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GlobeTrotter

Mon Dec 05, 2005 10:59 pm


Resulting Mirror Angles

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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?

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



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Tony

Tue Dec 06, 2005 9:39 am



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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 :wink: