public ContactList(ContactList contactList) : base(contactList)
{
}
/// <summary>
/// Returns the contact list from two possibly intersecting Geom's.
/// This is the stationary version of this function. It doesn't
/// account for linear or angular motion.
/// </summary>
/// <param name="geomA">The first Geom.</param>
/// <param name="geomB">The second Geom.</param>
/// <param name="contactList">Set of Contacts between the two Geoms.
/// NOTE- this will be empty if no contacts are present.</param>
public void Collide(Geom geomA, Geom geomB, ContactList contactList)
{
PolygonCollisionResult result = PolygonCollision(geomA.WorldVertices, geomB.WorldVertices);
float distance = result.MinimumTranslationVector.Length();
int contactsDetected = 0;
Vector2 normal = Vector2.Normalize(-result.MinimumTranslationVector);
int contactsHandled = 0;
if (result.Intersect && distance > 0.001f)
{
for (int i = 0; i < geomA.WorldVertices.Count; i++)
{
if (contactsDetected <= PhysicsSimulator.MaxContactsToDetect)
{
if (InsidePolygon(geomB.WorldVertices, geomA.WorldVertices[i]))
{
Contact c = new Contact(geomA.WorldVertices[i], normal, -distance, new ContactId(geomA.id, i, geomB.id));
contactList.Add(c);
contactsDetected++;
contactsHandled++;
}
}
else
{
break;
}
}
contactsDetected = 0;
for (int i = 0; i < geomB.WorldVertices.Count; i++)
{
if (contactsDetected <= PhysicsSimulator.MaxContactsToDetect)
{
if (InsidePolygon(geomA.WorldVertices, geomB.WorldVertices[i]))
{
Contact c = new Contact(geomB.WorldVertices[i], normal, -distance, new ContactId(geomB.id, i, geomA.id));
contactList.Add(c);
contactsDetected++;
contactsHandled++;
}
}
else
{
break;
}
}
// No vertices of either polygon are inside the other, despite their intersection.
// (Think of an X made of two rectangles of four vertices each.)
// So select the vertex that is furthest past the edge forming the
// separating axis as the contact point.
// - Andrew Russell
if (contactsHandled == 0)
{
int edgeIndex = result.bestEdgeIndex;
Geom separatingEdgeOn = geomA;
Geom otherPolygon = geomB;
if (result.bestEdgeIndex >= geomA.WorldVertices.Count)
{
edgeIndex -= geomA.WorldVertices.Count;
separatingEdgeOn = geomB;
otherPolygon = geomA;
}
Vector2 edge = separatingEdgeOn.WorldVertices.GetEdge(edgeIndex);
Vector2 axis = new Vector2(-edge.Y, edge.X);
axis.Normalize();
int mostPenetrationIndex = 0;
float mostPenetration = Vector2.Dot(axis, otherPolygon.WorldVertices[0]);
for (int i = 1; i < otherPolygon.WorldVertices.Count; i++)
{
float penetration = Vector2.Dot(axis, otherPolygon.WorldVertices[i]);
if (penetration < mostPenetration)
{
mostPenetration = penetration;
mostPenetrationIndex = i;
}
}
Contact c = new Contact(otherPolygon.WorldVertices[mostPenetrationIndex], normal, -distance,
new ContactId(otherPolygon.id, mostPenetrationIndex, separatingEdgeOn.id));
contactList.Add(c);
}
}
}
/// <summary>
/// Finds the contactpoints between the two geometries.
/// </summary>
/// <param name="geomA">The first geom.</param>
/// <param name="geomB">The second geom.</param>
/// <param name="contactList">The contact list.</param>
public void Collide(Geom geomA, Geom geomB, ContactList contactList)
{
int vertexIndex = -1;
//Lookup distancegrid A data from list
DistanceGridData geomAGridData = _distanceGrids[geomA.id];
//Iterate the second geometry vertices
for (int i = 0; i < geomB.worldVertices.Count; i++)
{
if (contactList.Count == PhysicsSimulator.MaxContactsToDetect)
{
break;
}
vertexIndex += 1;
_vertRef = geomB.WorldVertices[i];
geomA.TransformToLocalCoordinates(ref _vertRef, out _localVertex);
//The geometry intersects when distance <= 0
//Continue in the list if the current vector does not intersect
if (!geomAGridData.Intersect(ref _localVertex, out _feature))
{
continue;
}
//If the geometries collide, create a new contact and add it to the contact list.
if (_feature.Distance < 0f)
{
geomA.TransformNormalToWorld(ref _feature.Normal, out _feature.Normal);
Contact contact = new Contact(geomB.WorldVertices[i], _feature.Normal, _feature.Distance, new ContactId(geomB.id, vertexIndex, geomA.id));
contactList.Add(contact);
}
}
//Lookup distancegrid B data from list
DistanceGridData geomBGridData = _distanceGrids[geomB.id];
//Iterate the first geometry vertices
for (int i = 0; i < geomA.WorldVertices.Count; i++)
{
if (contactList.Count == PhysicsSimulator.MaxContactsToDetect)
{
break;
}
vertexIndex += 1;
_vertRef = geomA.WorldVertices[i];
geomB.TransformToLocalCoordinates(ref _vertRef, out _localVertex);
if (!geomBGridData.Intersect(ref _localVertex, out _feature))
{
continue;
}
if (_feature.Distance < 0f)
{
geomB.TransformNormalToWorld(ref _feature.Normal, out _feature.Normal);
_feature.Normal = -_feature.Normal;
Contact contact = new Contact(geomA.WorldVertices[i], _feature.Normal, _feature.Distance, new ContactId(geomA.id, vertexIndex, geomB.id));
contactList.Add(contact);
}
}
}
