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c#mathgeometrydistanceangle

Get the angle and the distance of point from center point

I'm trying to make a color picker and need some help, I need to get an angle of a point from a center point, starting from the top moving to the left, highest value being 1 and the lowest 0, as well as distance between the two points;

I skipped math in high school so I'm at a loss, any help would be appreciated

enter image description here

Solution

  • to find angle between center and the point in radians:

    Math.Atan2(point.y-center.y,point.x-center.x)

    normalize it:

    Math.Atan2(point.y-center.y,point.x-center.x)/Math.PI/2

    make it start from top:

    Math.Atan2(point.y-center.y,point.x-center.x)/Math.PI/2+0.25

    don't let it go below zero:

    (Math.Atan2(point.y-center.y,point.x-center.x)/Math.PI/2+0.25+1)%1

    invert it so it goes counterclockwise:

    1-(Math.Atan2(point.y-center.y,point.x-center.x)/Math.PI/2+0.25+1)%1

    you can rewrite it as:

    1-(Math.Atan2(point.y-center.y,point.x-center.x)/2/Math.PI+1.25)%1