public override void Step(TestSettings settings)
{
Manifold manifold;
Collision.CollidePolygons(out manifold, m_polygonA, m_transformA, m_polygonB, m_transformB);
WorldManifold worldManifold = new WorldManifold();
worldManifold.Initialize(manifold, m_transformA, m_polygonA.m_radius, m_transformB, m_polygonB.m_radius);
m_debugDraw.DrawString("point count = {0}", manifold.points.Count());
{
Color color = Color.FromArgb(225, 225, 225);
Vec2[] v = new Vec2[Settings._maxPolygonVertices];
for (int i = 0; i < m_polygonA.m_count; ++i)
{
v[i] = Utilities.Mul(m_transformA, m_polygonA.m_vertices[i]);
}
m_debugDraw.DrawPolygon(v, m_polygonA.m_count, color);
for (int i = 0; i < m_polygonB.m_count; ++i)
{
v[i] = Utilities.Mul(m_transformB, m_polygonB.m_vertices[i]);
}
m_debugDraw.DrawPolygon(v, m_polygonB.m_count, color);
}
for (int i = 0; i < manifold.points.Count(); ++i)
{
m_debugDraw.DrawPoint(worldManifold.points[i], 4.0f, Color.FromArgb(225, 75, 75));
}
}
public void InitializeVelocityConstraints() {
for (int i = 0; i < m_contacts.Count(); ++i) {
ContactVelocityConstraint vc = m_velocityConstraints[i];
ContactPositionConstraint pc = m_positionConstraints[i];
float radiusA = pc.radiusA;
float radiusB = pc.radiusB;
Manifold manifold = m_contacts[vc.contactIndex].GetManifold();
int indexA = vc.indexA;
int indexB = vc.indexB;
float mA = vc.invMassA;
float mB = vc.invMassB;
float iA = vc.invIA;
float iB = vc.invIB;
Vec2 localCenterA = pc.localCenterA;
Vec2 localCenterB = pc.localCenterB;
Vec2 cA = m_positions[indexA].c;
float aA = m_positions[indexA].a;
Vec2 vA = m_velocities[indexA].v;
float wA = m_velocities[indexA].w;
Vec2 cB = m_positions[indexB].c;
float aB = m_positions[indexB].a;
Vec2 vB = m_velocities[indexB].v;
float wB = m_velocities[indexB].w;
Utilities.Assert(manifold.points.Count() > 0);
Transform xfA = new Transform();
Transform xfB = new Transform();
xfA.q.Set(aA);
xfB.q.Set(aB);
xfA.p = cA - Utilities.Mul(xfA.q, localCenterA);
xfB.p = cB - Utilities.Mul(xfB.q, localCenterB);
WorldManifold worldManifold = new WorldManifold();
worldManifold.Initialize(manifold, xfA, radiusA, xfB, radiusB);
vc.normal = worldManifold.normal;
int pointCount = vc.points.Count;
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 = Utilities.Cross(vcp.rA, vc.normal);
float rnB = Utilities.Cross(vcp.rB, vc.normal);
float kNormal = mA + mB + iA * rnA * rnA + iB * rnB * rnB;
vcp.normalMass = kNormal > 0.0f ? 1.0f / kNormal : 0.0f;
Vec2 tangent = Utilities.Cross(vc.normal, 1.0f);
float rtA = Utilities.Cross(vcp.rA, tangent);
float rtB = Utilities.Cross(vcp.rB, tangent);
float kTangent = mA + mB + iA * rtA * rtA + iB * rtB * rtB;
vcp.tangentMass = kTangent > 0.0f ? 1.0f / kTangent : 0.0f;
// Setup a velocity bias for restitution.
vcp.velocityBias = 0.0f;
float vRel = Utilities.Dot(vc.normal, vB + Utilities.Cross(wB, vcp.rB) - vA - Utilities.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.points.Count() == 2) {
VelocityConstraintPoint vcp1 = vc.points[0];
VelocityConstraintPoint vcp2 = vc.points[1];
float rn1A = Utilities.Cross(vcp1.rA, vc.normal);
float rn1B = Utilities.Cross(vcp1.rB, vc.normal);
float rn2A = Utilities.Cross(vcp2.rA, vc.normal);
float rn2B = Utilities.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.ex.Set(k11, k12);
vc.K.ey.Set(k12, k22);
vc.normalMass = vc.K.GetInverse();
} else {
// The constraints are redundant, just use one.
// TODO_ERIN use deepest?
vc.points.Clear();
vc.points.Add(new VelocityConstraintPoint());
}
}
}
}
public void InitializeVelocityConstraints()
{
for (int i = 0; i < m_contacts.Count(); ++i)
{
ContactVelocityConstraint vc = m_velocityConstraints[i];
ContactPositionConstraint pc = m_positionConstraints[i];
float radiusA = pc.radiusA;
float radiusB = pc.radiusB;
Manifold manifold = m_contacts[vc.contactIndex].GetManifold();
int indexA = vc.indexA;
int indexB = vc.indexB;
float mA = vc.invMassA;
float mB = vc.invMassB;
float iA = vc.invIA;
float iB = vc.invIB;
Vec2 localCenterA = pc.localCenterA;
Vec2 localCenterB = pc.localCenterB;
Vec2 cA = m_positions[indexA].c;
float aA = m_positions[indexA].a;
Vec2 vA = m_velocities[indexA].v;
float wA = m_velocities[indexA].w;
Vec2 cB = m_positions[indexB].c;
float aB = m_positions[indexB].a;
Vec2 vB = m_velocities[indexB].v;
float wB = m_velocities[indexB].w;
Utilities.Assert(manifold.points.Count() > 0);
Transform xfA = new Transform();
Transform xfB = new Transform();
xfA.q.Set(aA);
xfB.q.Set(aB);
xfA.p = cA - Utilities.Mul(xfA.q, localCenterA);
xfB.p = cB - Utilities.Mul(xfB.q, localCenterB);
WorldManifold worldManifold = new WorldManifold();
worldManifold.Initialize(manifold, xfA, radiusA, xfB, radiusB);
vc.normal = worldManifold.normal;
int pointCount = vc.points.Count;
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 = Utilities.Cross(vcp.rA, vc.normal);
float rnB = Utilities.Cross(vcp.rB, vc.normal);
float kNormal = mA + mB + iA * rnA * rnA + iB * rnB * rnB;
vcp.normalMass = kNormal > 0.0f ? 1.0f / kNormal : 0.0f;
Vec2 tangent = Utilities.Cross(vc.normal, 1.0f);
float rtA = Utilities.Cross(vcp.rA, tangent);
float rtB = Utilities.Cross(vcp.rB, tangent);
float kTangent = mA + mB + iA * rtA * rtA + iB * rtB * rtB;
vcp.tangentMass = kTangent > 0.0f ? 1.0f / kTangent : 0.0f;
// Setup a velocity bias for restitution.
vcp.velocityBias = 0.0f;
float vRel = Utilities.Dot(vc.normal, vB + Utilities.Cross(wB, vcp.rB) - vA - Utilities.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.points.Count() == 2)
{
VelocityConstraintPoint vcp1 = vc.points[0];
VelocityConstraintPoint vcp2 = vc.points[1];
float rn1A = Utilities.Cross(vcp1.rA, vc.normal);
float rn1B = Utilities.Cross(vcp1.rB, vc.normal);
float rn2A = Utilities.Cross(vcp2.rA, vc.normal);
float rn2B = Utilities.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.ex.Set(k11, k12);
vc.K.ey.Set(k12, k22);
vc.normalMass = vc.K.GetInverse();
}
else
{
// The constraints are redundant, just use one.
// TODO_ERIN use deepest?
vc.points.Clear();
vc.points.Add(new VelocityConstraintPoint());
}
}
}
}
