// Find islands, integrate and solve constraints, solve position constraints
private void Solve(TimeStep step)
{
// Size the island for the worst case.
Island island = new Island(_bodyCount,
_contactManager._contactCount,
_jointCount,
_contactManager._contactListener);
// Clear all the island flags.
for (Body b = _bodyList; b != null; b = b._next)
{
b._flags &= ~Body.BodyFlags.Island;
}
for (Contact c = _contactManager._contactList; c != null; c = c.Next)
{
c.Flags &= ~ContactFlag.IslandFlag;
}
for (Joint j = _jointList; j != null; j = j._next)
{
j._islandFlag = false;
}
// Build and simulate all awake islands.
int stackSize = _bodyCount;
Body[] stack = new Body[stackSize];
for (Body seed = _bodyList; seed != null; seed = seed._next)
{
if ((seed._flags & (Body.BodyFlags.Island | Body.BodyFlags.Sleep)) != 0)
{
continue;
}
if (seed.IsStatic())
{
continue;
}
// Reset island and stack.
island.Clear();
int stackCount = 0;
stack[stackCount++] = seed;
seed._flags |= Body.BodyFlags.Island;
// Perform a depth first search (DFS) on the constraint graph.
while (stackCount > 0)
{
// Grab the next body off the stack and add it to the island.
Body b = stack[--stackCount];
island.Add(ref b);
// Make sure the body is awake.
b._flags &= ~Body.BodyFlags.Sleep;
// To keep islands as small as possible, we don't
// propagate islands across static bodies.
if (b.IsStatic())
{
continue;
}
// Search all contacts connected to this body.
for (ContactEdge ce = b._contactList; ce != null; ce = ce.Next)
{
// Has this contact already been added to an island?
if ((ce.Contact.Flags & ContactFlag.IslandFlag) != 0)
{
continue;
}
// Is this contact touching?
if (ce.Contact.IsSolid() == false || ce.Contact.IsTouching() == false)
{
continue;
}
island.Add(ref ce.Contact);
ce.Contact.Flags |= ContactFlag.IslandFlag;
Body other = ce.Other;
// Was the other body already added to this island?
if ((other._flags & Body.BodyFlags.Island) != 0)
{
continue;
}
Box2DXDebug.Assert(stackCount < stackSize);
stack[stackCount++] = other;
other._flags |= Body.BodyFlags.Island;
}
// Search all joints connect to this body.
for (JointEdge je = b._jointList; je != null; je = je.Next)
{
if (je.Joint._islandFlag == true)
{
continue;
}
island.Add(je.Joint);
je.Joint._islandFlag = true;
Body other = je.Other;
if ((other._flags & Body.BodyFlags.Island) != 0)
{
continue;
}
Box2DXDebug.Assert(stackCount < stackSize);
stack[stackCount++] = other;
other._flags |= Body.BodyFlags.Island;
}
}
island.Solve(step, _gravity, _allowSleep);
// Post solve cleanup.
for (int i = 0; i < island.BodyCount; ++i)
{
// Allow static bodies to participate in other islands.
Body b = island.Bodies[i];
if (b.IsStatic())
{
b._flags &= ~Body.BodyFlags.Island;
}
}
}
stack = null;
// Synchronize shapes, check for out of range bodies.
for (Body b = _bodyList; b != null; b = b.GetNext())
{
if ((b._flags & Body.BodyFlags.Sleep) != 0)
{
continue;
}
if (b.IsStatic())
{
continue;
}
// Update fixtures (for broad-phase).
b.SynchronizeFixtures();
}
// Look for new contacts.
_contactManager.FindNewContacts();
}
public void DrawDebugData()
{
if (_debugDraw == null)
{
return;
}
DebugDraw.DrawFlags flags = _debugDraw.Flags;
if ((flags & DebugDraw.DrawFlags.Shape) != 0)
{
for (Body b = _bodyList; b != null; b = b.GetNext())
{
Transform xf = b.GetTransform();
for (Fixture f = b.GetFixtureList(); f != null; f = f.GetNext())
{
if (b.IsStatic())
{
DrawShape(f, xf, new Color(0.5f, 0.9f, 0.5f));
}
else if (b.IsSleeping())
{
DrawShape(f, xf, new Color(0.5f, 0.5f, 0.9f));
}
else
{
DrawShape(f, xf, new Color(0.9f, 0.9f, 0.9f));
}
}
}
}
if ((flags & DebugDraw.DrawFlags.Joint) != 0)
{
for (Joint j = _jointList; j != null; j = j.GetNext())
{
if (j.GetType() != JointType.MouseJoint)
{
DrawJoint(j);
}
}
}
if ((flags & DebugDraw.DrawFlags.Pair) != 0)
{
// TODO_ERIN
}
if ((flags & DebugDraw.DrawFlags.Aabb) != 0)
{
Color color = new Color(0.9f, 0.3f, 0.9f);
BroadPhase bp = _contactManager._broadPhase;
for (Body b = _bodyList; b != null; b = b.GetNext())
{
for (Fixture f = b.GetFixtureList(); f != null; f = f.GetNext())
{
AABB aabb = bp.GetFatAABB(f.ProxyId);
Vec2[] vs = new Vec2[4];
vs[0].Set(aabb.LowerBound.X, aabb.LowerBound.Y);
vs[1].Set(aabb.UpperBound.X, aabb.LowerBound.Y);
vs[2].Set(aabb.UpperBound.X, aabb.UpperBound.Y);
vs[3].Set(aabb.LowerBound.X, aabb.UpperBound.Y);
_debugDraw.DrawPolygon(vs, 4, color);
}
}
}
if ((flags & DebugDraw.DrawFlags.CenterOfMass) != 0)
{
for (Body b = _bodyList; b != null; b = b.GetNext())
{
Transform xf = b.GetTransform();
xf.Position = b.GetWorldCenter();
_debugDraw.DrawXForm(xf);
}
}
}