bool IsObstructed(ref QuickList <CharacterContact> supportContacts, ref QuickList <CharacterContact> sideContacts, ref QuickList <CharacterContact> headContacts)
{
if (IsObstructed(ref sideContacts, ref headContacts))
{
return(true);
}
for (int i = 0; i < supportContacts.Count; ++i)
{
if (IsSupportContactObstructive(ref supportContacts.Elements[i].Contact))
{
return(true);
}
}
return(false);
}
CharacterContactPositionState TrySupportLocation(ConvexCollidable <CylinderShape> queryObject, ref Vector3 position, out float hintOffset,
ref QuickList <CharacterContact> tractionContacts, ref QuickList <CharacterContact> supportContacts, ref QuickList <CharacterContact> sideContacts, ref QuickList <CharacterContact> headContacts)
{
hintOffset = 0;
PrepareQueryObject(queryObject, ref position);
QueryManager.QueryContacts(queryObject, ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts, true);
bool obstructed = IsObstructed(ref sideContacts, ref headContacts);
if (obstructed)
{
return(CharacterContactPositionState.Obstructed);
}
if (supportContacts.Count > 0)
{
CharacterContactPositionState supportState;
CharacterContact supportContact;
QueryManager.AnalyzeSupportState(ref tractionContacts, ref supportContacts, out supportState, out supportContact);
var down = characterBody.orientationMatrix.Down;
//Note that traction is not tested for; it isn't important for the stance manager.
if (supportState == CharacterContactPositionState.Accepted)
{
//We're done! The guess found a good spot to stand on.
//We need to have fairly good contacts after this process, so only push it up a bit.
hintOffset = Math.Min(0, Vector3.Dot(supportContact.Contact.Normal, down) * (CollisionDetectionSettings.AllowedPenetration * .5f - supportContact.Contact.PenetrationDepth));
return(CharacterContactPositionState.Accepted);
}
else if (supportState == CharacterContactPositionState.TooDeep)
{
//Looks like we have to keep trying, but at least we found a good hint.
hintOffset = Math.Min(0, Vector3.Dot(supportContact.Contact.Normal, down) * (CollisionDetectionSettings.AllowedPenetration * .5f - supportContact.Contact.PenetrationDepth));
return(CharacterContactPositionState.TooDeep);
}
else //if (supportState == SupportState.Separated)
{
//It's not obstructed, but the support isn't quite right.
//It's got a negative penetration depth.
//We can use that as a hint.
hintOffset = -.001f - Vector3.Dot(supportContact.Contact.Normal, down) * supportContact.Contact.PenetrationDepth;
return(CharacterContactPositionState.NoHit);
}
}
else //Not obstructed, but no support.
{
return(CharacterContactPositionState.NoHit);
}
}
bool IsObstructed(ref QuickList <CharacterContact> sideContacts, ref QuickList <CharacterContact> headContacts)
{
//No head contacts can exist!
if (headContacts.Count > 0)
{
return(true);
}
//A contact is considered obstructive if its projected depth is deeper than any existing contact along the existing contacts' normals.
for (int i = 0; i < sideContacts.Count; i++)
{
if (SupportFinder.IsSideContactObstructive(ref sideContacts.Elements[i].Contact))
{
return(true);
}
}
return(false);
}
protected override void UpdateContainedPairs(float dt)
{
var overlappedElements = new QuickList <int>(BufferPools <int> .Thread);
BoundingBox localBoundingBox;
Vector3 sweep;
Vector3.Multiply(ref mobileMesh.entity.linearVelocity, dt, out sweep);
mobileMesh.Shape.GetSweptLocalBoundingBox(ref mobileMesh.worldTransform, ref mesh.worldTransform, ref sweep, out localBoundingBox);
mesh.Shape.GetOverlaps(localBoundingBox, ref overlappedElements);
for (int i = 0; i < overlappedElements.Count; i++)
{
TryToAdd(overlappedElements.Elements[i]);
}
overlappedElements.Dispose();
}
CharacterContactPositionState TryDownStepPosition(ref Vector3 position, ref Vector3 down,
ref QuickList <CharacterContact> tractionContacts, ref QuickList <CharacterContact> supportContacts, ref QuickList <CharacterContact> sideContacts, ref QuickList <CharacterContact> headContacts,
out float hintOffset)
{
hintOffset = 0;
PrepareQueryObject(ref position);
QueryManager.QueryContacts(currentQueryObject, ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts);
if (IsDownStepObstructed(ref sideContacts))
{
return(CharacterContactPositionState.Obstructed);
}
//Note the use of traction contacts. We only want to step down if there are traction contacts to support us.
if (tractionContacts.Count > 0)
{
CharacterContactPositionState supportState;
CharacterContact supportContact;
QueryManager.AnalyzeSupportState(ref tractionContacts, ref supportContacts, out supportState, out supportContact);
if (supportState == CharacterContactPositionState.Accepted)
{
//We're done! The guess found a good spot to stand on.
//The final state doesn't need to actually create contacts, so shove it up
//just barely to the surface.
hintOffset = -Vector3.Dot(supportContact.Contact.Normal, down) * supportContact.Contact.PenetrationDepth;
return(CharacterContactPositionState.Accepted);
}
else if (supportState == CharacterContactPositionState.TooDeep)
{
//Looks like we have to keep trying, but at least we found a good hint.
hintOffset = Math.Min(0, .001f - Vector3.Dot(supportContact.Contact.Normal, down) * supportContact.Contact.PenetrationDepth);
return(CharacterContactPositionState.TooDeep);
}
else //if (supportState == SupportState.Separated)
{
//It's not obstructed, but the support isn't quite right.
//It's got a negative penetration depth.
//We can use that as a hint.
hintOffset = -.001f - Vector3.Dot(supportContact.Contact.Normal, down) * supportContact.Contact.PenetrationDepth;
return(CharacterContactPositionState.NoHit);
}
}
else
{
return(CharacterContactPositionState.NoHit);
}
}
/// <summary>
/// Analyzes the support state of the character based on the speculative input support and traction contacts.
/// </summary>
/// <param name="tractionContacts">Contacts providing the character with traction.</param>
/// <param name="supportContacts">Contacts providing the character with support.</param>
/// <param name="state">State of the contacts relative to the speculative character position.</param>
/// <param name="supportContact">Representative contact to use, if any.</param>
public void AnalyzeSupportState(ref QuickList <CharacterContact> tractionContacts, ref QuickList <CharacterContact> supportContacts,
out CharacterContactPositionState state, out CharacterContact supportContact)
{
float maxDepth = -float.MaxValue;
int deepestIndex = -1;
if (tractionContacts.Count > 0)
{
//It has traction!
//But is it too deep?
//Find the deepest contact.
for (int i = 0; i < tractionContacts.Count; i++)
{
if (tractionContacts.Elements[i].Contact.PenetrationDepth > maxDepth)
{
maxDepth = tractionContacts.Elements[i].Contact.PenetrationDepth;
deepestIndex = i;
}
}
supportContact = tractionContacts.Elements[deepestIndex];
}
else if (supportContacts.Count > 0)
{
//It has support!
//But is it too deep?
//Find the deepest contact.
for (int i = 0; i < supportContacts.Count; i++)
{
if (supportContacts.Elements[i].Contact.PenetrationDepth > maxDepth)
{
maxDepth = supportContacts.Elements[i].Contact.PenetrationDepth;
deepestIndex = i;
}
}
supportContact = supportContacts.Elements[deepestIndex];
}
else
{
state = CharacterContactPositionState.NoHit;
supportContact = new CharacterContact();
return;
}
//Check the depth.
if (maxDepth > CollisionDetectionSettings.AllowedPenetration)
{
//It's too deep.
state = CharacterContactPositionState.TooDeep;
}
else if (maxDepth < 0)
{
//The depth is negative, meaning it's separated. This shouldn't happen with the initial implementation of the character controller,
//but this case could conceivably occur in other usages of a system like this (or in a future version of the character),
//so go ahead and handle it.
state = CharacterContactPositionState.NoHit;
}
else
{
//The deepest contact appears to be very nicely aligned with the ground!
//It's fully supported.
state = CharacterContactPositionState.Accepted;
}
}
/// <summary>
/// Finds contacts between the query object and any intersected objects within the character's bounding box.
/// </summary>
/// <param name="queryObject">Collidable to query for contacts with.</param>
/// <param name="tractionContacts">Output contacts that would provide traction.</param>
/// <param name="supportContacts">Output contacts that would provide support.</param>
/// <param name="sideContacts">Output contacts on the sides of the query object.</param>
/// <param name="headContacts">Output contacts on the head of the query object.</param>
/// <param name="forceStandardPairsToBeQueries">An extremely hacky control parameter that makes any mesh-cylinder pair treat the mesh as double sided. Useful for not going through the ceiling when changing stances.</param>
public void QueryContacts(EntityCollidable queryObject,
ref QuickList <CharacterContact> tractionContacts, ref QuickList <CharacterContact> supportContacts, ref QuickList <CharacterContact> sideContacts, ref QuickList <CharacterContact> headContacts,
bool forceStandardPairsToBeQueries = false)
{
var downDirection = characterBody.orientationMatrix.Down;
tractionContacts.Clear();
supportContacts.Clear();
sideContacts.Clear();
headContacts.Clear();
foreach (var collidable in characterBody.CollisionInformation.OverlappedCollidables)
{
//The query object is assumed to have a valid bounding box.
if (collidable.BoundingBox.Intersects(queryObject.BoundingBox))
{
var pair = new CollidablePair(collidable, queryObject);
var pairHandler = NarrowPhaseHelper.GetPairHandler(ref pair);
if (pairHandler.CollisionRule == CollisionRule.Normal)
{
if (forceStandardPairsToBeQueries)
{
//TODO: This is a massive hack that assumes a fixed set of collidable types. This won't work in the long run.
//The only reason it's here is that it was the easiest solution, combined with the fact that the character has to be rewritten for v2 anyway.
//Hopefully no one gets bit by this before the replacement is available.
//The core reason it exists is that one sided meshes don't generate contacts on their backside. That means a query shape can end up above a ceiling
//and it won't detect the ceiling. A better solution would be to let the caller choose whether or not to filter the contacts, and then use a
//direct test rather than stateful pair to perform the query here. Still some type-related annoyance to deal with, but a bit better.
var standardPair = pairHandler as StandardPairHandler;
if (standardPair != null)
{
standardPair.ContactManifold.IsQuery = true;
}
}
pairHandler.SuppressEvents = true;
pairHandler.UpdateCollision(0);
pairHandler.SuppressEvents = false;
if (forceStandardPairsToBeQueries)
{
//TODO: Again, superhack! Avoid this in v2.
var standardPair = pairHandler as StandardPairHandler;
if (standardPair != null)
{
standardPair.ContactManifold.IsQuery = false;
}
}
contactCategorizer.CategorizeContacts(pairHandler, characterBody.CollisionInformation, ref downDirection,
ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts);
}
//TODO: It would be nice if this was a bit easier.
//Having to remember to clean up AND give it back is a bit weird, especially with the property-diving.
//No one would ever just guess this correctly.
//At least hide it behind a NarrowPhaseHelper function.
pairHandler.CleanUp();
pairHandler.Factory.GiveBack(pairHandler);
}
}
}
/// <summary>
/// Checks if a transition from the current stance to the target stance is possible given the current environment.
/// </summary>
/// <param name="targetStance">Stance to check for transition safety.</param>
/// <param name="newHeight">If the transition is safe, the new height of the character. Zero otherwise.</param>
/// <param name="newPosition">If the transition is safe, the new location of the character body if the transition occurred. Zero vector otherwise.</param>
/// <returns>True if the target stance is different than the current stance and the transition is valid, false otherwise.</returns>
public bool CheckTransition(Stance targetStance, out float newHeight, out Vector3 newPosition)
{
var currentPosition = characterBody.position;
var down = characterBody.orientationMatrix.Down;
newPosition = new Vector3();
newHeight = 0;
if (CurrentStance != targetStance)
{
float currentHeight;
switch (CurrentStance)
{
case Stance.Prone:
currentHeight = proneHeight;
break;
case Stance.Crouching:
currentHeight = crouchingHeight;
break;
default:
currentHeight = standingHeight;
break;
}
float targetHeight;
switch (targetStance)
{
case Stance.Prone:
targetHeight = proneHeight;
break;
case Stance.Crouching:
targetHeight = crouchingHeight;
break;
default:
targetHeight = standingHeight;
break;
}
if (currentHeight >= targetHeight)
{
//The character is getting smaller, so no validation queries are required.
if (SupportFinder.HasSupport)
{
//On the ground, so need to move the position down.
newPosition = currentPosition + down * ((currentHeight - targetHeight) * 0.5f);
}
else
{
//We're in the air, so we don't have to change the position at all- just change the height.
newPosition = currentPosition;
}
newHeight = targetHeight;
return(true);
}
//The character is getting bigger, so validation is required.
ConvexCollidable <CylinderShape> queryObject;
switch (targetStance)
{
case Stance.Prone:
queryObject = proneQueryObject;
break;
case Stance.Crouching:
queryObject = crouchingQueryObject;
break;
default:
queryObject = standingQueryObject;
break;
}
var tractionContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
var supportContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
var sideContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
var headContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
try
{
if (SupportFinder.HasSupport)
{
//Increasing in size requires a query to verify that the new state is safe.
//TODO: State queries can be expensive if the character is crouching beneath something really detailed.
//There are some situations where you may want to do an upwards-pointing ray cast first. If it hits something,
//there's no need to do the full query.
newPosition = currentPosition - down * ((targetHeight - currentHeight) * .5f);
PrepareQueryObject(queryObject, ref newPosition);
QueryManager.QueryContacts(queryObject, ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts, true);
if (IsObstructed(ref supportContacts, ref sideContacts, ref headContacts))
{
//Can't stand up if something is in the way!
return(false);
}
newHeight = targetHeight;
return(true);
}
else
{
//This is a complicated case. We must perform a semi-downstep query.
//It's different than a downstep because the head may be obstructed as well. Also, in downstepping, the character always goes *down*.
//In this, while the bottom of the character is extending downward, the character position actually either stays the same or goes up.
//(We arbitrarily ignore the case where the character could push off a ceiling.)
//The goal is to put the feet of the character on any support that can be found, and then verify that the rest of its body fits in that location.
float lowestBound = 0;
float originalHighestBound = (targetHeight - currentHeight) * -.5f;
float highestBound = originalHighestBound;
float currentOffset = 0;
int attempts = 0;
//Don't keep querying indefinitely. If we fail to reach it in a few informed steps, it's probably not worth continuing.
//The bound size check prevents the system from continuing to search a meaninglessly tiny interval.
var lastState = CharacterContactPositionState.Accepted;
while (attempts++ < 5 && lowestBound - highestBound > Toolbox.BigEpsilon)
{
Vector3 candidatePosition = currentPosition + currentOffset * down;
float hintOffset;
switch (lastState = TrySupportLocation(queryObject, ref candidatePosition, out hintOffset, ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts))
{
case CharacterContactPositionState.Accepted:
currentOffset += hintOffset;
//Only use the new position location if the movement distance was the right size.
if (currentOffset <= 0 && currentOffset >= originalHighestBound)
{
newPosition = currentPosition + currentOffset * down;
newHeight = targetHeight;
return(true);
}
else
{
return(false);
}
case CharacterContactPositionState.NoHit:
highestBound = currentOffset + hintOffset;
currentOffset = (lowestBound + highestBound) * .5f;
break;
case CharacterContactPositionState.Obstructed:
lowestBound = currentOffset;
currentOffset = (highestBound + lowestBound) * .5f;
break;
case CharacterContactPositionState.TooDeep:
currentOffset += hintOffset;
lowestBound = currentOffset;
break;
}
}
//If it terminated in a safe state, it can increase in size.
//TODO: You could handle this more efficiently by early terminating the above loop once obstruction is clearly unavoidable.
//(Not messing with it right now because this is likely going to change completely.)
if (lastState == CharacterContactPositionState.Accepted || lastState == CharacterContactPositionState.NoHit)
{
newPosition = currentPosition;
newHeight = targetHeight;
return(true);
}
return(false);
}
}
finally
{
tractionContacts.Dispose();
supportContacts.Dispose();
sideContacts.Dispose();
headContacts.Dispose();
}
}
return(false);
}
///<summary>
/// Updates the manifold.
///</summary>
///<param name="dt">Timestep duration.</param>
public override void Update(float dt)
{
//First, refresh all existing contacts. This is an incremental manifold.
var transform = MeshTransform;
ContactRefresher.ContactRefresh(contacts, supplementData, ref convex.worldTransform, ref transform, contactIndicesToRemove);
RemoveQueuedContacts();
CleanUpOverlappingTriangles();
//Get all the overlapped triangle indices.
//Note that the collection of triangles is left up to the child implementation.
//We're basically treating the child class like an indexable collection.
//A little gross to have it organized this way instead of an explicit collection to separate the logic up. Would be nice to improve someday!
int triangleCount = FindOverlappingTriangles(dt);
//Just use 32 elements for all the lists and sets in this system.
const int bufferPoolSizePower = 5;
BoundarySets boundarySets;
if (UseImprovedBoundaryHandling)
{
boundarySets = new BoundarySets(bufferPoolSizePower);
}
else
{
boundarySets = new BoundarySets();
}
var candidatesToAdd = new QuickList <ContactData>(BufferPools <ContactData> .Thread, bufferPoolSizePower);
//A single triangle shape will be reused for all operations. It's pulled from a thread local pool to avoid holding a TriangleShape around for every single contact manifold or pair tester.
var localTriangleShape = PhysicsThreadResources.GetTriangle();
//Precompute the transform to take triangles from their native local space to the convex's local space.
RigidTransform inverseConvexWorldTransform;
RigidTransform.Invert(ref convex.worldTransform, out inverseConvexWorldTransform);
AffineTransform convexInverseWorldTransform;
AffineTransform.CreateFromRigidTransform(ref inverseConvexWorldTransform, out convexInverseWorldTransform);
AffineTransform fromMeshLocalToConvexLocal;
PrecomputeTriangleTransform(ref convexInverseWorldTransform, out fromMeshLocalToConvexLocal);
//Grab the convex's local space bounding box up front. This will be used for a secondary pruning step.
BoundingBox convexLocalBoundingBox;
convex.Shape.GetBoundingBox(ref Toolbox.RigidIdentity, out convexLocalBoundingBox);
Matrix3x3 orientation;
Matrix3x3.CreateFromQuaternion(ref convex.worldTransform.Orientation, out orientation);
var guaranteedContacts = 0;
for (int i = 0; i < triangleCount; i++)
{
//Initialize the local triangle.
TriangleIndices indices;
if (ConfigureLocalTriangle(i, localTriangleShape, out indices))
{
//Put the triangle into the local space of the convex.
AffineTransform.Transform(ref localTriangleShape.vA, ref fromMeshLocalToConvexLocal, out localTriangleShape.vA);
AffineTransform.Transform(ref localTriangleShape.vB, ref fromMeshLocalToConvexLocal, out localTriangleShape.vB);
AffineTransform.Transform(ref localTriangleShape.vC, ref fromMeshLocalToConvexLocal, out localTriangleShape.vC);
//Do one last AABB test between the convex and triangle in the convex's local space.
//This can prune out a lot of triangles when dealing with larger objects, and it's pretty cheap to do.
BoundingBox triangleBoundingBox;
Toolbox.GetTriangleBoundingBox(ref localTriangleShape.vA, ref localTriangleShape.vB, ref localTriangleShape.vC, out triangleBoundingBox);
bool intersecting;
triangleBoundingBox.Intersects(ref convexLocalBoundingBox, out intersecting);
if (!intersecting)
{
continue;
}
//Find a pairtester for the triangle.
TrianglePairTester pairTester;
if (!activePairTesters.TryGetValue(indices, out pairTester))
{
pairTester = GetTester();
pairTester.Initialize(convex.Shape);
activePairTesters.Add(indices, pairTester);
}
pairTester.Updated = true;
//Now, generate a contact between the two shapes.
TinyStructList <ContactData> contactList;
if (pairTester.GenerateContactCandidates(localTriangleShape, out contactList))
{
for (int j = 0; j < contactList.Count; j++)
{
ContactData contact;
contactList.Get(j, out contact);
if (UseImprovedBoundaryHandling)
{
if (AnalyzeCandidate(ref indices, localTriangleShape, pairTester, ref contact, ref boundarySets))
{
//This is let through if there's a face contact. Face contacts cannot be blocked.
guaranteedContacts++;
AddLocalContact(ref contact, ref orientation, ref candidatesToAdd);
}
}
else
{
AddLocalContact(ref contact, ref orientation, ref candidatesToAdd);
}
}
}
//Get the voronoi region from the contact candidate generation. Possibly just recalculate, since most of the systems don't calculate it.
//Depending on which voronoi region it is in (Switch on enumeration), identify the indices composing that region. For face contacts, don't bother- just add it if unique.
//For AB, AC, or BC, add an Edge to the blockedEdgeRegions set with the corresponding indices.
//For A, B, or C, add the index of the vertex to the blockedVertexRegions set.
//If the edge/vertex is already present in the set, then DO NOT add the contact.
//When adding a contact, add ALL other voronoi regions to the blocked sets.
}
}
if (UseImprovedBoundaryHandling)
{
//If there were no face contacts that absolutely must be included, we may get into a very rare situation
//where absolutely no contacts get created. For example, a sphere falling directly on top of a vertex in a flat terrain.
//It will generally get locked out of usage by belonging only to restricted regions (numerical issues make it visible by both edges and vertices).
//In some cases, the contacts will be ignored instead of corrected (e.g. spheres).
//To prevent objects from just falling through the ground in such a situation, force-correct the contacts regardless of the pair tester's desires.
//Sure, it might not be necessary under normal circumstances, but it's a better option than having no contacts.
//TODO: There is another option: Changing restricted regions so that a vertex only restricts the other two vertices and the far edge,
//and an edge only restricts the far vertex and other two edges. This introduces an occasional bump though...
//It's possible, in very specific instances, for an object to wedge itself between two adjacent triangles.
//For this state to continue beyond a brief instant generally requires the object be orientation locked and slender.
//However, some characters fit this description, so it can't be ignored!
//Conceptually, this issue can occur at either a vertex junction or a shared edge (usually on extremely flat surfaces only).
//However, an object stuck between multiple triangles is not in a stable state. In the edge case, the object gets shoved to one side
//as one contact 'wins' the solver war. That's not enough to escape, unfortunately.
//The vertex case, on the other hand, is degenerate and decays into an edge case rapidly thanks to this lack of stability.
//So, we don't have to explicitly handle the somewhat more annoying and computationally expensive vertex unstucking case, because the edge case handles both! :)
//This isn't a completely free operation, but it's guarded behind pretty rare conditions.
//Essentially, we will check to see if there's just edge contacts fighting against each other.
//If they are, then we will correct any stuck-contributing normals to the triangle normal.
if (boundarySets.VertexContacts.Count == 0 && guaranteedContacts == 0 && boundarySets.EdgeContacts.Count > 1)
{
//There are only edge contacts, check to see if:
//all normals are coplanar, and
//at least one normal faces against the other normals (meaning it's probably stuck, as opposed to just colliding on a corner).
bool allNormalsInSamePlane = true;
bool atLeastOneNormalAgainst = false;
var firstNormal = boundarySets.EdgeContacts.Elements[0].ContactData.Normal;
boundarySets.EdgeContacts.Elements[0].CorrectedNormal.Normalize();
float dot;
Vector3.Dot(ref firstNormal, ref boundarySets.EdgeContacts.Elements[0].CorrectedNormal, out dot);
if (Math.Abs(dot) > .01f)
{
//Go ahead and test the first contact separately, since we're using its contact normal to determine coplanarity.
allNormalsInSamePlane = false;
}
else
{
//TODO: Note that we're only checking the new edge contacts, not the existing contacts.
//It's possible that some existing contacts could interfere and cause issues, but for the sake of simplicity and due to rarity
//we'll ignore that possibility for now.
for (int i = 1; i < boundarySets.EdgeContacts.Count; i++)
{
Vector3.Dot(ref boundarySets.EdgeContacts.Elements[i].ContactData.Normal, ref firstNormal, out dot);
if (dot < 0)
{
atLeastOneNormalAgainst = true;
}
//Check to see if the normal is outside the plane.
Vector3.Dot(ref boundarySets.EdgeContacts.Elements[i].ContactData.Normal, ref boundarySets.EdgeContacts.Elements[0].CorrectedNormal, out dot);
if (Math.Abs(dot) > .01f)
{
//We are not stuck!
allNormalsInSamePlane = false;
break;
}
}
}
if (allNormalsInSamePlane && atLeastOneNormalAgainst)
{
//Uh oh! all the normals are parallel... The object is probably in a weird situation.
//Let's correct the normals!
//Already normalized the first contact above.
//We don't need to perform the perpendicularity test here- we did that before! We know it's perpendicular already.
boundarySets.EdgeContacts.Elements[0].ContactData.Normal = boundarySets.EdgeContacts.Elements[0].CorrectedNormal;
boundarySets.EdgeContacts.Elements[0].ShouldCorrect = true;
for (int i = 1; i < boundarySets.EdgeContacts.Count; i++)
{
//Must normalize the corrected normal before using it.
boundarySets.EdgeContacts.Elements[i].CorrectedNormal.Normalize();
Vector3.Dot(ref boundarySets.EdgeContacts.Elements[i].CorrectedNormal, ref boundarySets.EdgeContacts.Elements[i].ContactData.Normal, out dot);
if (dot < .01)
{
//Only bother doing the correction if the normal appears to be pointing nearly horizontally- implying that it's a contributor to the stuckness!
//If it's blocked, the next section will use the corrected normal- if it's not blocked, the next section will use the direct normal.
//Make them the same thing :)
boundarySets.EdgeContacts.Elements[i].ContactData.Normal = boundarySets.EdgeContacts.Elements[i].CorrectedNormal;
boundarySets.EdgeContacts.Elements[i].ShouldCorrect = true;
//Note that the penetration depth is NOT corrected. The contact's depth no longer represents the true depth.
//However, we only need to have some penetration depth to get the object to escape the rut.
//Furthermore, the depth computed from the horizontal opposing contacts is known to be less than the depth in the perpendicular direction.
//If the current depth was NOT less than the true depth along the corrected normal, then the collision detection system
//would have picked a different depth, as it finds a reasonable approximation of the minimum penetration!
//As a consequence, this contact will not be active beyond the object's destuckification, because its contact depth will be negative (or very close to it).
}
}
}
}
for (int i = 0; i < boundarySets.EdgeContacts.Count; i++)
{
//Only correct if it's allowed AND it's blocked.
//If it's not blocked, the contact being created is necessary!
//The normal generated by the triangle-convex tester is already known not to
//violate the triangle sidedness.
if (!boundarySets.BlockedEdgeRegions.Contains(boundarySets.EdgeContacts.Elements[i].Edge))
{
//If it's not blocked, use the contact as-is without correcting it.
AddLocalContact(ref boundarySets.EdgeContacts.Elements[i].ContactData, ref orientation, ref candidatesToAdd);
}
else if (boundarySets.EdgeContacts.Elements[i].ShouldCorrect || guaranteedContacts == 0)
{
//If it is blocked, we can still make use of the contact. But first, we need to change the contact normal to ensure that
//it will not interfere (and cause a bump or something).
float dot;
boundarySets.EdgeContacts.Elements[i].CorrectedNormal.Normalize();
Vector3.Dot(ref boundarySets.EdgeContacts.Elements[i].CorrectedNormal, ref boundarySets.EdgeContacts.Elements[i].ContactData.Normal, out dot);
boundarySets.EdgeContacts.Elements[i].ContactData.Normal = boundarySets.EdgeContacts.Elements[i].CorrectedNormal;
boundarySets.EdgeContacts.Elements[i].ContactData.PenetrationDepth *= MathHelper.Max(0, dot); //Never cause a negative penetration depth.
AddLocalContact(ref boundarySets.EdgeContacts.Elements[i].ContactData, ref orientation, ref candidatesToAdd);
}
//If it's blocked AND it doesn't allow correction, ignore its existence.
}
for (int i = 0; i < boundarySets.VertexContacts.Count; i++)
{
if (!boundarySets.BlockedVertexRegions.Contains(boundarySets.VertexContacts.Elements[i].Vertex))
{
//If it's not blocked, use the contact as-is without correcting it.
AddLocalContact(ref boundarySets.VertexContacts.Elements[i].ContactData, ref orientation, ref candidatesToAdd);
}
else if (boundarySets.VertexContacts.Elements[i].ShouldCorrect || guaranteedContacts == 0)
{
//If it is blocked, we can still make use of the contact. But first, we need to change the contact normal to ensure that
//it will not interfere (and cause a bump or something).
float dot;
boundarySets.VertexContacts.Elements[i].CorrectedNormal.Normalize();
Vector3.Dot(ref boundarySets.VertexContacts.Elements[i].CorrectedNormal, ref boundarySets.VertexContacts.Elements[i].ContactData.Normal, out dot);
boundarySets.VertexContacts.Elements[i].ContactData.Normal = boundarySets.VertexContacts.Elements[i].CorrectedNormal;
boundarySets.VertexContacts.Elements[i].ContactData.PenetrationDepth *= MathHelper.Max(0, dot); //Never cause a negative penetration depth.
AddLocalContact(ref boundarySets.VertexContacts.Elements[i].ContactData, ref orientation, ref candidatesToAdd);
}
//If it's blocked AND it doesn't allow correction, ignore its existence.
}
boundarySets.Dispose();
}
//Remove stale pair testers.
for (int i = activePairTesters.Count - 1; i >= 0; --i)
{
var tester = activePairTesters.Values[i];
if (!tester.Updated)
{
tester.CleanUp();
GiveBackTester(tester);
activePairTesters.FastRemove(activePairTesters.Keys[i]);
}
else
{
tester.Updated = false;
}
}
//Some child types will want to do some extra post processing on the manifold.
ProcessCandidates(ref candidatesToAdd);
//Check if adding the new contacts would overflow the manifold.
if (contacts.Count + candidatesToAdd.Count > 4)
{
//Adding all the contacts would overflow the manifold. Reduce to the best subset.
var reducedCandidates = new QuickList <ContactData>(BufferPools <ContactData> .Thread, bufferPoolSizePower);
ContactReducer.ReduceContacts(contacts, ref candidatesToAdd, contactIndicesToRemove, ref reducedCandidates);
RemoveQueuedContacts();
for (int i = reducedCandidates.Count - 1; i >= 0; i--)
{
Add(ref reducedCandidates.Elements[i]);
reducedCandidates.RemoveAt(i);
}
reducedCandidates.Dispose();
}
else if (candidatesToAdd.Count > 0)
{
//Won't overflow the manifold, so just toss it in PROVIDED that it isn't too close to something else.
for (int i = 0; i < candidatesToAdd.Count; i++)
{
Add(ref candidatesToAdd.Elements[i]);
}
}
PhysicsThreadResources.GiveBack(localTriangleShape);
candidatesToAdd.Dispose();
}
protected virtual void ProcessCandidates(ref QuickList <ContactData> candidates)
{
}
//This works in the general case where there can be any number of contacts and candidates. Could specialize it as an optimization to single-contact added incremental manifolds.
///<summary>
/// Reduces the contact manifold to a good subset.
///</summary>
///<param name="contacts">Contacts to reduce.</param>
///<param name="contactCandidates">Contact candidates to include in the reduction process.</param>
///<param name="contactsToRemove">Contacts that need to removed to reach the reduced state.</param>
///<param name="toAdd">Contact candidates that should be added to reach the reduced state.</param>
///<exception cref="InvalidOperationException">Thrown when the set being reduced is empty.</exception>
public static void ReduceContacts(RawList <Contact> contacts, ref QuickList <ContactData> contactCandidates, RawList <int> contactsToRemove, ref QuickList <ContactData> toAdd)
{
//Find the deepest point of all contacts/candidates, as well as a compounded 'normal' vector.
float maximumDepth = -float.MaxValue;
int deepestIndex = -1;
Vector3 normal = Toolbox.ZeroVector;
for (int i = 0; i < contacts.Count; i++)
{
Vector3.Add(ref normal, ref contacts.Elements[i].Normal, out normal);
if (contacts.Elements[i].PenetrationDepth > maximumDepth)
{
deepestIndex = i;
maximumDepth = contacts.Elements[i].PenetrationDepth;
}
}
for (int i = 0; i < contactCandidates.Count; i++)
{
Vector3.Add(ref normal, ref contactCandidates.Elements[i].Normal, out normal);
if (contactCandidates.Elements[i].PenetrationDepth > maximumDepth)
{
deepestIndex = contacts.Count + i;
maximumDepth = contactCandidates.Elements[i].PenetrationDepth;
}
}
//If the normals oppose each other, this can happen. It doesn't need to be normalized, but having SOME normal is necessary.
if (normal.LengthSquared() < Toolbox.Epsilon)
{
if (contacts.Count > 0)
{
normal = contacts.Elements[0].Normal;
}
else if (contactCandidates.Count > 0)
{
normal = contactCandidates.Elements[0].Normal; //This method is only called when there's too many contacts, so if contacts is empty, the candidates must NOT be empty.
}
else //This method should not have been called at all if it gets here.
{
throw new ArgumentException("Cannot reduce an empty contact set.");
}
}
//Find the contact (candidate) that is furthest away from the deepest contact (candidate).
Vector3 deepestPosition;
if (deepestIndex < contacts.Count)
{
deepestPosition = contacts.Elements[deepestIndex].Position;
}
else
{
deepestPosition = contactCandidates.Elements[deepestIndex - contacts.Count].Position;
}
float distanceSquared;
float furthestDistance = 0;
int furthestIndex = -1;
for (int i = 0; i < contacts.Count; i++)
{
Vector3.DistanceSquared(ref contacts.Elements[i].Position, ref deepestPosition, out distanceSquared);
if (distanceSquared > furthestDistance)
{
furthestDistance = distanceSquared;
furthestIndex = i;
}
}
for (int i = 0; i < contactCandidates.Count; i++)
{
Vector3.DistanceSquared(ref contactCandidates.Elements[i].Position, ref deepestPosition, out distanceSquared);
if (distanceSquared > furthestDistance)
{
furthestDistance = distanceSquared;
furthestIndex = contacts.Count + i;
}
}
if (furthestIndex == -1)
{
//Either this method was called when it shouldn't have been, or all contacts and contact candidates are at the same location.
if (contacts.Count > 0)
{
for (int i = 1; i < contacts.Count; i++)
{
contactsToRemove.Add(i);
}
return;
}
if (contactCandidates.Count > 0)
{
toAdd.Add(ref contactCandidates.Elements[0]);
return;
}
throw new ArgumentException("Cannot reduce an empty contact set.");
}
Vector3 furthestPosition;
if (furthestIndex < contacts.Count)
{
furthestPosition = contacts.Elements[furthestIndex].Position;
}
else
{
furthestPosition = contactCandidates.Elements[furthestIndex - contacts.Count].Position;
}
Vector3 xAxis;
Vector3.Subtract(ref deepestPosition, ref furthestPosition, out xAxis);
//Create the second axis of the 2d 'coordinate system' of the manifold.
Vector3 yAxis;
Vector3.Cross(ref xAxis, ref normal, out yAxis);
//Determine the furthest points along the axis.
float minYAxisDot = float.MaxValue, maxYAxisDot = -float.MaxValue;
int minYAxisIndex = -1, maxYAxisIndex = -1;
for (int i = 0; i < contacts.Count; i++)
{
float dot;
Vector3.Dot(ref contacts.Elements[i].Position, ref yAxis, out dot);
if (dot < minYAxisDot)
{
minYAxisIndex = i;
minYAxisDot = dot;
}
if (dot > maxYAxisDot)
{
maxYAxisIndex = i;
maxYAxisDot = dot;
}
}
for (int i = 0; i < contactCandidates.Count; i++)
{
float dot;
Vector3.Dot(ref contactCandidates.Elements[i].Position, ref yAxis, out dot);
if (dot < minYAxisDot)
{
minYAxisIndex = i + contacts.Count;
minYAxisDot = dot;
}
if (dot > maxYAxisDot)
{
maxYAxisIndex = i + contacts.Count;
maxYAxisDot = dot;
}
}
//the deepestIndex, furthestIndex, minYAxisIndex, and maxYAxisIndex are the extremal points.
//Cycle through the existing contacts. If any DO NOT MATCH the existing candidates, add them to the toRemove list.
//Cycle through the candidates. If any match, add them to the toAdd list.
//Repeated entries in the reduced manifold aren't a problem.
//-Contacts list does not include repeats with itself.
//-A contact is only removed if it doesn't match anything.
//-Contact candidates do not repeat with themselves.
//-Contact candidates do not repeat with contacts.
//-Contact candidates are added if they match any of the indices.
for (int i = 0; i < contactCandidates.Count; i++)
{
int totalIndex = i + contacts.Count;
if (totalIndex == deepestIndex || totalIndex == furthestIndex || totalIndex == minYAxisIndex || totalIndex == maxYAxisIndex)
{
//This contact is present in the new manifold. Add it.
toAdd.Add(ref contactCandidates.Elements[i]);
}
}
for (int i = 0; i < contacts.Count; i++)
{
if (!(i == deepestIndex || i == furthestIndex || i == minYAxisIndex || i == maxYAxisIndex))
{
//This contact is not present in the new manifold. Remove it.
contactsToRemove.Add(i);
}
}
}
protected override void ProcessCandidates(ref QuickList <ContactData> candidates)
{
if (candidates.Count == 0 && parentContactCount == 0 && Mesh.Shape.solidity == MobileMeshSolidity.Solid)
{
//If there's no new contacts on the mesh and it's supposed to be a solid,
//then we must check the convex for containment within the shell.
//We already know that it's not on the shell, meaning that the shape is either
//far enough away outside the shell that there's no contact (and we're done),
//or it's far enough inside the shell that the triangles cannot create contacts.
//To find out which it is, raycast against the shell.
Matrix3x3 orientation;
Matrix3x3.CreateFromQuaternion(ref mesh.worldTransform.Orientation, out orientation);
Ray ray;
Vector3.Subtract(ref convex.worldTransform.Position, ref mesh.worldTransform.Position, out ray.Position);
Matrix3x3.TransformTranspose(ref ray.Position, ref orientation, out ray.Position);
//Cast from the current position back to the previous position.
Vector3.Subtract(ref lastValidConvexPosition, ref ray.Position, out ray.Direction);
float rayDirectionLength = ray.Direction.LengthSquared();
if (rayDirectionLength < Toolbox.Epsilon)
{
//The object may not have moved enough to normalize properly. If so, choose something arbitrary.
//Try the direction from the center of the object to the convex's position.
ray.Direction = ray.Position;
rayDirectionLength = ray.Direction.LengthSquared();
if (rayDirectionLength < Toolbox.Epsilon)
{
//This is unlikely; just pick something completely arbitrary then.
ray.Direction = Vector3.Up;
rayDirectionLength = 1;
}
}
Vector3.Divide(ref ray.Direction, (float)Math.Sqrt(rayDirectionLength), out ray.Direction);
RayHit hit;
if (mesh.Shape.IsLocalRayOriginInMesh(ref ray, out hit))
{
ContactData newContact = new ContactData {
Id = 2
};
//Give it a special id so that we know that it came from the inside.
Matrix3x3.Transform(ref ray.Position, ref orientation, out newContact.Position);
Vector3.Add(ref newContact.Position, ref mesh.worldTransform.Position, out newContact.Position);
newContact.Normal = hit.Normal;
newContact.Normal.Normalize();
float factor;
Vector3.Dot(ref ray.Direction, ref newContact.Normal, out factor);
newContact.PenetrationDepth = -factor * hit.T + convex.Shape.MinimumRadius;
Matrix3x3.Transform(ref newContact.Normal, ref orientation, out newContact.Normal);
newContact.Validate();
//Do not yet create a new contact. Check to see if an 'inner contact' with id == 2 already exists.
bool addContact = true;
for (int i = 0; i < contacts.Count; i++)
{
if (contacts.Elements[i].Id == 2)
{
contacts.Elements[i].Position = newContact.Position;
contacts.Elements[i].Normal = newContact.Normal;
contacts.Elements[i].PenetrationDepth = newContact.PenetrationDepth;
supplementData.Elements[i].BasePenetrationDepth = newContact.PenetrationDepth;
supplementData.Elements[i].LocalOffsetA = new Vector3();
supplementData.Elements[i].LocalOffsetB = ray.Position; //convex local position in mesh.
addContact = false;
break;
}
}
if (addContact && contacts.Count == 0)
{
Add(ref newContact);
}
previousDepth = newContact.PenetrationDepth;
}
else
{
//It's possible that we had a false negative. The previous frame may have been in deep intersection, and this frame just failed to come to the same conclusion.
//If we set the target location to the current location, the object will never escape the mesh. Instead, only do that if two frames agree that we are no longer colliding.
if (previousDepth > 0)
{
//We're not touching the mesh.
lastValidConvexPosition = ray.Position;
}
previousDepth = 0;
}
}
}
CharacterContactPositionState TryUpStepPosition(ref Vector3 sideNormal, ref Vector3 position, ref Vector3 down,
ref QuickList <CharacterContact> tractionContacts, ref QuickList <CharacterContact> supportContacts, ref QuickList <CharacterContact> sideContacts, ref QuickList <CharacterContact> headContacts,
out float hintOffset)
{
hintOffset = 0;
PrepareQueryObject(ref position);
QueryManager.QueryContacts(currentQueryObject, ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts);
if (headContacts.Count > 0)
{
//The head is obstructed. This will define a maximum bound.
//Find the deepest contact on the head and use it to provide a hint.
float dot;
Vector3.Dot(ref down, ref headContacts.Elements[0].Contact.Normal, out dot);
hintOffset = -dot * headContacts.Elements[0].Contact.PenetrationDepth;
for (int i = 1; i < headContacts.Count; i++)
{
Vector3.Dot(ref down, ref headContacts.Elements[i].Contact.Normal, out dot);
dot *= -headContacts.Elements[i].Contact.PenetrationDepth;
if (dot > hintOffset)
{
hintOffset = dot;
}
}
return(CharacterContactPositionState.HeadObstructed);
}
bool obstructed = IsUpStepObstructedBySideContacts(ref sideNormal, ref sideContacts);
if (!obstructed && supportContacts.Count > 0)
{
CharacterContactPositionState supportState;
CharacterContact supportContact;
QueryManager.AnalyzeSupportState(ref tractionContacts, ref supportContacts, out supportState, out supportContact);
if (supportState == CharacterContactPositionState.Accepted)
{
if (tractionContacts.Count > 0)
{
//We're done! The guess found a good spot to stand on.
//Unlike down stepping, upstepping DOES need good contacts in the final state.
//Push it up if necessary, but don't push it too far.
//Putting it into the middle of the allowed penetration makes it very likely that it will properly generate contacts.
//Choosing something smaller than allowed penetration ensures that the search makes meaningful progress forward when the sizes get really tiny;
//we wouldn't want it edging every closer to AllowedPenetration and then exit because too many queries were made.
hintOffset = Math.Min(0, Vector3.Dot(supportContact.Contact.Normal, down) * (CollisionDetectionSettings.AllowedPenetration * .5f - supportContact.Contact.PenetrationDepth));
return(CharacterContactPositionState.Accepted);
}
else
{
//No traction... Before we give up and reject the step altogether, let's try one last thing. It's possible that the character is trying to step up onto the side of a ramp or something.
//In this scenario, the top-down ray cast detects a perfectly walkable slope. However, the contact queries will find a contact with a normal necessarily
//steeper than the one found by the ray cast because it is an edge contact. Not being able to step up in this scenario doesn't feel natural to the player
//even if it is technically consistent.
//So, let's try to ray cast down to the a point just barely beyond the contact (to ensure we don't land right on the edge, which would invite numerical issues).
//Note that this is NOT equivalent to the ray cast we performed earlier to test for an initial step height and surface normal.
//This one is based on the QUERY state and the QUERY's contact position.
//Find the down test ray's position.
Ray downRay;
downRay.Position = supportContact.Contact.Position + sideNormal * .001f;
float verticalOffset = Vector3.Dot(downRay.Position - position, down);
verticalOffset = characterBody.Height * .5f + verticalOffset;
downRay.Position -= verticalOffset * down;
downRay.Direction = down;
//First, we must ensure that the ray cast test origin is not obstructed. Starting very close to the very top of the character is safe because the process has already validated
//this location as accepted, just without traction.
Ray obstructionTestRay;
obstructionTestRay.Position = position - down * (characterBody.Height * .5f);
obstructionTestRay.Direction = downRay.Position - obstructionTestRay.Position;
if (!QueryManager.RayCastHitAnything(obstructionTestRay, 1))
{
//Okay! it's safe to cast down, then.
RayHit hit;
if (QueryManager.RayCast(downRay, characterBody.Height, out hit))
{
//Got a hit!
if (characterBody.Height - maximumStepHeight < hit.T)
{
//It's in range!
float dot;
hit.Normal.Normalize();
Vector3.Dot(ref hit.Normal, ref down, out dot);
if (Math.Abs(dot) > ContactCategorizer.TractionThreshold)
{
//Slope is shallow enough to stand on!
hintOffset = Math.Min(0, Vector3.Dot(supportContact.Contact.Normal, down) * (CollisionDetectionSettings.AllowedPenetration * .5f - supportContact.Contact.PenetrationDepth));
//ONE MORE thing to check. The new position of the center ray must be able to touch the ground!
downRay.Position = position;
if (QueryManager.RayCast(downRay, characterBody.Height * .5f + maximumStepHeight, out hit))
{
//It hit.. almost there!
hit.Normal.Normalize();
Vector3.Dot(ref hit.Normal, ref down, out dot);
if (Math.Abs(dot) > ContactCategorizer.TractionThreshold)
{
//It has traction! We can step!
return(CharacterContactPositionState.Accepted);
}
}
}
}
}
}
//If it didn't have traction, and this was the most valid location we could find, then there is no support.
return(CharacterContactPositionState.Rejected);
}
}
else if (supportState == CharacterContactPositionState.TooDeep)
{
//Looks like we have to keep trying, but at least we found a good hint.
hintOffset = Math.Min(0, Vector3.Dot(supportContact.Contact.Normal, down) * (CollisionDetectionSettings.AllowedPenetration * .5f - supportContact.Contact.PenetrationDepth));
return(CharacterContactPositionState.TooDeep);
}
else //if (supportState == SupportState.Separated)
{
//It's not obstructed, but the support isn't quite right.
//It's got a negative penetration depth.
//We can use that as a hint.
hintOffset = -.001f - Vector3.Dot(supportContact.Contact.Normal, down) * supportContact.Contact.PenetrationDepth;
return(CharacterContactPositionState.NoHit);
}
}
else if (obstructed)
{
return(CharacterContactPositionState.Obstructed);
}
else
{
return(CharacterContactPositionState.NoHit);
}
}
bool TryToStepUsingContact(ref ContactData contact, ref Vector3 down, out Vector3 newPosition)
{
Vector3 position = characterBody.Position;
//The normal of the contact may not be facing perfectly out to the side.
//The detection process allows a bit of slop.
//Correct it by removing any component of the normal along the local up vector.
Vector3 normal = contact.Normal;
float dot;
Vector3.Dot(ref normal, ref down, out dot);
Vector3 error;
Vector3.Multiply(ref down, dot, out error);
Vector3.Subtract(ref normal, ref error, out normal);
normal.Normalize();
//Now we need to ray cast out from the center of the character in the direction of this normal to check for obstructions.
//Compute the ray origin location. Fire it out of the top of the character; if we're stepping, this must be a valid location.
//Putting it as high as possible helps to reject more invalid step geometry.
Ray ray;
float downRayLength = characterBody.Height;// MaximumStepHeight + upStepMargin;
Vector3.Multiply(ref down, characterBody.Height * .5f - downRayLength, out ray.Position);
Vector3.Add(ref ray.Position, ref position, out ray.Position);
ray.Direction = normal;
//Include a little margin in the length.
//Technically, the character only needs to teleport horizontally by the complicated commented expression.
//That puts it just far enough to have traction on the new surface.
//In practice, the current contact refreshing approach used for many pair types causes contacts to persist horizontally a bit,
//which can cause side effects for the character.
float horizontalOffsetAmount = characterBody.CollisionInformation.Shape.CollisionMargin; // (float)((1 - character.SupportFinder.sinMaximumSlope) * character.Body.CollisionInformation.Shape.CollisionMargin + 0);
float length = characterBody.Radius + horizontalOffsetAmount; // -contact.PenetrationDepth;
if (QueryManager.RayCastHitAnything(ray, length))
{
//The step is obstructed!
newPosition = new Vector3();
return(false);
}
//The down-cast ray origin has been verified by the previous ray cast.
//Let's look for a support!
Vector3 horizontalOffset;
Vector3.Multiply(ref normal, length, out horizontalOffset);
Vector3.Add(ref ray.Position, ref horizontalOffset, out ray.Position);
ray.Direction = down;
//Find the earliest hit, if any.
RayHit earliestHit;
if (!QueryManager.RayCast(ray, downRayLength, out earliestHit) || //Can't do anything if it didn't hit.
earliestHit.T <= 0 || //Can't do anything if the hit was invalid.
earliestHit.T - downRayLength > -minimumUpStepHeight || //Don't bother doing anything if the step is too small.
earliestHit.T - downRayLength < -maximumStepHeight - upStepMargin) //Can't do anything if the step is too tall.
{
//No valid hit was detected.
newPosition = new Vector3();
return(false);
}
//Ensure the candidate surface supports traction.
Vector3 supportNormal;
Vector3.Normalize(ref earliestHit.Normal, out supportNormal);
//Calibrate the normal to face in the same direction as the down vector for consistency.
Vector3.Dot(ref supportNormal, ref down, out dot);
if (dot < 0)
{
Vector3.Negate(ref supportNormal, out supportNormal);
dot = -dot;
}
//If the new surface does not have traction, do not attempt to step up.
if (dot < ContactCategorizer.TractionThreshold)
{
newPosition = new Vector3();
return(false);
}
//Since contact queries are frequently expensive compared to ray cast tests,
//do one more ray cast test. This time, starting from the same position, cast upwards.
//In order to step up, the previous down-ray hit must be at least a character height away from the result of the up-ray.
Vector3.Negate(ref down, out ray.Direction);
//Find the earliest hit, if any.
//RayHit earliestHitUp = new RayHit();
//earliestHitUp.T = float.MaxValue;
float upLength = characterBody.Height - earliestHit.T;
//If the sum of the up and down distances is less than the height, the character can't fit.
if (QueryManager.RayCastHitAnything(ray, upLength))
{
newPosition = new Vector3();
return(false);
}
//By now, a valid ray hit has been found. Now we need to validate it using contact queries.
//This process is very similar in concept to the down step verification, but it has some extra
//requirements.
//Predict a hit location based on the time of impact and the normal at the intersection.
//Take into account the radius of the character (don't forget the collision margin!)
RigidTransform transform = characterBody.CollisionInformation.WorldTransform;
//The transform must be modified to position the query body at the right location.
//The horizontal offset of the queries ensures that a tractionable part of the character will be put onto the new support.
Vector3.Multiply(ref normal, horizontalOffsetAmount, out horizontalOffset);
Vector3.Add(ref transform.Position, ref horizontalOffset, out transform.Position);
Vector3 verticalOffset;
Vector3.Multiply(ref down, -downRayLength, out verticalOffset);
Vector3.Add(ref transform.Position, ref verticalOffset, out transform.Position);
//We know that the closest point to the plane will be the extreme point in the plane's direction.
//Use it as the ray origin.
Ray downRay;
characterBody.CollisionInformation.Shape.GetExtremePoint(supportNormal, ref transform, out downRay.Position);
downRay.Direction = down;
//Intersect the ray against the plane defined by the support hit.
Vector3 intersection;
Vector3.Dot(ref earliestHit.Location, ref supportNormal, out dot);
Plane plane = new Plane(supportNormal, dot);
Vector3 candidatePosition;
//Define the interval bounds to be used later.
//The words 'highest' and 'lowest' here refer to the position relative to the character's body.
//The ray cast points downward relative to the character's body.
float highestBound = -maximumStepHeight;
float lowestBound = characterBody.CollisionInformation.Shape.CollisionMargin - downRayLength + earliestHit.T;
float currentOffset = lowestBound;
float hintOffset;
var tractionContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
var supportContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
var sideContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
var headContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
try
{
//This guess may either win immediately, or at least give us a better idea of where to search.
float hitT;
if (Toolbox.GetRayPlaneIntersection(ref downRay, ref plane, out hitT, out intersection))
{
hitT = -downRayLength + hitT + CollisionDetectionSettings.AllowedPenetration;
if (hitT < highestBound)
{
//Don't try a location known to be too high.
hitT = highestBound;
}
currentOffset = hitT;
if (currentOffset > lowestBound)
{
lowestBound = currentOffset;
}
candidatePosition = characterBody.Position + down * currentOffset + horizontalOffset;
switch (TryUpStepPosition(ref normal, ref candidatePosition, ref down,
ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts,
out hintOffset))
{
case CharacterContactPositionState.Accepted:
currentOffset += hintOffset;
//Only use the new position location if the movement distance was the right size.
if (currentOffset < 0 && currentOffset > -maximumStepHeight - CollisionDetectionSettings.AllowedPenetration)
{
//It's possible that we let a just-barely-too-high step occur, limited by the allowed penetration.
//Just clamp the overall motion and let it penetrate a bit.
newPosition = characterBody.Position + Math.Max(-maximumStepHeight, currentOffset) * down + horizontalOffset;
return(true);
}
else
{
newPosition = new Vector3();
return(false);
}
case CharacterContactPositionState.Rejected:
newPosition = new Vector3();
return(false);
case CharacterContactPositionState.NoHit:
highestBound = currentOffset + hintOffset;
currentOffset = (lowestBound + currentOffset) * .5f;
break;
case CharacterContactPositionState.Obstructed:
lowestBound = currentOffset;
currentOffset = (highestBound + currentOffset) * .5f;
break;
case CharacterContactPositionState.HeadObstructed:
highestBound = currentOffset + hintOffset;
currentOffset = (lowestBound + currentOffset) * .5f;
break;
case CharacterContactPositionState.TooDeep:
currentOffset += hintOffset;
lowestBound = currentOffset;
break;
}
} //TODO: If the ray cast doesn't hit, that could be used to early out... Then again, it pretty much can't happen.
//Our guesses failed.
//Begin the regular process. Start at the time of impact of the ray itself.
//How about trying the time of impact of the ray itself?
//Since we wouldn't be here unless there were no contacts at the body's current position,
//testing the ray cast location gives us the second bound we need to do an informed binary search.
int attempts = 0;
//Don't keep querying indefinitely. If we fail to reach it in a few informed steps, it's probably not worth continuing.
//The bound size check prevents the system from continuing to search a meaninglessly tiny interval.
while (attempts++ < 5 && lowestBound - highestBound > Toolbox.BigEpsilon)
{
candidatePosition = characterBody.Position + currentOffset * down + horizontalOffset;
switch (TryUpStepPosition(ref normal, ref candidatePosition, ref down,
ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts,
out hintOffset))
{
case CharacterContactPositionState.Accepted:
currentOffset += hintOffset;
//Only use the new position location if the movement distance was the right size.
if (currentOffset < 0 && currentOffset > -maximumStepHeight - CollisionDetectionSettings.AllowedPenetration)
{
//It's possible that we let a just-barely-too-high step occur, limited by the allowed penetration.
//Just clamp the overall motion and let it penetrate a bit.
newPosition = characterBody.Position + Math.Max(-maximumStepHeight, currentOffset) * down + horizontalOffset;
return(true);
}
else
{
newPosition = new Vector3();
return(false);
}
case CharacterContactPositionState.Rejected:
newPosition = new Vector3();
return(false);
case CharacterContactPositionState.NoHit:
highestBound = currentOffset + hintOffset;
currentOffset = (lowestBound + highestBound) * .5f;
break;
case CharacterContactPositionState.Obstructed:
lowestBound = currentOffset;
currentOffset = (highestBound + lowestBound) * .5f;
break;
case CharacterContactPositionState.HeadObstructed:
highestBound = currentOffset + hintOffset;
currentOffset = (lowestBound + currentOffset) * .5f;
break;
case CharacterContactPositionState.TooDeep:
currentOffset += hintOffset;
lowestBound = currentOffset;
break;
}
}
}
finally
{
tractionContacts.Dispose();
supportContacts.Dispose();
sideContacts.Dispose();
headContacts.Dispose();
}
//Couldn't find a candidate.
newPosition = new Vector3();
return(false);
}
/// <summary>
/// Determines if a down step is possible, and if so, computes the location to which the character should teleport.
/// </summary>
/// <param name="newPosition">New position the character should teleport to if the down step is accepted.</param>
/// <returns>Whether or not the character should attempt to step down.</returns>
public bool TryToStepDown(out Vector3 newPosition)
{
//Don't bother trying to step down if we already have a support contact or if the support ray doesn't have traction.
if (!(SupportFinder.Supports.Count == 0 && SupportFinder.SupportRayData != null && SupportFinder.SupportRayData.Value.HasTraction))
{
newPosition = new Vector3();
return(false);
}
if (!(SupportFinder.SupportRayData.Value.HitData.T - SupportFinder.BottomDistance > minimumDownStepHeight)) //Don't do expensive stuff if it's, at most, a super tiny step that gravity will take care of.
{
newPosition = new Vector3();
return(false);
}
//Predict a hit location based on the time of impact and the normal at the intersection.
//Take into account the radius of the character (don't forget the collision margin!)
Vector3 normal = SupportFinder.SupportRayData.Value.HitData.Normal;
Vector3 down = characterBody.orientationMatrix.Down;
RigidTransform transform = characterBody.CollisionInformation.WorldTransform;
//We know that the closest point to the plane will be the extreme point in the plane's direction.
//Use it as the ray origin.
Ray ray;
characterBody.CollisionInformation.Shape.GetExtremePoint(normal, ref transform, out ray.Position);
ray.Direction = down;
//Intersect the ray against the plane defined by the support hit.
Vector3 intersection;
Plane plane = new Plane(normal, Vector3.Dot(SupportFinder.SupportRayData.Value.HitData.Location, normal));
Vector3 candidatePosition;
//Define the interval bounds to be used later.
//The words 'highest' and 'lowest' here refer to the position relative to the character's body.
//The ray cast points downward relative to the character's body.
float highestBound = 0;
//The lowest possible distance is the ray distance plus the collision margin because the ray could theoretically be on the outskirts of the collision margin
//where the shape would actually have to move more than the bottom distance difference would imply.
//(Could compute the true lowest bound analytically based on the horizontal position of the ray...)
float lowestBound = characterBody.CollisionInformation.Shape.CollisionMargin + SupportFinder.SupportRayData.Value.HitData.T - SupportFinder.BottomDistance;
float currentOffset = lowestBound;
float hintOffset;
var tractionContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
var supportContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
var sideContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
var headContacts = new QuickList <CharacterContact>(BufferPools <CharacterContact> .Thread);
try
{
//This guess may either win immediately, or at least give us a better idea of where to search.
float hitT;
if (Toolbox.GetRayPlaneIntersection(ref ray, ref plane, out hitT, out intersection))
{
currentOffset = hitT + CollisionDetectionSettings.AllowedPenetration * 0.5f;
candidatePosition = characterBody.Position + down * currentOffset;
switch (TryDownStepPosition(ref candidatePosition, ref down,
ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts,
out hintOffset))
{
case CharacterContactPositionState.Accepted:
currentOffset += hintOffset;
//Only use the new position location if the movement distance was the right size.
if (currentOffset > minimumDownStepHeight && currentOffset < maximumStepHeight)
{
newPosition = characterBody.Position + currentOffset * down;
return(true);
}
else
{
newPosition = new Vector3();
return(false);
}
case CharacterContactPositionState.NoHit:
highestBound = currentOffset + hintOffset;
currentOffset = (lowestBound + currentOffset) * .5f;
break;
case CharacterContactPositionState.Obstructed:
lowestBound = currentOffset;
currentOffset = (highestBound + currentOffset) * .5f;
break;
case CharacterContactPositionState.TooDeep:
currentOffset += hintOffset;
lowestBound = currentOffset;
break;
}
}
//Our guesses failed.
//Begin the regular process. Start at the time of impact of the ray itself.
//How about trying the time of impact of the ray itself?
//Since we wouldn't be here unless there were no contacts at the body's current position,
//testing the ray cast location gives us the second bound we need to do an informed binary search.
int attempts = 0;
//Don't keep querying indefinitely. If we fail to reach it in a few informed steps, it's probably not worth continuing.
//The bound size check prevents the system from continuing to search a meaninglessly tiny interval.
while (attempts++ < 5 && lowestBound - highestBound > Toolbox.BigEpsilon)
{
candidatePosition = characterBody.Position + currentOffset * down;
switch (TryDownStepPosition(ref candidatePosition, ref down, ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts, out hintOffset))
{
case CharacterContactPositionState.Accepted:
currentOffset += hintOffset;
//Only use the new position location if the movement distance was the right size.
if (currentOffset > minimumDownStepHeight && currentOffset < maximumStepHeight)
{
newPosition = characterBody.Position + currentOffset * down;
return(true);
}
else
{
newPosition = new Vector3();
return(false);
}
case CharacterContactPositionState.NoHit:
highestBound = currentOffset + hintOffset;
currentOffset = (lowestBound + highestBound) * .5f;
break;
case CharacterContactPositionState.Obstructed:
lowestBound = currentOffset;
currentOffset = (highestBound + lowestBound) * .5f;
break;
case CharacterContactPositionState.TooDeep:
currentOffset += hintOffset;
lowestBound = currentOffset;
break;
}
}
//Couldn't find a candidate.
newPosition = new Vector3();
return(false);
}
finally
{
tractionContacts.Dispose();
supportContacts.Dispose();
sideContacts.Dispose();
headContacts.Dispose();
}
}
