public void Initialize(b2TimeStep step, List <b2Contact> contacts, int contactCount, object allocator)
{
b2Contact contact;
m_step.Set(step);
m_allocator = allocator;
int i;
b2Vec2 tVec;
b2Mat22 tMat;
m_constraintCount = contactCount;
// fill vector to hold enough constraints
while (m_constraints.Count < m_constraintCount)
{
m_constraints.Add(new b2ContactConstraint());
}
for (i = 0; i < contactCount; ++i)
{
contact = contacts[i];
b2Fixture fixtureA = contact.m_fixtureA;
b2Fixture fixtureB = contact.m_fixtureB;
b2Shape shapeA = fixtureA.m_shape;
b2Shape shapeB = fixtureB.m_shape;
float radiusA = shapeA.m_radius;
float radiusB = shapeB.m_radius;
b2Body bodyA = fixtureA.m_body;
b2Body bodyB = fixtureB.m_body;
b2Manifold manifold = contact.GetManifold();
float friction = b2Settings.b2MixFriction(fixtureA.GetFriction(), fixtureB.GetFriction());;
float restitution = b2Settings.b2MixRestitution(fixtureA.GetRestitution(), fixtureB.GetRestitution());
//var vA:b2Vec2 = bodyA.m_linearVelocity.Copy();
float vAX = bodyA.m_linearVelocity.x;
float vAY = bodyA.m_linearVelocity.y;
//var vB:b2Vec2 = bodyB.m_linearVelocity.Copy();
float vBX = bodyB.m_linearVelocity.x;
float vBY = bodyB.m_linearVelocity.y;
float wA = bodyA.m_angularVelocity;
float wB = bodyB.m_angularVelocity;
b2Settings.b2Assert(manifold.m_pointCount > 0);
s_worldManifold.Initialize(manifold, bodyA.m_xf, radiusA, bodyB.m_xf, radiusB);
float normalX = s_worldManifold.m_normal.x;
float normalY = s_worldManifold.m_normal.y;
b2ContactConstraint cc = m_constraints[i];
cc.bodyA = bodyA; //p
cc.bodyB = bodyB; //p
cc.manifold = manifold; //p
//c.normal = normal;
cc.normal.x = normalX;
cc.normal.y = normalY;
cc.pointCount = manifold.m_pointCount;
cc.friction = friction;
//-----------------------------修改 2015/12/10 13:07 by kingBook------------------
float bevel = 10.0f;
float planeAngle;
int vx;
if (!bodyA.m_allowBevelSlither || bodyA.m_uphillZeroFriction)
{
planeAngle = Mathf.Atan2(normalY, normalX) * 57.3f + 90.0f;
vx = (int)(bodyA.m_linearVelocity.x);
if (planeAngle < 0.0f)
{
planeAngle += 360.0f;
}
if ((planeAngle > bevel && planeAngle < 90.0f - bevel) || (planeAngle > 180.0f + bevel && planeAngle < 270.0f - bevel))//斜面 左上角-右下角
{
if (!bodyA.m_allowBevelSlither)
{
if (vx >= 0.0f)
{
cc.friction = 1.0f;
}
}
if (bodyA.m_uphillZeroFriction)
{
if (vx < 0.0f)
{
cc.friction = 0.0f;
}
}
}
else if ((planeAngle > 90.0f && planeAngle < 180.0f - bevel) || (planeAngle > 270.0f + bevel && planeAngle < 360.0f - bevel))//斜面 左下角-右上角
{
if (!bodyA.m_allowBevelSlither)
{
if (vx <= 0.0f)
{
cc.friction = 1.0f;
}
}
if (bodyA.m_uphillZeroFriction)
{
if (vx > 0.0f)
{
cc.friction = 0.0f;
}
}
}
}
else if (!bodyB.m_allowBevelSlither || bodyB.m_uphillZeroFriction)
{
planeAngle = Mathf.Atan2(-normalY, -normalX) * 57.3f + 90.0f;
vx = (int)(bodyB.m_linearVelocity.x);
if (planeAngle < 0.0f)
{
planeAngle += 360.0f;
}
if ((planeAngle > bevel && planeAngle < 90.0f - bevel) || (planeAngle > 180.0f + bevel && planeAngle < 270.0f - bevel))//斜面 左上角-右下角
{
if (!bodyB.m_allowBevelSlither)
{
if (vx >= 0.0f)
{
cc.friction = 1.0f;
}
}
if (bodyB.m_uphillZeroFriction)
{
if (vx < 0.0f)
{
cc.friction = 0.0f;
}
}
}
else if ((planeAngle > 90.0f && planeAngle < 180.0f - bevel) || (planeAngle > 270.0f + bevel && planeAngle < 360.0f - bevel))//斜面 左下角-右上角
{
if (!bodyB.m_allowBevelSlither)
{
if (vx <= 0.0f)
{
cc.friction = 1.0f;
}
}
if (bodyB.m_uphillZeroFriction)
{
if (vx > 0)
{
cc.friction = 0.0f;
}
}
}
}
if (bodyA.m_isIgnoreFrictionX || bodyB.m_isIgnoreFrictionX)
{
if (Mathf.Abs(normalY) > 0.9f)
{
cc.friction = 0.0f;
}
}
else if (bodyA.m_isIgnoreFrictionY || bodyB.m_isIgnoreFrictionY)
{
if (Mathf.Abs(normalX) > 0.9f)
{
cc.friction = 0.0f;
}
}
//-----------------------------修改结束------------------
cc.restitution = restitution;
cc.localPlaneNormal.x = manifold.m_localPlaneNormal.x;
cc.localPlaneNormal.y = manifold.m_localPlaneNormal.y;
cc.localPoint.x = manifold.m_localPoint.x;
cc.localPoint.y = manifold.m_localPoint.y;
cc.radius = radiusA + radiusB;
cc.type = manifold.m_type;
for (int k = 0; k < cc.pointCount; ++k)
{
b2ManifoldPoint cp = manifold.m_points[k];
b2ContactConstraintPoint ccp = cc.points[k];
ccp.normalImpulse = cp.m_normalImpulse;
ccp.tangentImpulse = cp.m_tangentImpulse;
ccp.localPoint.SetV(cp.m_localPoint);
float rAX = ccp.rA.x = s_worldManifold.m_points[k].x - bodyA.m_sweep.c.x;
float rAY = ccp.rA.y = s_worldManifold.m_points[k].y - bodyA.m_sweep.c.y;
float rBX = ccp.rB.x = s_worldManifold.m_points[k].x - bodyB.m_sweep.c.x;
float rBY = ccp.rB.y = s_worldManifold.m_points[k].y - bodyB.m_sweep.c.y;
float rnA = rAX * normalY - rAY * normalX; //b2Math.b2Cross(r1, normal);
float rnB = rBX * normalY - rBY * normalX; //b2Math.b2Cross(r2, normal);
rnA *= rnA;
rnB *= rnB;
float kNormal = bodyA.m_invMass + bodyB.m_invMass + bodyA.m_invI * rnA + bodyB.m_invI * rnB;
//b2Settings.b2Assert(kNormal > Number.MIN_VALUE);
ccp.normalMass = 1.0f / kNormal;
float kEqualized = bodyA.m_mass * bodyA.m_invMass + bodyB.m_mass * bodyB.m_invMass;
kEqualized += bodyA.m_mass * bodyA.m_invI * rnA + bodyB.m_mass * bodyB.m_invI * rnB;
//b2Assert(kEqualized > Number.MIN_VALUE);
ccp.equalizedMass = 1.0f / kEqualized;
//var tangent:b2Vec2 = b2Math.b2CrossVF(normal, 1.0);
float tangentX = normalY;
float tangentY = -normalX;
//var rtA:Number = b2Math.b2Cross(rA, tangent);
float rtA = rAX * tangentY - rAY * tangentX;
//var rtB:Number = b2Math.b2Cross(rB, tangent);
float rtB = rBX * tangentY - rBY * tangentX;
rtA *= rtA;
rtB *= rtB;
float kTangent = bodyA.m_invMass + bodyB.m_invMass + bodyA.m_invI * rtA + bodyB.m_invI * rtB;
//b2Settings.b2Assert(kTangent > Number.MIN_VALUE);
ccp.tangentMass = 1.0f / kTangent;
// Setup a velocity bias for restitution.
ccp.velocityBias = 0.0f;
//b2Dot(c.normal, vB + b2Cross(wB, rB) - vA - b2Cross(wA, rA));
float tX = vBX + (-wB * rBY) - vAX - (-wA * rAY);
float tY = vBY + (wB * rBX) - vAY - (wA * rAX);
//var vRel:Number = b2Dot(cc.normal, t);
float vRel = cc.normal.x * tX + cc.normal.y * tY;
if (vRel < -b2Settings.b2_velocityThreshold)
{
ccp.velocityBias += -cc.restitution * vRel;
}
}
// If we have two points, then prepare the block solver.
if (cc.pointCount == 2)
{
b2ContactConstraintPoint ccp1 = cc.points[0];
b2ContactConstraintPoint ccp2 = cc.points[1];
float invMassA = bodyA.m_invMass;
float invIA = bodyA.m_invI;
float invMassB = bodyB.m_invMass;
float invIB = bodyB.m_invI;
//var rn1A:Number = b2Cross(ccp1.rA, normal);
//var rn1B:Number = b2Cross(ccp1.rB, normal);
//var rn2A:Number = b2Cross(ccp2.rA, normal);
//var rn2B:Number = b2Cross(ccp2.rB, normal);
float rn1A = ccp1.rA.x * normalY - ccp1.rA.y * normalX;
float rn1B = ccp1.rB.x * normalY - ccp1.rB.y * normalX;
float rn2A = ccp2.rA.x * normalY - ccp2.rA.y * normalX;
float rn2B = ccp2.rB.x * normalY - ccp2.rB.y * normalX;
float k11 = invMassA + invMassB + invIA * rn1A * rn1A + invIB * rn1B * rn1B;
float k22 = invMassA + invMassB + invIA * rn2A * rn2A + invIB * rn2B * rn2B;
float k12 = invMassA + invMassB + invIA * rn1A * rn2A + invIB * rn1B * rn2B;
// Ensure a reasonable condition number.
float k_maxConditionNumber = 100.0f;
if (k11 * k11 < k_maxConditionNumber * (k11 * k22 - k12 * k12))
{
// K is safe to invert.
cc.K.col1.Set(k11, k12);
cc.K.col2.Set(k12, k22);
cc.K.GetInverse(cc.normalMass);
}
else
{
// The constraints are redundant, just use one.
// TODO_ERIN use deepest?
cc.pointCount = 1;
}
}
}
//b2Settings.b2Assert(count == m_constraintCount);
}