public override void Update(double dt)
{
base.Update(dt);
foreach (GridFin gridFin in _gridFins)
{
gridFin.Update(dt);
}
foreach (LandingLeg landingLeg in _landingLegs)
{
landingLeg.Update(dt);
}
DVector2 velocity = GetRelativeVelocity();
double altitude = GetRelativeAltitude();
DVector2 normalizedVelocity = velocity.Clone();
normalizedVelocity.Normalize();
DVector2 rotation = new DVector2(Math.Cos(Pitch), Math.Sin(Pitch));
// If we are going retro-grade and firing rockets adds soot
if (altitude < 70000 && normalizedVelocity.Dot(rotation) < 0 && velocity.Length() > 400)
{
foreach (IEngine engine in Engines)
{
if (engine.IsActive && engine.Throttle > 0)
{
_sootRatio = Math.Min(_sootRatio + 0.015 * dt, 1.0);
}
}
}
}
/// <summary>
/// Find the closet point along this line from a_point
/// </summary>
/// <param name="a_point"></param>
/// <returns></returns>
public DVector2 ClosestPoint(DVector2 a_point)
{
DVector2 delta = v1 - v0;
double lengthSquared = delta.SqrMagnitude();
if (lengthSquared.Equals(0f))
{
return(v0);
}
double projection = DVector2.Dot(a_point - v0, delta);
double scale = projection / lengthSquared;
return(v0 + delta * scale);
}
public static DVector2 PredictShot(DVector2 origin, DReal projectileSpeed, DVector2 targetPosition, DVector2 targetVelocity)
{
var dp = targetPosition - origin;
// Try to lead the target.
var a = DVector2.Dot(targetVelocity, targetVelocity) - projectileSpeed * projectileSpeed;
var b = 2 * DVector2.Dot(targetVelocity, dp);
var c = DVector2.Dot(dp, dp);
var p = -b / (2 * a);
var discriminant = b * b - 4 * a * c;
if (discriminant <= 0)
{
return(targetPosition);
}
DReal q;
try {
q = DReal.Sqrt(discriminant) / (2 * a);
} catch (System.ArithmeticException) {
return(targetPosition);
}
var t1 = p - q;
var t2 = p + q;
DReal t;
if (t1 > t2 && t2 > 0)
{
t = t2;
}
else if (t1 > 0)
{
t = t1;
}
else
{
return(targetPosition);
}
return(targetPosition + targetVelocity * t);
}
// Gets bodies sorted by distance that point the direction of the camera normal
private static List <Tuple <double, int> > GetSortedBodyDistances(int currentIndex, IList <IGravitationalBody> bodies, DVector2 cameraNormal)
{
DVector2 targetCenter = bodies[currentIndex].Position;
var bodiesByDistance = new List <Tuple <double, int> >();
for (int i = 0; i < bodies.Count; i++)
{
if (i == currentIndex)
{
continue;
}
var spaceCraft = bodies[i] as ISpaceCraft;
// Skip terminated bodies
if (spaceCraft != null && spaceCraft.Terminated)
{
continue;
}
DVector2 difference = bodies[i].Position - targetCenter;
double distance = difference.LengthSquared();
difference.Normalize();
// Only add bodies in the same direction as the camera normal
if (difference.Dot(cameraNormal) > 0)
{
bodiesByDistance.Add(new Tuple <double, int>(distance, i));
}
}
bodiesByDistance.Sort(Compare);
return(bodiesByDistance);
}
public static bool IntersectLineCircle(DVector2 circleOrigin, DReal radius, DVector2 lineStart, DVector2 lineEnd, out DVector2 outIp)
{
var d = lineEnd - lineStart; // ray direction.
var f = lineStart - circleOrigin; // Vector from circle centre to ray start.
var a = DVector2.Dot(d, d);
var b = 2 * DVector2.Dot(f, d);
var c = DVector2.Dot(f, f) - radius * radius;
if (a == 0)
{
// start & end are close enough that distance = 0. Degrade to point/circle test.
outIp = lineStart;
return((lineStart - circleOrigin).sqrMagnitude < radius * radius);
}
var discriminant = b * b - 4 * a * c;
if (discriminant < 0)
{
outIp = new DVector2();
return(false);
}
// ray didn't totally miss sphere,
// so there is a solution to
// the equation.
discriminant = DReal.Sqrt(discriminant);
// either solution may be on or off the ray so need to test both
// t1 is always the smaller value, because BOTH discriminant and
// a are nonnegative.
var t1 = (-b - discriminant) / (2 * a);
var t2 = (-b + discriminant) / (2 * a);
// 3x HIT cases:
// -o-> --|--> | | --|->
// Impale(t1 hit,t2 hit), Poke(t1 hit,t2>1), ExitWound(t1<0, t2 hit),
// 3x MISS cases:
// -> o o -> | -> |
// FallShort (t1>1,t2>1), Past (t1<0,t2<0), CompletelyInside(t1<0, t2>1)
if (t1 >= 0 && t1 <= 1)
{
// t1 is the intersection, and it's closer than t2
// (since t1 uses -b - discriminant)
// Impale, Poke
outIp = circleOrigin + d.normalized * -radius;
return(true);
}
// here t1 didn't intersect so we are either started
// inside the sphere or completely past it
if (t2 >= 0 && t2 <= 1)
{
// ExitWound
outIp = circleOrigin + d.normalized * radius;
return(true);
}
// actually completely inside counts as a hit too.
var startSqrDist = (lineStart - circleOrigin).sqrMagnitude;
var endSqrDist = (lineEnd - circleOrigin).sqrMagnitude;
var sqrRadius = radius * radius;
if (startSqrDist < sqrRadius && endSqrDist < sqrRadius)
{
outIp = lineStart;
return(true);
}
// no intn: FallShort, Past, CompletelyInside
outIp = new DVector2();
return(false);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)] public static double LengthSquared(this DVector2 v) => v.Dot(v);
