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c#vectorxna

Getting a proper rotation from a vector direction

I currently have this code in my game:

Vector2 pixelpos = new Vector2(x, y);
Vector2 center = new Vector2(t.Width / 2, t.Height / 2);

Vector2 pixelposWorld = (pixelpos - center);

float rotation = (float)Math.Atan2(pixelposWorld.Y, pixelposWorld.X);
float rotationPercent = (MathHelper.ToDegrees(rotation) / 360);

My goal is to end up with rotationPercent to be a value between 0.0 and 1.0, 0 degrees being 0.0, 180 being 0.5 and 360 being 1.0.

Currently, rotationPercent only comes out as 1.0.

What can I do to fix this?

Solution

  • First of all, in your case, there is no need to convert it to degrees, since Math.aTan2 returns the angle in radians, just divide your rotation variable by (2*Pi).

    Secondly, check what you are doing at "t.Width / 2, t.Height / 2", as you haven't specified in your question what 't' is, make sure it's members are not integers.

    Now as far as your problem itself, there is not enough information supplied. Where does this contain your rotation information? Is the 'pixelpos' vector your world space position, or do you also use that as rotation?

    Brought back to a minimum, the following code works roughly like like you described?

    Vector2 pixelpos = new Vector2(0, 1);
float rotation = (float)(Math.Atan2(pixelpos.Y, pixelpos.X) / (2 * Math.PI));

    Which results 0.25, or 90 degrees.