/// <summary>
/// Workhorse for circle-circle collisions, compares origin distance
/// to the sum of the two circles' radii, returns a Manifold.
/// </summary>
///
private static Manifold TestCircles(
VoltWorld world,
VoltCircle shapeA,
VoltShape shapeB,
VoltVector2 overrideBCenter, // For testing vertices in circles
Fix64 overrideBRadius)
{
VoltVector2 r = overrideBCenter - shapeA.worldSpaceOrigin;
Fix64 min = shapeA.radius + overrideBRadius;
Fix64 distSq = r.sqrMagnitude;
if (distSq >= min * min)
{
return(null);
}
Fix64 dist = VoltMath.Sqrt(distSq);
// 최소값을 지정하여 divide by zero 방지
Fix64 distInv = Fix64.One / VoltMath.Max(dist, min / (Fix64)10);
VoltVector2 pos =
shapeA.worldSpaceOrigin +
(Fix64.One / (Fix64)2 + distInv * (shapeA.radius - min / (Fix64)2)) * r;
// Build the collision Manifold
Manifold manifold =
world.AllocateManifold().Assign(world, shapeA, shapeB);
manifold.AddContact(pos, distInv * r, dist - min);
return(manifold);
}
internal Manifold Assign(
VoltWorld world,
VoltShape shapeA,
VoltShape shapeB)
{
this.world = world;
this.ShapeA = shapeA;
this.ShapeB = shapeB;
this.Restitution = VoltMath.Sqrt(shapeA.Restitution * shapeB.Restitution);
this.Friction = VoltMath.Sqrt(shapeA.Friction * shapeB.Friction);
this.used = 0;
return(this);
}
/// <summary>
/// Checks a ray against a circle with a given origin and square radius.
/// </summary>
internal static bool CircleRayCast(
VoltShape shape,
VoltVector2 shapeOrigin,
Fix64 sqrRadius,
ref VoltRayCast ray,
ref VoltRayResult result)
{
VoltVector2 toOrigin = shapeOrigin - ray.origin;
if (toOrigin.sqrMagnitude < sqrRadius)
{
result.SetContained(shape);
return(true);
}
Fix64 slope = VoltVector2.Dot(toOrigin, ray.direction);
if (slope < Fix64.Zero)
{
return(false);
}
Fix64 sqrSlope = slope * slope;
Fix64 d = sqrRadius + sqrSlope - VoltVector2.Dot(toOrigin, toOrigin);
if (d < Fix64.Zero)
{
return(false);
}
Fix64 dist = slope - VoltMath.Sqrt(d);
if (dist < Fix64.Zero || dist > ray.distance)
{
return(false);
}
// N.B.: For historical raycasts this normal will be wrong!
// Must be either transformed back to world or invalidated later.
VoltVector2 normal = (dist * ray.direction - toOrigin).normalized;
result.Set(shape, dist, normal);
return(true);
}
