From 6be3750b38715c1d7c12b7eed5391744b9cb5687 Mon Sep 17 00:00:00 2001
From: Andrew Meadows <andrew@highfidelity.io>
Date: Tue, 27 Aug 2019 20:28:56 -0700
Subject: [PATCH] use collision brake feedback to prevent tunneling
---
interface/src/avatar/MyAvatar.cpp | 2 +
libraries/physics/src/CharacterController.cpp | 40 ++++++++++++++-----
libraries/physics/src/CharacterController.h | 2 +
3 files changed, 34 insertions(+), 10 deletions(-)
diff --git a/interface/src/avatar/MyAvatar.cpp b/interface/src/avatar/MyAvatar.cpp
index 089ff4c2bf..4d1c20010c 100644
--- a/interface/src/avatar/MyAvatar.cpp
+++ b/interface/src/avatar/MyAvatar.cpp
@@ -3586,6 +3586,8 @@ void MyAvatar::updateActionMotor(float deltaTime) {
float speedGrowthTimescale = 2.0f;
float speedIncreaseFactor = 1.8f * _walkSpeedScalar;
motorSpeed *= 1.0f + glm::clamp(deltaTime / speedGrowthTimescale, 0.0f, 1.0f) * speedIncreaseFactor;
+ // use feedback from CharacterController to prevent tunneling under high motorspeed
+ motorSpeed *= _characterController.getCollisionBrakeAttenuationFactor();
const float maxBoostSpeed = sensorToWorldScale * MAX_BOOST_SPEED;
if (_isPushing) {
diff --git a/libraries/physics/src/CharacterController.cpp b/libraries/physics/src/CharacterController.cpp
index 16b893977a..5cd5045d19 100755
--- a/libraries/physics/src/CharacterController.cpp
+++ b/libraries/physics/src/CharacterController.cpp
@@ -570,6 +570,11 @@ void CharacterController::setPhysicsEngine(const PhysicsEnginePointer& engine) {
}
}
+float CharacterController::getCollisionBrakeAttenuationFactor() const {
+ // _collisionBrake ranges from 0.0 (no brake) to 1.0 (max brake)
+ return 1.0f - 0.5f * _collisionBrake;
+}
+
void CharacterController::setCollisionless(bool collisionless) {
if (collisionless != _collisionless) {
_collisionless = collisionless;
@@ -787,18 +792,36 @@ void CharacterController::computeNewVelocity(btScalar dt, btVector3& velocity) {
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;
- const float STRONG_IMPACT_THRESHOLD = -1000.0f; // this tuned manually
- const float VERY_STRONG_IMPACT_THRESHOLD = -2000.0f; // this tuned manually
+ // NOTE: the thresholds are negative because that indicates the vectors oppose each other
+ const float STRONG_OPPOSING_IMPACT_THRESHOLD = -1000.0f;
+ const float VERY_STRONG_OPPOSING_IMPACT_THRESHOLD = -2000.0f;
float velocityDotImpulse = velocity.dot(_netCollisionImpulse);
- if ((velocityDotImpulse < VERY_STRONG_IMPACT_THRESHOLD && _stuckTransitionCount == 0) || _isStuck) {
- // we are either definitely NOT stuck, or definitely are --> nothing to do here
+ const float COLLISION_BRAKE_DECAY_TIMESCALE = 0.20f; // seconds
+ const float MIN_COLLISION_BRAKE = 0.05f;
+ if ((velocityDotImpulse > VERY_STRONG_OPPOSING_IMPACT_THRESHOLD && _stuckTransitionCount == 0) || _isStuck) {
+ // we are either definitely NOT stuck (in which case nothing to do)
+ // or definitely are (in which case we'll be temporarily disabling collisions with the offending object
+ // and we don't mind tunnelling as an escape route out of stuck)
+ if (_collisionBrake > MIN_COLLISION_BRAKE) {
+ _collisionBrake *= (1.0f - dt / COLLISION_BRAKE_DECAY_TIMESCALE);
+ if (_collisionBrake < MIN_COLLISION_BRAKE) {
+ _collisionBrake = 0.0f;
+ }
+ }
return;
}
- if (velocityDotImpulse < VERY_STRONG_IMPACT_THRESHOLD ||
- (velocity.length2() > SAFE_COLLISION_SPEED_SQUARED && velocityDotImpulse < STRONG_IMPACT_THRESHOLD)) {
- const float REFLECTION_COEFFICIENT = 1.5f;
+ if (velocityDotImpulse < VERY_STRONG_OPPOSING_IMPACT_THRESHOLD ||
+ (velocityDotImpulse < STRONG_OPPOSING_IMPACT_THRESHOLD && velocity.length2() > SAFE_COLLISION_SPEED_SQUARED)) {
+ if (_collisionBrake < 1.0f) {
+ _collisionBrake += (1.0f - _collisionBrake) * (dt / COLLISION_BRAKE_DECAY_TIMESCALE);
+ const float MAX_COLLISION_BRAKE = 1.0f - MIN_COLLISION_BRAKE;
+ if (_collisionBrake > MAX_COLLISION_BRAKE) {
+ _collisionBrake = 1.0f;
+ }
+ }
+ const float REFLECTION_COEFFICIENT = 1.0f;
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
@@ -810,9 +833,6 @@ void CharacterController::computeNewVelocity(btScalar dt, btVector3& velocity) {
// 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...
diff --git a/libraries/physics/src/CharacterController.h b/libraries/physics/src/CharacterController.h
index 472dcdd003..e7ad3ddfa8 100755
--- a/libraries/physics/src/CharacterController.h
+++ b/libraries/physics/src/CharacterController.h
@@ -128,6 +128,7 @@ public:
void setPhysicsEngine(const PhysicsEnginePointer& engine);
bool isEnabledAndReady() const { return (bool)_physicsEngine; }
bool isStuck() const { return _isStuck; }
+ float getCollisionBrakeAttenuationFactor() const;
void setCollisionless(bool collisionless);
@@ -221,6 +222,7 @@ protected:
bool _isPushingUp;
bool _isStuck { false };
bool _isSeated { false };
+ float _collisionBrake { 0.0f };
PhysicsEnginePointer _physicsEngine { nullptr };
btRigidBody* _rigidBody { nullptr };