Resulting Mirror Angles

[GlobeTrotter]

So, in my program, I have two vector-like things. Mainly, I'm just dealing with directions though. Basically, I have the original direction, and I have the direction of the "mirror" (The mirror really has two directions, 180 from each other.) How do I get from these two to the final direction. All directions are relative to the positive x axis.

I tried coming up with some examples, so that I could find the pattern but I can't see it.

The left column represents the original, the middle the mirror and the last column represents the resultant. How do I get from column 1 and 2 to 3?

code:

0   |45 /225 |90 270 |45 /225 |180 180 |135/315 |90 270 |135/315 |0 90  |45 /225 |0  180 |45 /225 |270 0   |135/315 |270 90  |135/315 |180 45  |90 /270 |135 315 |90 /270 |225 45  |180/0   |315 135 |180/0   |225 135 |90 /270 |315 225 |90 /270 |45 315 |180/0   |45 225 |180/0   |135 0   |90 /270 |180 90  |0  /180 |270 180 |90 /270 |0  270 |0  /180 |90

[Tony]

well with mirrors, the angle of incidence is equal to the angle of reflection.

I don't understand what you mean by the 2nd angle..

Though your mirror angle (column 2) * 2 is the difference between original angle (column 1) and the result (column 3)

0 |45 |90 => 45 * 2 = 90 - 0
270 |45 |180 => 45 * 2 = 270 - 180
180 |135 |90 => 135 * 2 = 90 - 180 ( - 90 is 270 equivalent)
270 |135 |0 => 135 * 2 = 270 - 0

You just have to figure out which direction (CW or CCW) you're going