/// <summary>
/// Initializes a new instance of the <see cref="Manifold" /> class
/// </summary>
public Manifold()
{
for (int i = 0; i < Settings.MaxManifoldPoints; i++)
{
Points[i] = new ManifoldPoint();
}
}
/// <summary>
/// Clones this instance
/// </summary>
/// <returns>The new point</returns>
public ManifoldPoint Clone()
{
ManifoldPoint newPoint = new ManifoldPoint();
newPoint.LocalPoint = LocalPoint;
newPoint.NormalImpulse = NormalImpulse;
newPoint.TangentImpulse = TangentImpulse;
newPoint.Id = Id;
return(newPoint);
}
/// <summary>
/// Clones this instance
/// </summary>
/// <returns>The new manifold</returns>
public Manifold Clone()
{
Manifold newManifold = new Manifold();
newManifold.LocalPlaneNormal = LocalPlaneNormal;
newManifold.LocalPoint = LocalPoint;
newManifold.Type = Type;
newManifold.PointCount = PointCount;
int pointCount = Points.Length;
ManifoldPoint[] tmp = new ManifoldPoint[pointCount];
for (int i = 0; i < pointCount; i++)
{
tmp[i] = Points[i].Clone();
}
newManifold.Points = tmp;
return(newManifold);
}
// Find edge normal of max separation on A - return if separating axis is found
// Find edge normal of max separation on B - return if separation axis is found
// Choose reference edge as min(minA, minB)
// Find incident edge
// Clip
// The normal points from 1 to 2
/// <summary>
/// Collides the polygons using the specified manifold
/// </summary>
/// <param name="manifold">The manifold</param>
/// <param name="polyA">The poly</param>
/// <param name="xfA">The xf</param>
/// <param name="polyB">The poly</param>
/// <param name="xfB">The xf</param>
public static void CollidePolygons(ref Manifold manifold,
PolygonShape polyA, XForm xfA, PolygonShape polyB, XForm xfB)
{
manifold.PointCount = 0;
float totalRadius = polyA.Radius + polyB.Radius;
int edgeA = 0;
float separationA = FindMaxSeparation(ref edgeA, polyA, xfA, polyB, xfB);
if (separationA > totalRadius)
{
return;
}
int edgeB = 0;
float separationB = FindMaxSeparation(ref edgeB, polyB, xfB, polyA, xfA);
if (separationB > totalRadius)
{
return;
}
PolygonShape poly1; // reference poly
PolygonShape poly2; // incident poly
XForm xf1, xf2;
int edge1; // reference edge
byte flip;
const float kRelativeTol = 0.98f;
const float kAbsoluteTol = 0.001f;
if (separationB > kRelativeTol * separationA + kAbsoluteTol)
{
poly1 = polyB;
poly2 = polyA;
xf1 = xfB;
xf2 = xfA;
edge1 = edgeB;
manifold.Type = ManifoldType.FaceB;
flip = 1;
}
else
{
poly1 = polyA;
poly2 = polyB;
xf1 = xfA;
xf2 = xfB;
edge1 = edgeA;
manifold.Type = ManifoldType.FaceA;
flip = 0;
}
ClipVertex[] incidentEdge;
FindIncidentEdge(out incidentEdge, poly1, xf1, edge1, poly2, xf2);
int count1 = poly1.VertexCount;
Vec2[] vertices1 = poly1.Vertices;
Vec2 v11 = vertices1[edge1];
Vec2 v12 = edge1 + 1 < count1 ? vertices1[edge1 + 1] : vertices1[0];
Vec2 dv = v12 - v11;
Vec2 localNormal = Vec2.Cross(dv, 1.0f);
localNormal.Normalize();
Vec2 planePoint = 0.5f * (v11 + v12);
Vec2 sideNormal = Math.Mul(xf1.R, v12 - v11);
sideNormal.Normalize();
Vec2 frontNormal = Vec2.Cross(sideNormal, 1.0f);
v11 = Math.Mul(xf1, v11);
v12 = Math.Mul(xf1, v12);
float frontOffset = Vec2.Dot(frontNormal, v11);
float sideOffset1 = -Vec2.Dot(sideNormal, v11);
float sideOffset2 = Vec2.Dot(sideNormal, v12);
// Clip incident edge against extruded edge1 side edges.
ClipVertex[] clipPoints1;
ClipVertex[] clipPoints2;
int np;
// Clip to box side 1
np = ClipSegmentToLine(out clipPoints1, incidentEdge, -sideNormal, sideOffset1);
if (np < 2)
{
return;
}
// Clip to negative box side 1
np = ClipSegmentToLine(out clipPoints2, clipPoints1, sideNormal, sideOffset2);
if (np < 2)
{
return;
}
// Now clipPoints2 contains the clipped points.
manifold.LocalPlaneNormal = localNormal;
manifold.LocalPoint = planePoint;
int pointCount = 0;
for (int i = 0; i < Settings.MaxManifoldPoints; ++i)
{
float separation = Vec2.Dot(frontNormal, clipPoints2[i].V) - frontOffset;
if (separation <= totalRadius)
{
ManifoldPoint cp = manifold.Points[pointCount];
cp.LocalPoint = Math.MulT(xf2, clipPoints2[i].V);
cp.Id = clipPoints2[i].Id;
cp.Id.Features.Flip = flip;
++pointCount;
}
}
manifold.PointCount = pointCount;
}
