/// <summary>
/// Checks if the grid intersects with the specified vector.
/// </summary>
/// <param name="vector">The vector.</param>
/// <param name="feature">The feature.</param>
/// <returns></returns>
public bool Intersect(ref Vector2 vector, out Feature feature)
{
//TODO: Keep and eye out for floating point accuracy issues here. Possibly some
//VERY intermittent errors exist?
if (AABB.Contains(ref vector))
{
int x = (int)Math.Floor((vector.X - AABB.Min.X) * GridCellSizeInv);
int y = (int)Math.Floor((vector.Y - AABB.Min.Y) * GridCellSizeInv);
float bottomLeft = Nodes[x, y];
float bottomRight = Nodes[x + 1, y];
float topLeft = Nodes[x, y + 1];
float topRight = Nodes[x + 1, y + 1];
if (bottomLeft <= 0 ||
bottomRight <= 0 ||
topLeft <= 0 ||
topRight <= 0)
{
float xPercent = (vector.X - (GridCellSize * x + AABB.Min.X)) * GridCellSizeInv;
float yPercent = (vector.Y - (GridCellSize * y + AABB.Min.Y)) * GridCellSizeInv;
float top = MathHelper.Lerp(topLeft, topRight, xPercent);
float bottom = MathHelper.Lerp(bottomLeft, bottomRight, xPercent);
float distance = MathHelper.Lerp(bottom, top, yPercent);
if (distance <= 0)
{
float right = MathHelper.Lerp(bottomRight, topRight, yPercent);
float left = MathHelper.Lerp(bottomLeft, topLeft, yPercent);
Vector2 normal = Vector2.Zero;
normal.X = right - left;
normal.Y = top - bottom;
//Uncommented by Daniel Pramel 08/17/08
//make sure the normal is not zero length.
if (normal.X != 0 || normal.Y != 0)
{
Vector2.Normalize(ref normal, out normal);
feature = new Feature(ref vector, ref normal, distance);
return true;
}
}
}
}
feature = new Feature();
return false;
}
public bool Equals(ref Feature other)
{
return ((Normal == other.Normal) && (Position == other.Position) && (Distance == other.Distance));
}