/// <summary>
/// Test whether a <see cref="OBBf"/> intersects this plane.
/// See: Ericson 2005, Real Time Collision Detection, p. 161 - 164
/// </summary>
/// <param name="obb">The axis aligned bounding box.</param>
public bool Intersects(OBBf obb)
{
var r = BoxExtendInNormalDirection(obb);
var s = SignedDistanceFromPoint(obb.Center);
return(System.Math.Abs(s) <= r);
}
/// <summary>
/// Calculates the projection interval radius of obb onto line L(t) = aabb.Center + t * plane.Normal (extend (radius) in direction of the plane normal).
/// <param name="obb">The object oriented bounding box.</param>
/// </summary>
private float BoxExtendInNormalDirection(OBBf obb)
{
var transformationMat = obb.Rotation * float4x4.CreateTranslation(obb.Translation); //without scale!
var xAxis = (float3.UnitX * transformationMat).Normalize();
var yAxis = (float3.UnitY * transformationMat).Normalize();
var zAxis = (float3.UnitZ * transformationMat).Normalize();
var boxExtend = obb.Size * 0.5f;
return(boxExtend.x * System.Math.Abs(float3.Dot(Normal, xAxis)) +
boxExtend.y * System.Math.Abs(float3.Dot(Normal, yAxis)) +
boxExtend.z * System.Math.Abs(float3.Dot(Normal, zAxis)));
}
/// <summary>
/// Test whether a <see cref="AABBf"/> intersects this plane.
/// See: Ericson 2005, Real Time Collision Detection, p. 161 - 164
/// CAREFUL: the definition whats completely inside and outside is flipped in comparison to Ericson,
/// because FUSEE defines a point with a negative signed distance to be inside.
/// </summary>
/// <param name="obb">The object oriented bounding box.</param>
public bool InsideOrIntersecting(OBBf obb)
{
var r = BoxExtendInNormalDirection(obb);
//Distance from obb center to plane
var s = SignedDistanceFromPoint(obb.Center);
//Completely outside
if (s <= -r)
{
return(true);
}
//Completely inside
else if (r <= s)
{
return(false);
}
//else intersecting
return(true);
}
