Exemple #1
0
        void DrawShape(Fixture fixture, Transform xf, Color color)
        {
            switch (fixture.ShapeType)
            {
            case ShapeType.Circle:
            {
                CircleShape circle = (CircleShape)fixture.GetShape();

                Vector2 center = MathUtils.Multiply(ref xf, circle._p);
                float   radius = circle._radius;
                Vector2 axis   = xf.R.col1;

                DebugDraw.DrawSolidCircle(center, radius, axis, color);
            }
            break;

            case ShapeType.Polygon:
            {
                PolygonShape poly        = (PolygonShape)fixture.GetShape();
                int          vertexCount = poly._vertexCount;
                Debug.Assert(vertexCount <= Settings.b2_maxPolygonVertices);
                FixedArray8 <Vector2> vertices = new FixedArray8 <Vector2>();

                for (int i = 0; i < vertexCount; ++i)
                {
                    vertices[i] = MathUtils.Multiply(ref xf, poly._vertices[i]);
                }

                DebugDraw.DrawSolidPolygon(ref vertices, vertexCount, color);
            }
            break;
            }
        }
Exemple #2
0
        public void Initialize(Contact[] contacts, int count, Body toiBody)
        {
            _count   = count;
            _toiBody = toiBody;
            if (_constraints.Length < _count)
            {
                _constraints = new TOIConstraint[Math.Max(_constraints.Length * 2, _count)];
            }

            for (int i = 0; i < _count; ++i)
            {
                Contact contact = contacts[i];

                Fixture  fixtureA = contact.GetFixtureA();
                Fixture  fixtureB = contact.GetFixtureB();
                Shape    shapeA   = fixtureA.GetShape();
                Shape    shapeB   = fixtureB.GetShape();
                float    radiusA  = shapeA._radius;
                float    radiusB  = shapeB._radius;
                Body     bodyA    = fixtureA.GetBody();
                Body     bodyB    = fixtureB.GetBody();
                Manifold manifold;
                contact.GetManifold(out manifold);

                Debug.Assert(manifold._pointCount > 0);

                TOIConstraint constraint = _constraints[i];
                constraint.bodyA       = bodyA;
                constraint.bodyB       = bodyB;
                constraint.localNormal = manifold._localNormal;
                constraint.localPoint  = manifold._localPoint;
                constraint.type        = manifold._type;
                constraint.pointCount  = manifold._pointCount;
                constraint.radius      = radiusA + radiusB;

                for (int j = 0; j < constraint.pointCount; ++j)
                {
                    constraint.localPoints[j] = manifold._points[j].LocalPoint;
                }

                _constraints[i] = constraint;
            }
        }
Exemple #3
0
        // Advance a dynamic body to its first time of contact
        // and adjust the position to ensure clearance.
        void SolveTOI(Body body)
        {
            // Find the minimum contact.
            Contact toiContact = null;
            float   toi        = 1.0f;
            bool    found;
            int     count;
            int     iter = 0;

            bool bullet = body.IsBullet;

            // Iterate until all contacts agree on the minimum TOI. We have
            // to iterate because the TOI algorithm may skip some intermediate
            // collisions when objects rotate through each other.
            do
            {
                count = 0;
                found = false;
                for (ContactEdge ce = body._contactList; ce != null; ce = ce.Next)
                {
                    Body     other = ce.Other;
                    BodyType type  = other.GetType();

                    // Only bullets perform TOI with dynamic bodies.
                    if (bullet == true)
                    {
                        // Bullets only perform TOI with bodies that have their TOI resolved.
                        if ((other._flags & BodyFlags.Toi) == 0)
                        {
                            continue;
                        }
                    }
                    else if (type == BodyType.Dynamic)
                    {
                        continue;
                    }

                    // Check for a disabled contact.
                    Contact contact = ce.Contact;
                    if (contact.IsEnabled() == false)
                    {
                        continue;
                    }

                    // Prevent infinite looping.
                    if (contact._toiCount > 10)
                    {
                        continue;
                    }

                    Fixture fixtureA = contact._fixtureA;
                    Fixture fixtureB = contact._fixtureB;

                    // Cull sensors.
                    if (fixtureA.IsSensor() || fixtureB.IsSensor())
                    {
                        continue;
                    }

                    Body bodyA = fixtureA._body;
                    Body bodyB = fixtureB._body;

                    // Compute the time of impact in interval [0, minTOI]
                    TOIInput input = new TOIInput();
                    input.proxyA.Set(fixtureA.GetShape());
                    input.proxyB.Set(fixtureB.GetShape());
                    input.sweepA = bodyA._sweep;
                    input.sweepB = bodyB._sweep;
                    input.tMax   = toi;

                    TOIOutput output;
                    TimeOfImpact.CalculateTimeOfImpact(out output, ref input);

                    if (output.State == TOIOutputState.Touching && output.t < toi)
                    {
                        toiContact = contact;
                        toi        = output.t;
                        found      = true;
                    }

                    ++count;
                }

                ++iter;
            } while (found && count > 1 && iter < 50);

            if (toiContact == null)
            {
                return;
            }

            // Advance the body to its safe time.
            Sweep backup = body._sweep;

            body.Advance(toi);

            ++toiContact._toiCount;

            // Update all the valid contacts on this body and build a contact island.
            count = 0;
            for (ContactEdge ce = body._contactList; (ce != null) && (count < Settings.b2_maxTOIContacts); ce = ce.Next)
            {
                Body     other = ce.Other;
                BodyType type  = other.GetType();

                // Only perform correction with static bodies, so the
                // body won't get pushed out of the world.
                if (type != BodyType.Static)
                {
                    continue;
                }

                // Check for a disabled contact.
                Contact contact = ce.Contact;
                if (contact.IsEnabled() == false)
                {
                    continue;
                }

                Fixture fixtureA = contact._fixtureA;
                Fixture fixtureB = contact._fixtureB;

                // Cull sensors.
                if (fixtureA.IsSensor() || fixtureB.IsSensor())
                {
                    continue;
                }

                // The contact likely has some new contact points. The listener
                // gives the user a chance to disable the contact;
                contact.Update(_contactManager.ContactListener);

                // Did the user disable the contact?
                if (contact.IsEnabled() == false)
                {
                    if (contact == toiContact)
                    {
                        // Restore the body's sweep.
                        body._sweep = backup;
                        body.SynchronizeTransform();

                        // Recurse because the TOI has been invalidated.
                        SolveTOI(body);
                        return;
                    }

                    // Skip this contact.
                    continue;
                }

                if (contact.IsTouching() == false)
                {
                    continue;
                }

                _toiContacts[count] = contact;
                ++count;
            }

            // Reduce the TOI body's overlap with the contact island.
            _toiSolver.Initialize(_toiContacts, count, body);

            const float k_toiBaumgarte = 0.75f;

            //bool solved = false;
            for (int i = 0; i < 20; ++i)
            {
                bool contactsOkay = _toiSolver.Solve(k_toiBaumgarte);
                if (contactsOkay)
                {
                    //solved = true;
                    break;
                }
            }
        }
        void DrawShape(Fixture fixture, Transform xf, Color color)
        {
            switch (fixture.ShapeType)
            {
                case ShapeType.Circle:
                    {
                        CircleShape circle = (CircleShape)fixture.GetShape();

                        Vector2 center = MathUtils.Multiply(ref xf, circle._p);
                        float radius = circle._radius;
                        Vector2 axis = xf.R.col1;

                        DebugDraw.DrawSolidCircle(center, radius, axis, color);
                    }
                    break;

                case ShapeType.Polygon:
                    {
                        PolygonShape poly = (PolygonShape)fixture.GetShape();
                        int vertexCount = poly._vertexCount;
                        Debug.Assert(vertexCount <= Settings.b2_maxPolygonVertices);
                        FixedArray8<Vector2> vertices = new FixedArray8<Vector2>();

                        for (int i = 0; i < vertexCount; ++i)
                        {
                            vertices[i] = MathUtils.Multiply(ref xf, poly._vertices[i]);
                        }

                        DebugDraw.DrawSolidPolygon(ref vertices, vertexCount, color);
                    }
                    break;
            }
        }
        public void Reset(Contact[] contacts, int contactCount, float impulseRatio)
        {
            _contacts = contacts;

            _constraintCount = contactCount;

            // grow the array
            if (_constraints == null || _constraints.Length < _constraintCount)
            {
                _constraints = new ContactConstraint[_constraintCount * 2];
            }

            for (int i = 0; i < _constraintCount; ++i)
            {
                Contact contact = contacts[i];

                Fixture  fixtureA = contact._fixtureA;
                Fixture  fixtureB = contact._fixtureB;
                Shape    shapeA   = fixtureA.GetShape();
                Shape    shapeB   = fixtureB.GetShape();
                float    radiusA  = shapeA._radius;
                float    radiusB  = shapeB._radius;
                Body     bodyA    = fixtureA.GetBody();
                Body     bodyB    = fixtureB.GetBody();
                Manifold manifold;
                contact.GetManifold(out manifold);

                float friction    = Settings.b2MixFriction(fixtureA.GetFriction(), fixtureB.GetFriction());
                float restitution = Settings.b2MixRestitution(fixtureA.GetRestitution(), fixtureB.GetRestitution());

                Vector2 vA = bodyA._linearVelocity;
                Vector2 vB = bodyB._linearVelocity;
                float   wA = bodyA._angularVelocity;
                float   wB = bodyB._angularVelocity;

                Debug.Assert(manifold._pointCount > 0);

                WorldManifold worldManifold = new WorldManifold(ref manifold, ref bodyA._xf, radiusA, ref bodyB._xf, radiusB);

                ContactConstraint cc = _constraints[i];
                cc.bodyA      = bodyA;
                cc.bodyB      = bodyB;
                cc.manifold   = manifold;
                cc.normal     = worldManifold._normal;
                cc.pointCount = manifold._pointCount;
                cc.friction   = friction;

                cc.localNormal = manifold._localNormal;
                cc.localPoint  = manifold._localPoint;
                cc.radius      = radiusA + radiusB;
                cc.type        = manifold._type;

                for (int j = 0; j < cc.pointCount; ++j)
                {
                    ManifoldPoint          cp  = manifold._points[j];
                    ContactConstraintPoint ccp = cc.points[j];

                    ccp.normalImpulse  = impulseRatio * cp.NormalImpulse;
                    ccp.tangentImpulse = impulseRatio * cp.TangentImpulse;

                    ccp.localPoint = cp.LocalPoint;

                    ccp.rA = worldManifold._points[j] - bodyA._sweep.c;
                    ccp.rB = worldManifold._points[j] - bodyB._sweep.c;

#if MATH_OVERLOADS
                    float rnA = MathUtils.Cross(ccp.rA, cc.normal);
                    float rnB = MathUtils.Cross(ccp.rB, cc.normal);
#else
                    float rnA = ccp.rA.X * cc.normal.Y - ccp.rA.Y * cc.normal.X;
                    float rnB = ccp.rB.X * cc.normal.Y - ccp.rB.Y * cc.normal.X;
#endif
                    rnA *= rnA;
                    rnB *= rnB;

                    float kNormal = bodyA._invMass + bodyB._invMass + bodyA._invI * rnA + bodyB._invI * rnB;

                    Debug.Assert(kNormal > Settings.b2_epsilon);
                    ccp.normalMass = 1.0f / kNormal;

#if MATH_OVERLOADS
                    Vector2 tangent = MathUtils.Cross(cc.normal, 1.0f);

                    float rtA = MathUtils.Cross(ccp.rA, tangent);
                    float rtB = MathUtils.Cross(ccp.rB, tangent);
#else
                    Vector2 tangent = new Vector2(cc.normal.Y, -cc.normal.X);

                    float rtA = ccp.rA.X * tangent.Y - ccp.rA.Y * tangent.X;
                    float rtB = ccp.rB.X * tangent.Y - ccp.rB.Y * tangent.X;
#endif
                    rtA *= rtA;
                    rtB *= rtB;
                    float kTangent = bodyA._invMass + bodyB._invMass + bodyA._invI * rtA + bodyB._invI * rtB;

                    Debug.Assert(kTangent > Settings.b2_epsilon);
                    ccp.tangentMass = 1.0f / kTangent;

                    // Setup a velocity bias for restitution.
                    ccp.velocityBias = 0.0f;
                    float vRel = Vector2.Dot(cc.normal, vB + MathUtils.Cross(wB, ccp.rB) - vA - MathUtils.Cross(wA, ccp.rA));
                    if (vRel < -Settings.b2_velocityThreshold)
                    {
                        ccp.velocityBias = -restitution * vRel;
                    }

                    cc.points[j] = ccp;
                }

                // If we have two points, then prepare the block solver.
                if (cc.pointCount == 2)
                {
                    ContactConstraintPoint ccp1 = cc.points[0];
                    ContactConstraintPoint ccp2 = cc.points[1];

                    float invMassA = bodyA._invMass;
                    float invIA    = bodyA._invI;
                    float invMassB = bodyB._invMass;
                    float invIB    = bodyB._invI;

                    float rn1A = MathUtils.Cross(ccp1.rA, cc.normal);
                    float rn1B = MathUtils.Cross(ccp1.rB, cc.normal);
                    float rn2A = MathUtils.Cross(ccp2.rA, cc.normal);
                    float rn2B = MathUtils.Cross(ccp2.rB, cc.normal);

                    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.
                    const float k_maxConditionNumber = 100.0f;
                    if (k11 * k11 < k_maxConditionNumber * (k11 * k22 - k12 * k12))
                    {
                        // K is safe to invert.
                        cc.K          = new Mat22(new Vector2(k11, k12), new Vector2(k12, k22));
                        cc.normalMass = cc.K.GetInverse();
                    }
                    else
                    {
                        // The constraints are redundant, just use one.
                        // TODO_ERIN use deepest?
                        cc.pointCount = 1;
                    }
                }

                _constraints[i] = cc;
            }
        }