public static float? FindCollision(Vector2 position, Vector2 movement, Line2 line)
{
if (Vector2.Dot(movement, line.Normal()) >= 0)
return null;
return SegmentsIntersection(position, position + movement, line.Start, line.End);
}
public static Collision2? FindCollision(Rectangle2 rectangle, Vector2 movement, Line2 line)
{
if (Vector2.Dot(movement, line.Normal()) >= 0)
return null;
var h = InFrontOf(rectangle.Center, line);
var j = InFrontOf(rectangle.Center + movement, line);
if (!h && !j)
return null;
var f1 = LineSegmentIntersection(line.Start, line.End, rectangle.TopLeft, rectangle.TopLeft + movement);
var f2 = LineSegmentIntersection(line.Start, line.End, rectangle.TopRight, rectangle.TopRight + movement);
var f3 = LineSegmentIntersection(line.Start, line.End, rectangle.BottomLeft, rectangle.BottomLeft + movement);
var f4 = LineSegmentIntersection(line.Start, line.End, rectangle.BottomRight, rectangle.BottomRight + movement);
if (!f1.HasValue && !f2.HasValue && !f3.HasValue && !f4.HasValue)
return null;
f1 = LinesIntersection(line.Start, line.End, rectangle.TopLeft, rectangle.TopLeft + movement);
f2 = LinesIntersection(line.Start, line.End, rectangle.TopRight, rectangle.TopRight + movement);
f3 = LinesIntersection(line.Start, line.End, rectangle.BottomLeft, rectangle.BottomLeft + movement);
f4 = LinesIntersection(line.Start, line.End, rectangle.BottomRight, rectangle.BottomRight + movement);
List<float> fs = new List<float>();
if ((Vector2.Dot(rectangle.Top.Normal(), line.Normal()) <= 0) && (Vector2.Dot(rectangle.Left.Normal(), line.Normal()) <= 0))
fs.Add(f1.Value);
if ((Vector2.Dot(rectangle.Top.Normal(), line.Normal()) <= 0) && (Vector2.Dot(rectangle.Right.Normal(), line.Normal()) <= 0))
fs.Add(f2.Value);
if ((Vector2.Dot(rectangle.Bottom.Normal(), line.Normal()) <= 0) && (Vector2.Dot(rectangle.Left.Normal(), line.Normal()) <= 0))
fs.Add(f3.Value);
if ((Vector2.Dot(rectangle.Bottom.Normal(), line.Normal()) <= 0) && (Vector2.Dot(rectangle.Right.Normal(), line.Normal()) <= 0))
fs.Add(f4.Value);
var array = fs.OrderBy(x => x);
if (!array.Any())
return null;
if (array.Last() < 0)
return null;
if (array.First() > 1)
return null;
Collision2 collision = new Collision2();
collision.Value = MinLinesIntersection(rectangle, movement, line);
collision.Line = line;
return collision;
}
public Rectangle2(float x1, float y1, float x2, float y2)
{
TopLeft = new Vector2(x1, y1);
TopRight = new Vector2(x2, y1);
BottomLeft = new Vector2(x1, y2);
BottomRight = new Vector2(x2, y2);
Top = new Line2(TopLeft, TopRight);
Left = new Line2(BottomLeft, TopLeft);
Right = new Line2(TopRight, BottomRight);
Bottom = new Line2(BottomRight, BottomLeft);
Center = new Vector2((x1 + x2) / 2, (y1 + y2) / 2);
}
public static Vector2? FindCollision(Rectangle2 rectangle, Line2 line)
{
var f1 = SegmentsIntersection(rectangle.Top, line);
var f2 = SegmentsIntersection(rectangle.Left, line);
var f3 = SegmentsIntersection(rectangle.Right, line);
var f4 = SegmentsIntersection(rectangle.Bottom, line);
if (!f1.HasValue && !f2.HasValue && !f3.HasValue && !f4.HasValue)
return null;
var d = Math.Min(Math.Min(Distance(rectangle.TopLeft, line), Distance(rectangle.TopRight, line)), Math.Min(Distance(rectangle.BottomLeft, line), Distance(rectangle.BottomRight, line)));
return -line.Normal() * d * 1.01f;
}
public static float Distance(Vector2 point, Line2 line)
{
var p2 = line.Start + line.Direction();
return ((line.Start.X - point.X) * (p2.Y - point.Y) - (line.Start.Y - point.Y) * (p2.X - point.X));
}
private static float MinLinesIntersection(Rectangle2 rectangle, Vector2 movement, Line2 line)
{
return Math.Min(
Math.Min(
LinesIntersection(rectangle.TopLeft, rectangle.TopLeft + movement, line.Start, line.End) ?? 1f,
LinesIntersection(rectangle.TopRight, rectangle.TopRight + movement, line.Start, line.End) ?? 1f),
Math.Min(
LinesIntersection(rectangle.BottomLeft, rectangle.BottomLeft + movement, line.Start, line.End) ?? 1f,
LinesIntersection(rectangle.BottomRight, rectangle.BottomRight + movement, line.Start, line.End) ?? 1f));
}
private static float? SegmentsIntersection(Line2 l1, Line2 l2)
{
return SegmentsIntersection(l1.Start, l1.End, l2.Start, l2.End);
}
public static bool Collides(Rectangle2 rectangle, Vector2 movement, Line2 line)
{
return FindCollision(rectangle, movement, line).HasValue;
}
public static bool InFrontOf(Vector2 point, Line2 line)
{
return (line.Start.X - point.X) * (line.End.Y - point.Y) - (line.Start.Y - point.Y) * (line.End.X - point.X) >= 0;
}
public static Vector2 FindMaxMovement(Rectangle2 rectangle, Vector2 movement, Line2 line)
{
var collision = FindCollision(rectangle, movement, line);
if (collision.HasValue)
return movement * collision.Value.Value;
else
return movement;
}
public static Vector2 FindMaxMovement(Vector2 position, Vector2 movement, Line2 line)
{
float? collision = FindCollision(position, movement, line);
if (collision.HasValue)
return movement * collision.Value;
else
return movement;
}
public static bool Collides(Vector2 position, Vector2 movement, Line2 line)
{
return FindCollision(position, movement, line).HasValue;
}
