mirror of
https://github.com/love2d/love.git
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Garrett Brown
106 lines
3.2 KiB
C++
106 lines
3.2 KiB
C++
// MIT License
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// Copyright (c) 2019 Erin Catto
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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#include "box2d/b2_circle_shape.h"
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#include "box2d/b2_block_allocator.h"
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#include <new>
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b2Shape* b2CircleShape::Clone(b2BlockAllocator* allocator) const
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{
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void* mem = allocator->Allocate(sizeof(b2CircleShape));
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b2CircleShape* clone = new (mem) b2CircleShape;
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*clone = *this;
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return clone;
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}
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int32 b2CircleShape::GetChildCount() const
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{
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return 1;
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}
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bool b2CircleShape::TestPoint(const b2Transform& transform, const b2Vec2& p) const
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{
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b2Vec2 center = transform.p + b2Mul(transform.q, m_p);
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b2Vec2 d = p - center;
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return b2Dot(d, d) <= m_radius * m_radius;
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}
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// Collision Detection in Interactive 3D Environments by Gino van den Bergen
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// From Section 3.1.2
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// x = s + a * r
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// norm(x) = radius
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bool b2CircleShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
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const b2Transform& transform, int32 childIndex) const
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{
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B2_NOT_USED(childIndex);
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b2Vec2 position = transform.p + b2Mul(transform.q, m_p);
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b2Vec2 s = input.p1 - position;
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float b = b2Dot(s, s) - m_radius * m_radius;
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// Solve quadratic equation.
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b2Vec2 r = input.p2 - input.p1;
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float c = b2Dot(s, r);
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float rr = b2Dot(r, r);
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float sigma = c * c - rr * b;
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// Check for negative discriminant and short segment.
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if (sigma < 0.0f || rr < b2_epsilon)
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{
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return false;
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}
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// Find the point of intersection of the line with the circle.
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float a = -(c + b2Sqrt(sigma));
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// Is the intersection point on the segment?
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if (0.0f <= a && a <= input.maxFraction * rr)
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{
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a /= rr;
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output->fraction = a;
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output->normal = s + a * r;
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output->normal.Normalize();
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return true;
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}
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return false;
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}
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void b2CircleShape::ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const
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{
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B2_NOT_USED(childIndex);
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b2Vec2 p = transform.p + b2Mul(transform.q, m_p);
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aabb->lowerBound.Set(p.x - m_radius, p.y - m_radius);
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aabb->upperBound.Set(p.x + m_radius, p.y + m_radius);
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}
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void b2CircleShape::ComputeMass(b2MassData* massData, float density) const
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{
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massData->mass = density * b2_pi * m_radius * m_radius;
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massData->center = m_p;
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// inertia about the local origin
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massData->I = massData->mass * (0.5f * m_radius * m_radius + b2Dot(m_p, m_p));
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}
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