File indexing completed on 2025-02-16 03:29:32

 /*
 * 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;
 }