void IBeforeSolverUpdateable.Update(float dt)
{
//Someone may want to use the Body.CollisionInformation.Tag for their own purposes.
//That could screw up the locking mechanism above and would be tricky to track down.
//Consider using the making the custom tag implement ICharacterTag, modifying LockCharacterPairs to analyze the different Tag type, or using the Entity.Tag for the custom data instead.
Debug.Assert(Body.CollisionInformation.Tag is ICharacterTag, "The character.Body.CollisionInformation.Tag must implement ICharacterTag to link the CharacterController and its body together for character-related locking to work in multithreaded simulations.");
//We can't let multiple characters manage the same pairs simultaneously. Lock it up!
LockCharacterPairs();
try
{
CorrectContacts();
bool hadSupport = SupportFinder.HasSupport;
CollectSupportData();
//Compute the initial velocities relative to the support.
Vector3 relativeVelocity;
ComputeRelativeVelocity(ref supportData, out relativeVelocity);
float verticalVelocity = Vector3.Dot(supportData.Normal, relativeVelocity);
//Don't attempt to use an object as support if we are flying away from it (and we were never standing on it to begin with).
if (SupportFinder.HasSupport && !hadSupport && verticalVelocity < 0)
{
SupportFinder.ClearSupportData();
supportData = new SupportData();
}
//Attempt to jump.
if (tryToJump && StanceManager.CurrentStance != Stance.Crouching) //Jumping while crouching would be a bit silly.
{
//In the following, note that the jumping velocity changes are computed such that the separating velocity is specifically achieved,
//rather than just adding some speed along an arbitrary direction. This avoids some cases where the character could otherwise increase
//the jump speed, which may not be desired.
if (SupportFinder.HasTraction)
{
//The character has traction, so jump straight up.
float currentDownVelocity = Vector3.Dot(Down, relativeVelocity);
//Target velocity is JumpSpeed.
float velocityChange = Math.Max(jumpSpeed + currentDownVelocity, 0);
ApplyJumpVelocity(ref supportData, Down * -velocityChange, ref relativeVelocity);
//Prevent any old contacts from hanging around and coming back with a negative depth.
foreach (var pair in Body.CollisionInformation.Pairs)
{
pair.ClearContacts();
}
SupportFinder.ClearSupportData();
supportData = new SupportData();
}
else if (SupportFinder.HasSupport)
{
//The character does not have traction, so jump along the surface normal instead.
float currentNormalVelocity = Vector3.Dot(supportData.Normal, relativeVelocity);
//Target velocity is JumpSpeed.
float velocityChange = Math.Max(slidingJumpSpeed - currentNormalVelocity, 0);
ApplyJumpVelocity(ref supportData, supportData.Normal * -velocityChange, ref relativeVelocity);
//Prevent any old contacts from hanging around and coming back with a negative depth.
foreach (var pair in Body.CollisionInformation.Pairs)
{
pair.ClearContacts();
}
SupportFinder.ClearSupportData();
supportData = new SupportData();
}
}
tryToJump = false;
//Try to step!
Vector3 newPosition;
//Note: downstepping is often not required.
//It's only really there for games that expect to be able to run down stairs at 40 miles an hour without zipping off into the void.
//Most of the time, you can just comment out downstepping, and so long as the character is running at a reasonable speed,
//gravity will do the work.
//If your game would work without teleportation-based downstepping, it's probably a good idea to comment it out.
//Downstepping can be fairly expensive.
//You can also avoid doing upstepping by fattening up the character's margin, turning it into more of a capsule.
//Instead of teleporting up steps, it would slide up.
//Without teleportation-based upstepping, steps usually need to be quite a bit smaller (i.e. fairly normal sized, instead of 2 feet tall).
if (StepManager.TryToStepDown(out newPosition) ||
StepManager.TryToStepUp(out newPosition))
{
TeleportToPosition(newPosition, dt);
}
if (StanceManager.UpdateStance(out newPosition))
{
TeleportToPosition(newPosition, dt);
}
}
finally
{
UnlockCharacterPairs();
}
//if (SupportFinder.HasTraction && SupportFinder.Supports.Count == 0)
//{
//There's another way to step down that is a lot cheaper, but less robust.
//This modifies the velocity of the character to make it fall faster.
//Impacts with the ground will be harder, so it will apply superfluous force to supports.
//Additionally, it will not be consistent with instant up-stepping.
//However, because it does not do any expensive queries, it is very fast!
////We are being supported by a ray cast, but we're floating.
////Let's try to get to the ground faster.
////How fast? Try picking an arbitrary velocity and setting our relative vertical velocity to that value.
////Don't go farther than the maximum distance, though.
//float maxVelocity = (SupportFinder.SupportRayData.Value.HitData.T - SupportFinder.RayLengthToBottom);
//if (maxVelocity > 0)
//{
// maxVelocity = (maxVelocity + .01f) / dt;
// float targetVerticalVelocity = -3;
// verticalVelocity = -Vector3.Dot(Down, relativeVelocity);
// float change = MathHelper.Clamp(targetVerticalVelocity - verticalVelocity, -maxVelocity, 0);
// ChangeVelocityUnilaterally(Down * -change, ref relativeVelocity);
//}
//}
//Vertical support data is different because it has the capacity to stop the character from moving unless
//contacts are pruned appropriately.
SupportData verticalSupportData;
Vector3 movementDirection;
HorizontalMotionConstraint.GetMovementDirectionIn3D(out movementDirection);
SupportFinder.GetTractionInDirection(ref movementDirection, out verticalSupportData);
//Warning:
//Changing a constraint's support data is not thread safe; it modifies simulation islands!
//If something other than a CharacterController can modify simulation islands is running
//simultaneously (in the IBeforeSolverUpdateable.Update stage), it will need to be synchronized.
//We don't need to synchronize this all the time- only when the support object changes.
bool needToLock = HorizontalMotionConstraint.SupportData.SupportObject != supportData.SupportObject ||
VerticalMotionConstraint.SupportData.SupportObject != verticalSupportData.SupportObject;
if (needToLock)
{
CharacterSynchronizer.ConstraintAccessLocker.Enter();
}
HorizontalMotionConstraint.SupportData = supportData;
VerticalMotionConstraint.SupportData = verticalSupportData;
if (needToLock)
{
CharacterSynchronizer.ConstraintAccessLocker.Exit();
}
}
void IBeforeSolverUpdateable.Update(float dt)
{
CorrectContacts();
bool hadTraction = SupportFinder.HasTraction;
var supportData = CollectSupportData();
//Compute the initial velocities relative to the support.
Vector3 relativeVelocity;
ComputeRelativeVelocity(ref supportData, out relativeVelocity);
float verticalVelocity = Vector3.Dot(supportData.Normal, relativeVelocity);
Vector3 horizontalVelocity = relativeVelocity - supportData.Normal * verticalVelocity;
//Don't attempt to use an object as support if we are flying away from it (and we were never standing on it to begin with).
if (SupportFinder.HasTraction && !hadTraction && verticalVelocity < 0)
{
SupportFinder.ClearSupportData();
HorizontalMotionConstraint.SupportData = new SupportData();
}
//If we can compute that we're separating faster than we can handle, take off.
if (SupportFinder.HasTraction && verticalVelocity < -VerticalMotionConstraint.MaximumGlueForce * dt / VerticalMotionConstraint.EffectiveMass)
{
SupportFinder.ClearSupportData();
supportData = new SupportData();
}
//Attempt to jump.
if (tryToJump && StanceManager.CurrentStance != Stance.Crouching) //Jumping while crouching would be a bit silly.
{
//In the following, note that the jumping velocity changes are computed such that the separating velocity is specifically achieved,
//rather than just adding some speed along an arbitrary direction. This avoids some cases where the character could otherwise increase
//the jump speed, which may not be desired.
if (SupportFinder.HasTraction)
{
//The character has traction, so jump straight up.
float currentUpVelocity = Vector3.Dot(Body.OrientationMatrix.Up, relativeVelocity);
//Target velocity is JumpSpeed.
float velocityChange = Math.Max(jumpSpeed - currentUpVelocity, 0);
ApplyJumpVelocity(ref supportData, Body.OrientationMatrix.Up * velocityChange, ref relativeVelocity);
//Prevent any old contacts from hanging around and coming back with a negative depth.
foreach (var pair in Body.CollisionInformation.Pairs)
{
pair.ClearContacts();
}
SupportFinder.ClearSupportData();
supportData = new SupportData();
}
else if (SupportFinder.HasSupport)
{
//The character does not have traction, so jump along the surface normal instead.
float currentNormalVelocity = Vector3.Dot(supportData.Normal, relativeVelocity);
//Target velocity is JumpSpeed.
float velocityChange = Math.Max(slidingJumpSpeed - currentNormalVelocity, 0);
ApplyJumpVelocity(ref supportData, supportData.Normal * -velocityChange, ref relativeVelocity);
//Prevent any old contacts from hanging around and coming back with a negative depth.
foreach (var pair in Body.CollisionInformation.Pairs)
{
pair.ClearContacts();
}
SupportFinder.ClearSupportData();
supportData = new SupportData();
}
}
tryToJump = false;
//Try to step!
Vector3 newPosition;
if (StepManager.TryToStepDown(out newPosition) ||
StepManager.TryToStepUp(out newPosition))
{
TeleportToPosition(newPosition, dt);
}
if (StanceManager.UpdateStance(out newPosition))
{
TeleportToPosition(newPosition, dt);
}
//if (SupportFinder.HasTraction && SupportFinder.Supports.Count == 0)
//{
//There's another way to step down that is a lot cheaper, but less robust.
//This modifies the velocity of the character to make it fall faster.
//Impacts with the ground will be harder, so it will apply superfluous force to supports.
//Additionally, it will not be consistent with instant up-stepping.
//However, because it does not do any expensive queries, it is very fast!
////We are being supported by a ray cast, but we're floating.
////Let's try to get to the ground faster.
////How fast? Try picking an arbitrary velocity and setting our relative vertical velocity to that value.
////Don't go farther than the maximum distance, though.
//float maxVelocity = (SupportFinder.SupportRayData.Value.HitData.T - SupportFinder.RayLengthToBottom);
//if (maxVelocity > 0)
//{
// maxVelocity = (maxVelocity + .01f) / dt;
// float targetVerticalVelocity = -3;
// verticalVelocity = Vector3.Dot(Body.OrientationMatrix.Up, relativeVelocity);
// float change = MathHelper.Clamp(targetVerticalVelocity - verticalVelocity, -maxVelocity, 0);
// ChangeVelocityUnilaterally(Body.OrientationMatrix.Up * change, ref relativeVelocity);
//}
//}
//Warning:
//Changing a constraint's support data is not thread safe; it modifies simulation islands!
//If your game can guarantee that character controllers will be the only ones performing such shared modifications
//while this updateable stage runs, then addressing this is fairly simple. Wrap this section (minimally, the SupportData property sets)
//in a critical section. A single contended resource isn't great, but then again, the lock will be fairly brief compared to the stepping
//and support queries performed above. Implementing such parallelization is probably only it worth when the number of characters gets fairly high.
//These characters seem to cost about 50-400 microseconds a piece on a single core of a [email protected], with 400 microseconds being a temporary worst case.
HorizontalMotionConstraint.SupportData = supportData;
//Vertical support data is different because it has the capacity to stop the character from moving unless
//contacts are pruned appropriately.
SupportData verticalSupportData;
Vector3 movement3d = new Vector3(HorizontalMotionConstraint.MovementDirection.X, HorizontalMotionConstraint.MovementDirection.Y, 0);
SupportFinder.GetTractionInDirection(ref movement3d, out verticalSupportData);
VerticalMotionConstraint.SupportData = verticalSupportData;
}