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Asked: 2026-05-16T09:11:42+00:00

i do have 2 points on a 2d plane. one has already an vector

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i do have 2 points on a 2d plane. one has already an vector that does determine in which direction it will move.

now i want to add a vector to this existing vector. so he accelerates in the direction of the other point.

to be a bit more clear, it is about 2 asteroids flying in space (only 2d) and gravitation should move them a bit closer to each other.

what i did build till now is this:

c = body.position - body2.position;
dist = c.Length();

acc = (body.masse * body2.masse) / (dist * dist);

xDist = body2.position.X - body.position.X;
yDist = body2.position.Y - body.position.Y;

direction = MathHelper.ToDegrees((float)(Math.Atan2((double)yDist, (double)xDist)));

body.velocity.Y = body.velocity.Y + (float)(Math.Sin(direction) * acc);
body.velocity.X = body.velocity.X + (float)(Math.Cos(direction) * acc);

in the moment the direction calculated is completly off. surely i am making just a stupid mistake, but i have no idea.

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1 Answer

  1. Editorial Team

    You need to pass your direction angle in in radians to Math.sin and Math.Cos (rather then in degree as you do in your smaple code).

    see also:
    http://msdn.microsoft.com/en-us/library/system.math.sin.aspx

    The angle, a, must be in radians. Multiply by Math.PI/180 to convert degrees to radians.

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