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Diffstat (limited to 'libjin/3rdparty/Box2D/Collision/Shapes/b2CircleShape.cpp')
| -rw-r--r-- | libjin/3rdparty/Box2D/Collision/Shapes/b2CircleShape.cpp | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/libjin/3rdparty/Box2D/Collision/Shapes/b2CircleShape.cpp b/libjin/3rdparty/Box2D/Collision/Shapes/b2CircleShape.cpp new file mode 100644 index 0000000..fa24dc8 --- /dev/null +++ b/libjin/3rdparty/Box2D/Collision/Shapes/b2CircleShape.cpp @@ -0,0 +1,99 @@ +/* +* 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)); +} |