void CharacterController::playerStep(btCollisionWorld* dynaWorld, btScalar dt) {
btVector3 velocity = _rigidBody->getLinearVelocity() - _parentVelocity;
computeNewVelocity(dt, velocity);
_rigidBody->setLinearVelocity(velocity + _parentVelocity);
// Dynamicaly compute a follow velocity to move this body toward the _followDesiredBodyTransform.
// Rather than add this velocity to velocity the RigidBody, we explicitly teleport the RigidBody towards its goal.
// This mirrors the computation done in MyAvatar::FollowHelper::postPhysicsUpdate().
const float MINIMUM_TIME_REMAINING = 0.005f;
const float MAX_DISPLACEMENT = 0.5f * _radius;
_followTimeRemaining -= dt;
if (_followTimeRemaining >= MINIMUM_TIME_REMAINING) {
btTransform bodyTransform = _rigidBody->getWorldTransform();
btVector3 startPos = bodyTransform.getOrigin();
btVector3 deltaPos = _followDesiredBodyTransform.getOrigin() - startPos;
btVector3 vel = deltaPos / _followTimeRemaining;
btVector3 linearDisplacement = clampLength(vel * dt, MAX_DISPLACEMENT); // clamp displacement to prevent tunneling.
btVector3 endPos = startPos + linearDisplacement;
btQuaternion startRot = bodyTransform.getRotation();
glm::vec2 currentFacing = getFacingDir2D(bulletToGLM(startRot));
glm::vec2 currentRight(currentFacing.y, -currentFacing.x);
glm::vec2 desiredFacing = getFacingDir2D(bulletToGLM(_followDesiredBodyTransform.getRotation()));
float deltaAngle = acosf(glm::clamp(glm::dot(currentFacing, desiredFacing), -1.0f, 1.0f));
float angularSpeed = deltaAngle / _followTimeRemaining;
float sign = copysignf(1.0f, glm::dot(desiredFacing, currentRight));
btQuaternion angularDisplacement = btQuaternion(btVector3(0.0f, 1.0f, 0.0f), sign * angularSpeed * dt);
btQuaternion endRot = angularDisplacement * startRot;
// in order to accumulate displacement of avatar position, we need to take _shapeLocalOffset into account.
btVector3 shapeLocalOffset = glmToBullet(_shapeLocalOffset);
btVector3 swingDisplacement = rotateVector(endRot, -shapeLocalOffset) - rotateVector(startRot, -shapeLocalOffset);
_followLinearDisplacement = linearDisplacement + swingDisplacement + _followLinearDisplacement;
_followAngularDisplacement = angularDisplacement * _followAngularDisplacement;
_rigidBody->setWorldTransform(btTransform(endRot, endPos));
}
_followTime += dt;
}
void CharacterController::playerStep(btCollisionWorld* dynaWorld, btScalar dt) {
const btScalar MIN_SPEED = 0.001f;
btVector3 actualVelocity = _rigidBody->getLinearVelocity();
if (actualVelocity.length() < MIN_SPEED) {
actualVelocity = btVector3(0.0f, 0.0f, 0.0f);
}
btVector3 desiredVelocity = _walkVelocity;
if (desiredVelocity.length() < MIN_SPEED) {
desiredVelocity = btVector3(0.0f, 0.0f, 0.0f);
}
// decompose into horizontal and vertical components.
btVector3 actualVertVelocity = actualVelocity.dot(_currentUp) * _currentUp;
btVector3 actualHorizVelocity = actualVelocity - actualVertVelocity;
btVector3 desiredVertVelocity = desiredVelocity.dot(_currentUp) * _currentUp;
btVector3 desiredHorizVelocity = desiredVelocity - desiredVertVelocity;
btVector3 finalVelocity;
switch (_state) {
case State::Ground:
case State::Takeoff:
{
// horizontal ground control
const btScalar WALK_ACCELERATION_TIMESCALE = 0.1f;
btScalar tau = dt / WALK_ACCELERATION_TIMESCALE;
finalVelocity = tau * desiredHorizVelocity + (1.0f - tau) * actualHorizVelocity + actualVertVelocity;
}
break;
case State::InAir:
{
// horizontal air control
const btScalar IN_AIR_ACCELERATION_TIMESCALE = 2.0f;
btScalar tau = dt / IN_AIR_ACCELERATION_TIMESCALE;
finalVelocity = tau * desiredHorizVelocity + (1.0f - tau) * actualHorizVelocity + actualVertVelocity;
}
break;
case State::Hover:
{
// vertical and horizontal air control
const btScalar FLY_ACCELERATION_TIMESCALE = 0.2f;
btScalar tau = dt / FLY_ACCELERATION_TIMESCALE;
finalVelocity = tau * desiredVelocity + (1.0f - tau) * actualVelocity;
}
break;
}
_rigidBody->setLinearVelocity(finalVelocity);
// Dynamicaly compute a follow velocity to move this body toward the _followDesiredBodyTransform.
// Rather then add this velocity to velocity the RigidBody, we explicitly teleport the RigidBody towards its goal.
// This mirrors the computation done in MyAvatar::FollowHelper::postPhysicsUpdate().
const float MINIMUM_TIME_REMAINING = 0.005f;
const float MAX_DISPLACEMENT = 0.5f * _radius;
_followTimeRemaining -= dt;
if (_followTimeRemaining >= MINIMUM_TIME_REMAINING) {
btTransform bodyTransform = _rigidBody->getWorldTransform();
btVector3 startPos = bodyTransform.getOrigin();
btVector3 deltaPos = _followDesiredBodyTransform.getOrigin() - startPos;
btVector3 vel = deltaPos / _followTimeRemaining;
btVector3 linearDisplacement = clampLength(vel * dt, MAX_DISPLACEMENT); // clamp displacement to prevent tunneling.
btVector3 endPos = startPos + linearDisplacement;
btQuaternion startRot = bodyTransform.getRotation();
glm::vec2 currentFacing = getFacingDir2D(bulletToGLM(startRot));
glm::vec2 currentRight(currentFacing.y, -currentFacing.x);
glm::vec2 desiredFacing = getFacingDir2D(bulletToGLM(_followDesiredBodyTransform.getRotation()));
float deltaAngle = acosf(glm::clamp(glm::dot(currentFacing, desiredFacing), -1.0f, 1.0f));
float angularSpeed = deltaAngle / _followTimeRemaining;
float sign = copysignf(1.0f, glm::dot(desiredFacing, currentRight));
btQuaternion angularDisplacement = btQuaternion(btVector3(0.0f, 1.0f, 0.0f), sign * angularSpeed * dt);
btQuaternion endRot = angularDisplacement * startRot;
// in order to accumulate displacement of avatar position, we need to take _shapeLocalOffset into account.
btVector3 shapeLocalOffset = glmToBullet(_shapeLocalOffset);
btVector3 swingDisplacement = rotateVector(endRot, -shapeLocalOffset) - rotateVector(startRot, -shapeLocalOffset);
_followLinearDisplacement = linearDisplacement + swingDisplacement + _followLinearDisplacement;
_followAngularDisplacement = angularDisplacement * _followAngularDisplacement;
_rigidBody->setWorldTransform(btTransform(endRot, endPos));
}
_followTime += dt;
}
