public override VoltShape PrepareShape(VoltWorld world)
{
this.shape = world.CreateCircleWorldSpace(
this.transform.position.ToTSVector2(),
this.radius,
this.density);
return(this.shape);
}
private static Manifold Circle_Polygon(
VoltWorld world,
VoltCircle circ,
VoltPolygon poly)
{
// Get the axis on the polygon closest to the circle's origin
float penetration;
int index =
Collision.FindAxisMaxPenetration(
circ.worldSpaceOrigin,
circ.radius,
poly,
out penetration);
if (index < 0)
return null;
Vector2 a, b;
poly.GetEdge(index, out a, out b);
Axis axis = poly.GetWorldAxis(index);
// If the circle is past one of the two vertices, check it like
// a circle-circle intersection where the vertex has radius 0
float d = VoltMath.Cross(axis.Normal, circ.worldSpaceOrigin);
if (d > VoltMath.Cross(axis.Normal, a))
return Collision.TestCircles(world, circ, poly, a, 0.0f);
if (d < VoltMath.Cross(axis.Normal, b))
return Collision.TestCircles(world, circ, poly, b, 0.0f);
// Build the collision Manifold
Manifold manifold = world.AllocateManifold().Assign(world, circ, poly);
Vector2 pos =
circ.worldSpaceOrigin - (circ.radius + penetration / 2) * axis.Normal;
manifold.AddContact(pos, -axis.Normal, penetration);
return manifold;
}
/// <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,
Vector2 overrideBCenter, // For testing vertices in circles
float overrideBRadius)
{
Vector2 r = overrideBCenter - shapeA.worldSpaceOrigin;
float min = shapeA.radius + overrideBRadius;
float distSq = r.sqrMagnitude;
if (distSq >= min * min)
return null;
float dist = Mathf.Sqrt(distSq);
float distInv = 1.0f / dist;
Vector2 pos =
shapeA.worldSpaceOrigin +
(0.5f + distInv * (shapeA.radius - min / 2.0f)) * r;
// Build the collision Manifold
Manifold manifold =
world.AllocateManifold().Assign(world, shapeA, shapeB);
manifold.AddContact(pos, distInv * r, dist - min);
return manifold;
}
private static Manifold Circle_Circle(
VoltWorld world,
VoltCircle circA,
VoltCircle circB)
{
return
TestCircles(
world,
circA,
circB,
circB.worldSpaceOrigin,
circB.radius);
}
