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watch for tunneling events and interfere before stuck

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This commit is contained in:
Andrew Meadows 2019-08-23 17:53:33 -07:00
parent 860b5d0970
commit 8135021b25
2 changed files with 48 additions and 9 deletions
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56
libraries/physics/src/CharacterController.cpp
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@ -189,7 +189,7 @@ void CharacterController::addToWorld() {
_rigidBody->setCollisionFlags(btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK);
// enable CCD
_rigidBody->setCcdSweptSphereRadius(_radius);
_rigidBody->setCcdSweptSphereRadius(2.0f * (_radius + _halfHeight));
_rigidBody->setCcdMotionThreshold(_radius);
btCollisionShape* shape = _rigidBody->getCollisionShape();
@ -225,6 +225,7 @@ bool CharacterController::checkForSupport(btCollisionWorld* collisionWorld) {
float deepestDistance = 0.0f;
float strongestImpulse = 0.0f;
_netCollisionImpulse = btVector3(0.0f, 0.0f, 0.0f);
for (int i = 0; i < numManifolds; i++) {
btPersistentManifold* contactManifold = dispatcher->getManifoldByIndexInternal(i);
if (_rigidBody == contactManifold->getBody1() || _rigidBody == contactManifold->getBody0()) {
@ -245,6 +246,7 @@ bool CharacterController::checkForSupport(btCollisionWorld* collisionWorld) {
deepestDistance = distance;
}
float impulse = contact.getAppliedImpulse();
_netCollisionImpulse += impulse * normal;
if (impulse > strongestImpulse) {
strongestImpulse = impulse;
}
@ -554,7 +556,7 @@ void CharacterController::setLocalBoundingBox(const glm::vec3& minCorner, const
if (_rigidBody) {
// update CCD with new _radius
_rigidBody->setCcdSweptSphereRadius(_radius);
_rigidBody->setCcdSweptSphereRadius(2.0f * (_radius + _halfHeight));
_rigidBody->setCcdMotionThreshold(_radius);
}
}
@ -777,14 +779,50 @@ void CharacterController::computeNewVelocity(btScalar dt, btVector3& velocity) {
velocity += dt * _linearAcceleration;
// Note the differences between these two variables:
// _targetVelocity = ideal final velocity according to input
// velocity = real final velocity after motors are applied to current velocity
// velocity = new final velocity after motors are applied to currentVelocity
bool gettingStuck = !_isStuck && _stuckTransitionCount > 1 && _state == State::Hover;
if (gettingStuck && velocity.length2() > currentVelocity.length2()) {
// we are probably trying to fly fast into a mesh obstacle
// which is causing us to tickle the "stuck" detection code
// so we average our new velocity with currentVeocity to prevent a "safe landing" response
velocity = 0.5f * (velocity + currentVelocity);
// but we want to avoid getting stuck and tunelling through geometry so we perform
// further checks and modify/abandon our velocity calculations
if (_isStuck || _stuckTransitionCount == 0) {
// we are either definitely stuck, or definitely not --> nothing to do
return;
}
const float SAFE_COLLISION_SPEED = glm::abs(STUCK_PENETRATION) * (float)NUM_SUBSTEPS_PER_SECOND;
const float SAFE_COLLISION_SPEED_SQUARED = SAFE_COLLISION_SPEED * SAFE_COLLISION_SPEED;
bool fast = velocity.length2() > SAFE_COLLISION_SPEED_SQUARED;
const float STRONG_IMPACT_IMPULSE_DOT = -1000.0f; // this tuned manually
bool strongImpact = velocity.dot(_netCollisionImpulse) < STRONG_IMPACT_IMPULSE_DOT;
if (fast && strongImpact) {
const float REFLECTION_COEFFICIENT = 1.5f;
if (velocity.dot(currentVelocity) > 0.0f) {
// our new velocity points in the same direction as our currentVelocity
// but strongImpact means new velocity points against netImpulse
if (currentVelocity.dot(_netCollisionImpulse) > 0.0f) {
// currentVelocity points positively with netImpulse
// so we will assume collisions will save us and use it for our new velocity
velocity = currentVelocity;
} else {
// can't trust physical simulation --> reflect velocity against netImpulse
btVector3 impulseDirection = _netCollisionImpulse.normalized();
velocity -= (REFLECTION_COEFFICIENT * velocity.dot(impulseDirection)) * impulseDirection;
// also attenuate the velocity to help slow down the character before its penetration gets worse
const float ATTENUATION_COEFFICIENT = 0.8f;
velocity *= ATTENUATION_COEFFICIENT;
}
} else {
// currentVelocity points against new velocity, which means it is probably better but...
// this doesn't mean it points in a good direction yet, so we must check
if (currentVelocity.dot(_netCollisionImpulse) < 0.0f) {
// currentVelocity points against netImpulse, so we reflect it
btVector3 impulseDirection = _netCollisionImpulse.normalized();
currentVelocity -= (REFLECTION_COEFFICIENT * currentVelocity.dot(impulseDirection)) * impulseDirection;
}
velocity = currentVelocity;
}
}
}

1
libraries/physics/src/CharacterController.h
View file

@ -215,6 +215,7 @@ protected:
btVector3 _followLinearDisplacement;
btQuaternion _followAngularDisplacement;
btVector3 _linearAcceleration;
btVector3 _netCollisionImpulse;
State _state;
bool _isPushingUp;