/// <summary>
/// Get collision data between two collliders. NOTE, this will not cause a physical collision, if you want to cause a collision use the function "collide()" in the object returned.
/// </summary>
/// <param name="a">Any circle collider.</param>
/// <param name="b">Any line collider.</param>
/// <returns>The collision data between the colliders, or null if no collision occured.</returns>
public static Collision getCollision(CircleCollider a, LineCollider b)
{
//precalculate gradient for efficiancy.
double gradient = b.globalGradient;
//squere distance between circle center to possible contact point
double sqrDistance = a.globalCenter.Y - b.globalCenter.Y + gradient * (b.globalCenter.X - a.globalCenter.X);
sqrDistance *= sqrDistance / (gradient * gradient + 1);
if (sqrDistance > a.radius * a.radius)
{
return(null);
}
if (a.globalCenter.sqrDistance(b.globalCenter) - sqrDistance > b.length * b.length / 4)
{
return(null);
}
Vector2d normal = b.globalNormalVector;
//look here for 1 directional colliders.
if ((a.globalCenter - b.globalCenter).cosineOfAngleBetween(normal) > 0)
{
normal *= -1;
}
return(new Collision(a,
b,
normal,
a.globalCenter + Sqrt(sqrDistance) * normal,
a.radius - Sqrt(sqrDistance)));
}
/// <summary>
/// Get collision data between two collliders. NOTE, this will not cause a physical collision, if you want to cause a collision use the function "collide()" in the object returned.
/// </summary>
/// <param name="a">Any line collider.</param>
/// <param name="b">Any line collider.</param>
/// <returns>The collision data between the colliders, or null if no collision occured.</returns>
public static Collision getCollision(LineCollider a, LineCollider b)
{
if (Abs(a.globalAngle - b.globalAngle) < 1)
{
return(null);
}
if ((a.length + b.length).sqr() < a.globalCenter.sqrDistance(b.globalCenter)) //quick check to exclude far away objects
{
return(null);
}
Vector2d aTangent = a.globalTangentVector;
Vector2d bTangent = b.globalTangentVector;
double a2 = (a.globalCenter.Y - b.globalCenter.Y + (b.globalCenter.X - a.globalCenter.X) * aTangent.Y / aTangent.X) / (bTangent.Y - bTangent.X * aTangent.Y / aTangent.X);
Vector2d contact = b.globalCenter + a2 * bTangent;
if (contact.sqrDistance(a.globalCenter) > a.length.sqr() / 4 || contact.sqrDistance(b.globalCenter) > b.length.sqr() / 4)
{
return(null); //contact is outside of line segment
}
double aDistanceFromEndpoint = a.length / 2 - contact.distance(a.globalCenter); //The distance of the contact point from a's closest endpoint
double bDistanceFromEndpoint = b.length / 2 - contact.distance(b.globalCenter); //The distance of the contact point from b's closest endpoint
Vector2d normal = aDistanceFromEndpoint > bDistanceFromEndpoint ? a.globalNormalVector : b.globalNormalVector;
if (aDistanceFromEndpoint > bDistanceFromEndpoint)
{
normal = a.globalNormalVector;
if (Vector2d.Dot(normal, contact - b.globalCenter) > 0)
{
normal *= -1;
}
}
else
{
normal = b.globalNormalVector;
if (Vector2d.Dot(normal, contact - a.globalCenter) < 0)
{
normal *= -1;
}
}
return(new Collision(a,
b,
normal,
contact,
Min(aDistanceFromEndpoint, bDistanceFromEndpoint)));
}
/// <summary>
/// Get collision data between two collliders. NOTE, this will not cause a physical collision, if you want to cause a collision use the function "collide()" in the object returned.
/// </summary>
/// <param name="a">Any line collider.</param>
/// <param name="b">Any Circle collider.</param>
/// <returns>The collision data between the colliders, or null if no collision occured.</returns>
public static Collision getCollision(LineCollider a, CircleCollider b)
{
return(getCollision(b, a));
}
