public void CompareInvertSpeed()
{
Matrix3x2 input = new Matrix3x2();
for (int i = 0; i < 10; i++)
{
Stopwatch w = Stopwatch.StartNew();
for (int j = 0; j < 10000000; j++)
{
Matrix3x2.Invert(input, out Matrix3x2 result);
input = result;
}
w.Stop();
output.WriteLine("builtin: " + w.ElapsedMilliseconds);
w.Restart();
for (int j = 0; j < 10000000; j++)
{
Matrex.Invert(input, out Matrix3x2 result);
input = result;
}
w.Stop();
output.WriteLine("ours: " + w.ElapsedMilliseconds);
}
}
public void InitializeVelocityConstraints()
{
for (int i = 0; i < _count; ++i)
{
ContactVelocityConstraint vc = _velocityConstraints[i];
ContactPositionConstraint pc = _positionConstraints[i];
float radiusA = pc.radiusA;
float radiusB = pc.radiusB;
Manifold manifold = _contacts[vc.contactIndex].Manifold;
int indexA = vc.indexA;
int indexB = vc.indexB;
float mA = vc.invMassA;
float mB = vc.invMassB;
float iA = vc.invIA;
float iB = vc.invIB;
Vector2 localCenterA = pc.localCenterA;
Vector2 localCenterB = pc.localCenterB;
Vector2 cA = _positions[indexA].c;
float aA = _positions[indexA].a;
Vector2 vA = _velocities[indexA].v;
float wA = _velocities[indexA].w;
Vector2 cB = _positions[indexB].c;
float aB = _positions[indexB].a;
Vector2 vB = _velocities[indexB].v;
float wB = _velocities[indexB].w;
//Debug.Assert(manifold.pointCount > 0);
Transform xfA = new Transform();
Transform xfB = new Transform();
xfA.q = Matrex.CreateRotation(aA); // Actually about twice as fast to use our own function
xfB.q = Matrex.CreateRotation(aB); // Actually about twice as fast to use our own function
xfA.p = cA - Vector2.Transform(localCenterA, xfA.q); // Common.Math.Mul(xfA.q, localCenterA);
xfB.p = cB - Vector2.Transform(localCenterB, xfB.q); // Common.Math.Mul(xfB.q, localCenterB);
WorldManifold worldManifold = new WorldManifold();
worldManifold.Initialize(manifold, xfA, radiusA, xfB, radiusB);
vc.normal = worldManifold.normal;
int pointCount = vc.pointCount;
for (int j = 0; j < pointCount; ++j)
{
VelocityConstraintPoint vcp = vc.points[j];
vcp.rA = worldManifold.points[j] - cA;
vcp.rB = worldManifold.points[j] - cB;
float rnA = Vectex.Cross(vcp.rA, vc.normal);
float rnB = Vectex.Cross(vcp.rB, vc.normal);
float kNormal = mA + mB + iA * rnA * rnA + iB * rnB * rnB;
vcp.normalMass = kNormal > 0f ? 1f / kNormal : 0f;
Vector2 tangent = Vectex.Cross(vc.normal, 1f);
float rtA = Vectex.Cross(vcp.rA, tangent);
float rtB = Vectex.Cross(vcp.rB, tangent);
float kTangent = mA + mB + iA * rtA * rtA + iB * rtB * rtB;
vcp.tangentMass = kTangent > 0f ? 1f / kTangent : 0f;
vcp.velocityBias = 0f;
float vRel = Vector2.Dot(vc.normal, vB + Vectex.Cross(wB, vcp.rB) - vA - Vectex.Cross(wA, vcp.rA));
if (vRel < -Settings.VelocityThreshold)
{
vcp.velocityBias = -vc.restitution * vRel;
}
}
// If we have two points, then prepare the block solver.
if (vc.pointCount == 2 && Settings.BlockSolve)
{
VelocityConstraintPoint vcp1 = vc.points[0];
VelocityConstraintPoint vcp2 = vc.points[1];
float rn1A = Vectex.Cross(vcp1.rA, vc.normal);
float rn1B = Vectex.Cross(vcp1.rB, vc.normal);
float rn2A = Vectex.Cross(vcp2.rA, vc.normal);
float rn2B = Vectex.Cross(vcp2.rB, vc.normal);
float k11 = mA + mB + iA * rn1A * rn1A + iB * rn1B * rn1B;
float k22 = mA + mB + iA * rn2A * rn2A + iB * rn2B * rn2B;
float k12 = mA + mB + iA * rn1A * rn2A + iB * rn1B * rn2B;
// Ensure a reasonable condition number.
const float k_maxConditionNumber = 1000.0f;
if (k11 * k11 < k_maxConditionNumber * (k11 * k22 - k12 * k12))
{
// K is safe to invert.
vc.K = new Matrix3x2(k11, k12, k12, k22, 0, 0);
// vc.K.ex = new Vector2(k11, k12);
// vc.K.ey = new Vector2(k12, k22);
/*Matrix3x2*/
Matrex.Invert(vc.K, out Matrix3x2 KT);
vc.normalMass = KT;
}
else
{
// The constraints are redundant, just use one.
// TODO_ERIN use deepest?
vc.pointCount = 1;
}
}
}
}