1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202
|
/*
* Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
*
* 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 "b2EdgeShape.h"
b2EdgeShape::b2EdgeShape(const b2Vec2& v1, const b2Vec2& v2, const b2ShapeDef* def)
: b2Shape(def)
{
b2Assert(def->type == e_edgeShape);
m_type = e_edgeShape;
m_prevEdge = NULL;
m_nextEdge = NULL;
m_v1 = v1;
m_v2 = v2;
m_direction = m_v2 - m_v1;
m_length = m_direction.Normalize();
m_normal.Set(m_direction.y, -m_direction.x);
m_coreV1 = -b2_toiSlop * (m_normal - m_direction) + m_v1;
m_coreV2 = -b2_toiSlop * (m_normal + m_direction) + m_v2;
m_cornerDir1 = m_normal;
m_cornerDir2 = -1.0f * m_normal;
}
void b2EdgeShape::UpdateSweepRadius(const b2Vec2& center)
{
// Update the sweep radius (maximum radius) as measured from
// a local center point.
b2Vec2 d = m_coreV1 - center;
float32 d1 = b2Dot(d,d);
d = m_coreV2 - center;
float32 d2 = b2Dot(d,d);
m_sweepRadius = b2Sqrt(d1 > d2 ? d1 : d2);
}
bool b2EdgeShape::TestPoint(const b2XForm& transform, const b2Vec2& p) const
{
B2_NOT_USED(transform);
B2_NOT_USED(p);
return false;
}
b2SegmentCollide b2EdgeShape::TestSegment(const b2XForm& transform,
float32* lambda,
b2Vec2* normal,
const b2Segment& segment,
float32 maxLambda) const
{
b2Vec2 r = segment.p2 - segment.p1;
b2Vec2 v1 = b2Mul(transform, m_v1);
b2Vec2 d = b2Mul(transform, m_v2) - v1;
b2Vec2 n = b2Cross(d, 1.0f);
const float32 k_slop = 100.0f * B2_FLT_EPSILON;
float32 denom = -b2Dot(r, n);
// Cull back facing collision and ignore parallel segments.
if (denom > k_slop)
{
// Does the segment intersect the infinite line associated with this segment?
b2Vec2 b = segment.p1 - v1;
float32 a = b2Dot(b, n);
if (0.0f <= a && a <= maxLambda * denom)
{
float32 mu2 = -r.x * b.y + r.y * b.x;
// Does the segment intersect this segment?
if (-k_slop * denom <= mu2 && mu2 <= denom * (1.0f + k_slop))
{
a /= denom;
n.Normalize();
*lambda = a;
*normal = n;
return e_hitCollide;
}
}
}
return e_missCollide;
}
void b2EdgeShape::ComputeAABB(b2AABB* aabb, const b2XForm& transform) const
{
b2Vec2 v1 = b2Mul(transform, m_v1);
b2Vec2 v2 = b2Mul(transform, m_v2);
aabb->lowerBound = b2Min(v1, v2);
aabb->upperBound = b2Max(v1, v2);
}
void b2EdgeShape::ComputeSweptAABB(b2AABB* aabb, const b2XForm& transform1, const b2XForm& transform2) const
{
b2Vec2 v1 = b2Mul(transform1, m_v1);
b2Vec2 v2 = b2Mul(transform1, m_v2);
b2Vec2 v3 = b2Mul(transform2, m_v1);
b2Vec2 v4 = b2Mul(transform2, m_v2);
aabb->lowerBound = b2Min(b2Min(b2Min(v1, v2), v3), v4);
aabb->upperBound = b2Max(b2Max(b2Max(v1, v2), v3), v4);
}
void b2EdgeShape::ComputeMass(b2MassData* massData) const
{
massData->mass = 0;
massData->center = m_v1;
// inertia about the local origin
massData->I = 0;
}
b2Vec2 b2EdgeShape::Support(const b2XForm& xf, const b2Vec2& d) const
{
b2Vec2 v1 = b2Mul(xf, m_coreV1);
b2Vec2 v2 = b2Mul(xf, m_coreV2);
return b2Dot(v1, d) > b2Dot(v2, d) ? v1 : v2;
}
void b2EdgeShape::SetPrevEdge(b2EdgeShape* edge, const b2Vec2& core, const b2Vec2& cornerDir, bool convex)
{
m_prevEdge = edge;
m_coreV1 = core;
m_cornerDir1 = cornerDir;
m_cornerConvex1 = convex;
}
void b2EdgeShape::SetNextEdge(b2EdgeShape* edge, const b2Vec2& core, const b2Vec2& cornerDir, bool convex)
{
m_nextEdge = edge;
m_coreV2 = core;
m_cornerDir2 = cornerDir;
m_cornerConvex2 = convex;
}
float32 b2EdgeShape::ComputeSubmergedArea( const b2Vec2& normal,
float32 offset,
const b2XForm& xf,
b2Vec2* c) const
{
//Note that v0 is independant of any details of the specific edge
//We are relying on v0 being consistent between multiple edges of the same body
b2Vec2 v0 = offset * normal;
//b2Vec2 v0 = xf.position + (offset - b2Dot(normal, xf.position)) * normal;
b2Vec2 v1 = b2Mul(xf, m_v1);
b2Vec2 v2 = b2Mul(xf, m_v2);
float32 d1 = b2Dot(normal, v1) - offset;
float32 d2 = b2Dot(normal, v2) - offset;
if(d1>0)
{
if(d2>0)
{
return 0;
}
else
{
v1 = -d2 / (d1 - d2) * v1 + d1 / (d1 - d2) * v2;
}
}
else
{
if(d2>0)
{
v2 = -d2 / (d1 - d2) * v1 + d1 / (d1 - d2) * v2;
}
else
{
//Nothing
}
}
// v0,v1,v2 represents a fully submerged triangle
float32 k_inv3 = 1.0f / 3.0f;
// Area weighted centroid
*c = k_inv3 * (v0 + v1 + v2);
b2Vec2 e1 = v1 - v0;
b2Vec2 e2 = v2 - v0;
return 0.5f * b2Cross(e1, e2);
}
|