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()); } } } }