/// <summary>
/// Creates a chain.
/// </summary>
/// <param name="world">The world.</param>
/// <param name="start">The start.</param>
/// <param name="end">The end.</param>
/// <param name="linkWidth">The width.</param>
/// <param name="linkHeight">The height.</param>
/// <param name="fixStart">if set to <c>true</c> [fix start].</param>
/// <param name="fixEnd">if set to <c>true</c> [fix end].</param>
/// <param name="numberOfLinks">The number of links.</param>
/// <param name="linkDensity">The link density.</param>
/// <returns></returns>
public static Path CreateChain(PhysicsWorld world, Vector2 start, Vector2 end, float linkWidth, float linkHeight,
bool fixStart, bool fixEnd, int numberOfLinks, float linkDensity)
{
//Chain start / end
Path path = new Path();
path.Add(start);
path.Add(end);
//A single chainlink
PolygonShape shape = new PolygonShape(PolygonTools.CreateRectangle(linkWidth, linkHeight), linkDensity);
//Use PathManager to create all the chainlinks based on the chainlink created before.
List<PhysicsBody> chainLinks = PathManager.EvenlyDistributeShapesAlongPath(world, path, shape, BodyType.Dynamic,
numberOfLinks);
if (fixStart)
{
//Fix the first chainlink to the world
JointFactory.CreateFixedRevoluteJoint(world, chainLinks[0], new Vector2(0, -(linkHeight / 2)),
chainLinks[0].Position);
}
if (fixEnd)
{
//Fix the last chainlink to the world
JointFactory.CreateFixedRevoluteJoint(world, chainLinks[chainLinks.Count - 1],
new Vector2(0, (linkHeight / 2)),
chainLinks[chainLinks.Count - 1].Position);
}
//Attach all the chainlinks together with a revolute joint
PathManager.AttachBodiesWithRevoluteJoint(world, chainLinks, new Vector2(0, -linkHeight),
new Vector2(0, linkHeight),
false, false);
return (path);
}
//TODO: Comment better
/// <summary>
/// Moves the body on the path.
/// </summary>
/// <param name="path">The path.</param>
/// <param name="body">The body.</param>
/// <param name="time">The time.</param>
/// <param name="strength">The strength.</param>
/// <param name="timeStep">The time step.</param>
public static void MoveBodyOnPath(Path path, PhysicsBody body, float time, float strength, float timeStep)
{
Vector2 destination = path.GetPosition(time);
Vector2 positionDelta = body.Position - destination;
Vector2 velocity = (positionDelta / timeStep) * strength;
body.LinearVelocity = -velocity;
}
public static List<PhysicsBody> EvenlyDistributeShapesAlongPath(PhysicsWorld world, Path path, Shape shape, BodyType type,
int copies)
{
return EvenlyDistributeShapesAlongPath(world, path, shape, type, copies, null);
}
/// <summary>
/// Duplicates the given Body along the given path for approximatly the given copies.
/// </summary>
/// <param name="world">The world.</param>
/// <param name="path">The path.</param>
/// <param name="shape">The shape.</param>
/// <param name="type">The type.</param>
/// <param name="copies">The copies.</param>
/// <param name="userData">The user data.</param>
/// <returns></returns>
public static List<PhysicsBody> EvenlyDistributeShapesAlongPath(PhysicsWorld world, Path path, Shape shape, BodyType type,
int copies, object userData)
{
List<Shape> shapes = new List<Shape>(1);
shapes.Add(shape);
return EvenlyDistributeShapesAlongPath(world, path, shapes, type, copies, userData);
}
/// <summary>
/// Duplicates the given Body along the given path for approximatly the given copies.
/// </summary>
/// <param name="world">The world.</param>
/// <param name="path">The path.</param>
/// <param name="shapes">The shapes.</param>
/// <param name="type">The type.</param>
/// <param name="copies">The copies.</param>
/// <param name="userData"></param>
/// <returns></returns>
public static List<PhysicsBody> EvenlyDistributeShapesAlongPath(PhysicsWorld world, Path path, IEnumerable<Shape> shapes,
BodyType type, int copies, object userData)
{
List<Vector3> centers = path.SubdivideEvenly(copies);
List<PhysicsBody> bodyList = new List<PhysicsBody>();
for (int i = 0; i < centers.Count; i++)
{
PhysicsBody b = new PhysicsBody(world);
// copy the type from original body
b.BodyType = type;
b.Position = new Vector2(centers[i].X, centers[i].Y);
b.Rotation = centers[i].Z;
foreach (Shape shape in shapes)
{
b.CreateFixture(shape, userData);
}
bodyList.Add(b);
}
return bodyList;
}
/// <summary>
/// Convert a closed path into a polygon.
/// Convex decomposition is automatically performed.
/// </summary>
/// <param name="path">The path.</param>
/// <param name="body">The body.</param>
/// <param name="density">The density.</param>
/// <param name="subdivisions">The subdivisions.</param>
public static void ConvertPathToPolygon(Path path, PhysicsBody body, float density, int subdivisions)
{
if (!path.Closed)
throw new Exception("The path must be closed to convert to a polygon.");
List<Vector2> verts = path.GetVertices(subdivisions);
List<Vertices> decomposedVerts = EarclipDecomposer.ConvexPartition(new Vertices(verts));
//List<Vertices> decomposedVerts = BayazitDecomposer.ConvexPartition(new Vertices(verts));
foreach (Vertices item in decomposedVerts)
{
body.CreateFixture(new PolygonShape(item, density));
}
}
//Contributed by Matthew Bettcher
/// <summary>
/// Convert a path into a set of edges and attaches them to the specified body.
/// Note: use only for static edges.
/// </summary>
/// <param name="path">The path.</param>
/// <param name="body">The body.</param>
/// <param name="subdivisions">The subdivisions.</param>
public static void ConvertPathToEdges(Path path, PhysicsBody body, int subdivisions)
{
Vertices verts = path.GetVertices(subdivisions);
if (path.Closed)
{
LoopShape loop = new LoopShape(verts);
body.CreateFixture(loop);
}
else
{
for (int i = 1; i < verts.Count; i++)
{
body.CreateFixture(new EdgeShape(verts[i], verts[i - 1]));
}
}
}
