void ConstructOctree()
{
var aabb = new AABB(transform.position, _radiusToSpawnIn * _octreeRadiusMultiplier);
var octConstructJob = _octree.CreateConstructJob(_particlePositions, aabb);
var job = octConstructJob.Schedule();
job.Complete();
}
public void Step(float dt)
{
Fluid.Gravity = _world.Gravity;
Fluid.Update(dt);
Collision.AABB fluidAABB = new Collision.AABB();
// Compute fluid AABB
for (int i = 0; i < Fluid.Particles.Count; ++i)
{
FluidParticle p = Fluid.Particles[i];
if (p.IsActive)
{
fluidAABB.LowerBound = Vector2.Min(p.Position, fluidAABB.LowerBound);
fluidAABB.UpperBound = Vector2.Max(p.Position, fluidAABB.UpperBound);
}
}
fluidAABB.LowerBound -= new Vector2(Fluid.Definition.InfluenceRadius, Fluid.Definition.InfluenceRadius);
fluidAABB.UpperBound += new Vector2(Fluid.Definition.InfluenceRadius, Fluid.Definition.InfluenceRadius);
// Query the world for fixtures near fluid
_fluidCollisions.Clear();
_world.QueryAABB(FluidQueryCallback, ref fluidAABB);
// Save states
for (int i = 0; i < _bodies.Count; ++i)
{
RigidBody rb = _bodies[i];
if (rb.Body.BodyType == BodyType.Dynamic)
{
rb.Reset();
rb.SaveState();
rb.Advance(dt, ref _world.Gravity);
}
}
// Fluid > Bodies
for (int ic = 0; ic < _fluidCollisions.Count; ++ic)
{
Fixture fixture = _fluidCollisions[ic];
if (fixture.RigidBody.Body.BodyType != BodyType.Dynamic)
continue;
if (fixture.IsSensor)
continue;
for (int ip = 0; ip < Fluid.Particles.Count; ++ip)
{
FluidParticle particle = Fluid.Particles[ip];
if (!particle.IsActive)
continue;
Feature result;
if (!fixture.RigidBody.Intersect(fixture, ref particle.Position, out result))
continue;
Vector2 impulse = new Vector2();
if (result.Distance < 0.0f) // Inside
{
Vector2 bodyVelocity = fixture.RigidBody.Body.GetLinearVelocityFromWorldPoint(ref particle.Position);
Vector2 velocity = (particle.Position - particle.PreviousPosition) - bodyVelocity * dt;
Vector2 velocityNormal = Vector2.Dot(velocity, result.Normal) * result.Normal;
Vector2 velocityTangent = velocity - velocityNormal;
impulse = velocityNormal + fixture.FluidProperties.Slip * velocityTangent;
}
else if (fixture.FluidProperties.IsSticky && result.Distance < fixture.FluidProperties.StickDistance) // Outside
{
impulse = -dt * fixture.FluidProperties.StickForce * result.Distance * (1.0f - result.Distance / fixture.FluidProperties.StickDistance) * result.Normal;
}
fixture.RigidBody.AddForce(ref impulse, ref particle.Position);
}
}
// Apply buffers to bodies
for (int i = 0; i < _bodies.Count; ++i)
{
RigidBody rb = _bodies[i];
if (rb.Body.BodyType == BodyType.Dynamic)
{
rb.RestoreState();
rb.bufferForce /= dt;
rb.bufferTorque /= dt;
if (Math.Abs(rb.bufferForce.X) > 0.0f && Math.Abs(rb.bufferForce.Y) > 0.0f)
{
rb.Body.ApplyLinearImpulse(ref rb.bufferForce);
}
if (Math.Abs(rb.bufferTorque) > 0.0f)
{
rb.Body.ApplyAngularImpulse(rb.bufferTorque);
}
}
}
// Physics step
_world.Step(dt);
// Bodies > Fluids
for (int ip = 0; ip < Fluid.Particles.Count; ++ip)
{
FluidParticle particle = Fluid.Particles[ip];
if (!particle.IsActive)
{
continue;
}
for (int ic = 0; ic < _fluidCollisions.Count; ++ic)
{
Fixture fixture = _fluidCollisions[ic];
if (fixture.IsSensor)
continue;
Feature result;
if (!fixture.RigidBody.Intersect(fixture, ref particle.Position, out result))
continue;
Vector2 impulse = new Vector2();
if (result.Distance < 0.0f) // Inside
{
Vector2 bodyVelocity = fixture.RigidBody.Body.GetLinearVelocityFromWorldPoint(ref particle.Position);
Vector2 velocity = (particle.Position - particle.PreviousPosition) - bodyVelocity * dt;
Vector2 velocityNormal = Vector2.Dot(velocity, result.Normal) * result.Normal;
Vector2 velocityTangent = velocity - velocityNormal;
impulse = velocityNormal + fixture.FluidProperties.Slip * velocityTangent;
}
else if (fixture.FluidProperties.IsSticky && result.Distance < fixture.FluidProperties.StickDistance) // Outside
{
impulse = -dt * fixture.FluidProperties.StickForce * result.Distance * (1.0f - result.Distance / fixture.FluidProperties.StickDistance) * result.Normal;
}
particle.Position -= impulse;
if (fixture.RigidBody.Intersect(fixture, ref particle.Position, out result))
{
if (result.Distance < 0.0f) // Still inside
{
particle.ApplyImpulse((result.Position - particle.Position) / dt);
particle.Position = result.Position;
}
}
}
}
// Correct velocities
Fluid.UpdateVelocities(dt);
}
/// <summary>
/// Get the fixture's AABB. This AABB may be enlarge and/or stale.
/// If you need a more accurate AABB, compute it using the Shape and
/// the body transform.
/// </summary>
/// <param name="aabb">The aabb.</param>
/// <param name="childIndex">Index of the child.</param>
public void GetAABB(out Collision.AABB aabb, int childIndex)
{
Debug.Assert(0 <= childIndex && childIndex < ProxyCount);
aabb = Proxies[childIndex].AABB;
}
