Question

I have a list with ellipse objects with the parameters (Point Begin, Point End, Color c). Now I want to ensure when I click somewhere if I did hit an ellipse.

I also do this with rectangles which already works and looks something like this:

 case 3: // Rectanglefill
        return p.X >= Begin.X && p.X <= End.X && p.Y >= Begin.Y && p.Y <= End.Y;

In this method I only want to return the bool True if I have a hit and False if the mouse click didn’t hit something.

Now for the ellipse I already have this:

case 4: // Ellipsfill
/*  int radiusx = Math.Abs(End.X - Begin.X) / 2;
    int radiusy = Math.Abs(End.Y - Begin.Y) / 2;
    int midpointx = (Begin.X + End.X) / 2;
    int midpointy = (Begin.Y + End.Y) / 2;

return ((Math.Pow((p.X -midpointx) / radiusx, 2) + Math.Pow((p.Y - midpointy) / radiusy, 2)) > 1);

But this doesn’t work.

Answer 1

Your equation is Ok, you just have to put <1 (or <=1 if you want to include the points on the ellipse) instead of >1

case 4: // Ellipsfill
    double radiusx = Math.Abs((double)End.X - (double)Begin.X) / 2.0;
    double radiusy = Math.Abs((double)End.Y - (double)Begin.Y) / 2.0;
    double midpointx = ((double)Begin.X + (double)End.X) / 2.0;
    double midpointy = ((double)Begin.Y + (double)End.Y) / 2.0;

return ((Math.Pow((p.X -midpointx) / radiusx, 2) + Math.Pow((p.Y - midpointy) / radiusy, 2)) < 1.0);