public override void UpdateTimeOfImpact(Collidable requester, float dt)
{
var collidableA = CollidableA as ConvexCollidable;
var collidableB = CollidableB as ConvexCollidable;
var modeA = collidableA.entity == null ? PositionUpdateMode.Discrete : collidableA.entity.PositionUpdateMode;
var modeB = collidableB.entity == null ? PositionUpdateMode.Discrete : collidableB.entity.PositionUpdateMode;
var overlap = BroadPhaseOverlap;
if (
(overlap.entryA.IsActive || overlap.entryB.IsActive) && //At least one has to be active.
(
(
modeA == PositionUpdateMode.Continuous && //If both are continuous, only do the process for A.
modeB == PositionUpdateMode.Continuous &&
overlap.entryA == requester
) ||
(
modeA == PositionUpdateMode.Continuous ^ //If only one is continuous, then we must do it.
modeB == PositionUpdateMode.Continuous
)
)
)
{
//Only perform the test if the minimum radii are small enough relative to the size of the velocity.
//Discrete objects have already had their linear motion integrated, so don't use their velocity.
Vector3 velocity;
if (modeA == PositionUpdateMode.Discrete)
{
//CollidableA is static for the purposes of this continuous test.
velocity = collidableB.entity.linearVelocity;
}
else if (modeB == PositionUpdateMode.Discrete)
{
//CollidableB is static for the purposes of this continuous test.
Vector3.Negate(ref collidableA.entity.linearVelocity, out velocity);
}
else
{
//Both objects are moving.
Vector3.Subtract(ref collidableB.entity.linearVelocity, ref collidableA.entity.linearVelocity, out velocity);
}
Vector3.Multiply(ref velocity, dt, out velocity);
float velocitySquared = velocity.LengthSquared();
var minimumRadiusA = collidableA.Shape.minimumRadius * MotionSettings.CoreShapeScaling;
timeOfImpact = 1;
if (minimumRadiusA * minimumRadiusA < velocitySquared)
{
//Spherecast A against B.
RayHit rayHit;
if (GJKToolbox.CCDSphereCast(new Ray(collidableA.worldTransform.Position, -velocity), minimumRadiusA, collidableB.Shape, ref collidableB.worldTransform, timeOfImpact, out rayHit))
timeOfImpact = rayHit.T;
}
var minimumRadiusB = collidableB.Shape.minimumRadius * MotionSettings.CoreShapeScaling;
if (minimumRadiusB * minimumRadiusB < velocitySquared)
{
//Spherecast B against A.
RayHit rayHit;
if (GJKToolbox.CCDSphereCast(new Ray(collidableB.worldTransform.Position, velocity), minimumRadiusB, collidableA.Shape, ref collidableA.worldTransform, timeOfImpact, out rayHit))
timeOfImpact = rayHit.T;
}
//If it's intersecting, throw our hands into the air and give up.
//This is generally a perfectly acceptable thing to do, since it's either sitting
//inside another object (no ccd makes sense) or we're still in an intersecting case
//from a previous frame where CCD took place and a contact should have been created
//to deal with interpenetrating velocity. Sometimes that contact isn't sufficient,
//but it's good enough.
if (timeOfImpact == 0)
timeOfImpact = 1;
}
}
