhase::QueryCallback(int32 proxyId)
{
// A proxy cannot form a pair with itself.
if (proxyId == m_queryProxyId)
{
return true;
}
// Grow the pair buffer as needed.
if (m_pairCount == m_pairCapacity)
{
b2Pair* oldBuffer = m_pairBuffer;
m_pairCapacity *= 2;
m_pairBuffer = (b2Pair*)b2Alloc(m_pairCapacity * sizeof(b2Pair));
memcpy(m_pairBuffer, oldBuffer, m_pairCount * sizeof(b2Pair));
b2Free(oldBuffer);
}
m_pairBuffer[m_pairCount].proxyIdA = b2Min(proxyId, m_queryProxyId);
m_pairBuffer[m_pairCount].proxyIdB = b2Max(proxyId, m_queryProxyId);
++m_pairCount;
return true;
}
/*
* 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_BROAD_PHASE_H
#define B2_BROAD_PHASE_H
#include "Box2D/Common/b2Settings.h"
#include "Box2D/Collision/b2Collision.h"
#include "Box2D/Collision/b2DynamicTree.h"
#include <algorithm>
struct b2Pair
{
int32 proxyIdA;
int32 proxyIdB;
};
/// The broad-phase is used for computing pairs and performing volume queries and ray casts.
/// This broad-phase does not persist pairs. Instead, this reports potentially new pairs.
/// It is up to the client to consume the new pairs and to track subsequent overlap.
class b2BroadPhase
{
public:
enum
{
e_nullProxy = -1
};
b2BroadPhase();
~b2BroadPhase();
/// Create a proxy with an initial AABB. Pairs are not reported until
/// UpdatePairs is called.
int32 CreateProxy(const b2AABB& aabb, void* userData);
/// Destroy a proxy. It is up to the client to remove any pairs.
void DestroyProxy(int32 proxyId);
/// Call MoveProxy as many times as you like, then when you are done
/// call UpdatePairs to finalized the proxy pairs (for your time step).
void MoveProxy(int32 proxyId, const b2AABB& aabb, const b2Vec2& displacement);
/// Call to trigger a re-processing of it's pairs on the next call to UpdatePairs.
void TouchProxy(int32 proxyId);
/// Get the fat AABB for a proxy.
const b2AABB& GetFatAABB(int32 proxyId) const;
/// Get user data from a proxy. Returns nullptr if the id is invalid.
void* GetUserData(int32 proxyId) const;
/// Test overlap of fat AABBs.
bool TestOverlap(int32 proxyIdA, int32 proxyIdB) const;
/// Get the number of proxies.
int32 GetProxyCount() const;
/// Update the pairs. This results in pair callbacks. This can only add pairs.
template <typename T>
void UpdatePairs(T* callback);
/// Query an AABB for overlapping proxies. The callback class
/// is called for each proxy that overlaps the supplied AABB.
template <typename T>
void Query(T* callback, const b2AABB& aabb) const;
/// Ray-cast against the proxies in the tree. This relies on the callback
/// to perform a exact ray-cast in the case were the proxy contains a shape.
/// The callback also performs the any collision filtering. This has performance
/// roughly equal to k * log(n), where k is the number of collisions and n is the
/// number of proxies in the tree.
/// @param input the ray-cast input data. The ray extends from p1 to p1 + maxFraction * (p2 - p1).
/// @param callback a callback class that is called for each proxy that is hit by the ray.
template <typename T>
void RayCast(T* callback, const b2RayCastInput& input) const;
/// Get the height of the embedded tree.
int32 GetTreeHeight() const;
/// Get the balance of the embedded tree.
int32 GetTreeBalance() const;
/// Get the quality metric of the embedded tree.
float32 GetTreeQuality() const;
/// Shift the world origin. Useful for large worlds.
/// The shift formula is: position -= newOrigin
/// @param newOrigin the new origin with respect to the old origin
void ShiftOrigin(const b2Vec2& newOrigin);
private:
friend class b2DynamicTree;
void BufferMove(int32 proxyId);
void UnBufferMove(int32 proxyId);
bool QueryCallback(int32 proxyId);
b2DynamicTree m_tree;
int32 m_proxyCount;
int32* m_moveBuffer;
int32 m_moveCapacity;
int32 m_moveCount;
b2Pair* m_pairBuffer;
int32 m_pairCapacity;
int32 m_pairCount;
int32 m_queryProxyId;
};
/// This is used to sort pairs.
inline bool b2PairLessThan(const b2Pair& pair1, const b2Pair& pair2)
{
if (pair1.proxyIdA < pair2.proxyIdA)
{
return true;
}
if (pair1.proxyIdA == pair2.proxyIdA)
{
return pair1.proxyIdB < pair2.proxyIdB;
}
return false;
}
inline void* b2BroadPhase::GetUserData(int32 proxyId) const
{
return m_tree.GetUserData(proxyId);
}
inline bool b2BroadPhase::TestOverlap(int32 proxyIdA, int32 proxyIdB) const
{
const b2AABB& aabbA = m_tree.GetFatAABB(proxyIdA);
const b2AABB& aabbB = m_tree.GetFatAABB(proxyIdB);
return b2TestOverlap(aabbA, aabbB);
}
inline const b2AABB& b2BroadPhase::GetFatAABB(int32 proxyId) const
{
return m_tree.GetFatAABB(proxyId);
}
inline int32 b2BroadPhase::GetProxyCount() const
{
return m_proxyCount;
}
inline int32 b2BroadPhase::GetTreeHeight() const
{
return m_tree.GetHeight();
}
inline int32 b2BroadPhase::GetTreeBalance() const
{
return m_tree.GetMaxBalance();
}
inline float32 b2BroadPhase::GetTreeQuality() const
{
return m_tree.GetAreaRatio();
}
template <typename T>
void b2BroadPhase::UpdatePairs(T* callback)
{
// Reset pair buffer
m_pairCount = 0;
// Perform tree queries for all moving proxies.
for (int32 i = 0; i < m_moveCount; ++i)
{
m_queryProxyId = m_moveBuffer[i];
if (m_queryProxyId == e_nullProxy)
{
continue;
}
// We have to query the tree with the fat AABB so that
// we don't fail to create a pair that may touch later.
const b2AABB& fatAABB = m_tree.GetFatAABB(m_queryProxyId);
// Query tree, create pairs and add them pair buffer.
m_tree.Query(this, fatAABB);
}
// Reset move buffer
m_moveCount = 0;
// Sort the pair buffer to expose duplicates.
std::sort(m_pairBuffer, m_pairBuffer + m_pairCount, b2PairLessThan);
// Send the pairs back to the client.
int32 i = 0;
while (i < m_pairCount)
{
b2Pair* primaryPair = m_pairBuffer + i;
void* userDataA = m_tree.GetUserData(primaryPair->proxyIdA);
void* userDataB = m_tree.GetUserData(primaryPair->proxyIdB);
callback->AddPair(userDataA, userDataB);
++i;
// Skip any duplicate pairs.
while (i < m_pairCount)
{
b2Pair* pair = m_pairBuffer + i;
if (pair->proxyIdA != primaryPair->proxyIdA || pair->proxyIdB != primaryPair->proxyIdB)
{
break;
}
++i;
}
}
// Try to keep the tree balanced.
//m_tree.Rebalance(4);
}
template <typename T>
inline void b2BroadPhase::Query(T* callback, const b2AABB& aabb) const
{
m_tree.Query(callback, aabb);
}
template <typename T>
inline void b2BroadPhase::RayCast(T* callback, const b2RayCastInput& input) const
{
m_tree.RayCast(callback, input);
}
inline void b2BroadPhase::ShiftOrigin(const b2Vec2& newOrigin)
{
m_tree.ShiftOrigin(newOrigin);
}
#endif
/*
* Copyright (c) 2007-2009 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/b2Collision.h"
#include "Box2D/Collision/Shapes/b2CircleShape.h"
#include "Box2D/Collision/Shapes/b2PolygonShape.h"
void b2CollideCircles(
b2Manifold* manifold,
const b2CircleShape* circleA, const b2Transform& xfA,
const b2CircleShape* circleB, const b2Transform& xfB)
{
manifold->pointCount = 0;
b2Vec2 pA = b2Mul(xfA, circleA->m_p);
b2Vec2 pB = b2Mul(xfB, circleB->m_p);
b2Vec2 d = pB - pA;
float32 distSqr = b2Dot(d, d);
float32 rA = circleA->m_radius, rB = circleB->m_radius;
float32 radius = rA + rB;
if (distSqr > radius * radius)
{
return;
}
manifold->type = b2Manifold::e_circles;
manifold->localPoint = circleA->m_p;
manifold->localNormal.SetZero();
manifold->pointCount = 1;
manifold->points[0].localPoint = circleB->m_p;
manifold->points[0].id.key = 0;
}
void b2CollidePolygonAndCircle(
b2Manifold* manifold,
const b2PolygonShape* polygonA, const b2Transform& xfA,
const b2CircleShape* circleB, const b2Transform& xfB)
{
manifold->pointCount = 0;
// Compute circle position in the frame of the polygon.
b2Vec2 c = b2Mul(xfB, circleB->m_p);
b2Vec2 cLocal = b2MulT(xfA, c);
// Find the min separating edge.
int32 normalIndex = 0;
float32 separation = -b2_maxFloat;
float32 radius = polygonA->m_radius + circleB->m_radius;
int32 vertexCount = polygonA->m_count;
const b2Vec2* vertices = polygonA->m_vertices;
const b2Vec2* normals = polygonA->m_normals;
for (int32 i = 0; i < vertexCount; ++i)
{
float32 s = b2Dot(normals[i], cLocal - vertices[i]);
if (s > radius)
{
// Early out.
return;
}
if (s > separation)
{
separation = s;
normalIndex = i;
}
}
// Vertices that subtend the incident face.
int32 vertIndex1 = normalIndex;
int32 vertIndex2 = vertIndex1 + 1 < vertexCount ? vertIndex1 + 1 : 0;
b2Vec2 v1 = vertices[vertIndex1];
b2Vec2 v2 = vertices[vertIndex2];
// If the center is inside the polygon ...
if (separation < b2_epsilon)
{
manifold->pointCount = 1;
manifold->type = b2Manifold::e_faceA;
manifold->localNormal = normals[normalIndex];
manifold->localPoint = 0.5f * (v1 + v2);
manifold->points[0].localPoint = circleB->m_p;
manifold->points[0].id.key = 0;
return;
}
// Compute barycentric coordinates
float32 u1 = b2Dot(cLocal - v1, v2 - v1);
float32 u2 = b2Dot(cLocal - v2, v1 - v2);
if (u1 <= 0.0f)
{
if (b2DistanceSquared(cLocal, v1) > radius * radius)
{
return;
}
manifold->pointCount = 1;
manifold->type = b2Manifold::e_faceA;
manifold->localNormal = cLocal - v1;
manifold->localNormal.Normalize();
manifold->localPoint = v1;
manifold->points[0].localPoint = circleB->m_p;
manifold->points[0].id.key = 0;
}
else if (u2 <= 0.0f)
{
if (b2DistanceSquared(cLocal, v2) > radius * radius)
{
return;
}
manifold->pointCount = 1;
manifold->type = b2Manifold::e_faceA;
manifold->localNormal = cLocal - v2;
manifold->localNormal.Normalize();
manifold->localPoint = v2;
manifold->points[0].localPoint = circleB->m_p;
manifold->points[0].id.key = 0;
}
else
{
b2Vec2 faceCenter = 0.5f * (v1 + v2);
float32 s = b2Dot(cLocal - faceCenter, normals[vertIndex1]);
if (s > radius)
{
return;
}
manifold->pointCount = 1;
manifold->type = b2Manifold::e_faceA;
manifold->localNormal = normals[vertIndex1];
manifold->localPoint = faceCenter;
manifold->points[0].localPoint = circleB->m_p;
manifold->points[0].id.key = 0;
}
}
/*
* Copyright (c) 2007-2009 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/b2Collision.h"
#include "Box2D/Collision/Shapes/b2CircleShape.h"
#include "Box2D/Collision/Shapes/b2EdgeShape.h"
#include "Box2D/Collision/Shapes/b2PolygonShape.h"
// Compute contact points for edge versus circle.
// This accounts for edge connectivity.
void b2CollideEdgeAndCircle(b2Manifold* manifold,
const b2EdgeShape* edgeA, const b2Transform& xfA,
const b2CircleShape* circleB, const b2Transform& xfB)
{
manifold->pointCount = 0;
// Compute circle in frame of edge
b2Vec2 Q = b2MulT(xfA, b2Mul(xfB, circleB->m_p));
b2Vec2 A = edgeA->m_vertex1, B = edgeA->m_vertex2;
b2Vec2 e = B - A;
// Barycentric coordinates
float32 u = b2Dot(e, B - Q);
float32 v = b2Dot(e, Q - A);
float32 radius = edgeA->m_radius + circleB->m_radius;
b2ContactFeature cf;
cf.indexB = 0;
cf.typeB = b2ContactFeature::e_vertex;
// Region A
if (v <= 0.0f)
{
b2Vec2 P = A;
b2Vec2 d = Q - P;
float32 dd = b2Dot(d, d);
if (dd > radius * radius)
{
return;
}
// Is there an edge connected to A?
if (edgeA->m_hasVertex0)
{
b2Vec2 A1 = edgeA->m_vertex0;
b2Vec2 B1 = A;
b2Vec2 e1 = B1 - A1;
float32 u1 = b2Dot(e1, B1 - Q);
// Is the circle in Region AB of the previous edge?
if (u1 > 0.0f)
{
return;
}
}
cf.indexA = 0;
cf.typeA = b2ContactFeature::e_vertex;
manifold->pointCount = 1;
manifold->type = b2Manifold::e_circles;
manifold->localNormal.SetZero();
manifold->localPoint = P;
manifold->points[0].id.key = 0;
manifold->points[0].id.cf = cf;
manifold->points[0].localPoint = circleB->m_p;
return;
}
// Region B
if (u <= 0.0f)
{
b2Vec2 P = B;
b2Vec2 d = Q - P;
float32 dd = b2Dot(d, d);
if (dd > radius * radius)
{
return;
}
// Is there an edge connected to B?
if (edgeA->m_hasVertex3)
{
b2Vec2 B2 = edgeA->m_vertex3;
b2Vec2 A2 = B;
b2Vec2 e2 = B2 - A2;
float32 v2 = b2Dot(e2, Q - A2);
// Is the circle in Region AB of the next edge?
if (v2 > 0.0f)
{
return;
}
}
cf.indexA = 1;
cf.typeA = b2ContactFeature::e_vertex;
manifold->pointCount = 1;
manifold->type = b2Manifold::e_circles;
manifold->localNormal.SetZero();
manifold->localPoint = P;
manifold->points[0].id.key = 0;
manifold->points[0].id.cf = cf;
manifold->points[0].localPoint = circleB->m_p;
return;
}
// Region AB
float32 den = b2Dot(e, e);
b2Assert(den > 0.0f);
b2Vec2 P = (1.0f / den) * (u * A + v * B);
b2Vec2 d = Q - P;
float32 dd = b2Dot(d, d);
if (dd > radius * radius)
{
return;
}
b2Vec2 n(-e.y, e.x);
if (b2Dot(n, Q - A) < 0.0f)
{
n.Set(-n.x, -n.y);
}
n.Normalize();
cf.indexA = 0;
cf.typeA = b2ContactFeature::e_face;
manifold->pointCount = 1;
manifold->type = b2Manifold::e_faceA;
manifold->localNormal = n;
manifold->localPoint = A;
manifold->points[0].id.key = 0;
manifold->points[0].id.cf = cf;
manifold->points[0].localPoint = circleB->m_p;
}
// This structure is used to keep track of the best separating axis.
struct b2EPAxis
{
enum Type
{
e_unknown,
e_edgeA,
e_edgeB
};
Type type;
int32 index;
float32 separation;
};
// This holds polygon B expressed in frame A.
struct b2TempPolygon
{
b2Vec2 vertices[b2_maxPolygonVertices];
b2Vec2 normals[b2_maxPolygonVertices];
int32 count;
};
// Reference face used for clipping
struct b2ReferenceFace
{
int32 i1, i2;
b2Vec2 v1, v2;
b2Vec2 normal;
b2Vec2 sideNormal1;
float32 sideOffset1;
b2Vec2 sideNormal2;
float32 sideOffset2;
};
// This class collides and edge and a polygon, taking into account edge adjacency.
struct b2EPCollider
{
void Collide(b2Manifold* manifold, const b2EdgeShape* edgeA, const b2Transform& xfA,
const b2PolygonShape* polygonB, const b2Transform& xfB);
b2EPAxis ComputeEdgeSeparation();
b2EPAxis ComputePolygonSeparation();
enum VertexType
{
e_isolated,
e_concave,
e_convex
};
b2TempPolygon m_polygonB;
b2Transform m_xf;
b2Vec2 m_centroidB;
b2Vec2 m_v0, m_v1, m_v2, m_v3;
b2Vec2 m_normal0, m_normal1, m_normal2;
b2Vec2 m_normal;
VertexType m_type1, m_type2;
b2Vec2 m_lowerLimit, m_upperLimit;
float32 m_radius;
bool m_front;
};
// Algorithm:
// 1. Classify v1 and v2
// 2. Classify polygon centroid as front or back
// 3. Flip normal if necessary
// 4. Initialize normal range to [-pi, pi] about face normal
// 5. Adjust normal range according to adjacent edges
// 6. Visit each separating axes, only accept axes within the range
// 7. Return if _any_ axis indicates separation
// 8. Clip
void b2EPCollider::Collide(b2Manifold* manifold, const b2EdgeShape* edgeA, const b2Transform& xfA,
const b2PolygonShape* polygonB, const b2Transform& xfB)
{
m_xf = b2MulT(xfA, xfB);
m_centroidB = b2Mul(m_xf, polygonB->m_centroid);
m_v0 = edgeA->m_vertex0;
m_v1 = edgeA->m_vertex1;
m_v2 = edgeA->m_vertex2;
m_v3 = edgeA->m_vertex3;
bool hasVertex0 = edgeA->m_hasVertex0;
bool hasVertex3 = edgeA->m_hasVertex3;
b2Vec2 edge1 = m_v2 - m_v1;
edge1.Normalize();
m_normal1.Set(edge1.y, -edge1.x);
float32 offset1 = b2Dot(m_normal1, m_centroidB - m_v1);
float32 offset0 = 0.0f, offset2 = 0.0f;
bool convex1 = false, convex2 = false;
// Is there a preceding edge?
if (hasVertex0)
{
b2Vec2 edge0 = m_v1 - m_v0;
edge0.Normalize();
m_normal0.Set(edge0.y, -edge0.x);
convex1 = b2Cross(edge0, edge1) >= 0.0f;
offset0 = b2Dot(m_normal0, m_centroidB - m_v0);
}
// Is there a following edge?
if (hasVertex3)
{
b2Vec2 edge2 = m_v3 - m_v2;
edge2.Normalize();
m_normal2.Set(edge2.y, -edge2.x);
convex2 = b2Cross(edge1, edge2) > 0.0f;
offset2 = b2Dot(m_normal2, m_centroidB - m_v2);
}
// Determine front or back collision. Determine collision normal limits.
if (hasVertex0 && hasVertex3)
{
if (convex1 && convex2)
{
m_front = offset0 >= 0.0f || offset1 >= 0.0f || offset2 >= 0.0f;
if (m_front)
{
m_normal = m_normal1;
m_lowerLimit = m_normal0;
m_upperLimit = m_normal2;
}
else
{
m_normal = -m_normal1;
m_lowerLimit = -m_normal1;
m_upperLimit = -m_normal1;
}
}
else if (convex1)
{
m_front = offset0 >= 0.0f || (offset1 >= 0.0f && offset2 >= 0.0f);
if (m_front)
{
m_normal = m_normal1;
m_lowerLimit = m_normal0;
m_upperLimit = m_normal1;
}
else
{
m_normal = -m_normal1;
m_lowerLimit = -m_normal2;
m_upperLimit = -m_normal1;
}
}
else if (convex2)
{
m_front = offset2 >= 0.0f || (offset0 >= 0.0f && offset1 >= 0.0f);
if (m_front)
{
m_normal = m_normal1;
m_lowerLimit = m_normal1;
m_upperLimit = m_normal2;
}
else
{
m_normal = -m_normal1;
m_lowerLimit = -m_normal1;
m_upperLimit = -m_normal0;
}
}
else
{
m_front = offset0 >= 0.0f && offset1 >= 0.0f && offset2 >= 0.0f;
if (m_front)
{
m_normal = m_normal1;
m_lowerLimit = m_normal1;
m_upperLimit = m_normal1;
}
else
{
m_normal = -m_normal1;
m_lowerLimit = -m_normal2;
m_upperLimit = -m_normal0;
}
}
}
else if (hasVertex0)
{
if (convex1)
{
m_front = offset0 >= 0.0f || offset1 >= 0.0f;
if (m_front)
{
m_normal = m_normal1;
m_lowerLimit = m_normal0;
m_upperLimit = -m_normal1;
}
else
{
m_normal = -m_normal1;
m_lowerLimit = m_normal1;
m_upperLimit = -m_normal1;
}
}
else
{
m_front = offset0 >= 0.0f && offset1 >= 0.0f;
if (m_front)
{
m_normal = m_normal1;
m_lowerLimit = m_normal1;
m_upperLimit = -m_normal1;
}
else
{
m_normal = -m_normal1;
m_lowerLimit = m_normal1;
m_upperLimit = -m_normal0;
}
}
}
else if (hasVertex3)
{
if (convex2)
{
m_front = offset1 >= 0.0f || offset2 >= 0.0f;
if (m_front)
{
m_normal = m_normal1;
m_lowerLimit = -m_normal1;
m_upperLimit = m_normal2;
}
else
{
m_normal = -m_normal1;
m_lowerLimit = -m_normal1;
m_upperLimit = m_normal1;
}
}
else
{
m_front = offset1 >= 0.0f && offset2 >= 0.0f;
if (m_front)
{
m_normal = m_normal1;
m_lowerLimit = -m_normal1;
m_upperLimit = m_normal1;
}
else
{
m_normal = -m_normal1;
m_lowerLimit = -m_normal2;
m_upperLimit = m_normal1;
}
}
}
else
{
m_front = offset1 >= 0.0f;
if (m_front)
{
m_normal = m_normal1;
m_lowerLimit = -m_normal1;
m_upperLimit = -m_normal1;
}
else
{
m_normal = -m_normal1;
m_lowerLimit = m_normal1;
m_upperLimit = m_normal1;
}
}
// Get polygonB in frameA
m_polygonB.count = polygonB->m_count;
for (int32 i = 0; i < polygonB->m_count; ++i)
{
m_polygonB.vertices[i] = b2Mul(m_xf, polygonB->m_vertices[i]);
m_polygonB.normals[i] = b2Mul(m_xf.q, polygonB->m_normals[i]);
}
m_radius = polygonB->m_radius + edgeA->m_radius;
manifold->pointCount = 0;
b2EPAxis edgeAxis = ComputeEdgeSeparation();
// If no valid normal can be found than this edge should not collide.
if (edgeAxis.type == b2EPAxis::e_unknown)
{
return;
}
if (edgeAxis.separation > m_radius)
{
return;
}
b2EPAxis polygonAxis = ComputePolygonSeparation();
if (polygonAxis.type != b2EPAxis::e_unknown && polygonAxis.separation > m_radius)
{
return;
}
// Use hysteresis for jitter reduction.
const float32 k_relativeTol = 0.98f;
const float32 k_absoluteTol = 0.001f;
b2EPAxis primaryAxis;
if (polygonAxis.type == b2EPAxis::e_unknown)
{
primaryAxis = edgeAxis;
}
else if (polygonAxis.separation > k_relativeTol * edgeAxis.separation + k_absoluteTol)
{
primaryAxis = polygonAxis;
}
else
{
primaryAxis = edgeAxis;
}
b2ClipVertex ie[2];
b2ReferenceFace rf;
if (primaryAxis.type == b2EPAxis::e_edgeA)
{
manifold->type = b2Manifold::e_faceA;
// Search for the polygon normal that is most anti-parallel to the edge normal.
int32 bestIndex = 0;
float32 bestValue = b2Dot(m_normal, m_polygonB.normals[0]);
for (int32 i = 1; i < m_polygonB.count; ++i)
{
float32 value = b2Dot(m_normal, m_polygonB.normals[i]);
if (value < bestValue)
{
bestValue = value;
bestIndex = i;
}
}
int32 i1 = bestIndex;
int32 i2 = i1 + 1 < m_polygonB.count ? i1 + 1 : 0;
ie[0].v = m_polygonB.vertices[i1];
ie[0].id.cf.indexA = 0;
ie[0].id.cf.indexB = static_cast<uint8>(i1);
ie[0].id.cf.typeA = b2ContactFeature::e_face;
ie[0].id.cf.typeB = b2ContactFeature::e_vertex;
ie[1].v = m_polygonB.vertices[i2];
ie[1].id.cf.indexA = 0;
ie[1].id.cf.indexB = static_cast<uint8>(i2);
ie[1].id.cf.typeA = b2ContactFeature::e_face;
ie[1].id.cf.typeB = b2ContactFeature::e_vertex;
if (m_front)
{
rf.i1 = 0;
rf.i2 = 1;
rf.v1 = m_v1;
rf.v2 = m_v2;
rf.normal = m_normal1;
}
else
{
rf.i1 = 1;
rf.i2 = 0;
rf.v1 = m_v2;
rf.v2 = m_v1;
rf.normal = -m_normal1;
}
}
else
{
manifold->type = b2Manifold::e_faceB;
ie[0].v = m_v1;
ie[0].id.cf.indexA = 0;
ie[0].id.cf.indexB = static_cast<uint8>(primaryAxis.index);
ie[0].id.cf.typeA = b2ContactFeature::e_vertex;
ie[0].id.cf.typeB = b2ContactFeature::e_face;
ie[1].v = m_v2;
ie[1].id.cf.indexA = 0;
ie[1].id.cf.indexB = static_cast<uint8>(primaryAxis.index);
ie[1].id.cf.typeA = b2ContactFeature::e_vertex;
ie[1].id.cf.typeB = b2ContactFeature::e_face;
rf.i1 = primaryAxis.index;
rf.i2 = rf.i1 + 1 < m_polygonB.count ? rf.i1 + 1 : 0;
rf.v1 = m_polygonB.vertices[rf.i1];
rf.v2 = m_polygonB.vertices[rf.i2];
rf.normal = m_polygonB.normals[rf.i1];
}
rf.sideNormal1.Set(rf.normal.y, -rf.normal.x);
rf.sideNormal2 = -rf.sideNormal1;
rf.sideOffset1 = b2Dot(rf.sideNormal1, rf.v1);
rf.sideOffset2 = b2Dot(rf.sideNormal2, rf.v2);
// Clip incident edge against extruded edge1 side edges.
b2ClipVertex clipPoints1[2];
b2ClipVertex clipPoints2[2];
int32 np;
// Clip to box side 1
np = b2ClipSegmentToLine(clipPoints1, ie, rf.sideNormal1, rf.sideOffset1, rf.i1);
if (np < b2_maxManifoldPoints)
{
return;
}
// Clip to negative box side 1
np = b2ClipSegmentToLine(clipPoints2, clipPoints1, rf.sideNormal2, rf.sideOffset2, rf.i2);
if (np < b2_maxManifoldPoints)
{
return;
}
// Now clipPoints2 contains the clipped points.
if (primaryAxis.type == b2EPAxis::e_edgeA)
{
manifold->localNormal = rf.normal;
manifold->localPoint = rf.v1;
}
else
{
manifold->localNormal = polygonB->m_normals[rf.i1];
manifold->localPoint = polygonB->m_vertices[rf.i1];
}
int32 pointCount = 0;
for (int32 i = 0; i < b2_maxManifoldPoints; ++i)
{
float32 separation;
separation = b2Dot(rf.normal, clipPoints2[i].v - rf.v1);
if (separation <= m_radius)
{
b2ManifoldPoint* cp = manifold->points + pointCount;
if (primaryAxis.type == b2EPAxis::e_edgeA)
{
cp->localPoint = b2MulT(m_xf, clipPoints2[i].v);
cp->id = clipPoints2[i].id;
}
else
{
cp->localPoint = clipPoints2[i].v;
cp->id.cf.typeA = clipPoints2[i].id.cf.typeB;
cp->id.cf.typeB = clipPoints2[i].id.cf.typeA;
cp->id.cf.indexA = clipPoints2[i].id.cf.indexB;
cp->id.cf.indexB = clipPoints2[i].id.cf.indexA;
}
++pointCount;
}
}
manifold->pointCount = pointCount;
}
b2EPAxis b2EPCollider::ComputeEdgeSeparation()
{
b2EPAxis axis;
axis.type = b2EPAxis::e_edgeA;
axis.index = m_front ? 0 : 1;
axis.separation = FLT_MAX;
for (int32 i = 0; i < m_polygonB.count; ++i)
{
float32 s = b2Dot(m_normal, m_polygonB.vertices[i] - m_v1);
if (s < axis.separation)
{
axis.separation = s;
}
}
return axis;
}
b2EPAxis b2EPCollider::ComputePolygonSeparation()
{
b2EPAxis axis;
axis.type = b2EPAxis::e_unknown;
axis.index = -1;
axis.separation = -FLT_MAX;
b2Vec2 perp(-m_normal.y, m_normal.x);
for (int32 i = 0; i < m_polygonB.count; ++i)
{
b2Vec2 n = -m_polygonB.normals[i];
float32 s1 = b2Dot(n, m_polygonB.vertices[i] - m_v1);
float32 s2 = b2Dot(n, m_polygonB.vertices[i] - m_v2);
float32 s = b2Min(s1, s2);
if (s > m_radius)
{
// No collision
axis.type = b2EPAxis::e_edgeB;
axis.index = i;
axis.separation = s;
return axis;
}
// Adjacency
if (b2Dot(n, perp) >= 0.0f)
{
if (b2Dot(n - m_upperLimit, m_normal) < -b2_angularSlop)
{
continue;
}
}
else
{
if (b2Dot(n - m_lowerLimit, m_normal) < -b2_angularSlop)
{
continue;
}
}
if (s > axis.separation)
{
axis.type = b2EPAxis::e_edgeB;
axis.index = i;
axis.separation = s;
}
}
return axis;
}
void b2CollideEdgeAndPolygon( b2Manifold* manifold,
const b2EdgeShape* edgeA, const b2Transform& xfA,
const b2PolygonShape* polygonB, const b2Transform& xfB)
{
b2EPCollider collider;
collider.Collide(manifold, edgeA, xfA, polygonB, xfB);
}
/*
* 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/b2Collision.h"
#include "Box2D/Collision/Shapes/b2PolygonShape.h"
// Find the max separation between poly1 and poly2 using edge normals from poly1.
static float32 b2FindMaxSeparation(int32* edgeIndex,
const b2PolygonShape* poly1, const b2Transform& xf1,
const b2PolygonShape* poly2, const b2Transform& xf2)
{
int32 count1 = poly1->m_count;
int32 count2 = poly2->m_count;
const b2Vec2* n1s = poly1->m_normals;
const b2Vec2* v1s = poly1->m_vertices;
const b2Vec2* v2s = poly2->m_vertices;
b2Transform xf = b2MulT(xf2, xf1);
int32 bestIndex = 0;
float32 maxSeparation = -b2_maxFloat;
for (int32 i = 0; i < count1; ++i)
{
// Get poly1 normal in frame2.
b2Vec2 n = b2Mul(xf.q, n1s[i]);
b2Vec2 v1 = b2Mul(xf, v1s[i]);
// Find deepest point for normal i.
float32 si = b2_maxFloat;
for (int32 j = 0; j < count2; ++j)
{
float32 sij = b2Dot(n, v2s[j] - v1);
if (sij < si)
{
si = sij;
}
}
if (si > maxSeparation)
{
maxSeparation = si;
bestIndex = i;
}
}
*edgeIndex = bestIndex;
return maxSeparation;
}
static void b2FindIncidentEdge(b2ClipVertex c[2],
const b2PolygonShape* poly1, const b2Transform& xf1, int32 edge1,
const b2PolygonShape* poly2, const b2Transform& xf2)
{
const b2Vec2* normals1 = poly1->m_normals;
int32 count2 = poly2->m_count;
const b2Vec2* vertices2 = poly2->m_vertices;
const b2Vec2* normals2 = poly2->m_normals;
b2Assert(0 <= edge1 && edge1 < poly1->m_count);
// Get the normal of the reference edge in poly2's frame.
b2Vec2 normal1 = b2MulT(xf2.q, b2Mul(xf1.q, normals1[edge1]));
// Find the incident edge on poly2.
int32 index = 0;
float32 minDot = b2_maxFloat;
for (int32 i = 0; i < count2; ++i)
{
float32 dot = b2Dot(normal1, normals2[i]);
if (dot < minDot)
{
minDot = dot;
index = i;
}
}
// Build the clip vertices for the incident edge.
int32 i1 = index;
int32 i2 = i1 + 1 < count2 ? i1 + 1 : 0;
c[0].v = b2Mul(xf2, vertices2[i1]);
c[0].id.cf.indexA = (uint8)edge1;
c[0].id.cf.indexB = (uint8)i1;
c[0].id.cf.typeA = b2ContactFeature::e_face;
c[0].id.cf.typeB = b2ContactFeature::e_vertex;
c[1].v = b2Mul(xf2, vertices2[i2]);
c[1].id.cf.indexA = (uint8)edge1;
c[1].id.cf.indexB = (uint8)i2;
c[1].id.cf.typeA = b2ContactFeature::e_face;
c[1].id.cf.typeB = b2ContactFeature::e_vertex;
}
// Find edge normal of max separation on A - return if separating axis is found
// Find edge normal of max separation on B - return if separation axis is found
// Choose reference edge as min(minA, minB)
// Find incident edge
// Clip
// The normal points from 1 to 2
void b2CollidePolygons(b2Manifold* manifold,
const b2PolygonShape* polyA, const b2Transform& xfA,
const b2PolygonShape* polyB, const b2Transform& xfB)
{
manifold->pointCount = 0;
float32 totalRadius = polyA->m_radius + polyB->m_radius;
int32 edgeA = 0;
float32 separationA = b2FindMaxSeparation(&edgeA, polyA, xfA, polyB, xfB);
if (separationA > totalRadius)
return;
int32 edgeB = 0;
float32 separationB = b2FindMaxSeparation(&edgeB, polyB, xfB, polyA, xfA);
if (separationB > totalRadius)
return;
const b2PolygonShape* poly1; // reference polygon
const b2PolygonShape* poly2; // incident polygon
b2Transform xf1, xf2;
int32 edge1; // reference edge
uint8 flip;
const float32 k_tol = 0.1f * b2_linearSlop;
if (separationB > separationA + k_tol)
{
poly1 = polyB;
poly2 = polyA;
xf1 = xfB;
xf2 = xfA;
edge1 = edgeB;
manifold->type = b2Manifold::e_faceB;
flip = 1;
}
else
{
poly1 = polyA;
poly2 = polyB;
xf1 = xfA;
xf2 = xfB;
edge1 = edgeA;
manifold->type = b2Manifold::e_faceA;
flip = 0;
}
b2ClipVertex incidentEdge[2];
b2FindIncidentEdge(incidentEdge, poly1, xf1, edge1, poly2, xf2);
int32 count1 = poly1->m_count;
const b2Vec2* vertices1 = poly1->m_vertices;
int32 iv1 = edge1;
int32 iv2 = edge1 + 1 < count1 ? edge1 + 1 : 0;
b2Vec2 v11 = vertices1[iv1];
b2Vec2 v12 = vertices1[iv2];
b2Vec2 localTangent = v12 - v11;
localTangent.Normalize();
b2Vec2 localNormal = b2Cross(localTangent, 1.0f);
b2Vec2 planePoint = 0.5f * (v11 + v12);
b2Vec2 tangent = b2Mul(xf1.q, localTangent);
b2Vec2 normal = b2Cross(tangent, 1.0f);
v11 = b2Mul(xf1, v11);
v12 = b2Mul(xf1, v12);
// Face offset.
float32 frontOffset = b2Dot(normal, v11);
// Side offsets, extended by polytope skin thickness.
float32 sideOffset1 = -b2Dot(tangent, v11) + totalRadius;
float32 sideOffset2 = b2Dot(tangent, v12) + totalRadius;
// Clip incident edge against extruded edge1 side edges.
b2ClipVertex clipPoints1[2];
b2ClipVertex clipPoints2[2];
int np;
// Clip to box side 1
np = b2ClipSegmentToLine(clipPoints1, incidentEdge, -tangent, sideOffset1, iv1);
if (np < 2)
return;
// Clip to negative box side 1
np = b2ClipSegmentToLine(clipPoints2, clipPoints1, tangent, sideOffset2, iv2);
if (np < 2)
{
return;
}
// Now clipPoints2 contains the clipped points.
manifold->localNormal = localNormal;
manifold->localPoint = planePoint;
int32 pointCount = 0;
for (int32 i = 0; i < b2_maxManifoldPoints; ++i)
{
float32 separation = b2Dot(normal, clipPoints2[i].v) - frontOffset;
if (separation <= totalRadius)
{
b2ManifoldPoint* cp = manifold->points + pointCount;
cp->localPoint = b2MulT(xf2, clipPoints2[i].v);
cp->id = clipPoints2[i].id;
if (flip)
{
// Swap features
b2ContactFeature cf = cp->id.cf;
cp->id.cf.indexA = cf.indexB;
cp->id.cf.indexB = cf.indexA;
cp->id.cf.typeA = cf.typeB;
cp->id.cf.typeB = cf.typeA;
}
++pointCount;
}
}
manifold->pointCount = pointCount;
}
/*
* Copyright (c) 2007-2009 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/b2Collision.h"
#include "Box2D/Collision/b2Distance.h"
void b2WorldManifold::Initialize(const b2Manifold* manifold,
const b2Transform& xfA, float32 radiusA,
const b2Transform& xfB, float32 radiusB)
{
if (manifold->pointCount == 0)
{
return;
}
switch (manifold->type)
{
case b2Manifold::e_circles:
{
normal.Set(1.0f, 0.0f);
b2Vec2 pointA = b2Mul(xfA, manifold->localPoint);
b2Vec2 pointB = b2Mul(xfB, manifold->points[0].localPoint);
if (b2DistanceSquared(pointA, pointB) > b2_epsilon * b2_epsilon)
{
normal = pointB - pointA;
normal.Normalize();
}
b2Vec2 cA = pointA + radiusA * normal;
b2Vec2 cB = pointB - radiusB * normal;
points[0] = 0.5f * (cA + cB);
separations[0] = b2Dot(cB - cA, normal);
}
break;
case b2Manifold::e_faceA:
{
normal = b2Mul(xfA.q, manifold->localNormal);
b2Vec2 planePoint = b2Mul(xfA, manifold->localPoint);
for (int32 i = 0; i < manifold->pointCount; ++i)
{
b2Vec2 clipPoint = b2Mul(xfB, manifold->points[i].localPoint);
b2Vec2 cA = clipPoint + (radiusA - b2Dot(clipPoint - planePoint, normal)) * normal;
b2Vec2 cB = clipPoint - radiusB * normal;
points[i] = 0.5f * (cA + cB);
separations[i] = b2Dot(cB - cA, normal);
}
}
break;
case b2Manifold::e_faceB:
{
normal = b2Mul(xfB.q, manifold->localNormal);
b2Vec2 planePoint = b2Mul(xfB, manifold->localPoint);
for (int32 i = 0; i < manifold->pointCount; ++i)
{
b2Vec2 clipPoint = b2Mul(xfA, manifold->points[i].localPoint);
b2Vec2 cB = clipPoint + (radiusB - b2Dot(clipPoint - planePoint, normal)) * normal;
b2Vec2 cA = clipPoint - radiusA * normal;
points[i] = 0.5f * (cA + cB);
separations[i] = b2Dot(cA - cB, normal);
}
// Ensure normal points from A to B.
normal = -normal;
}
break;
}
}
void b2GetPointStates(b2PointState state1[b2_maxManifoldPoints], b2PointState state2[b2_maxManifoldPoints],
const b2Manifold* manifold1, const b2Manifold* manifold2)
{
for (int32 i = 0; i < b2_maxManifoldPoints; ++i)
{
state1[i] = b2_nullState;
state2[i] = b2_nullState;
}
// Detect persists and removes.
for (int32 i = 0; i < manifold1->pointCount; ++i)
{
b2ContactID id = manifold1->points[i].id;
state1[i] = b2_removeState;
for (int32 j = 0; j < manifold2->pointCount; ++j)
{
if (manifold2->points[j].id.key == id.key)
{
state1[i] = b2_persistState;
break;
}
}
}
// Detect persists and adds.
for (int32 i = 0; i < manifold2->pointCount; ++i)
{
b2ContactID id = manifold2->points[i].id;
state2[i] = b2_addState;
for (int32 j = 0; j < manifold1->pointCount; ++j)
{
if (manifold1->points[j].id.key == id.key)
{
state2[i] = b2_persistState;
break;
}
}
}
}
// From Real-time Collision Detection, p179.
bool b2AABB::RayCast(b2RayCastOutput* output, const b2RayCastInput& input) const
{
float32 tmin = -b2_maxFloat;
float32 tmax = b2_maxFloat;
b2Vec2 p = input.p1;
b2Vec2 d = input.p2 - input.p1;
b2Vec2 absD = b2Abs(d);
b2Vec2 normal;
for (int32 i = 0; i < 2; ++i)
{
if (absD(i) < b2_epsilon)
{
// Parallel.
if (p(i) < lowerBound(i) || upperBound(i) < p(i))
{
return false;
}
}
else
{
float32 inv_d = 1.0f / d(i);
float32 t1 = (lowerBound(i) - p(i)) * inv_d;
float32 t2 = (upperBound(i) - p(i)) * inv_d;
// Sign of the normal vector.
float32 s = -1.0f;
if (t1 > t2)
{
b2Swap(t1, t2);
s = 1.0f;
}
// Push the min up
if (t1 > tmin)
{
normal.SetZero();
normal(i) = s;
tmin = t1;
}
// Pull the max down
tmax = b2Min(tmax, t2);
if (tmin > tmax)
{
return false;
}
}
}
// Does the ray start inside the box?
// Does the ray intersect beyond the max fraction?
if (tmin < 0.0f || input.maxFraction < tmin)
{
return false;
}
// Intersection.
output->fraction = tmin;
output->normal = normal;
return true;
}
// Sutherland-Hodgman clipping.
int32 b2ClipSegmentToLine(b2ClipVertex vOut[2], const b2ClipVertex vIn[2],
const b2Vec2& normal, float32 offset, int32 vertexIndexA)
{
// Start with no output points
int32 numOut = 0;
// Calculate the distance of end points to the line
float32 distance0 = b2Dot(normal, vIn[0].v) - offset;
float32 distance1 = b2Dot(normal, vIn[1].v) - offset;
// If the points are behind the plane
if (distance0 <= 0.0f) vOut[numOut++] = vIn[0];
if (distance1 <= 0.0f) vOut[numOut++] = vIn[1];
// If the points are on different sides of the plane
if (distance0 * distance1 < 0.0f)
{
// Find intersection point of edge and plane
float32 interp = distance0 / (distance0 - distance1);
vOut[numOut].v = vIn[0].v + interp * (vIn[1].v - vIn[0].v);
// VertexA is hitting edgeB.
vOut[numOut].id.cf.indexA = static_cast<uint8>(vertexIndexA);
vOut[numOut].id.cf.indexB = vIn[0].id.cf.indexB;
vOut[numOut].id.cf.typeA = b2ContactFeature::e_vertex;
vOut[numOut].id.cf.typeB = b2ContactFeature::e_face;
++numOut;
}
return numOut;
}
bool b2TestOverlap( const b2Shape* shapeA, int32 indexA,
const b2Shape* shapeB, int32 indexB,
const b2Transform& xfA, const b2Transform& xfB)
{
b2DistanceInput input;
input.proxyA.Set(shapeA, indexA);
input.proxyB.Set(shapeB, indexB);
input.transformA = xfA;
input.transformB = xfB;
input.useRadii = true;
b2SimplexCache cache;
cache.count = 0;
b2DistanceOutput output;
b2Distance(&output, &cache, &input);
return output.distance < 10.0f * b2_epsilon;
}
/*
* 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_DISTANCE_H
#define B2_DISTANCE_H
#include "Box2D/Common/b2Math.h"
class b2Shape;
/// A distance proxy is used by the GJK algorithm.
/// It encapsulates any shape.
struct b2DistanceProxy
{
b2DistanceProxy() : m_vertices(nullptr), m_count(0), m_radius(0.0f) {}
/// Initialize the proxy using the given shape. The shape
/// must remain in scope while the proxy is in use.
void Set(const b2Shape* shape, int32 index);
/// 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;
/// Get a vertex by index. Used by b2Distance.
const b2Vec2& GetVertex(int32 index) const;
b2Vec2 m_buffer[2];
const b2Vec2* m_vertices;
int32 m_count;
float32 m_radius;
};
/// Used to warm start b2Distance.
/// Set count to zero on first call.
struct b2SimplexCache
{
float32 metric; ///< length or area
uint16 count;
uint8 indexA[3]; ///< vertices on shape A
uint8 indexB[3]; ///< vertices on shape B
};
/// Input for b2Distance.
/// You have to option to use the shape radii
/// in the computation. Even
struct b2DistanceInput
{
b2DistanceProxy proxyA;
b2DistanceProxy proxyB;
b2Transform transformA;
b2Transform transformB;
bool useRadii;
};
/// Output for b2Distance.
struct b2DistanceOutput
{
b2Vec2 pointA; ///< closest point on shapeA
b2Vec2 pointB; ///< closest point on shapeB
float32 distance;
int32 iterations; ///< number of GJK iterations used
};
/// Compute the closest points between two shapes. Supports any combination of:
/// b2CircleShape, b2PolygonShape, b2EdgeShape. The simplex cache is input/output.
/// On the first call set b2SimplexCache.count to zero.
void b2Distance(b2DistanceOutput* output,
b2SimplexCache* cache,
const b2DistanceInput* input);
//////////////////////////////////////////////////////////////////////////
inline int32 b2DistanceProxy::GetVertexCount() const
{
return m_count;
}
inline const b2Vec2& b2DistanceProxy::GetVertex(int32 index) const
{
b2Assert(0 <= index && index < m_count);
return m_vertices[index];
}
inline int32 b2DistanceProxy::GetSupport(const b2Vec2& d) const
{
int32 bestIndex = 0;
float32 bestValue = b2Dot(m_vertices[0], d);
for (int32 i = 1; i < m_count; ++i)
{
float32 value = b2Dot(m_vertices[i], d);
if (value > bestValue)
{
bestIndex = i;
bestValue = value;
}
}
return bestIndex;
}
inline const b2Vec2& b2DistanceProxy::GetSupportVertex(const b2Vec2& d) const
{
int32 bestIndex = 0;
float32 bestValue = b2Dot(m_vertices[0], d);
for (int32 i = 1; i < m_count; ++i)
{
float32 value = b2Dot(m_vertices[i], d);
if (value > bestValue)
{
bestIndex = i;
bestValue = value;
}
}
return m_vertices[bestIndex];
}
#endif