public static Polygon FromRectangle(Rectangle source)
{
Polygon convertedRectangle = new Polygon();
convertedRectangle.Vertices.Add(new Vector2(source.X, source.Y));
convertedRectangle.Vertices.Add(new Vector2(source.X + source.Width, source.Y));
convertedRectangle.Vertices.Add(new Vector2(source.X + source.Width, source.Y + source.Height));
convertedRectangle.Vertices.Add(new Vector2(source.X, source.Y + source.Height));
return convertedRectangle;
}
public static Polygon PolygonCollisionData(string objectName)
{
Polygon collisionShape = new Polygon();
XElement dataElement = GetCollisionDataElement(objectName, ColliderShape.PolygonCollider);
if ((dataElement != null) && (dataElement.Elements("vertex").Count() > 0))
{
foreach (XElement vertex in dataElement.Elements("vertex"))
{
collisionShape.Vertices.Add(new Vector2(Utility.ToFloat(vertex.Attribute("x").Value), Utility.ToFloat(vertex.Attribute("y").Value)));
}
}
return collisionShape;
}
public static List<Polygon> CompoundPolygonCollisionData(string objectName)
{
List<Polygon> collisionShapes = new List<Polygon>();
XElement dataElement = GetCollisionDataElement(objectName, ColliderShape.CompoundPolygonCollider);
if ((dataElement != null) && (dataElement.Elements("polygon").Count() > 0))
{
foreach (XElement polygon in dataElement.Elements("polygon"))
{
if (polygon.Elements("vertex").Count() > 0)
{
Polygon component = new Polygon();
foreach (XElement vertex in polygon.Elements("vertex"))
{
component.Vertices.Add(new Vector2(Utility.ToFloat(vertex.Attribute("x").Value), Utility.ToFloat(vertex.Attribute("y").Value)));
}
collisionShapes.Add(component);
}
}
}
return collisionShapes;
}
public bool Intersects(Polygon target)
{
if ((this.Vertices.Count > 1) && (target.Vertices.Count > 1))
{
bool hasIntersected = true;
List<Vector2> edges = new List<Vector2>();
edges.AddRange(GetEdges(this));
edges.AddRange(GetEdges(target));
for (int i = 0; i < edges.Count; i++)
{
Vector2 axis = new Vector2(-edges[i].Y, edges[i].X);
axis.Normalize();
Range subjectProjection = ProjectOntoAxis(axis, this);
Range targetProjection = ProjectOntoAxis(axis, target);
if (IntervalDistance(subjectProjection, targetProjection) > 0) { hasIntersected = false; break; }
}
return hasIntersected;
}
return false;
}
public Polygon Clone()
{
Polygon copy = new Polygon();
for (int i = 0; i < Vertices.Count; i++) { copy.Vertices.Add(new Vector2(Vertices[i].X, Vertices[i].Y)); }
return copy;
}
private Range ProjectOntoAxis(Vector2 axis, Polygon toProject)
{
Range projection = new Range(Vector2.Dot(axis, toProject.Vertices[0]));
for (int i = 1; i < toProject.Vertices.Count; i++)
{
projection.Expand(Vector2.Dot(toProject.Vertices[i], axis));
}
return projection;
}
private List<Vector2> GetEdges(Polygon edgeSource)
{
List<Vector2> edges = new List<Vector2>();
for (int i = 0; i < edgeSource.Vertices.Count; i++)
{
edges.Add(edgeSource.Vertices[(i + 1) % edgeSource.Vertices.Count] - edgeSource.Vertices[i]);
}
return edges;
}
public Vector2 Separate(Polygon target, Vector2 velocity)
{
if ((this.Vertices.Count > 1) && (target.Vertices.Count > 1))
{
bool hasIntersected = true;
bool willIntersect = true;
Vector2 separationAxis = Vector2.Zero;
float separationInterval = float.PositiveInfinity;
List<Vector2> edges = new List<Vector2>();
edges.AddRange(GetEdges(this));
edges.AddRange(GetEdges(target));
for (int i = 0; i < edges.Count; i++)
{
Vector2 axis = new Vector2(-edges[i].Y, edges[i].X);
axis.Normalize();
Range subjectProjection = ProjectOntoAxis(axis, this);
Range targetProjection = ProjectOntoAxis(axis, target);
if (IntervalDistance(subjectProjection, targetProjection) > 0) { hasIntersected = false; }
float velocityProjection = Vector2.Dot(axis, velocity);
if (velocityProjection < 0) { subjectProjection.Minimum += velocityProjection; }
else { subjectProjection.Maximum += velocityProjection; }
float intervalDistance = IntervalDistance(subjectProjection, targetProjection);
if (intervalDistance > 0) { willIntersect = false; }
if ((!hasIntersected) && (!willIntersect)) { break; }
if ((intervalDistance <= 0.0f) && (Math.Abs(intervalDistance) < separationInterval))
{
separationInterval = Math.Min(Math.Abs(intervalDistance), separationInterval);
separationAxis = axis;
if (Vector2.Dot(this.Center - target.Center, separationAxis) < 0.0f) { separationAxis = -separationAxis; }
}
}
if (willIntersect) { return separationAxis * separationInterval; }
}
return Vector2.Zero;
}
