C# Collision Math Help
- by user36037
I am making my own collision detection in MonoGame. I have a PolyLine class That has a property to return the normal of that PolyLine instance. I have a ConvexPolySprite class that has a List LineSegments. I hav a CircleSprite class that has a Center Property and a Radius Property. I am using a static class for the collision detection method. I am testing it on a single line segment. Vector2(200,0) = Vector2(300, 200)
The problem is it detects the collision anywhere along the path of line out into space.
I cannot figure out why.
Thanks in advance;
public class PolyLine
{
//---------------------------------------------------------------------------------------------------------------------------
// Class Properties
/// <summary>
/// Property for the upper left-hand corner of the owner of this instance
/// </summary>
public Vector2 ParentPosition { get; set; }
/// <summary>
/// Relative start point of the line segment
/// </summary>
public Vector2 RelativeStartPoint { get; set; }
/// <summary>
/// Relative end point of the line segment
/// </summary>
public Vector2 RelativeEndPoint { get; set; }
/// <summary>
/// Property that gets the absolute position of the starting point of the line segment
/// </summary>
public Vector2 AbsoluteStartPoint
{
get
{
return ParentPosition + RelativeStartPoint;
}
}//end of AbsoluteStartPoint
/// <summary>
/// Gets the absolute position of the end point of the line segment
/// </summary>
public Vector2 AbsoluteEndPoint
{
get
{
return ParentPosition + RelativeEndPoint;
}
}//end of AbsoluteEndPoint
public Vector2 NormalizedLeftNormal
{
get
{
Vector2 P = AbsoluteEndPoint - AbsoluteStartPoint;
P.Normalize();
float x = P.X;
float y = P.Y;
return new Vector2(-y, x);
}
}//end of NormalizedLeftNormal
//---------------------------------------------------------------------------------------------------------------------------
// Class Constructors
/// <summary>
/// Sole ctor
/// </summary>
/// <param name="parentPosition"></param>
/// <param name="relStart"></param>
/// <param name="relEnd"></param>
public PolyLine(Vector2 parentPosition, Vector2 relStart, Vector2 relEnd)
{
ParentPosition = parentPosition;
RelativeEndPoint = relEnd;
RelativeStartPoint = relStart;
}//end of ctor
}//end of PolyLine class
public static bool Collided(CircleSprite circle, ConvexPolygonSprite poly)
{
var distance = Vector2.Dot(circle.Position -
poly.LineSegments[0].AbsoluteEndPoint, poly.LineSegments[0].NormalizedLeftNormal) + circle.Radius;
if (distance <= 0)
{
return false;
}
else
{
return true;
}
}//end of collided
