Angle to 2D Vector ?
Hi guys,
I'm trying to build an angle table that will store normalized 2D vectors.
When I do this:
rad=AngleToRed(ang); // just PI/180.0
v.x=sin(rad);
v.y=cos(rad);
...the zero angle faces North and subsequent angles go clockwise. Is that the way it's supposed to be ? It's confusing because when I use atan2() the zero angle is East (the positive x-axis) and they go counter-clockwise (which seems more natural ro me.)
Thanks.
I'm using VC++ 6 if that matters.
You'll have to swap cos and sin, and possibly negate the y-coord to use the screen's coordinate system instead of the standard mathematical one.
A vector of unitary lenght can be expressed by its angle a
with this definition
so you need a look up table to store only cosine and sine values.
v[a] = vector(cos(a), sin(a)) where a is the angle you rotate (1,0) CCW to get v[a]
with this definition
v[0] = vector(cos(0),sin(0)) = vector(1,0) = x when a increase v rotates CCW
so you need a look up table to store only cosine and sine values.
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