internal void ReadCache(ref SimplexCache cache,
ref DistanceProxy proxyA, ref Transform transformA,
ref DistanceProxy proxyB, ref Transform transformB)
{
Debug.Assert(cache.count <= 3);
// Copy data from cache.
_count = cache.count;
for (int i = 0; i < _count; ++i)
{
SimplexVertex v = _v[i];
v.indexA = cache.indexA[i];
v.indexB = cache.indexB[i];
Vector2 wALocal = proxyA.GetVertex(v.indexA);
Vector2 wBLocal = proxyB.GetVertex(v.indexB);
v.wA = MathUtils.Multiply(ref transformA, wALocal);
v.wB = MathUtils.Multiply(ref transformB, wBLocal);
v.w = v.wB - v.wA;
v.a = 0.0f;
_v[i] = v;
}
// Compute the new simplex metric, if it is substantially different than
// old metric then flush the simplex.
if (_count > 1)
{
float metric1 = cache.metric;
float metric2 = GetMetric();
if (metric2 < 0.5f * metric1 || 2.0f * metric1 < metric2 || metric2 < Settings.b2_epsilon)
{
// Reset the simplex.
_count = 0;
}
}
// If the cache is empty or invalid ...
if (_count == 0)
{
SimplexVertex v = _v[0];
v.indexA = 0;
v.indexB = 0;
Vector2 wALocal = proxyA.GetVertex(0);
Vector2 wBLocal = proxyB.GetVertex(0);
v.wA = MathUtils.Multiply(ref transformA, wALocal);
v.wB = MathUtils.Multiply(ref transformB, wBLocal);
v.w = v.wB - v.wA;
_v[0] = v;
_count = 1;
}
}
internal void ReadCache(ref SimplexCache cache,
ref DistanceProxy proxyA, ref Transform transformA,
ref DistanceProxy proxyB, ref Transform transformB)
{
Debug.Assert(cache.count <= 3);
// Copy data from cache.
_count = cache.count;
for (int i = 0; i < _count; ++i)
{
SimplexVertex v = _v[i];
v.indexA = cache.indexA[i];
v.indexB = cache.indexB[i];
Vector2 wALocal = proxyA.GetVertex(v.indexA);
Vector2 wBLocal = proxyB.GetVertex(v.indexB);
v.wA = MathUtils.Multiply(ref transformA, wALocal);
v.wB = MathUtils.Multiply(ref transformB, wBLocal);
v.w = v.wB - v.wA;
v.a = 0.0f;
_v[i] = v;
}
// Compute the new simplex metric, if it is substantially different than
// old metric then flush the simplex.
if (_count > 1)
{
float metric1 = cache.metric;
float metric2 = GetMetric();
if (metric2 < 0.5f * metric1 || 2.0f * metric1 < metric2 || metric2 < Settings.b2_epsilon)
{
// Reset the simplex.
_count = 0;
}
}
// If the cache is empty or invalid ...
if (_count == 0)
{
SimplexVertex v = _v[0];
v.indexA = 0;
v.indexB = 0;
Vector2 wALocal = proxyA.GetVertex(0);
Vector2 wBLocal = proxyB.GetVertex(0);
v.wA = MathUtils.Multiply(ref transformA, wALocal);
v.wB = MathUtils.Multiply(ref transformB, wBLocal);
v.w = v.wB - v.wA;
_v[0] = v;
_count = 1;
}
}
public SeparationFunction(ref SimplexCache cache,
ref DistanceProxy proxyA, ref Sweep sweepA,
ref DistanceProxy proxyB, ref Sweep sweepB)
{
_localPoint = Vector2.Zero;
_proxyA = proxyA;
_proxyB = proxyB;
int count = cache.count;
Debug.Assert(0 < count && count < 3);
_sweepA = sweepA;
_sweepB = sweepB;
Transform xfA, xfB;
_sweepA.GetTransform(out xfA, 0.0f);
_sweepB.GetTransform(out xfB, 0.0f);
if (count == 1)
{
_type = SeparationFunctionType.Points;
Vector2 localPointA = _proxyA.GetVertex(cache.indexA[0]);
Vector2 localPointB = _proxyB.GetVertex(cache.indexB[0]);
Vector2 pointA = MathUtils.Multiply(ref xfA, localPointA);
Vector2 pointB = MathUtils.Multiply(ref xfB, localPointB);
_axis = pointB - pointA;
_axis.Normalize();
return;
}
else if (cache.indexA[0] == cache.indexA[1])
{
// Two points on B and one on A.
_type = SeparationFunctionType.FaceB;
Vector2 localPointB1 = proxyB.GetVertex(cache.indexB[0]);
Vector2 localPointB2 = proxyB.GetVertex(cache.indexB[1]);
_axis = MathUtils.Cross(localPointB2 - localPointB1, 1.0f);
_axis.Normalize();
Vector2 normal = MathUtils.Multiply(ref xfB.R, _axis);
_localPoint = 0.5f * (localPointB1 + localPointB2);
Vector2 pointB = MathUtils.Multiply(ref xfB, _localPoint);
Vector2 localPointA = proxyA.GetVertex(cache.indexA[0]);
Vector2 pointA = MathUtils.Multiply(ref xfA, localPointA);
float s = Vector2.Dot(pointA - pointB, normal);
if (s < 0.0f)
{
_axis = -_axis;
s = -s;
}
return;
}
else
{
// Two points on A and one or two points on B.
_type = SeparationFunctionType.FaceA;
Vector2 localPointA1 = _proxyA.GetVertex(cache.indexA[0]);
Vector2 localPointA2 = _proxyA.GetVertex(cache.indexA[1]);
_axis = MathUtils.Cross(localPointA2 - localPointA1, 1.0f);
_axis.Normalize();
Vector2 normal = MathUtils.Multiply(ref xfA.R, _axis);
_localPoint = 0.5f * (localPointA1 + localPointA2);
Vector2 pointA = MathUtils.Multiply(ref xfA, _localPoint);
Vector2 localPointB = _proxyB.GetVertex(cache.indexB[0]);
Vector2 pointB = MathUtils.Multiply(ref xfB, localPointB);
float s = Vector2.Dot(pointB - pointA, normal);
if (s < 0.0f)
{
_axis = -_axis;
s = -s;
}
return;
}
}
public SeparationFunction(ref SimplexCache cache,
ref DistanceProxy proxyA, ref Sweep sweepA,
ref DistanceProxy proxyB, ref Sweep sweepB)
{
_localPoint = Vector2.Zero;
_proxyA = proxyA;
_proxyB = proxyB;
int count = cache.count;
Debug.Assert(0 < count && count < 3);
_sweepA = sweepA;
_sweepB = sweepB;
Transform xfA, xfB;
_sweepA.GetTransform(out xfA, 0.0f);
_sweepB.GetTransform(out xfB, 0.0f);
if (count == 1)
{
_type = SeparationFunctionType.Points;
Vector2 localPointA = _proxyA.GetVertex(cache.indexA[0]);
Vector2 localPointB = _proxyB.GetVertex(cache.indexB[0]);
Vector2 pointA = MathUtils.Multiply(ref xfA, localPointA);
Vector2 pointB = MathUtils.Multiply(ref xfB, localPointB);
_axis = pointB - pointA;
_axis.Normalize();
return;
}
else if (cache.indexA[0] == cache.indexA[1])
{
// Two points on B and one on A.
_type = SeparationFunctionType.FaceB;
Vector2 localPointB1 = proxyB.GetVertex(cache.indexB[0]);
Vector2 localPointB2 = proxyB.GetVertex(cache.indexB[1]);
_axis = MathUtils.Cross(localPointB2 - localPointB1, 1.0f);
_axis.Normalize();
Vector2 normal = MathUtils.Multiply(ref xfB.R, _axis);
_localPoint = 0.5f * (localPointB1 + localPointB2);
Vector2 pointB = MathUtils.Multiply(ref xfB, _localPoint);
Vector2 localPointA = proxyA.GetVertex(cache.indexA[0]);
Vector2 pointA = MathUtils.Multiply(ref xfA, localPointA);
float s = Vector2.Dot(pointA - pointB, normal);
if (s < 0.0f)
{
_axis = -_axis;
s = -s;
}
return;
}
else
{
// Two points on A and one or two points on B.
_type = SeparationFunctionType.FaceA;
Vector2 localPointA1 = _proxyA.GetVertex(cache.indexA[0]);
Vector2 localPointA2 = _proxyA.GetVertex(cache.indexA[1]);
_axis = MathUtils.Cross(localPointA2 - localPointA1, 1.0f);
_axis.Normalize();
Vector2 normal = MathUtils.Multiply(ref xfA.R, _axis);
_localPoint = 0.5f * (localPointA1 + localPointA2);
Vector2 pointA = MathUtils.Multiply(ref xfA, _localPoint);
Vector2 localPointB = _proxyB.GetVertex(cache.indexB[0]);
Vector2 pointB = MathUtils.Multiply(ref xfB, localPointB);
float s = Vector2.Dot(pointB - pointA, normal);
if (s < 0.0f)
{
_axis = -_axis;
s = -s;
}
return;
}
}
