void CustomDGRayCastCar::IntegrateTires (dFloat timestep, int threadIndex) { dMatrix bodyMatrix; // get the vehicle global matrix, and use it in several calculations NewtonBodyGetMatrix (m_body0, &bodyMatrix[0][0]); dMatrix chassisMatrix (m_localFrame * bodyMatrix); // get the chassis instantaneous linear and angular velocity in the local space of the chassis dVector bodyOmega; dVector bodyVelocity; NewtonBodyGetVelocity (m_body0, &bodyVelocity[0]); NewtonBodyGetOmega (m_body0, &bodyOmega[0]); // set the current vehicle speed m_curSpeed = bodyMatrix.m_front % bodyVelocity; for (int i = 0; i < m_tiresCount; i ++ ) { Tire& tire = m_tires[i]; /* if (tire.m_tireIsConstrained) { // the torqued generate by the tire can no be larger than the external torque on the tire // when this happens ther tire is spinning unde contrained rotation // V % dir + W * R % dir = 0 // where V is the tire Axel velocity // W is the tire local angular velocity // R is the tire radius // dir is the longitudinal direction of of the tire. dFloat contactRadius; dFloat axelLinealSpeed; dVector tireAxelPosit (chassisMatrix.TransformVector (tire.m_harpoint - m_localFrame.m_up.Scale (tire.m_posit))); dVector tireAxelVeloc = bodyVelocity + bodyOmega * (tireAxelPosit - chassisMatrix.m_posit) - tire.m_hitBodyPointVelocity; axelLinealSpeed = tireAxelVeloc % chassisMatrix.m_front; dVector tireRadius (tire.m_contactPoint - tire.m_tireAxelPosit); contactRadius = (tire.m_lateralPin * tireRadius) % tire.m_longitudinalPin; tire.m_angularVelocity = - axelLinealSpeed / contactRadius ; } else if (tire.m_tireIsOnAir) { if (tire.m_breakForce > 1.0e-3f) { tire.m_angularVelocity = 0.0f; } else { //the tire is on air, need to be integrate net toque and apply a drag coneficenct // dFloat nettorque = tire.m_angularVelocity; // // this checkup is suposed to fix a infinit division by zero... // if ( dAbs(tireContactSpeed) > 1.0e-3) { // nettorque = - (tireLinearSpeed) / (tireContactSpeed); // } //tire.m_angularVelocity = - tireLinearSpeed / tireContactSpeed; dFloat torque; torque = tire.m_torque - tire.m_angularVelocity * tire.m_Ixx * TIRE_VISCUOS_DAMP; tire.m_angularVelocity += torque * tire.m_IxxInv * timestep; } } else { // there is a next torque on the tire dFloat torque; torque = tire.m_torque - tire.m_angularVelocity * tire.m_Ixx * TIRE_VISCUOS_DAMP; tire.m_angularVelocity += torque * tire.m_IxxInv * timestep; } */ if (tire.m_tireIsOnAir) { if (tire.m_breakForce > 1.0e-3f) { tire.m_angularVelocity = 0.0f; } else { //the tire is on air, need to be integrate net toque and apply a drag coeficient dFloat torque; torque = tire.m_torque - tire.m_angularVelocity * tire.m_Ixx * TIRE_VISCUOS_DAMP; tire.m_angularVelocity += torque * tire.m_IxxInv * timestep; } } else if (tire.m_tireIsConstrained) { // the torqued generate by the tire can no be larger than the external torque on the tire // when this happens there tire is spinning under constrained rotation // V % dir + W * R % dir = 0 // where V is the tire Axel velocity // W is the tire local angular velocity // R is the tire radius // dir is the longitudinal direction of of the tire. dFloat contactRadius; dFloat axelLinealSpeed; dVector tireAxelPosit (chassisMatrix.TransformVector (tire.m_harpoint - m_localFrame.m_up.Scale (tire.m_posit))); dVector tireAxelVeloc = bodyVelocity + bodyOmega * (tireAxelPosit - chassisMatrix.m_posit) - tire.m_hitBodyPointVelocity; axelLinealSpeed = tireAxelVeloc % chassisMatrix.m_front; dVector tireRadius (tire.m_contactPoint - tire.m_tireAxelPosit); contactRadius = (tire.m_lateralPin * tireRadius) % tire.m_longitudinalPin; tire.m_angularVelocity = - axelLinealSpeed / contactRadius ; } else { // there is a next torque on the tire dFloat torque; torque = tire.m_torque - tire.m_angularVelocity * tire.m_Ixx * TIRE_VISCUOS_DAMP; tire.m_angularVelocity += torque * tire.m_IxxInv * timestep; } // spin the tire by the angular velocity tire.m_spinAngle = dMod (tire.m_spinAngle + tire.m_angularVelocity * timestep, 3.14159265f * 2.0f); // reset the tire torque tire.m_torque = 0.0f; tire.m_breakForce = 0.0f; } }
void CustomDGRayCastCar::SubmitConstraints (dFloat timestep, int threadIndex) { int constraintIndex; dFloat invTimestep; dMatrix bodyMatrix; // get the simulation time invTimestep = 1.0f / timestep ; // get the vehicle global matrix, and use it in several calculations NewtonBodyGetMatrix (m_body0, &bodyMatrix[0][0]); dMatrix chassisMatrix (m_localFrame * bodyMatrix); // get the chassis instantaneous linear and angular velocity in the local space of the chassis dVector bodyOmega; dVector bodyVelocity; NewtonBodyGetVelocity (m_body0, &bodyVelocity[0]); NewtonBodyGetOmega (m_body0, &bodyOmega[0]); // all tire is on air check m_vehicleOnAir = 0; constraintIndex = 0; for ( int i = 0; i < m_tiresCount; i ++ ) { Tire& tire = m_tires[i]; tire.m_tireIsOnAir = 1; tire.m_tireIsConstrained = 0; tire.m_tireForceAcc = dVector(0.0f, 0.0f, 0.0f, 0.0f); // calculate all suspension matrices in global space and tire collision dMatrix suspensionMatrix (CalculateSuspensionMatrix (i, 0.0f) * chassisMatrix); // calculate the tire collision CalculateTireCollision (tire, suspensionMatrix, threadIndex); // calculate the linear velocity of the tire at the ground contact tire.m_tireAxelPosit = chassisMatrix.TransformVector( tire.m_harpoint - m_localFrame.m_up.Scale (tire.m_posit)); tire.m_tireAxelVeloc = bodyVelocity + bodyOmega * (tire.m_tireAxelPosit - chassisMatrix.m_posit); tire.m_lateralPin = ( chassisMatrix.RotateVector ( tire.m_localAxis ) ); tire.m_longitudinalPin = ( chassisMatrix.m_up * tire.m_lateralPin ); if (tire.m_posit < tire.m_suspensionLenght ) { dFloat distance; dFloat sideSlipCoef; dFloat slipRatioCoef; dFloat tireForceMag; dFloat tireTorqueMag; dFloat suspensionSpeed; dFloat axelLinealSpeed; dFloat tireRotationSpeed; dFloat frictionCircleMag; dFloat longitudinalForceMag; dFloat lateralFrictionForceMag; tire.m_tireIsOnAir = 0; tire.m_hitBodyPointVelocity = dVector (0.0f, 0.0f, 0.0f, 1.0f); if (tire.m_HitBody){ dMatrix matrix; dVector com; dVector omega; NewtonBodyGetOmega (tire.m_HitBody, &omega[0]); NewtonBodyGetMatrix (tire.m_HitBody, &matrix[0][0]); NewtonBodyGetCentreOfMass (tire.m_HitBody, &com[0]); NewtonBodyGetVelocity (tire.m_HitBody, &tire.m_hitBodyPointVelocity[0]); tire.m_hitBodyPointVelocity += (tire.m_contactPoint - matrix.TransformVector (com)) * omega; } // calculate the relative velocity dVector relVeloc (tire.m_tireAxelVeloc - tire.m_hitBodyPointVelocity); suspensionSpeed = - (relVeloc % chassisMatrix.m_up); // now calculate the tire load at the contact point // Tire suspension distance and hard limit. distance = tire.m_suspensionLenght - tire.m_posit; _ASSERTE (distance <= tire.m_suspensionLenght); tire.m_tireLoad = - NewtonCalculateSpringDamperAcceleration (timestep, tire.m_springConst, distance, tire.m_springDamper, suspensionSpeed ); if ( tire.m_tireLoad < 0.0f ) { // since the tire is not a body with real mass it can only push the chassis. tire.m_tireLoad = 0.0f; } //this suspension is applying a normalize force to the car chassis, need to scales by the mass of the car tire.m_tireLoad *= (m_mass * 0.5f); tire.m_tireIsConstrained = (dAbs (tire.m_torque) < 0.3f); // convert the tire load force magnitude to a torque and force. // accumulate the force doe to the suspension spring and damper tire.m_tireForceAcc += chassisMatrix.m_up.Scale (tire.m_tireLoad); // calculate relative velocity at the tire center dVector tireAxelRelativeVelocity (tire.m_tireAxelVeloc - tire.m_hitBodyPointVelocity); // axle linear speed axelLinealSpeed = tireAxelRelativeVelocity % chassisMatrix.m_front; // calculate tire rotation velocity at the tire radio dVector tireAngularVelocity (tire.m_lateralPin.Scale (tire.m_angularVelocity)); dVector tireRadius (tire.m_contactPoint - tire.m_tireAxelPosit); dVector tireRotationalVelocityAtContact (tireAngularVelocity * tireRadius); longitudinalForceMag = 0.0f; // if (!tire.m_tireIsConstrained) { // calculate slip ratio and max longitudinal force tireRotationSpeed = tireRotationalVelocityAtContact % tire.m_longitudinalPin; slipRatioCoef = (dAbs (axelLinealSpeed) > 1.e-3f) ? ((-tireRotationSpeed - axelLinealSpeed) / dAbs (axelLinealSpeed)) : 0.0f; // calculate the formal longitudinal force the tire apply to the chassis longitudinalForceMag = m_normalizedLongitudinalForce.GetValue (slipRatioCoef) * tire.m_tireLoad * tire.m_groundFriction; // } // now calculate relative velocity a velocity at contact point dVector tireContactRelativeVelocity (tireAxelRelativeVelocity + tireRotationalVelocityAtContact); // calculate the sideslip as the angle between the tire lateral speed and longitudila speed sideSlipCoef = dAtan2 (dAbs (tireContactRelativeVelocity % tire.m_lateralPin), dAbs (axelLinealSpeed)); lateralFrictionForceMag = m_normalizedLateralForce.GetValue (sideSlipCoef) * tire.m_tireLoad * tire.m_groundFriction; // Apply brake, need some little fix here. // The fix is need to generate axial force when the brake is apply when the vehicle turn from the steer or on sliding. if ( tire.m_breakForce > 1.0e-3f ) { // row constrained force is save for later determine the dynamic state of this tire tire.m_isBrakingForceIndex = constraintIndex; constraintIndex ++; frictionCircleMag = tire.m_tireLoad * tire.m_groundFriction; if (tire.m_breakForce > frictionCircleMag) { tire.m_breakForce = frictionCircleMag; } //NewtonUserJointAddLinearRow ( m_joint, &tire.m_tireAxelPosit[0], &tire.m_tireAxelPosit[0], &chassisMatrix.m_front.m_x ); NewtonUserJointAddLinearRow (m_joint, &tire.m_tireAxelPosit[0], &tire.m_tireAxelPosit[0], &tire.m_longitudinalPin.m_x); NewtonUserJointSetRowMaximumFriction( m_joint, tire.m_breakForce); NewtonUserJointSetRowMinimumFriction( m_joint, -tire.m_breakForce); // there is a longitudinal force that will reduce the lateral force, we need to recalculate the lateral force tireForceMag = lateralFrictionForceMag * lateralFrictionForceMag + tire.m_breakForce * tire.m_breakForce; if (tireForceMag > (frictionCircleMag * frictionCircleMag)) { lateralFrictionForceMag *= 0.25f * frictionCircleMag / dSqrt (tireForceMag); } } //project the longitudinal and lateral forces over the circle of friction for this tire; frictionCircleMag = tire.m_tireLoad * tire.m_groundFriction; tireForceMag = lateralFrictionForceMag * lateralFrictionForceMag + longitudinalForceMag * longitudinalForceMag; if (tireForceMag > (frictionCircleMag * frictionCircleMag)) { dFloat invMag2; invMag2 = frictionCircleMag / dSqrt (tireForceMag); longitudinalForceMag *= invMag2; lateralFrictionForceMag *= invMag2; } // submit this constraint for calculation of side slip forces lateralFrictionForceMag = dAbs (lateralFrictionForceMag); tire.m_lateralForceIndex = constraintIndex; constraintIndex ++; NewtonUserJointAddLinearRow (m_joint, &tire.m_tireAxelPosit[0], &tire.m_tireAxelPosit[0], &tire.m_lateralPin[0]); NewtonUserJointSetRowMaximumFriction (m_joint, lateralFrictionForceMag); NewtonUserJointSetRowMinimumFriction (m_joint, -lateralFrictionForceMag); // accumulate the longitudinal force dVector tireForce (tire.m_longitudinalPin.Scale (longitudinalForceMag)); tire.m_tireForceAcc += tireForce; // now we apply the combined tire force generated by this tire, to the car chassis dVector torque ((tire.m_tireAxelPosit - chassisMatrix.m_posit) * tire.m_tireForceAcc); NewtonBodyAddForce (m_body0, &tire.m_tireForceAcc[0]); NewtonBodyAddTorque( m_body0, &torque[0] ); // calculate the net torque on the tire tireTorqueMag = -((tireRadius * tireForce) % tire.m_lateralPin); if (dAbs (tireTorqueMag) > dAbs (tire.m_torque)) { // the tire reaction force can no be larger than the applied engine torque // when this happens the net torque is zero and the tire is constrained to the vehicle linear motion tire.m_tireIsConstrained = 1; tireTorqueMag = tire.m_torque; } tire.m_torque -= tireTorqueMag; } } }
void CustomDGRayCastCar::SubmitConstraints (dFloat timestep, int threadIndex) { // get the simulation time // dFloat invTimestep = 1.0f / timestep ; // get the vehicle global matrix, and use it in several calculations dMatrix bodyMatrix; NewtonBodyGetMatrix (m_body0, &bodyMatrix[0][0]); dMatrix chassisMatrix (m_localFrame * bodyMatrix); // get the chassis instantaneous linear and angular velocity in the local space of the chassis dVector bodyForce; dVector bodyOmega; dVector bodyVelocity; NewtonBodyGetVelocity (m_body0, &bodyVelocity[0]); NewtonBodyGetOmega (m_body0, &bodyOmega[0]); //static int xxx; //dTrace (("frame %d veloc(%f %f %f)\n", xxx, bodyVelocity[0], bodyVelocity[1], bodyVelocity[2])); //xxx ++; //if (xxx >= 210) { //xxx *=1; //bodyVelocity.m_x = 0; //bodyVelocity.m_z = 10; //NewtonBodySetVelocity (m_body0, &bodyVelocity[0]); //} // dVector normalForces (0.0f, 0.0f, 0.0f, 0.0f); // all tire is on air check m_vehicleOnAir = 0; // int constraintIndex = 0; for (int i = 0; i < m_tiresCount; i ++) { // dTrace (("tire: %d ", i)); Tire& tire = m_tires[i]; tire.m_tireIsOnAir = 1; // tire.m_tireIsConstrained = 0; tire.m_tireForceAcc = dVector(0.0f, 0.0f, 0.0f, 0.0f); // calculate all suspension matrices in global space and tire collision dMatrix suspensionMatrix (CalculateSuspensionMatrix (i, 0.0f) * chassisMatrix); // calculate the tire collision CalculateTireCollision (tire, suspensionMatrix, threadIndex); // calculate the linear velocity of the tire at the ground contact tire.m_tireAxelPositGlobal = chassisMatrix.TransformVector (tire.m_harpointInJointSpace - m_localFrame.m_up.Scale (tire.m_posit)); tire.m_tireAxelVelocGlobal = bodyVelocity + bodyOmega * (tire.m_tireAxelPositGlobal - chassisMatrix.m_posit); tire.m_lateralPinGlobal = chassisMatrix.RotateVector (tire.m_localAxisInJointSpace); tire.m_longitudinalPinGlobal = chassisMatrix.m_up * tire.m_lateralPinGlobal; if (tire.m_posit < tire.m_suspensionLenght ) { tire.m_tireIsOnAir = 0; tire.m_hitBodyPointVelocity = dVector (0.0f, 0.0f, 0.0f, 1.0f); if (tire.m_HitBody){ dMatrix matrix; dVector com; dVector omega; NewtonBodyGetOmega (tire.m_HitBody, &omega[0]); NewtonBodyGetMatrix (tire.m_HitBody, &matrix[0][0]); NewtonBodyGetCentreOfMass (tire.m_HitBody, &com[0]); NewtonBodyGetVelocity (tire.m_HitBody, &tire.m_hitBodyPointVelocity[0]); tire.m_hitBodyPointVelocity += (tire.m_contactPoint - matrix.TransformVector (com)) * omega; } // calculate the relative velocity dVector tireHubVeloc (tire.m_tireAxelVelocGlobal - tire.m_hitBodyPointVelocity); dFloat suspensionSpeed = - (tireHubVeloc % chassisMatrix.m_up); // now calculate the tire load at the contact point // Tire suspension distance and hard limit. dFloat distance = tire.m_suspensionLenght - tire.m_posit; _ASSERTE (distance <= tire.m_suspensionLenght); tire.m_tireLoad = - NewtonCalculateSpringDamperAcceleration (timestep, tire.m_springConst, distance, tire.m_springDamper, suspensionSpeed ); if ( tire.m_tireLoad < 0.0f ) { // since the tire is not a body with real mass it can only push the chassis. tire.m_tireLoad = 0.0f; } //this suspension is applying a normalize force to the car chassis, need to scales by the mass of the car tire.m_tireLoad *= (m_mass * 0.5f); // dTrace (("(load = %f) ", tire.m_tireLoad)); //tire.m_tireIsConstrained = (dAbs (tire.m_torque) < 0.3f); // convert the tire load force magnitude to a torque and force. // accumulate the force doe to the suspension spring and damper tire.m_tireForceAcc += chassisMatrix.m_up.Scale (tire.m_tireLoad); // calculate relative velocity at the tire center //dVector tireAxelRelativeVelocity (tire.m_tireAxelVeloc - tire.m_hitBodyPointVelocity); // axle linear speed //axelLinealSpeed = tireAxelRelativeVelocity % chassisMatrix.m_front; dFloat axelLinearSpeed = tireHubVeloc % chassisMatrix.m_front; // calculate tire rotation velocity at the tire radio //dVector tireAngularVelocity (tire.m_lateralPinGlobal.Scale (tire.m_angularVelocity)); //dVector tireRadius (tire.m_contactPoint - tire.m_tireAxelPositGlobal); //dVector tireRotationalVelocityAtContact (tireAngularVelocity * tireRadius); // calculate slip ratio and max longitudinal force //dFloat tireRotationSpeed = -(tireRotationalVelocityAtContact % tire.m_longitudinalPinGlobal); //dFloat slipRatioCoef = (dAbs (axelLinearSpeed) > 1.e-3f) ? ((tireRotationSpeed - axelLinearSpeed) / dAbs (axelLinearSpeed)) : 0.0f; //dTrace (("(slipRatio = %f) ", slipRatioCoef)); // calculate the formal longitudinal force the tire apply to the chassis //dFloat longitudinalForceMag = m_normalizedLongitudinalForce.GetValue (slipRatioCoef) * tire.m_tireLoad * tire.m_groundFriction; dFloat longitudinalForceMag = CalculateLongitudinalForce (i, axelLinearSpeed, tire.m_tireLoad * tire.m_groundFriction); // dTrace (("(longForce = %f) ", longitudinalForceMag)); #if 0 // now calculate relative velocity a velocity at contact point //dVector tireContactRelativeVelocity (tireAxelRelativeVelocity + tireRotationalVelocityAtContact); //dVector tireContactAbsoluteVelocity (tireHubVeloc + tireRotationalVelocityAtContact); // calculate the side slip as the angle between the tire lateral speed and longitudinal speed //dFloat lateralSpeed = tireContactRelativeVelocity % tire.m_lateralPin; dFloat lateralSpeed = tireHubVeloc % tire.m_lateralPinGlobal; dFloat sideSlipCoef = dAtan2 (dAbs (lateralSpeed), dAbs (axelLinearSpeed)); dFloat lateralFrictionForceMag = m_normalizedLateralForce.GetValue (sideSlipCoef) * tire.m_tireLoad * tire.m_groundFriction; // Apply brake, need some little fix here. // The fix is need to generate axial force when the brake is apply when the vehicle turn from the steer or on sliding. if ( tire.m_breakForce > 1.0e-3f ) { _ASSERTE (0); /* // row constrained force is save for later determine the dynamic state of this tire tire.m_isBrakingForceIndex = constraintIndex; constraintIndex ++; frictionCircleMag = tire.m_tireLoad * tire.m_groundFriction; if (tire.m_breakForce > frictionCircleMag) { tire.m_breakForce = frictionCircleMag; } //NewtonUserJointAddLinearRow ( m_joint, &tire.m_tireAxelPosit[0], &tire.m_tireAxelPosit[0], &chassisMatrix.m_front.m_x ); NewtonUserJointAddLinearRow (m_joint, &tire.m_tireAxelPosit[0], &tire.m_tireAxelPosit[0], &tire.m_longitudinalPin.m_x); NewtonUserJointSetRowMaximumFriction( m_joint, tire.m_breakForce); NewtonUserJointSetRowMinimumFriction( m_joint, -tire.m_breakForce); // there is a longitudinal force that will reduce the lateral force, we need to recalculate the lateral force tireForceMag = lateralFrictionForceMag * lateralFrictionForceMag + tire.m_breakForce * tire.m_breakForce; if (tireForceMag > (frictionCircleMag * frictionCircleMag)) { lateralFrictionForceMag *= 0.25f * frictionCircleMag / dSqrt (tireForceMag); } */ } //project the longitudinal and lateral forces over the circle of friction for this tire; dFloat frictionCircleMag = tire.m_tireLoad * tire.m_groundFriction; dFloat tireForceMag = lateralFrictionForceMag * lateralFrictionForceMag + longitudinalForceMag * longitudinalForceMag; if (tireForceMag > (frictionCircleMag * frictionCircleMag)) { dFloat invMag2; invMag2 = frictionCircleMag / dSqrt (tireForceMag); longitudinalForceMag *= invMag2; lateralFrictionForceMag *= invMag2; } // submit this constraint for calculation of side slip forces lateralFrictionForceMag = dAbs (lateralFrictionForceMag); tire.m_lateralForceIndex = constraintIndex; constraintIndex ++; NewtonUserJointAddLinearRow (m_joint, &tire.m_tireAxelPositGlobal[0], &tire.m_tireAxelPositGlobal[0], &tire.m_lateralPinGlobal[0]); NewtonUserJointSetRowMaximumFriction (m_joint, lateralFrictionForceMag); NewtonUserJointSetRowMinimumFriction (m_joint, -lateralFrictionForceMag); #endif // accumulate the longitudinal force dVector tireForce (tire.m_longitudinalPinGlobal.Scale (longitudinalForceMag)); tire.m_tireForceAcc += tireForce; // now we apply the combined tire force generated by this tire, to the car chassis dVector r (tire.m_tireAxelPositGlobal - chassisMatrix.m_posit); // add the toque the tire asserts on the car body (principle of action reaction) dVector torque (r * tire.m_tireForceAcc - tire.m_lateralPinGlobal.Scale (tire.m_torque)); NewtonBodyAddForce (m_body0, &tire.m_tireForceAcc[0]); NewtonBodyAddTorque( m_body0, &torque[0] ); /* // calculate the net torque on the tire dFloat tireTorqueMag = -((tireRadius * tireForce) % tire.m_lateralPinGlobal); if (dAbs (tireTorqueMag) > dAbs (tire.m_torque)) { // the tire reaction force cannot be larger than the applied engine torque // when this happens the net torque is zero and the tire is constrained to the vehicle linear motion tire.m_tireIsConstrained = 1; tireTorqueMag = tire.m_torque; } tire.m_torque -= tireTorqueMag; */ // normalForces += tire.m_tireForceAcc; } else { // there is a next torque on the tire tire.m_torque -= tire.m_angularVelocity * tire.m_Ixx * DG_TIRE_VISCUOS_DAMP; tire.m_angularVelocity += tire.m_torque * tire.m_IxxInv * timestep; if (m_tires[i].m_breakForce > dFloat (0.1f)) { tire.m_angularVelocity = 0.0f; } } // dTrace (("(tireTorque = %f) ", tire.m_torque)); // spin the tire by the angular velocity tire.m_spinAngle = dMod (tire.m_spinAngle + tire.m_angularVelocity * timestep, 3.14159265f * 2.0f); // reset the tire torque tire.m_torque = 0.0f; tire.m_breakForce = 0.0f; // dTrace (("\n")); } // add a row to simulate the engine rolling resistance // float bodyWeight = dAbs (normalForces % chassisMatrix.m_up) * m_rollingResistance; // if (bodyWeight > (1.0e-3f) * m_mass) { // NewtonUserJointAddLinearRow (m_joint, &chassisMatrix.m_posit[0], &chassisMatrix.m_posit[0], &chassisMatrix.m_front[0]); // NewtonUserJointSetRowMaximumFriction( m_joint, bodyWeight); // NewtonUserJointSetRowMinimumFriction( m_joint, -bodyWeight); // } }