public override void UpdateTimeOfImpact(Collidable requester, float dt)
{
//Notice that we don't test for convex entity null explicitly. The convex.IsActive property does that for us.
if (convex.IsActive && convex.entity.PositionUpdateMode == PositionUpdateMode.Continuous)
{
//TODO: This system could be made more robust by using a similar region-based rejection of edges.
//CCD events are awfully rare under normal circumstances, so this isn't usually an issue.
//Only perform the test if the minimum radii are small enough relative to the size of the velocity.
Vector3 velocity;
Vector3.Multiply(ref convex.entity.linearVelocity, dt, out velocity);
float velocitySquared = velocity.LengthSquared();
var minimumRadius = convex.Shape.minimumRadius * MotionSettings.CoreShapeScaling;
timeOfImpact = 1;
if (minimumRadius * minimumRadius < velocitySquared)
{
var triangle = PhysicsResources.GetTriangle();
triangle.collisionMargin = 0;
Vector3 terrainUp = new Vector3(terrain.worldTransform.LinearTransform.M21, terrain.worldTransform.LinearTransform.M22, terrain.worldTransform.LinearTransform.M23);
//Spherecast against all triangles to find the earliest time.
for (int i = 0; i < TerrainManifold.overlappedTriangles.Count; i++)
{
terrain.Shape.GetTriangle(ref TerrainManifold.overlappedTriangles.Elements[i], ref terrain.worldTransform, out triangle.vA, out triangle.vB, out triangle.vC);
//Put the triangle into 'localish' space of the convex.
Vector3.Subtract(ref triangle.vA, ref convex.worldTransform.Position, out triangle.vA);
Vector3.Subtract(ref triangle.vB, ref convex.worldTransform.Position, out triangle.vB);
Vector3.Subtract(ref triangle.vC, ref convex.worldTransform.Position, out triangle.vC);
RayHit rayHit;
if (GJKToolbox.CCDSphereCast(new Ray(Toolbox.ZeroVector, velocity), minimumRadius, triangle, ref Toolbox.RigidIdentity, timeOfImpact, out rayHit) &&
rayHit.T > Toolbox.BigEpsilon)
{
Vector3 AB, AC;
Vector3.Subtract(ref triangle.vB, ref triangle.vA, out AB);
Vector3.Subtract(ref triangle.vC, ref triangle.vA, out AC);
Vector3 normal;
Vector3.Cross(ref AC, ref AB, out normal);
float dot;
Vector3.Dot(ref normal, ref terrainUp, out dot);
if (dot < 0)
Vector3.Dot(ref normal, ref rayHit.Normal, out dot);
else
{
Vector3.Dot(ref normal, ref rayHit.Normal, out dot);
dot = -dot;
}
//Only perform sweep if the object is in danger of hitting the object.
//Triangles can be one sided, so check the impact normal against the triangle normal.
if (dot < 0)
{
timeOfImpact = rayHit.T;
}
}
}
PhysicsResources.GiveBack(triangle);
}
}
}
