/// <summary>
/// Calculates if there is a separating axis between two polygon colliders
/// </summary>
/// <param name="normal"></param>
/// <param name="col1"></param>
/// <param name="col2"></param>
/// <returns></returns>
static bool IsSeparatingAxis(Vector2 normal, PolygonCollider col1, PolygonCollider col2)
{
double min1 = double.PositiveInfinity;
double max1 = double.NegativeInfinity;
double min2 = double.PositiveInfinity;
double max2 = double.NegativeInfinity;
foreach (Vector2 point in col1.Vertices)
{
double projection = Vector2.Dot(point, normal);
min1 = Math.Min(min1, projection);
max1 = Math.Max(max1, projection);
}
foreach (Vector2 point in col2.Vertices)
{
double projection = Vector2.Dot(point, normal);
min2 = Math.Min(min2, projection);
max2 = Math.Max(max2, projection);
}
if (max1 >= min2 && max2 >= min1)
{
return(false);
}
return(true);
}
/// <summary>
/// Checks to see if a polygon and a circle are colliding
/// </summary>
/// <param name="col1"></param>
/// <param name="col2"></param>
/// <returns></returns>
public static bool IsCollidingPolygonCircle(PolygonCollider col1, CircleCollider col2)
{
List <Vector2> edges = new List <Vector2>();
edges = CalculateEdges(col1.Vertices);
for (int i = 0; i < edges.Count; i++)
{
if (Vector2.Distance(col2.centre, edges[i]) < col2.radius)
{
return(true);
}
}
return(false);
}
/// <summary>
/// Checks to see if 2 polygons are colliding
/// </summary>
/// <param name="col1"></param>
/// <param name="col2"></param>
/// <returns></returns>
public static bool IsCollidingPolygons(PolygonCollider col1, PolygonCollider col2)
{
List <Vector2> edges = CalculateEdges(col1.Vertices);
edges.AddRange(CalculateEdges(col2.Vertices));
List <Vector2> normals = new List <Vector2>();
foreach (Vector2 edge in edges)
{
normals.Add(CalculateNormal(edge));
}
foreach (Vector2 normal in normals)
{
bool isSeparated = IsSeparatingAxis(normal, col1, col2);
if (!isSeparated)
{
return(false);
}
}
return(true);
}
